metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2414-3146

catena-Poly[bis­­(4-methyl­benzyl­ammonium) [[di­bromido­cadmate(II)]-di-μ-bromido]]

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aDepartment of Physics, Government Arts College (Autonomous), Kumbakonam 612 002, Tamilnadu, India, and bPrincipal, Kunthavai Naacchiyaar Government Arts College for Women (Autonomous), Thanjavur 613 007, Tamilnadu, India
*Correspondence e-mail: thiruvalluvar.a@gmail.com

Edited by M. Weil, Vienna University of Technology, Austria (Received 14 May 2018; accepted 25 May 2018; online 31 May 2018)

The asymmetric unit of the centrosymmetric organic–inorganic hybrid salt, {(C8H12N)2[CdBr4]}n, comprises of one 4-methyl­benzyl­ammonium cation and one half of a disordered [CdBr4]2− anion that is completed by application of mirror symmetry. The resulting CdBr6 octa­hedra share edges to form 2[CdBr4/2Br2/2]2− layers parallel to the ac plane. Cations and anions are connected by N—H⋯Br and C—H⋯Br hydrogen bonds. No ππ stacking inter­actions are observed between the benzene rings, but C—H⋯π inter­actions towards them are found.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

Non-linear optical materials are suitable candidates for photonics and optoelectronic industries. Applications such as frequency conversion, optical switching etc., can be well provided using these materials (Marcy et al., 1992[Marcy, H. O., Warren, L. F., Webb, M. S., Ebbers, C. A., Velsko, S. P., Kennedy, G. C. & Catella, G. C. (1992). Appl. Opt. 31, 5051-5060.]). Organic non-linear optical crystals with conjugated π electrons usually show a higher non-linear optical response in comparison with inorganic crystals. However, due to weak inter­molecular inter­actions, organic crystals frequently have a lower mechanical and thermal stability, which does not allow them to be used in high-power laser applications. On the other hand, inorganic crystals have better mechanical and thermal stability, but they are not efficient in producing large non-linear optical effects due to the presence of ionic or covalent bonds (Jiang & Fang, 1999[Jiang, M. & Fang, Q. (1999). Adv. Mater. 11, 1147-1151.]). To overcome the disadvantage of organic and inorganic crystals in this respect, organic–inorganic hybrid crystals may be used by combining their beneficial properties. Moreover, these organic–inorganic hybrid crystals often possess greater third order non-linear optical properties. Herein we report the synthesis and crystal structure of a new organic–inorganic hybrid compound, bis­(4-methyl­benzyl­ammonium) tetra­bromido­cadmate.

The asymmetric unit of the the title compound consists of one half of a tetra­bromido­cadmate anion, [CdBr4]2−, and one 4-methyl­benzyl­ammonium cation, (C8H12N)+, as shown in Fig. 1[link]. The cadmium cation is located on a mirror plane (Wyckoff position 4c) and its resulting coordination environment is distorted octa­hedral. The three unique bromine ligands are disordered around the mirror plane. Individual CdBr6 octa­hedra share four corners to form polymeric 2[CdBr4/2Br2/2]2– layers extending parallel to the ac plane (Fig. 2[link]).

[Figure 1]
Figure 1
A view of the asymmetric unit showing the atom numbering and displacement ellipsoids drawn at the 30% probability level. Only the major part of the disordered anion is displayed. Dashed lines indicate hydrogen-bonding inter­action.
[Figure 2]
Figure 2
Packing diagram of the title compound viewed down the c axis, showing the alternate stacking of organic and inorganic layers. Dashed lines indicate the hydrogen-bonding network.

The 4-methyl­benzyl­ammonium cations are sandwiched between the tetra­bromido­cadmate layers (Fig. 2[link]). They are linked among themselves by weak (meth­yl)C—H⋯π inter­actions (Fig. 3[link], Table 1[link]). The crystal packing is assured by a complex hydrogen-bonding system, involving the positively charged ammonium groups and to a minor extent the methylene group as donor groups, and the bromide ligands of the anionic layers as acceptor groups (Table 1[link]). Bond lengths and angles within the cation have their usual values as reported for the isotypic compound bis­(4-methyl­benzyl­ammonium) tetra­chlorido­cadmate (Kefi et al., 2011[Kefi, R., Zeller, M., Lefebvre, F. & Ben Nasr, C. (2011). Int. J. Inorg. Chem. Article ID, 274073, 1-7.]). However, the anion in the latter shows no disorder.

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C1–C6 benzene ring.

D—H⋯A D—H H⋯A DA D—H⋯A
C8—H8B⋯Br1′i 0.97 3.03 3.707 (8) 128
N1—H1B⋯Br3i 0.85 (2) 2.79 (4) 3.521 (7) 145 (5)
N1—H1B⋯Br1′ 0.85 (2) 3.11 (4) 3.597 (7) 119 (3)
N1—H1B⋯Br3′i 0.85 (2) 2.83 (4) 3.59 (2) 150 (5)
N1—H1B⋯Br3′ii 0.85 (2) 3.01 (4) 3.74 (2) 147 (5)
N1—H1C⋯Br2i 0.86 (2) 2.84 (3) 3.604 (6) 149 (4)
N1—H1C⋯Br3iii 0.86 (2) 3.05 (4) 3.647 (7) 129 (4)
N1—H1C⋯Br2′i 0.86 (2) 2.63 (3) 3.371 (12) 145 (4)
N1—H1C⋯Br3′iii 0.86 (2) 2.82 (4) 3.43 (2) 130 (4)
N1—H1C⋯Br3′iv 0.86 (2) 2.97 (5) 3.59 (3) 132 (4)
N1—H1A⋯Br1iii 0.85 (2) 3.06 (3) 3.825 (8) 150 (4)
N1—H1A⋯Br2 0.85 (2) 2.96 (5) 3.579 (7) 131 (5)
N1—H1A⋯Br2′ 0.85 (2) 2.57 (5) 3.239 (13) 136 (5)
C7—H7CCg1v 0.96 2.95 3.824 (5) 152
Symmetry codes: (i) x, y, z+1; (ii) [x, -y+{\script{1\over 2}}, z+1]; (iii) [x+{\script{1\over 2}}, y, -z+{\script{1\over 2}}]; (iv) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (v) -x+1, -y+1, -z+1.
[Figure 3]
Figure 3
Partial packing showing the C7—H7Cπ inter­action involving the C1–C6 benzene ring.

Synthesis and crystallization

Bis(4-methyl­benzyl­ammonium) tetra­bromido­cadmate(II) single crystals were grown by the solution growth solvent evaporation method. A mixture of 4-methyl­benzyl­amine (2 mmol, 1.27 ml) and cadmium bromide (CdBr2) (1 mmol, 1.36 g) was dissolved in diluted hydro­bromic acid (HBr) (10 ml, 1 M). The resultant solution was stirred using a magnetic stirrer for 3 h and kept in a constant temperature bath at 311 K. After 15 d colourless single crystals of the title compound were harvested.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. The anionic structure shows disorder of all bromine atoms relative to the mirror plane, with occupancies of 0.720 (11) for the major part and 0.280 (11) for the minor part (denoted by primed characters). Similarity restraints (SIMU) were used to model the disorder.

Table 2
Experimental details

Crystal data
Chemical formula (C8H12N)2[CdBr4]
Mr 676.41
Crystal system, space group Orthorhombic, Pnma
Temperature (K) 296
a, b, c (Å) 11.2127 (5), 32.8269 (15), 5.6279 (3)
V3) 2071.51 (17)
Z 4
Radiation type Mo Kα
μ (mm−1) 8.77
Crystal size (mm) 0.15 × 0.10 × 0.10
 
Data collection
Diffractometer Bruker Kappa APEXII CCD
Absorption correction Multi-scan (SADABS; Bruker, 2004[Bruker (2004). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.389, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 37568, 2984, 1970
Rint 0.069
(sin θ/λ)max−1) 0.697
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.088, 1.05
No. of reflections 2984
No. of parameters 142
No. of restraints 24
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.81, −1.00
Computer programs: APEX2 and SAINT (Bruker, 2004[Bruker (2004). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT2018 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2018 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]), PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]), Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Structural data


Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXT2018 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012), PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2018 (Sheldrick, 2015b), PLATON (Spek, 2009) and publCIF (Westrip, 2010).

catena-Poly[bis(4-methylbenzylammonium) [[dibromidocadmate(II)]-di-µ-bromido]] top
Crystal data top
(C8H12N)2[CdBr4]Dx = 2.169 Mg m3
Mr = 676.41Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, PnmaCell parameters from 6170 reflections
a = 11.2127 (5) Åθ = 2.5–27.5°
b = 32.8269 (15) ŵ = 8.77 mm1
c = 5.6279 (3) ÅT = 296 K
V = 2071.51 (17) Å3Block, colourless
Z = 40.15 × 0.10 × 0.10 mm
F(000) = 1288
Data collection top
Bruker Kappa APEXII CCD
diffractometer
2984 independent reflections
Radiation source: fine-focus sealed tube1970 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.069
ω and φ scanθmax = 29.7°, θmin = 2.5°
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
h = 1415
Tmin = 0.389, Tmax = 0.746k = 4545
37568 measured reflectionsl = 77
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.037 w = 1/[σ2(Fo2) + (0.0277P)2 + 5.1831P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.088(Δ/σ)max = 0.001
S = 1.05Δρmax = 0.81 e Å3
2984 reflectionsΔρmin = 1.00 e Å3
142 parametersExtinction correction: SHELXL2018 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
24 restraintsExtinction coefficient: 0.0082 (2)
Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
C10.4324 (4)0.44964 (12)0.3872 (7)0.0372 (9)
C20.5437 (4)0.43565 (14)0.3195 (8)0.0456 (10)
H20.5793470.4460110.1830980.055*
C30.6027 (4)0.40631 (14)0.4526 (9)0.0472 (11)
H30.6770090.3969890.4032560.057*
C40.5526 (4)0.39089 (12)0.6566 (8)0.0412 (10)
C50.4428 (5)0.40513 (14)0.7255 (8)0.0472 (11)
H50.4079200.3951400.8635710.057*
C60.3835 (4)0.43407 (14)0.5926 (8)0.0459 (11)
H60.3091330.4432350.6426220.055*
C70.3682 (5)0.48134 (15)0.2413 (8)0.0520 (11)
H7A0.2907100.4861810.3078850.078*
H7B0.3599380.4718080.0808590.078*
H7C0.4132620.5062170.2421790.078*
C80.6147 (5)0.35857 (15)0.8012 (9)0.0597 (14)
H8A0.7002470.3618690.7839220.072*
H8B0.5952270.3624800.9675290.072*
Cd10.34125 (3)0.2500000.23592 (6)0.02551 (12)
Br10.3312 (5)0.32949 (4)0.2275 (4)0.0651 (6)0.720 (11)
Br20.5909 (3)0.2500000.2364 (9)0.0747 (17)0.720 (11)
Br30.3399 (6)0.2500000.2602 (13)0.0559 (8)0.720 (11)
Br1'0.3826 (6)0.32979 (8)0.2391 (5)0.0347 (11)0.280 (11)
Br2'0.5958 (6)0.2653 (3)0.247 (2)0.0274 (13)0.140 (6)
Br3'0.3238 (17)0.2539 (8)0.275 (4)0.0559 (8)0.140 (6)
N10.5829 (5)0.31794 (13)0.7335 (10)0.0681 (13)
H1B0.5098 (18)0.3121 (17)0.719 (8)0.082*
H1C0.614 (4)0.3004 (15)0.828 (7)0.082*
H1A0.617 (4)0.3150 (18)0.599 (5)0.082*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.044 (2)0.030 (2)0.038 (2)0.0022 (17)0.0081 (18)0.0000 (17)
C20.048 (3)0.041 (2)0.048 (2)0.002 (2)0.002 (2)0.0096 (19)
C30.039 (2)0.043 (3)0.059 (3)0.001 (2)0.001 (2)0.004 (2)
C40.051 (2)0.027 (2)0.045 (2)0.0041 (19)0.017 (2)0.0010 (17)
C50.064 (3)0.042 (2)0.035 (2)0.002 (2)0.002 (2)0.0024 (19)
C60.051 (3)0.040 (3)0.047 (3)0.008 (2)0.003 (2)0.002 (2)
C70.057 (3)0.045 (2)0.053 (3)0.010 (2)0.009 (2)0.006 (2)
C80.083 (4)0.037 (2)0.059 (3)0.007 (2)0.030 (3)0.005 (2)
Cd10.02616 (19)0.02671 (18)0.02367 (19)0.0000.00016 (16)0.000
Br10.074 (2)0.0250 (4)0.0961 (8)0.0072 (5)0.0031 (9)0.0004 (4)
Br20.0194 (7)0.158 (5)0.0468 (9)0.0000.0007 (7)0.000
Br30.0405 (19)0.110 (2)0.0168 (10)0.0000.0038 (11)0.000
Br1'0.0312 (19)0.0227 (8)0.0502 (14)0.0024 (8)0.0081 (11)0.0006 (8)
Br2'0.0191 (19)0.019 (2)0.044 (3)0.0048 (17)0.001 (2)0.008 (3)
Br3'0.0405 (19)0.110 (2)0.0168 (10)0.0000.0038 (11)0.000
N10.078 (3)0.031 (2)0.095 (4)0.003 (2)0.018 (3)0.011 (3)
Geometric parameters (Å, º) top
C1—C61.378 (6)Cd1—Br12.6124 (11)
C1—C21.383 (6)Cd1—Br1i2.6125 (11)
C1—C71.508 (6)Cd1—Br1'2.660 (2)
C2—C31.388 (6)Cd1—Br1'i2.660 (2)
C2—H20.9300Cd1—Br3'ii2.77 (2)
C3—C41.374 (6)Cd1—Br3'iii2.77 (2)
C3—H30.9300Cd1—Br32.792 (8)
C4—C51.373 (7)Cd1—Br22.799 (3)
C4—C81.507 (6)Cd1—Br2'iv2.800 (7)
C5—C61.380 (6)Cd1—Br2'v2.800 (7)
C5—H50.9300Cd1—Br2v2.812 (3)
C6—H60.9300Cd1—Br3ii2.836 (8)
C7—H7A0.9600Br2'—Br2'i1.008 (19)
C7—H7B0.9600Br3'—Br3'i0.26 (6)
C7—H7C0.9600N1—H1B0.846 (18)
C8—N11.432 (6)N1—H1C0.857 (18)
C8—H8A0.9700N1—H1A0.853 (18)
C8—H8B0.9700
C6—C1—C2117.8 (4)Br1i—Cd1—Br3'iii88.2 (6)
C6—C1—C7121.6 (4)Br1—Cd1—Br388.95 (5)
C2—C1—C7120.6 (4)Br1i—Cd1—Br388.95 (5)
C1—C2—C3120.8 (4)Br1—Cd1—Br292.47 (13)
C1—C2—H2119.6Br1i—Cd1—Br292.47 (13)
C3—C2—H2119.6Br3—Cd1—Br290.36 (17)
C4—C3—C2120.8 (4)Br1—Cd1—Br2'iv97.9 (3)
C4—C3—H3119.6Br1i—Cd1—Br2'iv77.20 (18)
C2—C3—H3119.6Br3—Cd1—Br2'iv91.6 (3)
C5—C4—C3118.5 (4)Br2—Cd1—Br2'iv169.44 (19)
C5—C4—C8120.1 (5)Br1—Cd1—Br2'v77.20 (18)
C3—C4—C8121.4 (5)Br1i—Cd1—Br2'v97.9 (3)
C4—C5—C6120.9 (4)Br3—Cd1—Br2'v91.6 (3)
C4—C5—H5119.5Br2—Cd1—Br2'v169.44 (19)
C6—C5—H5119.5Br1—Cd1—Br2v87.59 (12)
C1—C6—C5121.2 (4)Br1i—Cd1—Br2v87.59 (12)
C1—C6—H6119.4Br3—Cd1—Br2v92.87 (17)
C5—C6—H6119.4Br2—Cd1—Br2v176.769 (15)
C1—C7—H7A109.5Br1—Cd1—Br3ii91.03 (5)
C1—C7—H7B109.5Br1i—Cd1—Br3ii91.03 (5)
H7A—C7—H7B109.5Br3—Cd1—Br3ii179.4 (3)
C1—C7—H7C109.5Br2—Cd1—Br3ii90.26 (17)
H7A—C7—H7C109.5Br2v—Cd1—Br3ii86.51 (17)
H7B—C7—H7C109.5Cd1—Br2—Cd1vi176.9 (2)
N1—C8—C4113.4 (4)Cd1—Br3—Cd1vii179.4 (3)
N1—C8—H8A108.9Br2'i—Br2'—Cd179.99 (18)
C4—C8—H8A108.9Cd1vi—Br2'—Cd1159.6 (4)
N1—C8—H8B108.9Br3'i—Br3'—Cd187.5 (5)
C4—C8—H8B108.9Cd1vii—Br3'—Cd1170.5 (8)
H8A—C8—H8B107.7C8—N1—H1B119 (4)
Br1—Cd1—Br1i174.6 (3)C8—N1—H1C111 (4)
Br1—Cd1—Br1'i172.4 (3)H1B—N1—H1C108 (3)
Br1i—Cd1—Br1'i12.59 (4)C8—N1—H1A103 (4)
Br1—Cd1—Br3'ii88.2 (6)H1B—N1—H1A109 (3)
Br1i—Cd1—Br3'ii93.5 (6)H1C—N1—H1A107 (3)
Br1—Cd1—Br3'iii93.5 (6)
C6—C1—C2—C31.2 (7)C8—C4—C5—C6178.6 (4)
C7—C1—C2—C3179.7 (4)C2—C1—C6—C50.7 (7)
C1—C2—C3—C40.9 (7)C7—C1—C6—C5179.9 (4)
C2—C3—C4—C50.1 (7)C4—C5—C6—C10.1 (7)
C2—C3—C4—C8179.1 (4)C5—C4—C8—N187.8 (6)
C3—C4—C5—C60.4 (7)C3—C4—C8—N191.2 (6)
Symmetry codes: (i) x, y+1/2, z; (ii) x, y, z+1; (iii) x, y+1/2, z+1; (iv) x1/2, y+1/2, z+1/2; (v) x1/2, y, z+1/2; (vi) x+1/2, y, z+1/2; (vii) x, y, z1.
Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the C1–C6 benzene ring.
D—H···AD—HH···AD···AD—H···A
C8—H8B···Br1ii0.973.033.707 (8)128
N1—H1B···Br3ii0.85 (2)2.79 (4)3.521 (7)145 (5)
N1—H1B···Br10.85 (2)3.11 (4)3.597 (7)119 (3)
N1—H1B···Br3ii0.85 (2)2.83 (4)3.59 (2)150 (5)
N1—H1B···Br3iii0.85 (2)3.01 (4)3.74 (2)147 (5)
N1—H1C···Br2ii0.86 (2)2.84 (3)3.604 (6)149 (4)
N1—H1C···Br3vi0.86 (2)3.05 (4)3.647 (7)129 (4)
N1—H1C···Br2ii0.86 (2)2.63 (3)3.371 (12)145 (4)
N1—H1C···Br3vi0.86 (2)2.82 (4)3.43 (2)130 (4)
N1—H1C···Br3viii0.86 (2)2.97 (5)3.59 (3)132 (4)
N1—H1A···Br1vi0.85 (2)3.06 (3)3.825 (8)150 (4)
N1—H1A···Br20.85 (2)2.96 (5)3.579 (7)131 (5)
N1—H1A···Br20.85 (2)2.57 (5)3.239 (13)136 (5)
C7—H7C···Cg1ix0.962.953.824 (5)152
Symmetry codes: (ii) x, y, z+1; (iii) x, y+1/2, z+1; (vi) x+1/2, y, z+1/2; (viii) x+1/2, y+1/2, z+1/2; (ix) x+1, y+1, z+1.
 

Acknowledgements

The authors are thankful to the Sophisticated Analytical Instrument Facility (SAIF), IITM, Chennai 600 036, Tamilnadu, India for the single-crystal X-ray diffraction data.

Funding information

Funding for this research was provided by: Council of Scientific and Industrial Research (CSIR), New Delhi, India [grant No. 03(1301)13/EMR II to CR].

References

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