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A novel chain molybdenum compound, {[Mo2O6(C6H5NO2)]·H2O}n, which was synthesized under hydro­thermal conditions, consists of an infinite rail-like chain formed by molybdenum oxide units linked by zwitterionic nicotinic acid ligands. Each Mo atom is coordinated octahedrally by six O atoms and the MoO6 octahedra are linked to one another via edge-sharing to produce a zigzag polymeric chain, with nicotinic acid ligands located, alternately, on each side of the rail-like chain plane.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104016944/ta1466sup1.cif
Contains datablocks I, a

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104016944/ta1466Isup2.hkl
Contains datablock I

CCDC reference: 251290

Comment top

Chemists are increasingly interested in topics concerning transition metal oxides, owing mainly to their structural variety and promising potential applications in catalysis, biology, medicine and materials science (Pope & Müller, 1999). The molybdenum oxides are an important subclass and have been reported frequently (Rarig & Zubieta, 2001). It has been recognized that molybdenum in its higher oxidation states readily forms polynuclear anionic metal–oxygen clusters, and many giant polymolybdates have been reported (Müller & Kögerler, 1999). However, the number of dimeric structures of molybdenum oxides that are known is much smaller; only a few compounds, such as [Mo2O4(C2O4)2(H2O)2]2− (Strukan & Cindric, 2000) and [Mo2(iPr-O)6(Cat)2] (iPr-O is isopropoxy and Cat is tetrachloro-o-catecholato; Timothy et al., 1988), have been reported. Recently, compounds based on polyoxometalates linked by clusters, organic ligands and so on have been of a hot topic in this research area (Müller et al., 1999), but solid materials of one-dimensional structure with only molybdenum oxide frameworks have rarely been reported. On the other hand, nicotinic acid has often been used as a ligand to prepare transition-metal cation compounds. To our knowledge, only one Mo compound, [Mo2Cl2(C6H4NO2)4]Cl2·6H2O (Cotton et al., 1990), that is directly coordinated by nicotinic acid has been reported. Recently, we have launched a systematic program aimed at linking polyoxometalates by organic ligands and (or) transition-metal fragments, in order to generate distinctive architectures. We have succeeded in obtaining an infinite rail-like chain compound, [Mo2O6(nic)]n.nH2O (nic is nicotinic acid), (I), by hydrothermal reaction. The preparation, elemental analysis, IR spectrum and crystal structure of this compound are presented here.

Compound (I) consists of an infinite rail-like chain formed by molybdate oxide units linked by nicotinic acid ligands. As shown in Figs. 1 and 2, every Mo is octahedrally coordinated by six O atoms, which can be divided into three groups according to their Mo—O distances; two short terminal bonds [Mo—O = 1.685 (5) and 1.712 (5) Å], two medium-length bonds [1.958 (5) Å] and two longer bonds [2.231 (5) and 2.293 (5) Å] are observed. It is known that nicotinic acid can offer three coordination atoms, namely two O atoms and one N atom, and has several coordination modes (Chen et al., 2001). In (I), each nicotinic acid ligand bridges two Mo centers only by the two O atoms of its carboxylate group. The most interesting structural feature of (I), however, is that all nicotinic acid ligands are coordinated to Mo atoms in a bridging mode [Mo1···Mo2 = 3.3965 (9) Å].

As shown in Fig. 2, the MoO6 octahedra are linked to one another via edge sharing to produce a zigzag polymeric chain. In this one-dimensional structural motif, nicotinic acid ligands are located, alternately, on each side of the rail-like chain plane. Such a coordination mode for the nicotinic acid ligand has been reported previously but infrequently for other related compounds (Chen et al., 2001).

Fig. 3 shows the structure of (I), with the one-dimensional chains viewed end on. It can be seen that the chains are held together in two-dimensional layers by weak ππ stacking contacts between interleaved pyridine rings from adjacent chains. One pyridine ring of a chain and another pyridine ring of an adjacent chain form ππ stacks with a dihedral angle of 18.2°, and the shortest and the longest atom-to-centroid distances are 3.761 and 4.639 Å, respectively. This two-dimensional structure is further extended into a three-dimensional structure by interlayer hydrogen-bonded water molecules (Table 2).

Experimental top

A mixture of Na2MoO4·H2O (0.24 g, 1 mmol), nicotinic acid (0.25 g, 2.0 mmol), (C2H5)4NCl·H2O (0.18 g, 1.0 mmol) and NH2OH.HCl(0.18 g, 2.5 mmol) in H2O (10 ml) was heated at 413 K for 3 d. After the reaction was cooled to room temperature over a period of 72 h, colorless crystals of (I) were produced (yield 51% based on Mo). Analysis calculated for C6NH7Mo2O9: C 16.80, H 1.64, N 3.26%; found: C 16.99, H 1.48, N 3.11%. IR (KBr, cm−1): 3541 (m), 1637 (s), 1585 (m), 1416 (s), 953 (versus), 924 (s), 544 (s).

Refinement top

H atoms attached to C and N atoms were positioned geometrically and included in the refinement using a riding model [C—H = 0.93 Å, N—H = 0.86 Å and Uiso(H) = 1.2Ueq(C,N)]. The water H atoms were located from difference maps and their positions were refined isotropically, with the O—H distances fixed at 0.82 (6) and 0.82 (8) Å [Uiso(H) = 1.5Ueq(O)]. The −1.119 Å−3 hole in the final difference map is 1.05 Å from atom Mo1.

Computing details top

Data collection: SMART (Siemens, 1996); cell refinement: SMART and SAINT (Siemens,1994); data reduction: XPREP in SHELXTL (Siemens, 1994); program(s) used to solve structure: SHELXTL; program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The independent unit in (I), with 30% probability displacement ellipsoids. H atoms are shown as small spheres of arbitrary radii. [Symmetry codes: (i) 1 − x, −y, 1 − z; (ii) 1 − x, 1 − y, 1 − z.]
[Figure 2] Fig. 2. A view of the extended structure of (I), with 30% probability displacement ellipsoids, showing the rail-like chain. H atoms and water molecules have been omitted for clarity. Atoms with the suffixes A and B are at the symmetry positions (1 − x, 1 − y, 1 − z) and (x, 1 + y, z), respectively.
[Figure 3] Fig. 3. The crystal structure of (I), with the one-dimensional chains viewed approximately end-on. Intermolecular hydrogen bonds are shown as dotted lines.
catena-Poly[[µ-nicotinato-bis[dioxomolybdenum(VI)]-di-µ3-oxo] monohydrate top
Crystal data top
[Mo2O6(C6H5NO2)]·H2OF(000) = 824
Mr = 429.01Dx = 2.538 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 1888 reflections
a = 8.5404 (6) Åθ = 2.3–25.1°
b = 7.3459 (5) ŵ = 2.28 mm1
c = 18.3735 (11) ÅT = 293 K
β = 103.045 (2)°Prism, colorless
V = 1122.95 (13) Å30.28 × 0.10 × 0.06 mm
Z = 4
Data collection top
Siemens SMART CCD area detector
diffractometer
1987 independent reflections
Radiation source: fine-focus sealed tube1501 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
ϕ and ω scansθmax = 25.1°, θmin = 2.3°
Absorption correction: empirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
h = 106
Tmin = 0.761, Tmax = 0.872k = 88
3942 measured reflectionsl = 1721
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.041Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.126H atoms treated by a mixture of independent and constrained refinement
S = 0.99 w = 1/[σ2(Fo2) + (0.0683P)2 + 10.3372P]
where P = (Fo2 + 2Fc2)/3
1987 reflections(Δ/σ)max = 0.001
169 parametersΔρmax = 0.71 e Å3
2 restraintsΔρmin = 1.12 e Å3
Crystal data top
[Mo2O6(C6H5NO2)]·H2OV = 1122.95 (13) Å3
Mr = 429.01Z = 4
Monoclinic, P21/nMo Kα radiation
a = 8.5404 (6) ŵ = 2.28 mm1
b = 7.3459 (5) ÅT = 293 K
c = 18.3735 (11) Å0.28 × 0.10 × 0.06 mm
β = 103.045 (2)°
Data collection top
Siemens SMART CCD area detector
diffractometer
1987 independent reflections
Absorption correction: empirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
1501 reflections with I > 2σ(I)
Tmin = 0.761, Tmax = 0.872Rint = 0.030
3942 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0412 restraints
wR(F2) = 0.126H atoms treated by a mixture of independent and constrained refinement
S = 0.99 w = 1/[σ2(Fo2) + (0.0683P)2 + 10.3372P]
where P = (Fo2 + 2Fc2)/3
1987 reflectionsΔρmax = 0.71 e Å3
169 parametersΔρmin = 1.12 e Å3
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.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Mo10.35759 (7)0.12365 (9)0.44005 (3)0.0160 (2)
Mo20.66692 (7)0.37571 (9)0.53880 (3)0.0155 (2)
O10.2951 (6)0.1656 (8)0.5503 (3)0.0248 (12)
O1W0.7871 (8)0.0687 (11)0.7544 (3)0.0383 (16)
H1WB0.809 (13)0.028 (14)0.797 (3)0.058*
H1WA0.737 (12)0.010 (11)0.727 (5)0.058*
O20.4387 (7)0.0888 (7)0.3639 (3)0.0227 (12)
O30.1590 (7)0.1258 (8)0.4016 (3)0.0291 (13)
O40.6083 (6)0.1222 (7)0.5183 (3)0.0176 (11)
O50.5002 (6)0.3275 (7)0.6193 (3)0.0226 (12)
O60.7675 (7)0.4084 (8)0.4706 (3)0.0294 (14)
O70.8135 (7)0.3678 (8)0.6176 (3)0.0281 (13)
O80.4215 (6)0.3787 (7)0.4564 (3)0.0181 (11)
N10.0791 (9)0.1644 (11)0.7295 (4)0.0329 (18)
H1A0.02260.14740.72350.039*
C10.3969 (10)0.2199 (11)0.7488 (4)0.0261 (18)
H10.50620.24350.75550.031*
C20.3018 (9)0.2097 (11)0.6776 (4)0.0215 (17)
C30.1395 (10)0.1846 (12)0.6682 (5)0.0278 (19)
H30.07250.18160.62060.033*
C40.3310 (11)0.1952 (13)0.8111 (5)0.035 (2)
H40.39510.19620.85930.041*
C50.1690 (10)0.1696 (12)0.7985 (5)0.0298 (19)
H50.12090.15550.83880.036*
C60.3709 (9)0.2375 (10)0.6099 (4)0.0201 (17)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mo10.0198 (4)0.0127 (4)0.0133 (4)0.0009 (3)0.0010 (3)0.0002 (3)
Mo20.0190 (4)0.0123 (4)0.0141 (4)0.0008 (3)0.0012 (3)0.0007 (3)
O10.028 (3)0.027 (3)0.022 (3)0.003 (2)0.011 (2)0.000 (2)
O1W0.036 (4)0.062 (5)0.017 (3)0.020 (3)0.005 (3)0.004 (3)
O20.031 (3)0.018 (3)0.018 (3)0.000 (2)0.004 (2)0.002 (2)
O30.025 (3)0.027 (3)0.030 (3)0.001 (3)0.004 (2)0.002 (3)
O40.021 (3)0.013 (3)0.017 (2)0.001 (2)0.000 (2)0.002 (2)
O50.031 (3)0.018 (3)0.018 (3)0.003 (2)0.004 (2)0.001 (2)
O60.039 (3)0.028 (3)0.027 (3)0.000 (3)0.020 (3)0.000 (3)
O70.029 (3)0.028 (3)0.025 (3)0.002 (3)0.001 (2)0.003 (3)
O80.028 (3)0.009 (3)0.017 (3)0.001 (2)0.003 (2)0.002 (2)
N10.024 (4)0.046 (5)0.030 (4)0.006 (3)0.010 (3)0.006 (4)
C10.028 (4)0.029 (5)0.021 (4)0.006 (4)0.004 (3)0.001 (4)
C20.024 (4)0.017 (4)0.024 (4)0.001 (3)0.006 (3)0.004 (3)
C30.027 (4)0.034 (5)0.019 (4)0.001 (4)0.000 (3)0.003 (4)
C40.042 (5)0.039 (5)0.022 (4)0.011 (4)0.006 (4)0.006 (4)
C50.035 (5)0.034 (5)0.024 (4)0.001 (4)0.014 (4)0.001 (4)
C60.031 (4)0.017 (4)0.013 (4)0.008 (3)0.008 (3)0.001 (3)
Geometric parameters (Å, º) top
Mo1—O31.683 (5)O1W—H1WA0.82 (8)
Mo1—O21.714 (5)O5—C61.265 (9)
Mo1—O81.956 (5)N1—C51.327 (11)
Mo1—O4i1.957 (5)N1—C31.348 (11)
Mo1—O12.230 (5)N1—H1A0.8600
Mo1—O42.295 (5)C1—C21.377 (11)
Mo1—Mo23.3965 (9)C1—C41.397 (12)
Mo2—O61.688 (5)C1—H10.9300
Mo2—O71.688 (5)C2—C31.371 (11)
Mo2—O41.943 (5)C2—C61.507 (11)
Mo2—O8ii1.965 (5)C3—H30.9300
Mo2—O82.291 (5)C4—C51.363 (12)
Mo2—O52.300 (5)C4—H40.9300
O1—C61.255 (9)C5—H50.9300
O1W—H1WB0.82 (6)
O3—Mo1—O2102.3 (3)O6—Mo2—Mo198.4 (2)
O3—Mo1—O8106.0 (2)O7—Mo2—Mo1140.9 (2)
O2—Mo1—O896.8 (2)O4—Mo2—Mo140.43 (14)
O3—Mo1—O4i102.7 (2)O8ii—Mo2—Mo1105.29 (15)
O2—Mo1—O4i97.4 (2)O8—Mo2—Mo133.63 (12)
O8—Mo1—O4i144.3 (2)O5—Mo2—Mo174.91 (13)
O3—Mo1—O187.4 (2)C6—O1—Mo1131.9 (5)
O2—Mo1—O1170.2 (2)H1WB—O1W—H1WA107 (10)
O8—Mo1—O181.0 (2)C6—O5—Mo2129.8 (5)
O4i—Mo1—O179.5 (2)Mo1—O8—Mo2ii142.1 (3)
O3—Mo1—O4166.5 (2)Mo1—O8—Mo2105.9 (2)
O2—Mo1—O491.1 (2)Mo2ii—O8—Mo2106.4 (2)
O8—Mo1—O473.70 (19)C5—N1—C3123.2 (8)
O4i—Mo1—O473.5 (2)C5—N1—H1A118.4
O1—Mo1—O479.16 (19)C3—N1—H1A118.4
O3—Mo1—Mo2143.9 (2)C2—C1—C4120.7 (8)
O2—Mo1—Mo296.21 (18)C2—C1—H1119.6
O8—Mo1—Mo240.45 (15)C4—C1—H1119.6
O4i—Mo1—Mo2105.38 (14)C3—C2—C1119.4 (7)
O1—Mo1—Mo275.89 (14)C3—C2—C6119.1 (7)
O4—Mo1—Mo233.31 (12)C1—C2—C6121.4 (7)
O6—Mo2—O7103.8 (3)N1—C3—C2118.4 (8)
O6—Mo2—O498.3 (2)N1—C3—H3120.8
O7—Mo2—O4104.0 (2)C2—C3—H3120.8
O6—Mo2—O8ii99.6 (2)C5—C4—C1117.4 (8)
O7—Mo2—O8ii102.2 (2)C5—C4—H4121.3
O4—Mo2—O8ii143.5 (2)C1—C4—H4121.3
O6—Mo2—O893.0 (2)N1—C5—C4120.8 (8)
O7—Mo2—O8163.2 (2)N1—C5—H5119.6
O4—Mo2—O874.00 (19)C4—C5—H5119.6
O8ii—Mo2—O873.6 (2)O1—C6—O5127.0 (7)
O6—Mo2—O5172.5 (2)O1—C6—C2116.2 (7)
O7—Mo2—O583.7 (2)O5—C6—C2116.8 (7)
O4—Mo2—O578.9 (2)Mo2—O4—Mo1i143.1 (3)
O8ii—Mo2—O579.2 (2)Mo2—O4—Mo1106.3 (2)
O8—Mo2—O579.59 (18)Mo1i—O4—Mo1106.5 (2)
Symmetry codes: (i) x+1, y, z+1; (ii) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WB···O7iii0.82 (6)2.39 (7)3.059 (8)141 (10)
O1W—H1WB···O5iii0.82 (6)2.47 (7)3.151 (9)142 (10)
O1W—H1WA···O2i0.82 (8)2.07 (6)2.809 (8)151 (11)
N1—H1A···O1Wiv0.861.932.727 (9)154
Symmetry codes: (i) x+1, y, z+1; (iii) x+3/2, y1/2, z+3/2; (iv) x1, y, z.

Experimental details

Crystal data
Chemical formula[Mo2O6(C6H5NO2)]·H2O
Mr429.01
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)8.5404 (6), 7.3459 (5), 18.3735 (11)
β (°) 103.045 (2)
V3)1122.95 (13)
Z4
Radiation typeMo Kα
µ (mm1)2.28
Crystal size (mm)0.28 × 0.10 × 0.06
Data collection
DiffractometerSiemens SMART CCD area detector
diffractometer
Absorption correctionEmpirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.761, 0.872
No. of measured, independent and
observed [I > 2σ(I)] reflections
3942, 1987, 1501
Rint0.030
(sin θ/λ)max1)0.596
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.041, 0.126, 0.99
No. of reflections1987
No. of parameters169
No. of restraints2
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
w = 1/[σ2(Fo2) + (0.0683P)2 + 10.3372P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)0.71, 1.12

Computer programs: SMART (Siemens, 1996), SMART and SAINT (Siemens,1994), XPREP in SHELXTL (Siemens, 1994), SHELXTL.

Selected geometric parameters (Å, º) top
Mo1—O31.683 (5)Mo2—O61.688 (5)
Mo1—O21.714 (5)Mo2—O71.688 (5)
Mo1—O81.956 (5)Mo2—O41.943 (5)
Mo1—O4i1.957 (5)Mo2—O8ii1.965 (5)
Mo1—O12.230 (5)Mo2—O82.291 (5)
Mo1—O42.295 (5)Mo2—O52.300 (5)
Mo1—Mo23.3965 (9)
O3—Mo1—O2102.3 (3)O6—Mo2—O7103.8 (3)
O3—Mo1—O8106.0 (2)O6—Mo2—O498.3 (2)
O2—Mo1—O896.8 (2)O7—Mo2—O4104.0 (2)
O3—Mo1—O187.4 (2)O6—Mo2—O893.0 (2)
O2—Mo1—O1170.2 (2)O7—Mo2—O8163.2 (2)
O8—Mo1—O181.0 (2)O4—Mo2—O874.00 (19)
O3—Mo1—O4166.5 (2)O6—Mo2—O5172.5 (2)
O2—Mo1—O491.1 (2)O7—Mo2—O583.7 (2)
O8—Mo1—O473.70 (19)O4—Mo2—O578.9 (2)
O1—Mo1—O479.16 (19)O8—Mo2—O579.59 (18)
Symmetry codes: (i) x+1, y, z+1; (ii) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WB···O7iii0.82 (6)2.39 (7)3.059 (8)141 (10)
O1W—H1WB···O5iii0.82 (6)2.47 (7)3.151 (9)142 (10)
O1W—H1WA···O2i0.82 (8)2.07 (6)2.809 (8)151 (11)
N1—H1A···O1Wiv0.861.932.727 (9)154.3
Symmetry codes: (i) x+1, y, z+1; (iii) x+3/2, y1/2, z+3/2; (iv) x1, y, z.
 

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