{2-[(3-Bromo­benzyl­idene)amino]-5-chloro­phen­yl}(phen­yl)methanone

Aslam, M.; Anis, I.; Afza, N.; Safder, M.; Yousuf, S.

doi:10.1107/S1600536812004667

organic compounds

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ISSN: 2056-9890

Volume 68| Part 3| March 2012| Page o645

doi:10.1107/S1600536812004667

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{2-[(3-Bromobenzylidene)amino]-5-chlorophenyl}(phenyl)methanone

M. Aslam,^a,^b ‡ I. Anis,^b N. Afza,^a M. Safder ^c and S. Yousuf ^c ^*

^aPharmaceutical Research Centre, PCSIR Laboratories Complex, Karachi, Pakistan, ^bDepartment of Chemistry, University of Karachi, Karachi, Pakistan, and ^cHEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
^*Correspondence e-mail: dr.sammer.yousuf@gmail.com

(Received 8 January 2012; accepted 3 February 2012; online 10 February 2012)

In the title compound, C₂₀H₁₃BrClNO, the azomethine double bond [C=N = 1.246 (4) Å] adopts an E conformation. The bromo- and chlorophenyl rings are inclined to one another by 13.70 (11)°, and form dihedral angles of 76.68 (10) and 74.24 (7)°, respectively, with the phenyl ring. In the crystal, molecules are linked by C—H⋯O hydrogen bonds to form double stranded chains propagating along the b-axis direction.

Related literature

For background information and preparation of Schiff bases, see: Khan et al. (2009 ); Aslam et al. (2011a ,b ); Zeb & Yousuf (2011 ). For the crystal structures of related Schiff bases, see: Aslam et al. (2011a,b); Cox et al. (2008 ).

Experimental

Crystal data

C₂₀H₁₃BrClNO
M_r = 398.67
Orthorhombic, P b c a
a = 16.2068 (12) Å
b = 7.8839 (6) Å
c = 27.262 (2) Å
V = 3483.4 (5) Å³
Z = 8
Mo Kα radiation
μ = 2.52 mm⁻¹
T = 273 K
0.52 × 0.21 × 0.15 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ) T_min = 0.354, T_max = 0.704
19261 measured reflections
3243 independent reflections
1931 reflections with I > 2σ(I)
R_int = 0.056

Refinement

R[F² > 2σ(F²)] = 0.045
wR(F²) = 0.115
S = 1.01
3243 reflections
217 parameters
H-atom parameters constrained
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.64 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C12—H12A⋯O1ⁱ	0.93	2.44	3.346 (4)	166
C17—H17A⋯O1ⁱⁱ	0.93	2.51	3.428 (5)	168
Symmetry codes: (i) -x, -y-1, -z+1; (ii) x, y+1, z.

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL, PARST (Nardelli, 1995 ) and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812004667/pv2506sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812004667/pv2506Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812004667/pv2506Isup3.cml

checkCIF report

Comment top

The title compound was prepared as a part of our ongoing reasearch on schiff bases (Khan et al., 2009; Aslam et al., 2011a,b; Zeb & Yousuf, 2011).

In the title compound (Fig. 1), the azomethine double bond (C═N, 1.246 (4) Å) adopts an E configuration with torsion angle C6—C7—N1—C8 174.9 (3)°. The bond lengths and angle are similar as in other structurally realted compounds (Aslam et al., 2011a,b; Cox et al., 2008). In the crystal structure the molecules are arranged in parallel sheets along the b-axis via C—H···O type intermolecular hydrogen bonds (Fig. 2).

Related literature top

For background information and preparation of Schiff bases, see: Khan et al. (2009); Aslam et al. (2011a,b); Zeb & Yousuf (2011). For the crystal structures of related Schiff bases, see: Aslam et al. (2011a,b); Cox et al. (2008).

Experimental top

A mixture of 3-bromobenzaldehyde (1 mol) and 2-amino-5-chlorobenzophenone (1 mol) in ethanol (50 ml) along with 3 drops of conc. H₂SO₄ was refluxed for 5 h at 343 K. After cooling, the mixture was concentrated to one third under reduced pressure. The concentrated reaction mixture was kept at room temperature and orange red crystals were obtained after five days. The crystalline product was collected, washed with methanol and dried to afford the title compound in 87% yield. Slow evaporation of a methanol solution afforded yellow crystals suitable for single-crystal X-ray diffraction studies. All chemicals were purchased from Sigma-Aldrich.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), PARST (Nardelli, 1995) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as small spheres of arbitrary radius.
	Fig. 2. A view of the C—-H···O hydrogen bonds (dotted lines) in the crystal structure of the title compound. H atoms non-participating in hydrogen- bonding were omitted for clarity.

{2-[(3-Bromobenzylidene)-amino]-5-chlorophenyl}(phenyl)methanone top

Crystal data top

C₂₀H₁₃BrClNO	F(000) = 1600
M_r = 398.67	D_x = 1.520 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 2145 reflections
a = 16.2068 (12) Å	θ = 2.5–20.5°
b = 7.8839 (6) Å	µ = 2.52 mm⁻¹
c = 27.262 (2) Å	T = 273 K
V = 3483.4 (5) Å³	Block, yellow
Z = 8	0.52 × 0.21 × 0.15 mm

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	1931 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.056
ω scan	θ_max = 25.5°, θ_min = 1.5°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −19→19
T_min = 0.354, T_max = 0.704	k = −9→9
19261 measured reflections	l = −33→33
3243 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.115	H-atom parameters constrained
S = 1.01	w = 1/[σ²(F_o²) + (0.0377P)² + 3.0254P] where P = (F_o² + 2F_c²)/3
3243 reflections	(Δ/σ)_max < 0.001
217 parameters	Δρ_max = 0.40 e Å⁻³
0 restraints	Δρ_min = −0.64 e Å⁻³

Crystal data top

C₂₀H₁₃BrClNO	V = 3483.4 (5) Å³
M_r = 398.67	Z = 8
Orthorhombic, Pbca	Mo Kα radiation
a = 16.2068 (12) Å	µ = 2.52 mm⁻¹
b = 7.8839 (6) Å	T = 273 K
c = 27.262 (2) Å	0.52 × 0.21 × 0.15 mm

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	3243 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2000)	1931 reflections with I > 2σ(I)
T_min = 0.354, T_max = 0.704	R_int = 0.056
19261 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.045	0 restraints
wR(F²) = 0.115	H-atom parameters constrained
S = 1.01	Δρ_max = 0.40 e Å⁻³
3243 reflections	Δρ_min = −0.64 e Å⁻³
217 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.

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

	x	y	z	U_iso*/U_eq
Br1	0.08907 (4)	0.01989 (9)	0.238025 (19)	0.1197 (3)
Cl1	0.20842 (7)	−0.43108 (16)	0.61666 (4)	0.0784 (4)
O1	0.04701 (14)	−0.5034 (3)	0.44146 (10)	0.0608 (7)
N1	0.21723 (16)	−0.2133 (4)	0.40923 (10)	0.0480 (7)
C1	0.1977 (2)	−0.0784 (5)	0.31387 (12)	0.0564 (10)
H1B	0.1496	−0.1092	0.3302	0.068*
C2	0.1939 (3)	−0.0077 (5)	0.26789 (13)	0.0657 (11)
C3	0.2627 (3)	0.0425 (5)	0.24302 (14)	0.0756 (13)
H3A	0.2585	0.0912	0.2121	0.091*
C4	0.3383 (3)	0.0196 (6)	0.26466 (15)	0.0806 (14)
H4A	0.3859	0.0535	0.2484	0.097*
C5	0.3439 (2)	−0.0533 (6)	0.31041 (14)	0.0720 (12)
H5A	0.3955	−0.0691	0.3246	0.086*
C6	0.2739 (2)	−0.1034 (5)	0.33568 (12)	0.0508 (9)
C7	0.2795 (2)	−0.1732 (5)	0.38504 (12)	0.0517 (9)
H7A	0.3314	−0.1883	0.3990	0.062*
C8	0.22119 (19)	−0.2687 (4)	0.45845 (11)	0.0421 (8)
C9	0.2910 (2)	−0.2620 (5)	0.48817 (12)	0.0501 (9)
H9A	0.3406	−0.2225	0.4753	0.060*
C10	0.2873 (2)	−0.3135 (5)	0.53632 (12)	0.0534 (9)
H10A	0.3342	−0.3089	0.5559	0.064*
C11	0.2143 (2)	−0.3715 (5)	0.55527 (12)	0.0508 (9)
C12	0.1447 (2)	−0.3843 (4)	0.52657 (12)	0.0485 (9)
H12A	0.0960	−0.4277	0.5396	0.058*
C13	0.14765 (18)	−0.3321 (4)	0.47808 (11)	0.0400 (8)
C14	0.07325 (18)	−0.3588 (5)	0.44606 (11)	0.0431 (8)
C15	0.03203 (19)	−0.2139 (4)	0.42183 (11)	0.0427 (8)
C16	0.0429 (2)	−0.0504 (5)	0.43778 (14)	0.0581 (10)
H16A	0.0776	−0.0286	0.4642	0.070*
C18	−0.0479 (3)	0.0481 (6)	0.37522 (18)	0.0799 (13)
H18A	−0.0746	0.1369	0.3593	0.096*
C19	−0.0588 (2)	−0.1138 (6)	0.35928 (15)	0.0706 (12)
H19A	−0.0930	−0.1352	0.3326	0.085*
C17	0.0027 (2)	0.0814 (6)	0.41493 (17)	0.0750 (12)
H17A	0.0096	0.1920	0.4261	0.090*
C20	−0.0199 (2)	−0.2447 (5)	0.38228 (13)	0.0553 (9)
H20A	−0.0281	−0.3553	0.3714	0.066*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.1021 (4)	0.1846 (7)	0.0725 (4)	0.0117 (4)	−0.0213 (3)	0.0344 (4)
Cl1	0.0843 (7)	0.0996 (9)	0.0513 (5)	−0.0078 (6)	−0.0055 (5)	0.0208 (6)
O1	0.0485 (14)	0.0481 (16)	0.0857 (19)	−0.0091 (13)	−0.0129 (13)	−0.0014 (13)
N1	0.0384 (15)	0.059 (2)	0.0470 (16)	−0.0057 (14)	0.0019 (13)	0.0018 (14)
C1	0.060 (2)	0.066 (3)	0.043 (2)	−0.005 (2)	0.0067 (17)	−0.0031 (18)
C2	0.081 (3)	0.072 (3)	0.044 (2)	−0.002 (2)	−0.0013 (19)	−0.003 (2)
C3	0.109 (4)	0.077 (3)	0.041 (2)	−0.012 (3)	0.012 (2)	−0.001 (2)
C4	0.087 (4)	0.100 (4)	0.055 (2)	−0.028 (3)	0.024 (2)	−0.005 (2)
C5	0.060 (2)	0.099 (3)	0.056 (2)	−0.016 (2)	0.0112 (19)	−0.006 (2)
C6	0.054 (2)	0.056 (2)	0.0417 (18)	−0.0070 (18)	0.0043 (16)	−0.0089 (17)
C7	0.042 (2)	0.065 (3)	0.048 (2)	−0.0048 (18)	−0.0032 (17)	−0.0059 (18)
C8	0.0406 (18)	0.041 (2)	0.0442 (18)	−0.0010 (16)	−0.0002 (15)	−0.0022 (15)
C9	0.0437 (19)	0.056 (2)	0.051 (2)	−0.0079 (18)	−0.0024 (17)	0.0021 (17)
C10	0.046 (2)	0.063 (3)	0.051 (2)	−0.0029 (18)	−0.0121 (17)	0.0017 (18)
C11	0.055 (2)	0.051 (2)	0.0462 (19)	−0.0017 (19)	−0.0016 (17)	0.0047 (17)
C12	0.0436 (19)	0.049 (2)	0.053 (2)	−0.0058 (17)	0.0027 (16)	0.0057 (17)
C13	0.0356 (18)	0.0359 (19)	0.0483 (19)	−0.0002 (15)	−0.0017 (14)	0.0002 (15)
C14	0.0329 (17)	0.048 (2)	0.0480 (19)	−0.0035 (17)	0.0048 (14)	−0.0056 (17)
C15	0.0356 (17)	0.042 (2)	0.0503 (19)	0.0025 (16)	0.0022 (15)	−0.0020 (16)
C16	0.046 (2)	0.052 (3)	0.077 (3)	0.0043 (19)	−0.0056 (19)	−0.007 (2)
C18	0.066 (3)	0.076 (3)	0.098 (3)	0.016 (3)	−0.003 (3)	0.026 (3)
C19	0.059 (3)	0.084 (3)	0.069 (3)	0.007 (2)	−0.015 (2)	0.011 (2)
C17	0.065 (3)	0.052 (3)	0.109 (3)	0.006 (2)	0.002 (3)	−0.001 (2)
C20	0.050 (2)	0.061 (2)	0.055 (2)	0.0024 (19)	−0.0054 (18)	−0.0049 (19)

Geometric parameters (Å, º) top

Br1—C2	1.896 (4)	C9—H9A	0.9300
Cl1—C11	1.741 (3)	C10—C11	1.369 (5)
O1—C14	1.223 (4)	C10—H10A	0.9300
N1—C7	1.246 (4)	C11—C12	1.377 (4)
N1—C8	1.412 (4)	C12—C13	1.385 (4)
C1—C2	1.373 (5)	C12—H12A	0.9300
C1—C6	1.384 (5)	C13—C14	1.503 (4)
C1—H1B	0.9300	C14—C15	1.479 (5)
C2—C3	1.365 (6)	C15—C16	1.372 (5)
C3—C4	1.371 (6)	C15—C20	1.389 (4)
C3—H3A	0.9300	C16—C17	1.376 (5)
C4—C5	1.376 (6)	C16—H16A	0.9300
C4—H4A	0.9300	C18—C19	1.360 (6)
C5—C6	1.385 (5)	C18—C17	1.383 (6)
C5—H5A	0.9300	C18—H18A	0.9300
C6—C7	1.457 (5)	C19—C20	1.363 (5)
C7—H7A	0.9300	C19—H19A	0.9300
C8—C9	1.393 (4)	C17—H17A	0.9300
C8—C13	1.399 (4)	C20—H20A	0.9300
C9—C10	1.375 (4)

C7—N1—C8	123.0 (3)	C10—C11—C12	121.2 (3)
C2—C1—C6	119.4 (4)	C10—C11—Cl1	120.0 (3)
C2—C1—H1B	120.3	C12—C11—Cl1	118.8 (3)
C6—C1—H1B	120.3	C11—C12—C13	119.4 (3)
C3—C2—C1	122.3 (4)	C11—C12—H12A	120.3
C3—C2—Br1	119.1 (3)	C13—C12—H12A	120.3
C1—C2—Br1	118.6 (3)	C12—C13—C8	120.1 (3)
C2—C3—C4	118.6 (4)	C12—C13—C14	119.0 (3)
C2—C3—H3A	120.7	C8—C13—C14	120.7 (3)
C4—C3—H3A	120.7	O1—C14—C15	121.1 (3)
C3—C4—C5	120.2 (4)	O1—C14—C13	118.0 (3)
C3—C4—H4A	119.9	C15—C14—C13	120.9 (3)
C5—C4—H4A	119.9	C16—C15—C20	119.3 (3)
C4—C5—C6	121.1 (4)	C16—C15—C14	121.7 (3)
C4—C5—H5A	119.5	C20—C15—C14	119.0 (3)
C6—C5—H5A	119.5	C15—C16—C17	120.4 (4)
C1—C6—C5	118.4 (3)	C15—C16—H16A	119.8
C1—C6—C7	120.4 (3)	C17—C16—H16A	119.8
C5—C6—C7	121.1 (3)	C19—C18—C17	120.4 (4)
N1—C7—C6	122.3 (3)	C19—C18—H18A	119.8
N1—C7—H7A	118.9	C17—C18—H18A	119.8
C6—C7—H7A	118.9	C18—C19—C20	120.2 (4)
C9—C8—C13	118.9 (3)	C18—C19—H19A	119.9
C9—C8—N1	125.3 (3)	C20—C19—H19A	119.9
C13—C8—N1	115.8 (3)	C16—C17—C18	119.4 (4)
C10—C9—C8	120.6 (3)	C16—C17—H17A	120.3
C10—C9—H9A	119.7	C18—C17—H17A	120.3
C8—C9—H9A	119.7	C19—C20—C15	120.3 (4)
C11—C10—C9	119.8 (3)	C19—C20—H20A	119.8
C11—C10—H10A	120.1	C15—C20—H20A	119.8
C9—C10—H10A	120.1

C6—C1—C2—C3	−1.4 (6)	C11—C12—C13—C8	0.7 (5)
C6—C1—C2—Br1	178.4 (3)	C11—C12—C13—C14	175.4 (3)
C1—C2—C3—C4	0.7 (6)	C9—C8—C13—C12	1.1 (5)
Br1—C2—C3—C4	−179.0 (3)	N1—C8—C13—C12	−177.9 (3)
C2—C3—C4—C5	0.3 (7)	C9—C8—C13—C14	−173.5 (3)
C3—C4—C5—C6	−0.6 (7)	N1—C8—C13—C14	7.5 (4)
C2—C1—C6—C5	1.0 (6)	C12—C13—C14—O1	−57.2 (4)
C2—C1—C6—C7	178.1 (3)	C8—C13—C14—O1	117.5 (4)
C4—C5—C6—C1	0.0 (6)	C12—C13—C14—C15	121.4 (3)
C4—C5—C6—C7	−177.1 (4)	C8—C13—C14—C15	−63.9 (4)
C8—N1—C7—C6	−174.9 (3)	O1—C14—C15—C16	159.3 (3)
C1—C6—C7—N1	0.3 (6)	C13—C14—C15—C16	−19.3 (5)
C5—C6—C7—N1	177.3 (4)	O1—C14—C15—C20	−19.9 (5)
C7—N1—C8—C9	10.0 (5)	C13—C14—C15—C20	161.6 (3)
C7—N1—C8—C13	−171.1 (3)	C20—C15—C16—C17	0.1 (5)
C13—C8—C9—C10	−1.4 (5)	C14—C15—C16—C17	−179.0 (3)
N1—C8—C9—C10	177.5 (3)	C17—C18—C19—C20	−0.1 (6)
C8—C9—C10—C11	−0.1 (5)	C15—C16—C17—C18	−0.9 (6)
C9—C10—C11—C12	2.0 (6)	C19—C18—C17—C16	0.9 (6)
C9—C10—C11—Cl1	−178.2 (3)	C18—C19—C20—C15	−0.8 (6)
C10—C11—C12—C13	−2.3 (5)	C16—C15—C20—C19	0.7 (5)
Cl1—C11—C12—C13	177.9 (3)	C14—C15—C20—C19	179.9 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C12—H12A···O1ⁱ	0.93	2.44	3.346 (4)	166
C17—H17A···O1ⁱⁱ	0.93	2.51	3.428 (5)	168

Symmetry codes: (i) −x, −y−1, −z+1; (ii) x, y+1, z.

Experimental details

Crystal data
Chemical formula	C₂₀H₁₃BrClNO
M_r	398.67
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	273
a, b, c (Å)	16.2068 (12), 7.8839 (6), 27.262 (2)
V (Å³)	3483.4 (5)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	2.52
Crystal size (mm)	0.52 × 0.21 × 0.15

Data collection
Diffractometer	Bruker SMART APEX CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2000)
T_min, T_max	0.354, 0.704
No. of measured, independent and observed [I > 2σ(I)] reflections	19261, 3243, 1931
R_int	0.056
(sin θ/λ)_max (Å⁻¹)	0.606

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.045, 0.115, 1.01
No. of reflections	3243
No. of parameters	217
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.40, −0.64

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), PARST (Nardelli, 1995) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C12—H12A···O1ⁱ	0.93	2.44	3.346 (4)	166
C17—H17A···O1ⁱⁱ	0.93	2.51	3.428 (5)	168

Symmetry codes: (i) −x, −y−1, −z+1; (ii) x, y+1, z.

Footnotes

‡Additional correspondence author, e-mail: maslamchemist@hotmail.com.

Acknowledgements

MA express his gratitude to the Pakistan Council of Scientific and Industrial Research Laboratories, Karachi, the Department of Chemistry, University of Karachi, and the HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, for providing financial support, research facilities and X-ray diffraction facilities, respectively.

References

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