research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 72| Part 2| February 2016| Pages 124-127

Crystal structure of an organic–inorganic supra­molecular salt based on a 4,4′-methyl­enebis(3,5-di­methyl-1H-pyrazol-2-ium) cation and a β-octa­molybdate anion

CROSSMARK_Color_square_no_text.svg

aDepartment of Chemistry, CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal
*Correspondence e-mail: filipe.paz@ua.pt

Edited by M. Gdaniec, Adam Mickiewicz University, Poland (Received 1 December 2015; accepted 21 December 2015; online 6 January 2016)

The asymmetric unit of the title compound, bis­[4,4′-methyl­enebis(3,5-dimethyl-1H-pyrazol-2-ium)] β-octa­molybdate, (C11H18N4)2[Mo8O26] or (H4mbdpz)2[Mo8O26], is composed of an H4mbdpz2+ cation and half of the β-octa­molybdate anion which is completed by inversion symmetry. The organic mol­ecular units are engaged in a series of N—H⋯O hydrogen bonds with neighbouring anions, with N⋯O distances and N—H⋯O angles in the ranges 2.730 (2)–2.941 (2) Å and 122–166°, respectively. These inter­actions lead to the formation of a supra­molecular two-dimensional network parallel to the (010) plane.

1. Chemical context

4,4′-Methyl­enebis(3,5-di­methyl­pyrazole) (H2mbdpz) is a flexible organic mol­ecule which has been extensively used in the last few years by various research groups to design coordin­ation-based and organic solids. While, on the one hand, the central methyl­ene moiety confers some conformational flexibility to the entire mol­ecular unit, on the other the two peripheral pyrazole rings permit not only the coordination to various types of metal atoms but also the involvement of these moieties in complex networks based on hydrogen bonds. It is, thus, not surprising to encounter a rich chemistry and structural diversity associated with this mol­ecule. A search in the literature and in the Cambridge Structural Database (CSD; Allen, 2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]; Groom & Allen, 2014[Groom, C. R. & Allen, F. H. (2014). Angew. Chem. Int. Ed. 53, 662-671.]) reveals, for example, that H2mbdpz has been used as an effective bending spacer to construct a large number of metal-organic frameworks (MOFs) or coordination polymers with various remarkable topologies based on a rather diverse range of d-block metals (Goswami et al., 2013[Goswami, A., Bala, S., Pachfule, P. & Mondal, R. (2013). Cryst. Growth Des. 13, 5487-5498.]; Mondal et al., 2008[Mondal, R., Bhunia, M. K. & Dhara, K. (2008). CrystEngComm, 10, 1167-1174.]; Timokhin et al., 2015[Timokhin, I., Pettinari, C., Marchetti, F., Pettinari, R., Condello, F., Galli, S., Alegria, E. C. B. A., Martins, L. M. D. R. S. & Pombeiro, A. J. L. (2015). Cryst. Growth Des. 15, 2303-2317.]). H2mbdpz and its derivatives have also been used to prepare a range of supra­molecular networks based on either neutral organic mol­ecules or in the formation of salts with a wide range of anions (since, typically, the two pyrazole moieties appear protonated) (Basu et al., 2009[Basu, T., Sparkes, H. A. & Mondal, R. (2009). Cryst. Growth Des. 9, 5164-5175.]; Basu & Mondal, 2010[Basu, T. & Mondal, R. (2010). CrystEngComm, 12, 366-369.]; Hazra et al., 2010[Hazra, D. K., Chatterjee, R., Ali, M. & Mukherjee, M. (2010). Acta Cryst. C66, o190-o193.]). Most of these structural reports available in the literature either use H2mbdpz purchased from commercial sources or the authors prepare the mol­ecule using published procedures. For the latter case, the standard method dates back to that reported by Trofimenko (1970[Trofimenko, S. (1970). J. Am. Chem. Soc. 92, 5118-5126.]), but more recent and alternative approaches are also employed to prepare the intended mol­ecule (Kruger et al., 2000[Kruger, P. E., Moubaraki, B., Fallon, G. D. & Murray, K. S. (2000). J. Chem. Soc. Dalton Trans. pp. 713-718.]).

[Scheme 1]

In this communication, we report the unexpected isolation of a new supra­molecular salt in which 4,4′-methyl­enebis(3,5-dimethyl-1H-pyrazol-2-ium) (H4mbdpz2+) is prepared in situ, inside the autoclave reaction vessel, starting from 3,5-di­methyl­pyrazole in a reaction catalysed by MoVI ions in the presence of hydrogen peroxide. To balance the cationic charge of the protonated H4mbdpz2+ moiety, the crystal contains the well-known β-octa­molybdate anion. It is remarkable to note that, despite the intensive research on supra­molecular structures based on H2mbdpz, only a couple of very recent reports contain polyoxidometalate-type anions. Indeed, Tian et al. (2014[Tian, A., Yang, Y., Ying, J., Li, N., Lin, X.-L., Zhang, J.-W. & Wang, X.-L. (2014). Dalton Trans. 43, 8405-8413.], 2015[Tian, A., Ning, Y., Yang, Y., Hou, X., Ying, J., Liu, G., Zhang, J. & Wang, X. (2015). Dalton Trans. 44, 16486-16493.]) described various Ag+-based MOFs (or coord­in­ation polymers) in which MoVI or WVI Keggin and/or Wells–Dawson polyoxidometalates balance the positive charge of the cationic architectures.

2. Structural commentary

The asymmetric unit of the title compound is composed of a 4,4′-methyl­enebis(3,5-dimethyl-1H-pyrazol-2-ium) cation (H4mbdpz2+), and one half of the β-octa­molybdate anion, β-[Mo8O26]4− (Fig. 1[link]).

[Figure 1]
Figure 1
Schematic representation of the mol­ecular entities composing the asymmetric unit of the title compound. The β-octa­molybdate anion has been completed by inversion symmetry for the sake of chemical accuracy. All non-hydrogen atoms are represented as displacement ellipsoids drawn at the 60% probability level and hydrogen atoms as small spheres with arbitrary radii. Non-hydrogen atoms belonging to the asymmetric unit have been labelled for clarity. Dashed violet lines indicate N—H⋯O hydrogen-bonding inter­actions (see Table 1[link] for geometrical details).

The H4mbdpz2+ cation exhibits the typical structural features found in related compounds. The considerable steric hindrance imposed by the two peripheral 3,5-dimethyl-1H-pyrazol-2-ium moieties induces a tetra­hedral angle of the bridging methyl­ene group of 113.56 (17)°, which is very close to the median value found in similar structures (from the CSD: median of 114.7° from 109 hits with range of 111.0–120.0°). Conversely, the dihedral angle subtended by these two peripheral moieties is significantly more dependent on the crystal structure itself, with the literature values (from 109 hits in the CSD) ranging from as low as 55.1° (a chiral coordination polymer with Cu2+ described by Lin et al., 2014[Lin, L., Yu, R., Wu, X.-Y., Yang, W.-B., Zhang, J., Guo, X.-G., Lin, Z.-J. & Lu, C.-Z. (2014). Inorg. Chem. 53, 4794-4796.]) to 90.0° (an Ni2+ layered network described by Goswami et al., 2013[Goswami, A., Bala, S., Pachfule, P. & Mondal, R. (2013). Cryst. Growth Des. 13, 5487-5498.]). Nevertheless, the inter­planar angle registered for the title compound, 77.85 (15)°, agrees well with the median value of all structures deposited in the CSD (81.1°).

The mol­ecular geometrical parameters for the β-octa­molybdate anion are typical, exhibiting the usual four families of Mo—O bonds: Mo—Ot to terminal oxido groups [bond lengths in the 1.6883 (14)–1.7077 (15) Å range]; Mo—Ob to μ2-bridging oxido groups [bond lengths in the 1.7506 (15)–2.2304 (15) Å range]; Mo—Oc to μ3-bridging oxido groups [bond lengths in the 1.9431 (14)–2.4033 (14) Å range]; Mo—Oc to μ5-bridging oxido groups [bond lengths in the 2.1441 (14)–2.3577 (14) Å range]. The four crystallographically independent MoVI metal atoms are hexa­coordinated in a typical {MoO6} fashion resembling highly distorted octa­hedra: while the trans inter­nal O—Mo—O octa­hedral angles are found in the 142.75 (6)–174.00 (6)° range, the cis angles refine instead in the 71.04 (5)–105.61 (8)° inter­val. This wide dispersion for the inter­nal octa­hedral angles is a notable and well-known consequence of the marked trans effect created by the terminal oxido groups, which displace the metal atoms from the center of the octa­hedra. The inter­metallic MoVI distances within the β-octa­molybdate anion range from 3.1875 (5) Å (for the Mo1⋯Mo2 distance) to 3.5810 (5) Å [for the Mo1⋯Mo1i distance across the inversion center of the anion; symmetry operation: (i) −x, 1 − y, 1 − z].

3. Supra­molecular features

The crystal packing of the title compound is essentially mediated by the presence of various N—H⋯O hydrogen-bonding inter­actions between the H4mbdpz2+ cation (which acts as the donor – D) and the β-octa­molybdate anion (the acceptor – A) (Fig. 2[link]a). As depicted in Table 1[link], the DA distances are relatively short, ranging between 2.730 (2) and 2.977 (2) Å. It is noteworthy that the latter is associated with the N2—H2 group which is engaged in a bifurcated inter­action with the neighbouring β-octa­molybdate anion (as depicted in Fig. 2[link]a), hence leading to an average increase of the inter­atomic distances.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1⋯O10i 0.94 2.34 2.941 (2) 122
N2—H2⋯O5i 0.94 2.05 2.852 (2) 143
N2—H2⋯O8i 0.94 2.31 2.977 (2) 127
N3—H3⋯O7ii 0.94 1.97 2.759 (2) 141
N4—H4⋯O2 0.94 1.81 2.730 (2) 166
Symmetry codes: (i) -x, -y+1, -z; (ii) -x, -y+1, -z+1.
[Figure 2]
Figure 2
Schematic representation of the type and role of N—H⋯O hydrogen bond inter­actions present in the crystal structure of the title compound: (a) description of all inter­actions which connect the crystallographically independent 4,4′-methyl­enebis(3,5-dimethyl-1H-pyrazol-2-ium) cation to two neighbouring β-octa­molybdate anions; (b) portion of the two-dimensional supra­molecular layer placed in the ac plane of the unit cell formed by the connection between the mol­ecular units present in the title compound. For geometrical details of the represented hydrogen bonds (as violet dashed lines) see Table 1[link]. Symmetry operations used to generate equivalent atoms: (i) −x, 1 − y, 1 − z; (ii) −x, 1 − y, −z.

Besides these inter­actions, the crystal structure is also rich in weak hydrogen bonds of the C—H⋯O type (not shown) involving mainly the terminal methyl groups of the organic mol­ecule. The various C—H⋯O inter­actions present in the crystal structure are rather weak, with C⋯O distances ranging from 3.203 (3) to 3.457 (3) Å, with <(CHO) inter­action angles in the 123–168° inter­val.

The aforementioned hydrogen bonds between cations and anions lead to the formation of a two-dimensional supra­molecular network parallel to the (010) plane (Fig. 2[link]b). Individual supra­molecular entities close-pack perpendicular to (010) to produce the crystal structure of the title compound (Fig. 3[link]).

[Figure 3]
Figure 3
Ball-and-stick schematic representation of the crystal packing of the title compound viewed in perspective along the [100] direction. The figure emphasizes, on the one hand, how the inorganic component of the crystal structure is fully embedded into an organic matrix based on the 4,4′-methyl­enebis(3,5-dimethyl-1H-pyrazol-2-ium) cation. On the other it shows how supra­molecular hydrogen-bonded layers pack closely perpendicular to (010).

4. Synthesis and crystallization

MoO3 (Analar, BDH Chemicals, 99.5%), 3,5-di­methyl­pyrazole (Aldrich, 99%) and H2O2 (50% in water, Sigma–Aldrich) were obtained from commercial sources and used as received. FT–IR spectra were collected using KBr pellets (Sigma–Aldrich, 99%, FT–IR grade) on a Mattson-7000 infrared spectrophotometer.

A mixture of MoO3 (0.349 g, 2.42 mmol), 3,5-di­methyl­pyrazole (0.116 g, 1.21 mmol), water (23 mL) and H2O2 (2 mL) was heated in a Teflon-lined stainless steel digestion bomb at 433 K for 26 h, at 373 K for 25 h, and finally slowly cooled down to ambient temperature over a period of 13 h. Single crystals of the title compound were obtained inside the Teflon vessel along with a yellow aqueous mother liquor (pH = 6) and a blueish solid, which was confirmed by powder X-ray diffraction studies to be residues of unreacted MoO3.

FT–IR (cm−1): ν~ = 3218 (vs); 3127 (s); 3008 (s); 2859 (s); 2719 (s); 1606 (m); 1579 (s); 1535 (m); 1517 (m); 1438 (s); 1394 (m); 1365 (m); 1253 (m); 1184 (m); 1153 (w); 1070 (w); 1047 (w); 948 (vs); 925 (s); 908 (vs); 844 (s); 721 (s); 705 (s); 671 (s); 655 (s); 543 (s); 522 (m); 480 (w); 458 (w); 445 (w); 414 (m); 401 (m); 360 (m).

5. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. Hydrogen atoms bound to carbon were placed at idealized positions with C—H = 0.99 and 0.98 Å for the –CH2– and methyl groups, respectively, and included in the final structural model in the riding-motion approximation with isotropic displacement parameters fixed at 1.2 or 1.5Ueq, respectively, of the carbon atom to which they are attached.

Table 2
Experimental details

Crystal data
Chemical formula (C11H18N4)[Mo8O26]
Mr 1596.11
Crystal system, space group Triclinic, P[\overline{1}]
Temperature (K) 180
a, b, c (Å) 8.6394 (10), 12.0694 (13), 12.2249 (14)
α, β, γ (°) 113.343 (3), 110.629 (4), 96.540 (4)
V3) 1046.6 (2)
Z 1
Radiation type Mo Kα
μ (mm−1) 2.42
Crystal size (mm) 0.28 × 0.18 × 0.15
 
Data collection
Diffractometer Bruker D8 QUEST
Absorption correction Multi-scan (SADABS; Bruker, 2001[Bruker (2001). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.595, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 58761, 5605, 4669
Rint 0.032
(sin θ/λ)max−1) 0.685
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.021, 0.045, 1.05
No. of reflections 5605
No. of parameters 305
No. of restraints 4
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.45, −0.38
Computer programs: APEX2 (Bruker, 2012[Bruker (2012). SAINT and APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.]) and SAINT (Bruker, 2012[Bruker (2012). SAINT and APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2014 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), DIAMOND (Brandenburg, 1999[Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.]).

Hydrogen atoms associated with nitro­gen atoms were directly located from difference Fourier maps and included in the model with the N—H distances restrained to 0.95 (1) Å in order to ensure a chemically reasonable environment for these moieties. These hydrogen atoms were modelled with isotropic thermal displacement parameters fixed at 1.5Ueq(N).

Supporting information


Chemical context top

4,4'-Methyl­enebis(3,5-di­methyl­pyrazole) (H2mbdpz) is a flexible organic molecule which has been extensively used in the last few years by various research groups to design coordination-based and organic solids. While, on the one hand, the central methyl­ene moiety confers some conformational flexibility to the entire molecular unit, on the other the two peripheral pyrazole rings permit not only the coordination to various types of metal atoms but also the involvement of these moieties in complex networks based on hydrogen bonds. It is, thus, not surprising to encounter a rich chemistry and structural diversity associated with this molecule. A search in the literature and in the Cambridge Structural Database (CSD; Allen, 2002; Groom & Allen, 2014) reveals, for example, that H2mbdpz has been used as an effective bending spacer to construct a large number of metal-organic frameworks (MOFs) or coordination polymers with various remarkable topologies based on a rather diverse range of d-block metals (Goswami et al., 2013; Mondal et al., 2008; Timokhin et al., 2015). H2mbdpz and its derivatives have also been used to prepare a range of supra­molecular networks based on either neutral organic molecules or in the formation of salts with a wide range of anions (since, typically, the two pyrazole moieties appear protonated) (Basu et al., 2009; Basu & Mondal, 2010; Hazra et al., 2010). Most of these structural reports available in the literature either use H2mbdpz purchased from commercial sources or the authors prepare the molecule using published procedures. For the latter case, the standard method dates back to that reported by Trofimenko (1970), but more recent and alternative approaches are also employed to prepare the intended molecule (Kruger et al., 2000).

In this communication, we report the unexpected isolation of a new supra­molecular salt in which 4,4'-methyl­enebis(3,5-di­methyl-1H-pyrazol-2-ium) (H4mbdpz2+) is prepared in situ, inside the autoclave reaction vessel, starting from 3,5-di­methyl­pyrazole in a reaction catalysed by MoVI ions in the presence of hydrogen peroxide. To balance the cationic charge of the protonated H4mbdpz2+ moiety, the crystal contains the well known β-o­cta­molybdate anion. It is remarkable to note that, despite the intensive research on supra­molecular structures based on H2mbdpz, only a couple of very recent reports contain polyoxidometalate-type anions. Indeed, Tian et al. (2014, 2015) described various Ag+-based MOFs (or coordination polymers) in which MoVI or WVI Keggin and/or Wells–Dawson polyoxidometalates balance the positive charge of the cationic architectures.

Structural commentary top

The asymmetric unit of the title compound is composed of a 4,4'-methyl­enebis(3,5-di­methyl-1H-pyrazol-2-ium) cation (H4mbdpz2+), and one half of the β-o­cta­molybdate anion, β-[Mo8O26]4− (Fig. 1).

The H4mbdpz2+ cation exhibits the typical structural features found in related compounds. The considerable steric hindrance imposed by the two peripheral 3,5-di­methyl-1H-pyrazol-2-ium moieties induces a tetra­hedral angle of the bridging methyl­ene group of 113.56 (17)°, which is very close to the median value found in similar structures (from the CSD: median of 114.7° from 109 hits with range of 111.0–120.0°). Conversely, the dihedral angle subtended by these two peripheral moieties is significantly more dependent on the crystal structure itself, with the literature values (from 109 hits in the CSD) ranging from as low as 55.1° (a chiral coordination polymer with Cu2+ described by Lin et al., 2014) to 90.0° (an Ni2+ layered network described by Goswami et al., 2013). Nevertheless, the inter­planar angle registered for the title compound, 77.85 (15)°, agrees well with the median value of all structures deposited in the CSD (81.1°).

The molecular geometrical parameters for the β-o­cta­molybdate anion are typical, exhibiting the usual four families of Mo—O bonds: Mo—Ot to terminal oxido groups [bond lengths in the 1.6883 (14)–1.7077 (15) Å range]; Mo—Ob to µ2-bridging oxido groups [bond lengths in the 1.7506 (15)–2.2304 (15) Å range]; Mo—Oc to µ3-bridging oxido groups [bond lengths in the 1.9431 (14)–2.4033 (14) Å range]; Mo—Oc to µ5-bridging oxido groups [bond lengths in the 2.1441 (14)–2.3577 (14) Å range]. The four crystallographically independent MoVI metal centers are hexacoordinated in a typical {MoO6} fashion resembling highly distorted o­cta­hedra: while the trans inter­nal O—Mo—O o­cta­hedral angles are found in the 142.75 (6)–174.00 (6)° range, the cis angles refine instead in the 71.04 (5)–105.61 (8)° inter­val. This wide dispersion for the inter­nal o­cta­hedral angles is a notable and well known consequence of the marked trans effect created by the terminal oxido groups, which displace the metal atoms from the center of the o­cta­hedra. The inter­metallic MoVI distances within the β-o­cta­molybdate anion range from 3.1875 (5) Å (for the Mo1···Mo2 distance) to 3.5810 (5) Å [for the Mo1···Mo1i distance across the inversion center of the anion; symmetry operation: (i) −x, 1 − y, 1 − z].

Supra­molecular features top

The crystal packing of the title compound is essentially mediated by the presence of various N—H···O hydrogen-bonding inter­actions between the H4mbdpz2+ cation (which acts as the donor – D) and the β-o­cta­molybdate anion (the acceptor – A) (Fig. 2a). As depicted in Table 1, the D···A distances are relatively short, ranging between 2.730 (2) and 2.977 (2) Å. It is noteworthy that the latter is associated with the N2—H2 group which is engaged in a bifurcated inter­action with the neighbouring β-o­cta­molybdate anion (as depicted in Fig. 2a), hence leading to an average increase of the inter­atomic distances.

Besides these inter­actions, the crystal structure is also rich in weak hydrogen bonds of the C—H···O type (not shown) involving mainly the terminal methyl groups of the organic molecule. The various C—H···O inter­actions present in the crystal structure are rather weak, with C···O distances ranging from 3.203 (3) to 3.457 (3) Å, with <(CHO) inter­action angles in the 123–168° inter­val.

The aforementioned hydrogen bonds between cations and anions lead to the formation of a two-dimensional supra­molecular network parallel to the (010) plane (Fig. 2b). Individual supra­molecular entities close pack along the [010] direction to produce the crystal structure of the title compound (Fig. 3).

Synthesis and crystallization top

MoO3 (Analar, BDH Chemicals, 99.5%), 3,5-di­methyl­pyrazole (Aldrich, 99%) and H2O2 (50% in water, Sigma–Aldrich) were obtained from commercial sources and used as received. FT–IR spectra were collected using KBr pellets (Sigma–Aldrich, 99%, FT–IR grade) on a Mattson-7000 infrared spectrophotometer.

A mixture of MoO3 (0.349 g, 2.42 mmol), 3,5-di­methyl­pyrazole (0.116 g, 1.21 mmol), water (23 ml) and H2O2 (2 ml) was heated in a Teflon-lined stainless steel digestion bomb at 433 K for 26 h, at 373 K for 25 h, and finally slowly cooled down to ambient temperature over a period of 13 h. Single crystals of the title compound were obtained inside the Teflon vessel along with a yellow aqueous mother liquor (pH = 6) and a blueish solid, which was confirmed by powder X-ray diffraction studies to be residues of unreacted MoO3.

FT–IR (cm−1): ñ = 3218 (vs); 3127 (s); 3008 (s); 2859 (s); 2719 (s); 1606 (m); 1579 (s); 1535 (m); 1517 (m); 1438 (s); 1394 (m); 1365 (m); 1253 (m); 1184 (m); 1153 (w); 1070 (w); 1047 (w); 948 (vs); 925 (s); 908 (vs); 844 (s); 721 (s); 705 (s); 671 (s); 655 (s); 543 (s); 522 (m); 480 (w); 458 (w); 445 (w); 414 (m); 401 (m); 360 (m).

Refinement details top

Crystal data, data collection and structure refinement details are summarized in Table 2. Hydrogen atoms bound to carbon were placed at idealized positions with C—H = 0.99 and 0.98 Å for the –CH2-– and methyl groups, respectively, and included in the final structural model in the riding-motion approximation with the isotropic displacement parameters fixed at 1.2 or 1.5Ueq, respectively, of the carbon atom to which they are attached.

Hydrogen atoms associated with nitro­gen atoms were directly located from difference Fourier maps and included in the model with the N—H distances restrained to 0.95 (1) Å in order to ensure a chemically reasonable environment for these moieties. These hydrogen atoms were modelled with the isotropic thermal displacement parameters fixed at 1.5Ueq(N).

Structure description top

4,4'-Methyl­enebis(3,5-di­methyl­pyrazole) (H2mbdpz) is a flexible organic molecule which has been extensively used in the last few years by various research groups to design coordination-based and organic solids. While, on the one hand, the central methyl­ene moiety confers some conformational flexibility to the entire molecular unit, on the other the two peripheral pyrazole rings permit not only the coordination to various types of metal atoms but also the involvement of these moieties in complex networks based on hydrogen bonds. It is, thus, not surprising to encounter a rich chemistry and structural diversity associated with this molecule. A search in the literature and in the Cambridge Structural Database (CSD; Allen, 2002; Groom & Allen, 2014) reveals, for example, that H2mbdpz has been used as an effective bending spacer to construct a large number of metal-organic frameworks (MOFs) or coordination polymers with various remarkable topologies based on a rather diverse range of d-block metals (Goswami et al., 2013; Mondal et al., 2008; Timokhin et al., 2015). H2mbdpz and its derivatives have also been used to prepare a range of supra­molecular networks based on either neutral organic molecules or in the formation of salts with a wide range of anions (since, typically, the two pyrazole moieties appear protonated) (Basu et al., 2009; Basu & Mondal, 2010; Hazra et al., 2010). Most of these structural reports available in the literature either use H2mbdpz purchased from commercial sources or the authors prepare the molecule using published procedures. For the latter case, the standard method dates back to that reported by Trofimenko (1970), but more recent and alternative approaches are also employed to prepare the intended molecule (Kruger et al., 2000).

In this communication, we report the unexpected isolation of a new supra­molecular salt in which 4,4'-methyl­enebis(3,5-di­methyl-1H-pyrazol-2-ium) (H4mbdpz2+) is prepared in situ, inside the autoclave reaction vessel, starting from 3,5-di­methyl­pyrazole in a reaction catalysed by MoVI ions in the presence of hydrogen peroxide. To balance the cationic charge of the protonated H4mbdpz2+ moiety, the crystal contains the well known β-o­cta­molybdate anion. It is remarkable to note that, despite the intensive research on supra­molecular structures based on H2mbdpz, only a couple of very recent reports contain polyoxidometalate-type anions. Indeed, Tian et al. (2014, 2015) described various Ag+-based MOFs (or coordination polymers) in which MoVI or WVI Keggin and/or Wells–Dawson polyoxidometalates balance the positive charge of the cationic architectures.

The asymmetric unit of the title compound is composed of a 4,4'-methyl­enebis(3,5-di­methyl-1H-pyrazol-2-ium) cation (H4mbdpz2+), and one half of the β-o­cta­molybdate anion, β-[Mo8O26]4− (Fig. 1).

The H4mbdpz2+ cation exhibits the typical structural features found in related compounds. The considerable steric hindrance imposed by the two peripheral 3,5-di­methyl-1H-pyrazol-2-ium moieties induces a tetra­hedral angle of the bridging methyl­ene group of 113.56 (17)°, which is very close to the median value found in similar structures (from the CSD: median of 114.7° from 109 hits with range of 111.0–120.0°). Conversely, the dihedral angle subtended by these two peripheral moieties is significantly more dependent on the crystal structure itself, with the literature values (from 109 hits in the CSD) ranging from as low as 55.1° (a chiral coordination polymer with Cu2+ described by Lin et al., 2014) to 90.0° (an Ni2+ layered network described by Goswami et al., 2013). Nevertheless, the inter­planar angle registered for the title compound, 77.85 (15)°, agrees well with the median value of all structures deposited in the CSD (81.1°).

The molecular geometrical parameters for the β-o­cta­molybdate anion are typical, exhibiting the usual four families of Mo—O bonds: Mo—Ot to terminal oxido groups [bond lengths in the 1.6883 (14)–1.7077 (15) Å range]; Mo—Ob to µ2-bridging oxido groups [bond lengths in the 1.7506 (15)–2.2304 (15) Å range]; Mo—Oc to µ3-bridging oxido groups [bond lengths in the 1.9431 (14)–2.4033 (14) Å range]; Mo—Oc to µ5-bridging oxido groups [bond lengths in the 2.1441 (14)–2.3577 (14) Å range]. The four crystallographically independent MoVI metal centers are hexacoordinated in a typical {MoO6} fashion resembling highly distorted o­cta­hedra: while the trans inter­nal O—Mo—O o­cta­hedral angles are found in the 142.75 (6)–174.00 (6)° range, the cis angles refine instead in the 71.04 (5)–105.61 (8)° inter­val. This wide dispersion for the inter­nal o­cta­hedral angles is a notable and well known consequence of the marked trans effect created by the terminal oxido groups, which displace the metal atoms from the center of the o­cta­hedra. The inter­metallic MoVI distances within the β-o­cta­molybdate anion range from 3.1875 (5) Å (for the Mo1···Mo2 distance) to 3.5810 (5) Å [for the Mo1···Mo1i distance across the inversion center of the anion; symmetry operation: (i) −x, 1 − y, 1 − z].

The crystal packing of the title compound is essentially mediated by the presence of various N—H···O hydrogen-bonding inter­actions between the H4mbdpz2+ cation (which acts as the donor – D) and the β-o­cta­molybdate anion (the acceptor – A) (Fig. 2a). As depicted in Table 1, the D···A distances are relatively short, ranging between 2.730 (2) and 2.977 (2) Å. It is noteworthy that the latter is associated with the N2—H2 group which is engaged in a bifurcated inter­action with the neighbouring β-o­cta­molybdate anion (as depicted in Fig. 2a), hence leading to an average increase of the inter­atomic distances.

Besides these inter­actions, the crystal structure is also rich in weak hydrogen bonds of the C—H···O type (not shown) involving mainly the terminal methyl groups of the organic molecule. The various C—H···O inter­actions present in the crystal structure are rather weak, with C···O distances ranging from 3.203 (3) to 3.457 (3) Å, with <(CHO) inter­action angles in the 123–168° inter­val.

The aforementioned hydrogen bonds between cations and anions lead to the formation of a two-dimensional supra­molecular network parallel to the (010) plane (Fig. 2b). Individual supra­molecular entities close pack along the [010] direction to produce the crystal structure of the title compound (Fig. 3).

Synthesis and crystallization top

MoO3 (Analar, BDH Chemicals, 99.5%), 3,5-di­methyl­pyrazole (Aldrich, 99%) and H2O2 (50% in water, Sigma–Aldrich) were obtained from commercial sources and used as received. FT–IR spectra were collected using KBr pellets (Sigma–Aldrich, 99%, FT–IR grade) on a Mattson-7000 infrared spectrophotometer.

A mixture of MoO3 (0.349 g, 2.42 mmol), 3,5-di­methyl­pyrazole (0.116 g, 1.21 mmol), water (23 ml) and H2O2 (2 ml) was heated in a Teflon-lined stainless steel digestion bomb at 433 K for 26 h, at 373 K for 25 h, and finally slowly cooled down to ambient temperature over a period of 13 h. Single crystals of the title compound were obtained inside the Teflon vessel along with a yellow aqueous mother liquor (pH = 6) and a blueish solid, which was confirmed by powder X-ray diffraction studies to be residues of unreacted MoO3.

FT–IR (cm−1): ñ = 3218 (vs); 3127 (s); 3008 (s); 2859 (s); 2719 (s); 1606 (m); 1579 (s); 1535 (m); 1517 (m); 1438 (s); 1394 (m); 1365 (m); 1253 (m); 1184 (m); 1153 (w); 1070 (w); 1047 (w); 948 (vs); 925 (s); 908 (vs); 844 (s); 721 (s); 705 (s); 671 (s); 655 (s); 543 (s); 522 (m); 480 (w); 458 (w); 445 (w); 414 (m); 401 (m); 360 (m).

Refinement details top

Crystal data, data collection and structure refinement details are summarized in Table 2. Hydrogen atoms bound to carbon were placed at idealized positions with C—H = 0.99 and 0.98 Å for the –CH2-– and methyl groups, respectively, and included in the final structural model in the riding-motion approximation with the isotropic displacement parameters fixed at 1.2 or 1.5Ueq, respectively, of the carbon atom to which they are attached.

Hydrogen atoms associated with nitro­gen atoms were directly located from difference Fourier maps and included in the model with the N—H distances restrained to 0.95 (1) Å in order to ensure a chemically reasonable environment for these moieties. These hydrogen atoms were modelled with the isotropic thermal displacement parameters fixed at 1.5Ueq(N).

Computing details top

Data collection: APEX2 (Bruker, 2012); cell refinement: SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015b).

Figures top
[Figure 1] Fig. 1. Schematic representation of the molecular entities composing the asymmetric unit of the title compound. The β-octamolybdate anion has been completed by inversion symmetry for the sake of chemical accuracy. All non-hydrogen atoms are represented as displacement ellipsoids drawn at the 60% probability level and hydrogen atoms as small spheres with arbitrary radii. Non-hydrogen atoms belonging to the asymmetric unit have been labelled for clarity. Dashed violet lines indicate N—H···O hydrogen-bonding interactions (see Table 1 for geometrical details).
[Figure 2] Fig. 2. Schematic representation of the type and role of N—H···O hydrogen bond interactions present in the crystal structure of the title compound: (a) description of all interactions which connect the crystallographically independent 4,4'-methylenebis(3,5-dimethyl-1H-pyrazol-2-ium) cation to two neighbouring β-octamolybdate anions; (b) portion of the two-dimensional supramolecular layer placed in the ac plane of the unit cell formed by the connection between the molecular units present in the title compound. For geometrical details of the represented hydrogen bonds (as violet dashed lines) see Table 1. Symmetry operations used to generate equivalent atoms: (i) −x, 1 − y, 1 − z; (ii) −x, 1 − y, −z.
[Figure 3] Fig. 3. Ball-and-stick schematic representation of the crystal packing of the title compound viewed in perspective along the [100] direction. The figure emphasizes, on the one hand, how the inorganic component of the crystal structure is fully embedded into an organic matrix based on the 4,4'-methylenebis(3,5-dimethyl-1H-pyrazol-2-ium) cation. On the other it shows how supramolecular hydrogen-bonded layers pack closely along the [010] direction.
Bis[4,4'-methylenebis(3,5-dimethyl-1H-pyrazol-2-ium)] β-octamolybdate top
Crystal data top
(C11H18N4)[Mo8O26]Z = 1
Mr = 1596.11F(000) = 768
Triclinic, P1Dx = 2.532 Mg m3
a = 8.6394 (10) ÅMo Kα radiation, λ = 0.71073 Å
b = 12.0694 (13) ÅCell parameters from 9149 reflections
c = 12.2249 (14) Åθ = 2.5–29.0°
α = 113.343 (3)°µ = 2.42 mm1
β = 110.629 (4)°T = 180 K
γ = 96.540 (4)°Plate, colourless
V = 1046.6 (2) Å30.28 × 0.18 × 0.15 mm
Data collection top
Bruker D8 QUEST
diffractometer
5605 independent reflections
Radiation source: Sealed tube4669 reflections with I > 2σ(I)
Multi-layer X-ray mirror monochromatorRint = 0.032
Detector resolution: 10.4167 pixels mm-1θmax = 29.1°, θmin = 3.6°
ω / φ scansh = 1111
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
k = 1615
Tmin = 0.595, Tmax = 0.746l = 1616
58761 measured reflections
Refinement top
Refinement on F24 restraints
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.021H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.045 w = 1/[σ2(Fo2) + (0.0188P)2 + 0.8837P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.002
5605 reflectionsΔρmax = 0.45 e Å3
305 parametersΔρmin = 0.38 e Å3
Crystal data top
(C11H18N4)[Mo8O26]γ = 96.540 (4)°
Mr = 1596.11V = 1046.6 (2) Å3
Triclinic, P1Z = 1
a = 8.6394 (10) ÅMo Kα radiation
b = 12.0694 (13) ŵ = 2.42 mm1
c = 12.2249 (14) ÅT = 180 K
α = 113.343 (3)°0.28 × 0.18 × 0.15 mm
β = 110.629 (4)°
Data collection top
Bruker D8 QUEST
diffractometer
5605 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
4669 reflections with I > 2σ(I)
Tmin = 0.595, Tmax = 0.746Rint = 0.032
58761 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0214 restraints
wR(F2) = 0.045H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 0.45 e Å3
5605 reflectionsΔρmin = 0.38 e Å3
305 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Mo10.21482 (2)0.51375 (2)0.44384 (2)0.01325 (5)
Mo20.03289 (2)0.47766 (2)0.25116 (2)0.01588 (5)
Mo30.09806 (2)0.76466 (2)0.66882 (2)0.01539 (5)
Mo40.29881 (2)0.72827 (2)0.48193 (2)0.01568 (5)
O10.03817 (17)0.59486 (13)0.47061 (13)0.0144 (3)
O20.20451 (18)0.57180 (14)0.31700 (14)0.0173 (3)
O30.5019 (2)0.78869 (15)0.50477 (16)0.0241 (3)
O40.30714 (18)0.80224 (14)0.65515 (14)0.0181 (3)
O50.1782 (2)0.81272 (15)0.42422 (15)0.0231 (3)
O60.1581 (2)0.85684 (15)0.83252 (15)0.0250 (4)
O70.10203 (18)0.63200 (13)0.63336 (13)0.0154 (3)
O80.0215 (2)0.83770 (14)0.59176 (15)0.0221 (3)
O90.37025 (18)0.41295 (14)0.45016 (14)0.0171 (3)
O100.32215 (19)0.60161 (14)0.38551 (14)0.0194 (3)
O110.20542 (18)0.39078 (13)0.28676 (13)0.0158 (3)
O120.0557 (2)0.35530 (15)0.10928 (15)0.0250 (4)
O130.1414 (2)0.57098 (15)0.20309 (16)0.0240 (3)
N10.3125 (3)0.17745 (19)0.33840 (19)0.0245 (4)
H10.327 (3)0.200 (2)0.400 (2)0.037*
N20.1581 (3)0.15545 (18)0.33513 (19)0.0236 (4)
H20.065 (2)0.170 (3)0.391 (2)0.035*
N30.2863 (2)0.27594 (18)0.22445 (18)0.0216 (4)
H30.242 (3)0.280 (2)0.285 (2)0.032*
N40.3249 (2)0.37686 (18)0.20751 (19)0.0222 (4)
H40.302 (3)0.4503 (16)0.255 (2)0.033*
C10.6179 (3)0.2024 (3)0.2101 (3)0.0315 (6)
H1A0.65260.27670.22010.047*
H1B0.63130.12870.27490.047*
H1C0.69100.21750.12050.047*
C20.4340 (3)0.1784 (2)0.2327 (2)0.0208 (5)
C30.3525 (3)0.1549 (2)0.1608 (2)0.0167 (4)
C40.1777 (3)0.1416 (2)0.2286 (2)0.0190 (4)
C50.0296 (3)0.1179 (2)0.1979 (2)0.0279 (5)
H5A0.07850.07940.27940.042*
H5B0.02600.19800.13510.042*
H5C0.04340.06070.15870.042*
C60.4344 (3)0.1463 (2)0.0344 (2)0.0188 (4)
H6A0.56180.17760.00170.023*
H6B0.40390.05650.05490.023*
C70.2913 (3)0.0554 (2)0.1437 (2)0.0265 (5)
H7A0.24360.05940.20650.040*
H7B0.40200.03670.17030.040*
H7C0.21010.01130.05480.040*
C80.3187 (3)0.1786 (2)0.1426 (2)0.0181 (4)
C90.3792 (3)0.2204 (2)0.0700 (2)0.0167 (4)
C100.3814 (3)0.3458 (2)0.1134 (2)0.0194 (4)
C110.4314 (3)0.4388 (2)0.0725 (2)0.0280 (5)
H11A0.45450.52430.14150.042*
H11B0.33710.42330.01050.042*
H11C0.53590.43050.05940.042*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mo10.01265 (9)0.01485 (9)0.01065 (9)0.00461 (7)0.00402 (7)0.00530 (7)
Mo20.01593 (9)0.01973 (10)0.01075 (9)0.00480 (7)0.00481 (7)0.00702 (7)
Mo30.01680 (9)0.01357 (9)0.01255 (9)0.00375 (7)0.00645 (7)0.00330 (7)
Mo40.01521 (9)0.01665 (10)0.01562 (9)0.00504 (7)0.00687 (7)0.00775 (7)
O10.0138 (7)0.0161 (7)0.0114 (7)0.0040 (6)0.0047 (6)0.0055 (6)
O20.0176 (7)0.0210 (8)0.0145 (7)0.0060 (6)0.0081 (6)0.0083 (6)
O30.0201 (8)0.0265 (9)0.0267 (9)0.0054 (7)0.0115 (7)0.0127 (7)
O40.0158 (7)0.0176 (8)0.0151 (7)0.0020 (6)0.0045 (6)0.0050 (6)
O50.0253 (8)0.0244 (9)0.0235 (8)0.0106 (7)0.0105 (7)0.0139 (7)
O60.0301 (9)0.0218 (8)0.0158 (8)0.0046 (7)0.0092 (7)0.0036 (7)
O70.0154 (7)0.0162 (7)0.0121 (7)0.0039 (6)0.0061 (6)0.0044 (6)
O80.0229 (8)0.0200 (8)0.0229 (8)0.0075 (7)0.0098 (7)0.0094 (7)
O90.0145 (7)0.0192 (8)0.0156 (7)0.0049 (6)0.0051 (6)0.0075 (6)
O100.0193 (8)0.0207 (8)0.0182 (8)0.0082 (6)0.0067 (6)0.0098 (6)
O110.0147 (7)0.0175 (8)0.0112 (7)0.0039 (6)0.0038 (6)0.0049 (6)
O120.0259 (9)0.0284 (9)0.0159 (8)0.0052 (7)0.0085 (7)0.0072 (7)
O130.0219 (8)0.0309 (9)0.0236 (8)0.0101 (7)0.0081 (7)0.0177 (7)
N10.0309 (11)0.0266 (11)0.0215 (10)0.0096 (9)0.0126 (9)0.0151 (9)
N20.0243 (10)0.0250 (11)0.0203 (10)0.0107 (8)0.0055 (8)0.0123 (8)
N30.0214 (10)0.0241 (10)0.0181 (9)0.0042 (8)0.0127 (8)0.0059 (8)
N40.0198 (10)0.0206 (10)0.0201 (10)0.0071 (8)0.0083 (8)0.0042 (8)
C10.0293 (13)0.0458 (16)0.0349 (14)0.0136 (12)0.0208 (12)0.0265 (13)
C20.0255 (12)0.0210 (12)0.0194 (11)0.0087 (9)0.0107 (9)0.0115 (9)
C30.0201 (11)0.0164 (11)0.0150 (10)0.0071 (8)0.0089 (9)0.0069 (8)
C40.0215 (11)0.0148 (11)0.0199 (11)0.0074 (9)0.0084 (9)0.0074 (9)
C50.0215 (12)0.0335 (14)0.0304 (13)0.0101 (10)0.0128 (10)0.0148 (11)
C60.0214 (11)0.0247 (12)0.0178 (11)0.0103 (9)0.0121 (9)0.0127 (9)
C70.0346 (14)0.0221 (12)0.0201 (12)0.0007 (10)0.0132 (10)0.0084 (10)
C80.0157 (10)0.0216 (11)0.0131 (10)0.0028 (8)0.0058 (8)0.0057 (9)
C90.0132 (10)0.0215 (11)0.0136 (10)0.0041 (8)0.0049 (8)0.0078 (9)
C100.0143 (10)0.0237 (12)0.0156 (10)0.0051 (8)0.0029 (8)0.0083 (9)
C110.0323 (13)0.0220 (12)0.0236 (12)0.0038 (10)0.0048 (10)0.0125 (10)
Geometric parameters (Å, º) top
Mo1—O101.6883 (14)N2—C41.332 (3)
Mo1—O91.7506 (15)N2—H20.935 (10)
Mo1—O111.9431 (14)N3—N41.339 (3)
Mo1—O71.9561 (14)N3—C81.342 (3)
Mo1—O12.1441 (14)N3—H30.937 (10)
Mo1—O1i2.3577 (14)N4—C101.341 (3)
Mo1—Mo23.1874 (4)N4—H40.937 (10)
Mo1—Mo33.2153 (4)C1—C21.485 (3)
Mo2—O131.6939 (15)C1—H1A0.9800
Mo2—O121.7005 (16)C1—H1B0.9800
Mo2—O21.9304 (15)C1—H1C0.9800
Mo2—O111.9933 (15)C2—C31.391 (3)
Mo2—O12.2824 (14)C3—C41.397 (3)
Mo2—O7i2.4033 (14)C3—C61.508 (3)
Mo3—O61.6984 (15)C4—C51.484 (3)
Mo3—O81.7063 (15)C5—H5A0.9800
Mo3—O41.8928 (15)C5—H5B0.9800
Mo3—O72.0078 (15)C5—H5C0.9800
Mo3—O12.2975 (14)C6—C91.509 (3)
Mo3—O11i2.3502 (14)C6—H6A0.9900
Mo4—O31.6999 (15)C6—H6B0.9900
Mo4—O51.7077 (15)C7—C81.485 (3)
Mo4—O41.9147 (15)C7—H7A0.9800
Mo4—O21.9416 (15)C7—H7B0.9800
Mo4—O9i2.2304 (15)C7—H7C0.9800
O1—Mo1i2.3577 (14)C8—C91.393 (3)
O7—Mo2i2.4033 (14)C9—C101.386 (3)
O9—Mo4i2.2304 (15)C10—C111.477 (3)
O11—Mo3i2.3502 (14)C11—H11A0.9800
N1—C21.342 (3)C11—H11B0.9800
N1—N21.347 (3)C11—H11C0.9800
N1—H10.935 (10)
O10—Mo1—O9104.79 (7)O4—Mo4—O9i78.01 (6)
O10—Mo1—O11101.71 (7)O2—Mo4—O9i77.29 (6)
O9—Mo1—O1197.75 (6)Mo1—O1—Mo292.07 (5)
O10—Mo1—O7100.07 (7)Mo1—O1—Mo392.69 (5)
O9—Mo1—O796.20 (6)Mo2—O1—Mo3160.42 (7)
O11—Mo1—O7150.11 (6)Mo1—O1—Mo1i105.30 (6)
O10—Mo1—O199.34 (7)Mo2—O1—Mo1i99.34 (5)
O9—Mo1—O1155.85 (6)Mo3—O1—Mo1i97.70 (5)
O11—Mo1—O178.04 (6)Mo2—O2—Mo4116.88 (7)
O7—Mo1—O178.43 (6)Mo3—O4—Mo4117.46 (7)
O10—Mo1—O1i174.00 (6)Mo1—O7—Mo3108.41 (7)
O9—Mo1—O1i81.15 (6)Mo1—O7—Mo2i108.04 (6)
O11—Mo1—O1i78.01 (5)Mo3—O7—Mo2i103.79 (6)
O7—Mo1—O1i78.19 (5)Mo1—O9—Mo4i120.16 (7)
O1—Mo1—O1i74.70 (6)Mo1—O11—Mo2108.13 (7)
O10—Mo1—Mo289.83 (5)Mo1—O11—Mo3i109.11 (6)
O9—Mo1—Mo2134.21 (5)Mo2—O11—Mo3i106.18 (6)
O11—Mo1—Mo236.46 (4)C2—N1—N2109.03 (18)
O7—Mo1—Mo2124.12 (4)C2—N1—H1128.8 (17)
O1—Mo1—Mo245.69 (4)N2—N1—H1121.5 (17)
O1i—Mo1—Mo286.48 (3)C4—N2—N1109.52 (18)
O10—Mo1—Mo389.84 (5)C4—N2—H2129.5 (17)
O9—Mo1—Mo3132.50 (5)N1—N2—H2119.3 (17)
O11—Mo1—Mo3123.58 (4)N4—N3—C8109.53 (18)
O7—Mo1—Mo336.33 (4)N4—N3—H3120.5 (16)
O1—Mo1—Mo345.54 (4)C8—N3—H3129.9 (16)
O1i—Mo1—Mo385.40 (4)N3—N4—C10109.06 (18)
Mo2—Mo1—Mo389.640 (10)N3—N4—H4118.4 (16)
O13—Mo2—O12105.61 (8)C10—N4—H4132.4 (16)
O13—Mo2—O2101.67 (7)C2—C1—H1A109.5
O12—Mo2—O299.58 (7)C2—C1—H1B109.5
O13—Mo2—O1199.61 (7)H1A—C1—H1B109.5
O12—Mo2—O1199.06 (7)C2—C1—H1C109.5
O2—Mo2—O11146.63 (6)H1A—C1—H1C109.5
O13—Mo2—O195.07 (7)H1B—C1—H1C109.5
O12—Mo2—O1159.06 (7)N1—C2—C3107.6 (2)
O2—Mo2—O178.95 (5)N1—C2—C1120.7 (2)
O11—Mo2—O173.82 (5)C3—C2—C1131.8 (2)
O13—Mo2—O7i165.12 (6)C2—C3—C4106.25 (19)
O12—Mo2—O7i87.62 (6)C2—C3—C6127.50 (19)
O2—Mo2—O7i82.35 (6)C4—C3—C6126.25 (19)
O11—Mo2—O7i71.04 (5)N2—C4—C3107.61 (19)
O1—Mo2—O7i71.46 (5)N2—C4—C5121.7 (2)
O13—Mo2—Mo186.49 (5)C3—C4—C5130.7 (2)
O12—Mo2—Mo1134.42 (6)C4—C5—H5A109.5
O2—Mo2—Mo1121.20 (4)C4—C5—H5B109.5
O11—Mo2—Mo135.40 (4)H5A—C5—H5B109.5
O1—Mo2—Mo142.24 (4)C4—C5—H5C109.5
O7i—Mo2—Mo179.26 (3)H5A—C5—H5C109.5
O6—Mo3—O8104.89 (8)H5B—C5—H5C109.5
O6—Mo3—O4102.17 (7)C3—C6—C9113.56 (17)
O8—Mo3—O4101.97 (7)C3—C6—H6A108.9
O6—Mo3—O797.97 (7)C9—C6—H6A108.9
O8—Mo3—O796.88 (7)C3—C6—H6B108.9
O4—Mo3—O7147.68 (6)C9—C6—H6B108.9
O6—Mo3—O1161.95 (7)H6A—C6—H6B107.7
O8—Mo3—O192.20 (6)C8—C7—H7A109.5
O4—Mo3—O179.39 (6)C8—C7—H7B109.5
O7—Mo3—O173.84 (5)H7A—C7—H7B109.5
O6—Mo3—O11i90.45 (7)C8—C7—H7C109.5
O8—Mo3—O11i162.37 (6)H7A—C7—H7C109.5
O4—Mo3—O11i82.78 (6)H7B—C7—H7C109.5
O7—Mo3—O11i71.98 (5)N3—C8—C9107.23 (19)
O1—Mo3—O11i71.81 (5)N3—C8—C7120.65 (19)
O6—Mo3—Mo1133.10 (6)C9—C8—C7132.1 (2)
O8—Mo3—Mo184.13 (5)C10—C9—C8106.44 (19)
O4—Mo3—Mo1121.16 (4)C10—C9—C6126.00 (19)
O7—Mo3—Mo135.26 (4)C8—C9—C6127.6 (2)
O1—Mo3—Mo141.77 (3)N4—C10—C9107.7 (2)
O11i—Mo3—Mo178.97 (4)N4—C10—C11121.0 (2)
O3—Mo4—O5105.36 (8)C9—C10—C11131.3 (2)
O3—Mo4—O4105.00 (7)C10—C11—H11A109.5
O5—Mo4—O496.53 (7)C10—C11—H11B109.5
O3—Mo4—O2104.14 (7)H11A—C11—H11B109.5
O5—Mo4—O297.61 (7)C10—C11—H11C109.5
O4—Mo4—O2142.75 (6)H11A—C11—H11C109.5
O3—Mo4—O9i94.00 (6)H11B—C11—H11C109.5
O5—Mo4—O9i160.64 (7)
O6—Mo3—O4—Mo4175.31 (8)N1—N2—C4—C5179.2 (2)
O8—Mo3—O4—Mo466.98 (9)C2—C3—C4—N20.6 (2)
O7—Mo3—O4—Mo457.37 (15)C6—C3—C4—N2179.9 (2)
O1—Mo3—O4—Mo423.03 (8)C2—C3—C4—C5178.8 (2)
O11i—Mo3—O4—Mo495.79 (8)C6—C3—C4—C50.7 (4)
Mo1—Mo3—O4—Mo423.37 (10)C2—C3—C6—C9133.1 (2)
O10—Mo1—O9—Mo4i178.98 (8)C4—C3—C6—C946.3 (3)
O11—Mo1—O9—Mo4i74.63 (8)N4—N3—C8—C90.5 (2)
O7—Mo1—O9—Mo4i78.87 (8)N4—N3—C8—C7178.4 (2)
O1—Mo1—O9—Mo4i3.4 (2)N3—C8—C9—C100.3 (2)
O1i—Mo1—O9—Mo4i1.88 (7)C7—C8—C9—C10178.5 (2)
Mo2—Mo1—O9—Mo4i74.35 (9)N3—C8—C9—C6179.6 (2)
Mo3—Mo1—O9—Mo4i77.24 (9)C7—C8—C9—C60.7 (4)
C2—N1—N2—C40.2 (3)C3—C6—C9—C1050.6 (3)
C8—N3—N4—C100.6 (2)C3—C6—C9—C8130.3 (2)
N2—N1—C2—C30.6 (3)N3—N4—C10—C90.4 (2)
N2—N1—C2—C1179.2 (2)N3—N4—C10—C11179.19 (19)
N1—C2—C3—C40.7 (2)C8—C9—C10—N40.0 (2)
C1—C2—C3—C4179.0 (2)C6—C9—C10—N4179.2 (2)
N1—C2—C3—C6179.8 (2)C8—C9—C10—C11179.5 (2)
C1—C2—C3—C60.4 (4)C6—C9—C10—C111.3 (4)
N1—N2—C4—C30.2 (2)
Symmetry code: (i) x, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10ii0.942.342.941 (2)122
N2—H2···O5ii0.942.052.852 (2)143
N2—H2···O8ii0.942.312.977 (2)127
N3—H3···O7i0.941.972.759 (2)141
N4—H4···O20.941.812.730 (2)166
Symmetry codes: (i) x, y+1, z+1; (ii) x, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10i0.942.342.941 (2)122
N2—H2···O5i0.942.052.852 (2)143
N2—H2···O8i0.942.312.977 (2)127
N3—H3···O7ii0.941.972.759 (2)141
N4—H4···O20.941.812.730 (2)166
Symmetry codes: (i) x, y+1, z; (ii) x, y+1, z+1.

Experimental details

Crystal data
Chemical formula(C11H18N4)[Mo8O26]
Mr1596.11
Crystal system, space groupTriclinic, P1
Temperature (K)180
a, b, c (Å)8.6394 (10), 12.0694 (13), 12.2249 (14)
α, β, γ (°)113.343 (3), 110.629 (4), 96.540 (4)
V3)1046.6 (2)
Z1
Radiation typeMo Kα
µ (mm1)2.42
Crystal size (mm)0.28 × 0.18 × 0.15
Data collection
DiffractometerBruker D8 QUEST
Absorption correctionMulti-scan
(SADABS; Bruker, 2001)
Tmin, Tmax0.595, 0.746
No. of measured, independent and
observed [I > 2σ(I)] reflections
58761, 5605, 4669
Rint0.032
(sin θ/λ)max1)0.685
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.021, 0.045, 1.05
No. of reflections5605
No. of parameters305
No. of restraints4
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.45, 0.38

Computer programs: APEX2 (Bruker, 2012), SAINT (Bruker, 2012), SHELXT (Sheldrick, 2015a), SHELXL2014 (Sheldrick, 2015b), DIAMOND (Brandenburg, 1999).

 

Acknowledgements

Funding Sources and Entities: the Fundação para a Ciência e a Tecnologia (FCT, Portugal), the European Union, QREN, FEDER through Programa Operacional Factores de Competitividade (COMPETE), CICECO–Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013) financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement.Projects and Individual grants: We wish to thank the FCT for funding the R&D project FCOMP-01–0124-FEDER-041282 (reference FCT EXPL/CTM-NAN/0013/2013), and also CICECO for specific funding towards the purchase of the single-crystal diffractometer. The FCT is gratefully acknowledged for the post-doctoral research grant No. SFRH/BPD/97660/2013 (to TRA).

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Volume 72| Part 2| February 2016| Pages 124-127
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