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

Aarthi, R.; Thiruvalluvar, A.A.; Ramachandra Raja, C.

doi:10.1107/S2414314618007800

metal-organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 3| Part 5| May 2018| x180780

https://doi.org/10.1107/S2414314618007800

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

Ramkumar Aarthi,^a Aravazhi Amalan Thiruvalluvar ^b ^* and Chidambaram Ramachandra Raja ^a

^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_∞[CdBr_4/2Br_2/2]²⁻ layers parallel to the ac plane. Cations and anions are connected by N—H⋯Br and C—H⋯Br hydrogen bonds. No π–π stacking interactions are observed between the benzene rings, but C—H⋯π interactions towards them are found.

Keywords: crystal structure; centrosymmetric organic–inorganic hybrid material; C—H⋯Br and N—H⋯Br hydrogen bondings; C—H⋯π interactions; disorder.

CCDC reference: 1845375

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 ). 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 ). 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. 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_∞[CdBr_4/2Br_2/2]^2– layers extending parallel to the ac plane (Fig. 2).

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
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). They are linked among themselves by weak (methyl)C—H⋯π interactions (Fig. 3, Table 1). 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). 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 ). 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	D⋯A	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—H7C⋯Cg1^v	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
Partial packing showing the C7—H7C⋯π 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. 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]
M_r	676.41
Crystal system, space group	Orthorhombic, Pnma
Temperature (K)	296
a, b, c (Å)	11.2127 (5), 32.8269 (15), 5.6279 (3)
V (Å³)	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 )
T_min, T_max	0.389, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	37568, 2984, 1970
R_int	0.069
(sin θ/λ)_max (Å⁻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
Δρ_max, Δρ_min (e Å⁻³)	0.81, −1.00
Computer programs: APEX2 and SAINT (Bruker, 2004), SHELXT2018 (Sheldrick, 2015a ), SHELXL2018 (Sheldrick, 2015b ), ORTEP-3 for Windows (Farrugia, 2012 ), PLATON (Spek, 2009 ), Mercury (Macrae et al., 2008 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1845375

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314618007800/wm4080sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314618007800/wm4080Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314618007800/wm4080Isup3.cdx

checkCIF report

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]	D_x = 2.169 Mg m⁻³
M_r = 676.41	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnma	Cell parameters from 6170 reflections
a = 11.2127 (5) Å	θ = 2.5–27.5°
b = 32.8269 (15) Å	µ = 8.77 mm⁻¹
c = 5.6279 (3) Å	T = 296 K
V = 2071.51 (17) Å³	Block, colourless
Z = 4	0.15 × 0.10 × 0.10 mm
F(000) = 1288

Data collection top

Bruker Kappa APEXII CCD diffractometer	2984 independent reflections
Radiation source: fine-focus sealed tube	1970 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.069
ω and φ scan	θ_max = 29.7°, θ_min = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −14→15
T_min = 0.389, T_max = 0.746	k = −45→45
37568 measured reflections	l = −7→7

Refinement top

Refinement on F²	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.037	w = 1/[σ²(F_o²) + (0.0277P)² + 5.1831P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.088	(Δ/σ)_max = 0.001
S = 1.05	Δρ_max = 0.81 e Å⁻³
2984 reflections	Δρ_min = −1.00 e Å⁻³
142 parameters	Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
24 restraints	Extinction 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

	x	y	z	U_iso*/U_eq	Occ. (<1)
C1	0.4324 (4)	0.44964 (12)	0.3872 (7)	0.0372 (9)
C2	0.5437 (4)	0.43565 (14)	0.3195 (8)	0.0456 (10)
H2	0.579347	0.446011	0.183098	0.055*
C3	0.6027 (4)	0.40631 (14)	0.4526 (9)	0.0472 (11)
H3	0.677009	0.396989	0.403256	0.057*
C4	0.5526 (4)	0.39089 (12)	0.6566 (8)	0.0412 (10)
C5	0.4428 (5)	0.40513 (14)	0.7255 (8)	0.0472 (11)
H5	0.407920	0.395140	0.863571	0.057*
C6	0.3835 (4)	0.43407 (14)	0.5926 (8)	0.0459 (11)
H6	0.309133	0.443235	0.642622	0.055*
C7	0.3682 (5)	0.48134 (15)	0.2413 (8)	0.0520 (11)
H7A	0.290710	0.486181	0.307885	0.078*
H7B	0.359938	0.471808	0.080859	0.078*
H7C	0.413262	0.506217	0.242179	0.078*
C8	0.6147 (5)	0.35857 (15)	0.8012 (9)	0.0597 (14)
H8A	0.700247	0.361869	0.783922	0.072*
H8B	0.595227	0.362480	0.967529	0.072*
Cd1	0.34125 (3)	0.250000	0.23592 (6)	0.02551 (12)
Br1	0.3312 (5)	0.32949 (4)	0.2275 (4)	0.0651 (6)	0.720 (11)
Br2	0.5909 (3)	0.250000	0.2364 (9)	0.0747 (17)	0.720 (11)
Br3	0.3399 (6)	0.250000	−0.2602 (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)
N1	0.5829 (5)	0.31794 (13)	0.7335 (10)	0.0681 (13)
H1B	0.5098 (18)	0.3121 (17)	0.719 (8)	0.082*
H1C	0.614 (4)	0.3004 (15)	0.828 (7)	0.082*
H1A	0.617 (4)	0.3150 (18)	0.599 (5)	0.082*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.044 (2)	0.030 (2)	0.038 (2)	0.0022 (17)	−0.0081 (18)	0.0000 (17)
C2	0.048 (3)	0.041 (2)	0.048 (2)	−0.002 (2)	0.002 (2)	0.0096 (19)
C3	0.039 (2)	0.043 (3)	0.059 (3)	0.001 (2)	−0.001 (2)	0.004 (2)
C4	0.051 (2)	0.027 (2)	0.045 (2)	−0.0041 (19)	−0.017 (2)	0.0010 (17)
C5	0.064 (3)	0.042 (2)	0.035 (2)	0.002 (2)	0.002 (2)	0.0024 (19)
C6	0.051 (3)	0.040 (3)	0.047 (3)	0.008 (2)	0.003 (2)	−0.002 (2)
C7	0.057 (3)	0.045 (2)	0.053 (3)	0.010 (2)	−0.009 (2)	0.006 (2)
C8	0.083 (4)	0.037 (2)	0.059 (3)	0.007 (2)	−0.030 (3)	0.005 (2)
Cd1	0.02616 (19)	0.02671 (18)	0.02367 (19)	0.000	0.00016 (16)	0.000
Br1	0.074 (2)	0.0250 (4)	0.0961 (8)	0.0072 (5)	0.0031 (9)	0.0004 (4)
Br2	0.0194 (7)	0.158 (5)	0.0468 (9)	0.000	−0.0007 (7)	0.000
Br3	0.0405 (19)	0.110 (2)	0.0168 (10)	0.000	−0.0038 (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)	0.000	−0.0038 (11)	0.000
N1	0.078 (3)	0.031 (2)	0.095 (4)	0.003 (2)	−0.018 (3)	0.011 (3)

Geometric parameters (Å, º) top

C1—C6	1.378 (6)	Cd1—Br1	2.6124 (11)
C1—C2	1.383 (6)	Cd1—Br1ⁱ	2.6125 (11)
C1—C7	1.508 (6)	Cd1—Br1'	2.660 (2)
C2—C3	1.388 (6)	Cd1—Br1'ⁱ	2.660 (2)
C2—H2	0.9300	Cd1—Br3'ⁱⁱ	2.77 (2)
C3—C4	1.374 (6)	Cd1—Br3'ⁱⁱⁱ	2.77 (2)
C3—H3	0.9300	Cd1—Br3	2.792 (8)
C4—C5	1.373 (7)	Cd1—Br2	2.799 (3)
C4—C8	1.507 (6)	Cd1—Br2'^iv	2.800 (7)
C5—C6	1.380 (6)	Cd1—Br2'^v	2.800 (7)
C5—H5	0.9300	Cd1—Br2^v	2.812 (3)
C6—H6	0.9300	Cd1—Br3ⁱⁱ	2.836 (8)
C7—H7A	0.9600	Br2'—Br2'ⁱ	1.008 (19)
C7—H7B	0.9600	Br3'—Br3'ⁱ	0.26 (6)
C7—H7C	0.9600	N1—H1B	0.846 (18)
C8—N1	1.432 (6)	N1—H1C	0.857 (18)
C8—H8A	0.9700	N1—H1A	0.853 (18)
C8—H8B	0.9700

C6—C1—C2	117.8 (4)	Br1ⁱ—Cd1—Br3'ⁱⁱⁱ	88.2 (6)
C6—C1—C7	121.6 (4)	Br1—Cd1—Br3	88.95 (5)
C2—C1—C7	120.6 (4)	Br1ⁱ—Cd1—Br3	88.95 (5)
C1—C2—C3	120.8 (4)	Br1—Cd1—Br2	92.47 (13)
C1—C2—H2	119.6	Br1ⁱ—Cd1—Br2	92.47 (13)
C3—C2—H2	119.6	Br3—Cd1—Br2	90.36 (17)
C4—C3—C2	120.8 (4)	Br1—Cd1—Br2'^iv	97.9 (3)
C4—C3—H3	119.6	Br1ⁱ—Cd1—Br2'^iv	77.20 (18)
C2—C3—H3	119.6	Br3—Cd1—Br2'^iv	91.6 (3)
C5—C4—C3	118.5 (4)	Br2—Cd1—Br2'^iv	169.44 (19)
C5—C4—C8	120.1 (5)	Br1—Cd1—Br2'^v	77.20 (18)
C3—C4—C8	121.4 (5)	Br1ⁱ—Cd1—Br2'^v	97.9 (3)
C4—C5—C6	120.9 (4)	Br3—Cd1—Br2'^v	91.6 (3)
C4—C5—H5	119.5	Br2—Cd1—Br2'^v	169.44 (19)
C6—C5—H5	119.5	Br1—Cd1—Br2^v	87.59 (12)
C1—C6—C5	121.2 (4)	Br1ⁱ—Cd1—Br2^v	87.59 (12)
C1—C6—H6	119.4	Br3—Cd1—Br2^v	92.87 (17)
C5—C6—H6	119.4	Br2—Cd1—Br2^v	176.769 (15)
C1—C7—H7A	109.5	Br1—Cd1—Br3ⁱⁱ	91.03 (5)
C1—C7—H7B	109.5	Br1ⁱ—Cd1—Br3ⁱⁱ	91.03 (5)
H7A—C7—H7B	109.5	Br3—Cd1—Br3ⁱⁱ	179.4 (3)
C1—C7—H7C	109.5	Br2—Cd1—Br3ⁱⁱ	90.26 (17)
H7A—C7—H7C	109.5	Br2^v—Cd1—Br3ⁱⁱ	86.51 (17)
H7B—C7—H7C	109.5	Cd1—Br2—Cd1^vi	176.9 (2)
N1—C8—C4	113.4 (4)	Cd1—Br3—Cd1^vii	179.4 (3)
N1—C8—H8A	108.9	Br2'ⁱ—Br2'—Cd1	79.99 (18)
C4—C8—H8A	108.9	Cd1^vi—Br2'—Cd1	159.6 (4)
N1—C8—H8B	108.9	Br3'ⁱ—Br3'—Cd1	87.5 (5)
C4—C8—H8B	108.9	Cd1^vii—Br3'—Cd1	170.5 (8)
H8A—C8—H8B	107.7	C8—N1—H1B	119 (4)
Br1—Cd1—Br1ⁱ	174.6 (3)	C8—N1—H1C	111 (4)
Br1—Cd1—Br1'ⁱ	172.4 (3)	H1B—N1—H1C	108 (3)
Br1ⁱ—Cd1—Br1'ⁱ	12.59 (4)	C8—N1—H1A	103 (4)
Br1—Cd1—Br3'ⁱⁱ	88.2 (6)	H1B—N1—H1A	109 (3)
Br1ⁱ—Cd1—Br3'ⁱⁱ	93.5 (6)	H1C—N1—H1A	107 (3)
Br1—Cd1—Br3'ⁱⁱⁱ	93.5 (6)

C6—C1—C2—C3	1.2 (7)	C8—C4—C5—C6	−178.6 (4)
C7—C1—C2—C3	−179.7 (4)	C2—C1—C6—C5	−0.7 (7)
C1—C2—C3—C4	−0.9 (7)	C7—C1—C6—C5	−179.9 (4)
C2—C3—C4—C5	0.1 (7)	C4—C5—C6—C1	−0.1 (7)
C2—C3—C4—C8	179.1 (4)	C5—C4—C8—N1	87.8 (6)
C3—C4—C5—C6	0.4 (7)	C3—C4—C8—N1	−91.2 (6)

Symmetry codes: (i) x, −y+1/2, z; (ii) x, y, z+1; (iii) x, −y+1/2, z+1; (iv) x−1/2, −y+1/2, −z+1/2; (v) x−1/2, y, −z+1/2; (vi) x+1/2, y, −z+1/2; (vii) x, y, z−1.

Hydrogen-bond geometry (Å, º) top

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

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8B···Br1′ⁱⁱ	0.97	3.03	3.707 (8)	128
N1—H1B···Br3ⁱⁱ	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′ⁱⁱ	0.85 (2)	2.83 (4)	3.59 (2)	150 (5)
N1—H1B···Br3′ⁱⁱⁱ	0.85 (2)	3.01 (4)	3.74 (2)	147 (5)
N1—H1C···Br2ⁱⁱ	0.86 (2)	2.84 (3)	3.604 (6)	149 (4)
N1—H1C···Br3^vi	0.86 (2)	3.05 (4)	3.647 (7)	129 (4)
N1—H1C···Br2′ⁱⁱ	0.86 (2)	2.63 (3)	3.371 (12)	145 (4)
N1—H1C···Br3′^vi	0.86 (2)	2.82 (4)	3.43 (2)	130 (4)
N1—H1C···Br3′^viii	0.86 (2)	2.97 (5)	3.59 (3)	132 (4)
N1—H1A···Br1^vi	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—H7C···Cg1^ix	0.96	2.95	3.824 (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].

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