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

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ISSN: 2414-3146

Bis(4-methyl­benzyl­ammonium) tetra­bromido­zincate

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 19 April 2018; accepted 26 April 2018; online 1 May 2018)

The structure of the non-centrosymmetric organic–inorganic hybrid material, (C8H12N)2[ZnBr4], consists of two 4-methyl­benzyl­ammonium cations and one [ZnBr4]2− anion connected by N—H⋯Br and C—H⋯Br hydrogen bonds. The ZnII cation has a slightly distorted tetra­hedral coordination environment. No ππ stacking inter­actions between the phenyl­ene rings but C—H⋯π inter­actions towards them are observed. The structure was refined as a two-component inversion twin.

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

Structure description

Non-linear optical (NLO) materials play a vital role in the field of photonics as they generate coherent radiation at new frequencies that are not available with conventional laser sources. Organic crystals with non-linear optical properties frequently have poor mechanical and thermal properties due to the presence of weak van der Waals inter­actions and hydrogen bonds (Dolbecq et al., 2010[Dolbecq, A., Dumas, E., Mayer, C. R. & Mialane, P. (2010). Chem. Rev. 110, 6009-6048.]), whereas inorganic crystals possess good mechanical and thermal properties but have low NLO properties due to the presence of strong covalent or ionic inter­actions (Jiang & Fang, 1999[Jiang, M. & Fang, Q. (1999). Adv. Mater. 11, 1147-1151.]). Hence, attempts have been made by several groups to synthesize new organic–inorganic materials with NLO properties, combining the features of both organic and inorganic crystals. In this context we report here the synthesis and crystal structure of a new organic–inorganic hybrid compound, bis­(4-methyl­benzyl­ammonium) tetra­bromido­zincate. This salt crystallizes in the non-centrosymmetric space group type Pna21, and hence could be a potential candidate for second order non-linear optical properties.

The asymmetric unit of the title compound consists of an isolated tetra­bromido­zincate anion, [ZnBr4]2−, and two 4-methyl­benzyl­ammonium cations, (C8H12N)+, as shown in Fig. 1[link]. The Zn2+ cation is tetra­hedrally coordinated by four bromide ligands with Zn—Br bond lengths ranging from 2.399 (3) to 2.426 (3) Å, and Br—Zn—Br bond angles varying between 104.90 (12) and 113.82 (13)°.

[Figure 1]
Figure 1
A view of the asymmetric unit, showing the atom numbering and displacement ellipsoids drawn at the 30% probability level. Dashed lines indicate hydrogen-bonding inter­actions.

The crystal structure consists of layers of 4-methyl­benzyl­ammonium cations sandwiched between tetra­bromido­zincate layers extending parallel to the ac plane, as shown in Fig. 2[link]. The cationic units are linked into a two-dimensional network by two weak 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 lesser extent the methylene groups of the cations as donors and the bromide ligands of the isolated tetra­hedral [ZnBr4]2− units as acceptors (Table 1[link]), which reinforce the Coulombic inter­actions, as depicted in Fig. 2[link].

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 and Cg2 are the centroids of the C1–C6 and C9–C14 benzene rings, respectively.

D—H⋯A D—H H⋯A DA D—H⋯A
C2—H2⋯Cg2i 0.93 2.94 3.73 (3) 143
C14—H14⋯Cg1ii 0.93 2.94 3.72 (2) 143
C8—H8B⋯Br3iii 0.97 2.88 3.81 (2) 161
C8—H8A⋯Br1iv 0.97 2.91 3.82 (3) 157
C16—H16B⋯Br4v 0.97 3.03 3.90 (3) 150
N1—H1A⋯Br1vi 0.89 2.58 3.427 (17) 159
N1—H1B⋯Br2iv 0.89 2.92 3.626 (17) 137
N1—H1B⋯Br4vi 0.89 2.94 3.613 (16) 133
N1—H1C⋯Br2vii 0.89 2.96 3.414 (17) 113
N1—H1C⋯Br4vii 0.89 2.82 3.563 (17) 142
N2—H2A⋯Br2 0.89 2.61 3.46 (2) 159
N2—H2B⋯Br3viii 0.89 2.47 3.34 (2) 166
N2—H2C⋯Br3 0.89 2.79 3.45 (3) 132
Symmetry codes: (i) x, y, z-1; (ii) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z+1]; (iii) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z]; (iv) [-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z-{\script{1\over 2}}]; (v) x, y, z+1; (vi) [-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z+{\script{1\over 2}}]; (vii) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z]; (viii) [-x+1, -y+1, z+{\script{1\over 2}}].
[Figure 2]
Figure 2
Packing diagram of the title compound viewed along the c axis, showing the alternate stacking, along the b axis, of organic and inorganic layers. Dashed lines indicate the hydrogen-bonding network.
[Figure 3]
Figure 3
Partial packing diagram showing the C2—H2⋯π inter­action involving the C9–C14 benzene ring and C14—H14⋯π inter­action involving the C1–C6 benzene ring.

Synthesis and crystallization

Bis(4-methyl­benzyl­ammonium) tetra­bromido­zincate single crystals were obtained by the solution growth solvent evaporation method. A mixture of 4-methyl­benzyl­amine (2 mmol, 2.73 ml), zinc bromide (1 mmol, 1.125 g) and HBr (2 mmol, 2.73 ml) in water (20 ml) was well stirred using a magnetic stirrer for 3 h and left to stand at room temperature. 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 refinement was finalized under consideration of inversion twinning.

Table 2
Experimental details

Crystal data
Chemical formula (C8H12N)2[ZnBr4]
Mr 629.38
Crystal system, space group Orthorhombic, Pna21
Temperature (K) 296
a, b, c (Å) 11.0702 (5), 26.0585 (13), 7.7302 (3)
V3) 2229.95 (17)
Z 4
Radiation type Mo Kα
μ (mm−1) 8.27
Crystal size (mm) 0.15 × 0.15 × 0.10
 
Data collection
Diffractometer Bruker Kappa APEX3 CMOS
Absorption correction Multi-scan (SADABS; Bruker, 2016[Bruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.309, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 27881, 3809, 3481
Rint 0.056
(sin θ/λ)max−1) 0.595
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.074, 0.156, 1.36
No. of reflections 3809
No. of parameters 213
No. of restraints 1
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 1.40, −1.01
Absolute structure Refined as an inversion twin
Absolute structure parameter 0.18 (6)
Computer programs: APEX3 and SAINT (Bruker, 2016[Bruker (2016). APEX3, 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: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); 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).

Bis(4-methylbenzylammonium) tetrabromidozincate top
Crystal data top
(C8H12N)2[ZnBr4]Dx = 1.875 Mg m3
Mr = 629.38Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pna21Cell parameters from 9620 reflections
a = 11.0702 (5) Åθ = 3.0–27.9°
b = 26.0585 (13) ŵ = 8.27 mm1
c = 7.7302 (3) ÅT = 296 K
V = 2229.95 (17) Å3Block, colourless
Z = 40.15 × 0.15 × 0.10 mm
F(000) = 1216
Data collection top
Bruker Kappa APEX3 CMOS
diffractometer
3809 independent reflections
Radiation source: fine-focus sealed tube3481 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.056
ω and φ scanθmax = 25.0°, θmin = 3.0°
Absorption correction: multi-scan
(SADABS; Bruker, 2016)
h = 1313
Tmin = 0.309, Tmax = 0.746k = 3030
27881 measured reflectionsl = 99
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.074 w = 1/[σ2(Fo2) + 30.013P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.156(Δ/σ)max < 0.001
S = 1.36Δρmax = 1.40 e Å3
3809 reflectionsΔρmin = 1.01 e Å3
213 parametersAbsolute structure: Refined as an inversion twin
1 restraintAbsolute structure parameter: 0.18 (6)
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.

Refinement. Refined as a two-component inversion twin All H atoms were placed geometrically and refined using a riding-model approximation, with C—H distances of 0.93 (aromatic), 0.97 (methylene) or 0.96 Å (methyl), and N—H distances of 0.89 Å. The torsion angles of the methyl and ammonium H atoms were allowed to refine to best fit the experimental electron density map, and the Uiso(H) values of the these groups were constrained to 1.5 times that of their carrier atom. For the other hydrogen atoms Uiso was set to 1.2 times Ueq of the carrier atom.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.732 (2)0.2421 (9)0.275 (3)0.057 (6)
C20.636 (2)0.2194 (11)0.189 (3)0.062 (7)
H20.5785120.2394230.1339590.074*
C30.628 (2)0.1666 (11)0.187 (3)0.056 (6)
H30.5652680.1513370.1250720.067*
C40.7094 (17)0.1354 (8)0.274 (3)0.042 (5)
C50.8041 (18)0.1597 (9)0.363 (3)0.046 (5)
H50.8597520.1401490.4248160.055*
C60.815 (2)0.2123 (9)0.359 (3)0.049 (6)
H60.8790080.2278820.4160050.059*
C70.742 (3)0.2997 (9)0.270 (5)0.103 (12)
H7A0.7769470.3101500.1617710.154*
H7B0.7933940.3109990.3631770.154*
H7C0.6637150.3146290.2826200.154*
C80.705 (2)0.0772 (9)0.264 (4)0.064 (7)
H8A0.6939240.0665880.1449810.077*
H8B0.7816940.0632200.3040810.077*
C90.5269 (16)0.3365 (8)0.850 (3)0.043 (5)
C100.617 (2)0.3142 (10)0.755 (4)0.070 (8)
H100.6853250.3328210.7253020.084*
C110.604 (3)0.2637 (12)0.702 (4)0.074 (8)
H110.6642170.2490890.6337430.088*
C120.506 (2)0.2346 (8)0.747 (3)0.053 (6)
C130.4183 (19)0.2578 (9)0.842 (4)0.060 (6)
H130.3501920.2390500.8725810.072*
C140.4268 (17)0.3085 (9)0.894 (3)0.046 (6)
H140.3650460.3234510.9583890.056*
C150.496 (3)0.1779 (11)0.695 (5)0.102 (12)
H15A0.4484710.1598210.7784110.153*
H15B0.5756880.1631740.6900460.153*
H15C0.4588510.1753360.5830380.153*
C160.540 (3)0.3897 (10)0.913 (3)0.070 (8)
H16A0.4689090.3987400.9784430.084*
H16B0.6087490.3909790.9911970.084*
N10.6051 (15)0.0563 (6)0.373 (2)0.044 (4)
H1A0.6195360.0631810.4834610.066*
H1B0.6002840.0224740.3579290.066*
H1C0.5356990.0707740.3410580.066*
N20.558 (2)0.4277 (8)0.780 (4)0.091 (9)
H2A0.6367140.4317340.7607900.136*
H2B0.5261850.4573490.8140560.136*
H2C0.5220540.4173940.6830120.136*
Zn10.74939 (18)0.47543 (8)0.3213 (3)0.0353 (5)
Br10.7646 (2)0.56660 (8)0.2732 (3)0.0568 (7)
Br20.8370 (2)0.44791 (8)0.5903 (3)0.0473 (5)
Br30.53762 (18)0.45225 (9)0.3424 (4)0.0561 (6)
Br40.8535 (2)0.43435 (8)0.0869 (3)0.0480 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.069 (16)0.056 (14)0.046 (13)0.003 (12)0.001 (12)0.008 (12)
C20.059 (16)0.079 (19)0.047 (14)0.010 (14)0.011 (12)0.017 (13)
C30.051 (14)0.081 (19)0.036 (12)0.014 (13)0.004 (11)0.011 (13)
C40.031 (10)0.049 (12)0.048 (12)0.003 (9)0.010 (9)0.008 (11)
C50.036 (10)0.072 (16)0.029 (12)0.008 (10)0.009 (9)0.004 (11)
C60.049 (12)0.058 (15)0.041 (13)0.014 (10)0.010 (11)0.008 (11)
C70.16 (3)0.032 (14)0.12 (3)0.010 (18)0.01 (3)0.023 (18)
C80.046 (13)0.063 (16)0.082 (18)0.003 (11)0.019 (13)0.008 (15)
C90.032 (10)0.051 (12)0.046 (12)0.004 (9)0.012 (11)0.004 (11)
C100.049 (14)0.071 (18)0.09 (2)0.004 (13)0.016 (14)0.025 (16)
C110.052 (16)0.10 (2)0.067 (18)0.026 (16)0.008 (14)0.021 (16)
C120.072 (16)0.044 (13)0.042 (13)0.011 (12)0.019 (12)0.008 (10)
C130.048 (12)0.068 (16)0.063 (14)0.013 (11)0.011 (15)0.005 (15)
C140.021 (10)0.082 (17)0.036 (12)0.000 (10)0.006 (8)0.007 (11)
C150.13 (3)0.056 (18)0.12 (3)0.014 (19)0.04 (2)0.020 (19)
C160.082 (19)0.073 (18)0.055 (15)0.012 (16)0.020 (15)0.013 (15)
N10.055 (11)0.044 (11)0.033 (11)0.006 (8)0.001 (8)0.008 (8)
N20.11 (2)0.046 (13)0.11 (2)0.011 (12)0.059 (17)0.013 (14)
Zn10.0342 (10)0.0417 (12)0.0299 (10)0.0021 (9)0.0006 (11)0.0021 (10)
Br10.0774 (17)0.0412 (12)0.0519 (13)0.0059 (11)0.0131 (12)0.0037 (10)
Br20.0508 (12)0.0592 (13)0.0319 (10)0.0072 (10)0.0009 (11)0.0076 (13)
Br30.0352 (10)0.0574 (14)0.0757 (15)0.0107 (9)0.0000 (13)0.0002 (14)
Br40.0532 (13)0.0552 (13)0.0355 (11)0.0062 (10)0.0054 (11)0.0036 (14)
Geometric parameters (Å, º) top
C1—C61.37 (3)C11—C121.37 (4)
C1—C21.38 (3)C11—H110.9300
C1—C71.51 (3)C12—C131.36 (3)
C2—C31.38 (4)C12—C151.54 (3)
C2—H20.9300C13—C141.39 (3)
C3—C41.39 (3)C13—H130.9300
C3—H30.9300C14—H140.9300
C4—C51.41 (3)C15—H15A0.9600
C4—C81.52 (3)C15—H15B0.9600
C5—C61.38 (3)C15—H15C0.9600
C5—H50.9300C16—N21.44 (3)
C6—H60.9300C16—H16A0.9700
C7—H7A0.9600C16—H16B0.9700
C7—H7B0.9600N1—H1A0.8900
C7—H7C0.9600N1—H1B0.8900
C8—N11.49 (3)N1—H1C0.8900
C8—H8A0.9700N2—H2A0.8900
C8—H8B0.9700N2—H2B0.8900
C9—C141.37 (3)N2—H2C0.8900
C9—C101.37 (3)Zn1—Br42.399 (3)
C9—C161.47 (3)Zn1—Br22.404 (3)
C10—C111.38 (4)Zn1—Br12.411 (3)
C10—H100.9300Zn1—Br32.426 (3)
C6—C1—C2120 (2)C13—C12—C11117 (2)
C6—C1—C7122 (3)C13—C12—C15122 (3)
C2—C1—C7118 (3)C11—C12—C15121 (3)
C3—C2—C1119 (2)C12—C13—C14122 (2)
C3—C2—H2120.5C12—C13—H13118.8
C1—C2—H2120.5C14—C13—H13118.8
C2—C3—C4122 (2)C9—C14—C13119 (2)
C2—C3—H3118.9C9—C14—H14120.3
C4—C3—H3118.9C13—C14—H14120.3
C3—C4—C5117 (2)C12—C15—H15A109.5
C3—C4—C8123 (2)C12—C15—H15B109.5
C5—C4—C8120 (2)H15A—C15—H15B109.5
C6—C5—C4120 (2)C12—C15—H15C109.5
C6—C5—H5120.0H15A—C15—H15C109.5
C4—C5—H5120.0H15B—C15—H15C109.5
C1—C6—C5121 (2)N2—C16—C9115 (2)
C1—C6—H6119.3N2—C16—H16A108.4
C5—C6—H6119.3C9—C16—H16A108.4
C1—C7—H7A109.5N2—C16—H16B108.4
C1—C7—H7B109.5C9—C16—H16B108.4
H7A—C7—H7B109.5H16A—C16—H16B107.5
C1—C7—H7C109.5C8—N1—H1A109.5
H7A—C7—H7C109.5C8—N1—H1B109.5
H7B—C7—H7C109.5H1A—N1—H1B109.5
N1—C8—C4111.0 (19)C8—N1—H1C109.5
N1—C8—H8A109.4H1A—N1—H1C109.5
C4—C8—H8A109.4H1B—N1—H1C109.5
N1—C8—H8B109.4C16—N2—H2A109.5
C4—C8—H8B109.4C16—N2—H2B109.5
H8A—C8—H8B108.0H2A—N2—H2B109.5
C14—C9—C10120 (2)C16—N2—H2C109.5
C14—C9—C16120 (2)H2A—N2—H2C109.5
C10—C9—C16120 (2)H2B—N2—H2C109.5
C9—C10—C11119 (2)Br4—Zn1—Br2109.05 (11)
C9—C10—H10120.3Br4—Zn1—Br1106.84 (11)
C11—C10—H10120.3Br2—Zn1—Br1113.53 (12)
C12—C11—C10122 (2)Br4—Zn1—Br3113.82 (13)
C12—C11—H11119.0Br2—Zn1—Br3104.90 (12)
C10—C11—H11119.0Br1—Zn1—Br3108.86 (11)
C6—C1—C2—C32 (4)C14—C9—C10—C111 (4)
C7—C1—C2—C3178 (3)C16—C9—C10—C11178 (2)
C1—C2—C3—C43 (4)C9—C10—C11—C122 (5)
C2—C3—C4—C51 (3)C10—C11—C12—C132 (4)
C2—C3—C4—C8177 (2)C10—C11—C12—C15177 (3)
C3—C4—C5—C61 (3)C11—C12—C13—C141 (4)
C8—C4—C5—C6174 (2)C15—C12—C13—C14178 (3)
C2—C1—C6—C50 (4)C10—C9—C14—C131 (4)
C7—C1—C6—C5180 (2)C16—C9—C14—C13177 (2)
C4—C5—C6—C12 (3)C12—C13—C14—C90 (4)
C3—C4—C8—N176 (3)C14—C9—C16—N2124 (3)
C5—C4—C8—N1109 (2)C10—C9—C16—N259 (4)
Hydrogen-bond geometry (Å, º) top
Cg1 and Cg2 are the centroids of the C1–C6 and C9–C14 benzene rings, respectively.
D—H···AD—HH···AD···AD—H···A
C2—H2···Cg2i0.932.943.73 (3)143
C14—H14···Cg1ii0.932.943.72 (2)143
C8—H8B···Br3iii0.972.883.81 (2)161
C8—H8A···Br1iv0.972.913.82 (3)157
C16—H16B···Br4v0.973.033.90 (3)150
N1—H1A···Br1vi0.892.583.427 (17)159
N1—H1B···Br2iv0.892.923.626 (17)137
N1—H1B···Br4vi0.892.943.613 (16)133
N1—H1C···Br2vii0.892.963.414 (17)113
N1—H1C···Br4vii0.892.823.563 (17)142
N2—H2A···Br20.892.613.46 (2)159
N2—H2B···Br3viii0.892.473.34 (2)166
N2—H2C···Br30.892.793.45 (3)132
Symmetry codes: (i) x, y, z1; (ii) x1/2, y+1/2, z+1; (iii) x+1/2, y+1/2, z; (iv) x+3/2, y1/2, z1/2; (v) x, y, z+1; (vi) x+3/2, y1/2, z+1/2; (vii) x1/2, y+1/2, z; (viii) x+1, y+1, z+1/2.
 

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 the Council of Scientific and Industrial Research (CSIR), New Delhi, India [grant No. 03(1301)13/EMR II to CR].

References

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