4,4′-[2,2-Dimethyl­propane-1,3-diyl­bis(nitrilo­methyl­idyne)]dibenzonitrile

Fun, H.-K.; Kargar, H.; Kia, R.

doi:10.1107/S1600536808018345

organic compounds

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ISSN: 2056-9890

Volume 64| Part 7| July 2008| Page o1308

doi:10.1107/S1600536808018345

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4,4′-[2,2-Dimethylpropane-1,3-diylbis(nitrilomethylidyne)]dibenzonitrile

Hoong-Kun Fun,^a ^* Hadi Kargar ^b ‡ and Reza Kia ^a §

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bDepartment of Chemistry, School of Science, Payame Noor University (PNU), Ardakan, Yazd, Iran
^*Correspondence e-mail: hkfun@usm.my

(Received 16 June 2008; accepted 17 June 2008; online 19 June 2008)

The title compound, C₂₁H₂₀N₄, is a bidentate Schiff base ligand. An intramolecular C—H⋯N hydrogen bond forms a five-membered ring, producing an S(5) ring motif. The cyano and imino [–C(H₂)—N=C–] functional groups are coplanar with the benzene ring in each half of the molecule. The packing of the molecules is controlled by C—H⋯π and π–π interactions [centroid-to-centroid distance = 3.6944 (8) Å].

Related literature

For related literature on hydrogen-bond motifs, see Bernstein et al. (1995 ). For values of bond lengths, see Allen et al. (1987 ). For related structures, see, for example: Li et al. (2005 ); Bomfim et al. (2005 ); Glidewell et al. (2005 , 2006 ); Sun et al. (2004 ); Habibi et al. (2007 ); Fun et al. (2008 ).

Experimental

Crystal data

C₂₁H₂₀N₄
M_r = 328.41
Monoclinic, P 2₁ /c
a = 6.3833 (2) Å
b = 34.0679 (8) Å
c = 8.5190 (2) Å
β = 100.654 (2)°
V = 1820.65 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 100.0 (1) K
0.42 × 0.20 × 0.19 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker 2005 ) T_min = 0.970, T_max = 0.986
21813 measured reflections
5329 independent reflections
3711 reflections with I > 2σ(I)
R_int = 0.046

Refinement

R[F² > 2σ(F²)] = 0.056
wR(F²) = 0.139
S = 1.04
5329 reflections
228 parameters
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C12–C17 benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C20—H20B⋯N2	0.96	2.57	2.923 (2)	102
C21—H21C⋯Cg1ⁱ	0.96	2.95	3.7193 (16)	138
Symmetry code: (i) x, y, z-1.

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808018345/at2578sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808018345/at2578Isup2.hkl

checkCIF report

Comment top

Schiff bases are one of most prevalent mixed-donor ligands in the field of coordination chemistry. They play an important role in the development of coordination chemistry related to catalysis and enzymatic reactions, magnetism, and supramolecular architectures. Structures of Schiff bases derived from substituted benzaldehydes and closely related to the title compound have been reported (Li et al., 2005; Bomfim et al., 2005; Glidewell et al., 2005, 2006; Sun et al., 2004; Habibi et al., 2007; Fun et al., 2008).

An intramolecular C—H···N hydrogen bond forms a five-membered ring, producing an S(5) ring motif (Bernstein et al., 1995). The bond lengths and angles in the molecule (Fig. 1) are within normal ranges (Allen et al., 1987). The cyano and imino (—C(H₂)—N═C—) functional groups are coplanar with the benzene ring in each half of the molcule. The torsion angles of C6—C7—N1—C8 and C12—C11—N2—C10 are -178.95 (13) and -179.43 (12)°, respectively. The packing of the molecule, (Fig. 2), is controlled by C—H···π and π–π interactions [centroid-centroid distance being 3.6944 (8) Å] (Table 1).

Related literature top

For related literature on hydrogen-bond motifs, see Bernstein et al. (1995). For values of bond lengths, see Allen et al. (1987). For related structures, see, for example: Li et al. (2005); Bomfim et al. (2005); Glidewell et al. (2005, 2006); Sun et al., (2004); Habibi et al. (2007); Fun et al., (2008).

Experimental top

The synthetic method has been described earlier (Fun et al., 2008). Single crystals suitable for X-ray diffraction were obtained by evaporation of an ethanol solution at room temperature.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures top

	Fig. 1. The molecular structure of the title compound with atom labels and 50% probability ellipsoids for non-H atoms. Intramolecular hydrogen bond is shown as a dashed line.
	Fig. 2. The crystal packing, viewed down the a axis, showing stacking of the benzene rings. Intramolecular H bonds are drawn as dashed lines.

4,4'-[2,2-Dimethylpropane-1,3-diylbis(nitrilomethylidyne)]dibenzonitrile top

Crystal data top

C₂₁H₂₀N₄	F(000) = 696
M_r = 328.41	D_x = 1.198 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3870 reflections
a = 6.3833 (2) Å	θ = 2.4–29.3°
b = 34.0679 (8) Å	µ = 0.07 mm⁻¹
c = 8.5190 (2) Å	T = 100 K
β = 100.654 (2)°	Block, colourless
V = 1820.65 (8) Å³	0.42 × 0.20 × 0.19 mm
Z = 4

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	5329 independent reflections
Radiation source: fine-focus sealed tube	3711 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.046
ϕ and ω scans	θ_max = 30.2°, θ_min = 1.2°
Absorption correction: multi-scan (SADABS; Bruker 2005)	h = −9→7
T_min = 0.970, T_max = 0.986	k = −48→48
21813 measured reflections	l = −12→12

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)] = 0.056	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.139	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.0568P)² + 0.5007P] where P = (F_o² + 2F_c²)/3
5329 reflections	(Δ/σ)_max < 0.001
228 parameters	Δρ_max = 0.24 e Å⁻³
0 restraints	Δρ_min = −0.20 e Å⁻³

Crystal data top

C₂₁H₂₀N₄	V = 1820.65 (8) Å³
M_r = 328.41	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 6.3833 (2) Å	µ = 0.07 mm⁻¹
b = 34.0679 (8) Å	T = 100 K
c = 8.5190 (2) Å	0.42 × 0.20 × 0.19 mm
β = 100.654 (2)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	5329 independent reflections
Absorption correction: multi-scan (SADABS; Bruker 2005)	3711 reflections with I > 2σ(I)
T_min = 0.970, T_max = 0.986	R_int = 0.046
21813 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.056	0 restraints
wR(F²) = 0.139	H-atom parameters constrained
S = 1.04	Δρ_max = 0.24 e Å⁻³
5329 reflections	Δρ_min = −0.20 e Å⁻³
228 parameters

Special details top

Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.

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
N1	0.8180 (2)	0.14310 (4)	1.22220 (14)	0.0240 (3)
N2	0.7297 (2)	0.07939 (4)	0.76666 (14)	0.0243 (3)
N3	0.1075 (3)	0.23585 (4)	1.75196 (17)	0.0346 (4)
N4	0.2208 (2)	0.01242 (4)	−0.06341 (15)	0.0278 (3)
C1	0.4959 (3)	0.16261 (4)	1.41380 (17)	0.0234 (3)
H1A	0.4844	0.1376	1.3689	0.028*
C2	0.3530 (3)	0.17457 (4)	1.50763 (17)	0.0243 (3)
H2A	0.2462	0.1576	1.5267	0.029*
C3	0.3698 (3)	0.21224 (4)	1.57374 (16)	0.0226 (3)
C4	0.5288 (3)	0.23767 (4)	1.54525 (17)	0.0254 (3)
H4A	0.5386	0.2628	1.5886	0.031*
C5	0.6719 (3)	0.22545 (4)	1.45229 (17)	0.0237 (3)
H5A	0.7789	0.2424	1.4335	0.028*
C6	0.6573 (3)	0.18785 (4)	1.38618 (16)	0.0211 (3)
C7	0.8171 (3)	0.17624 (4)	1.29000 (16)	0.0224 (3)
H7A	0.9230	0.1942	1.2785	0.027*
C8	0.9911 (3)	0.13680 (4)	1.13468 (17)	0.0245 (3)
H8A	1.0761	0.1147	1.1816	0.029*
H8B	1.0823	0.1598	1.1469	0.029*
C9	0.9149 (3)	0.12886 (4)	0.95573 (16)	0.0215 (3)
C10	0.7881 (3)	0.09017 (4)	0.93463 (16)	0.0232 (3)
H10A	0.8736	0.0694	0.9923	0.028*
H10B	0.6600	0.0930	0.9796	0.028*
C11	0.5405 (3)	0.06825 (4)	0.71580 (16)	0.0226 (3)
H11A	0.4445	0.0675	0.7857	0.027*
C12	0.4686 (3)	0.05644 (4)	0.54744 (16)	0.0212 (3)
C13	0.6067 (3)	0.05915 (4)	0.43861 (17)	0.0231 (3)
H13A	0.7442	0.0687	0.4719	0.028*
C14	0.5402 (3)	0.04776 (4)	0.28203 (17)	0.0233 (3)
H14A	0.6322	0.0497	0.2096	0.028*
C15	0.3345 (3)	0.03329 (4)	0.23295 (16)	0.0212 (3)
C16	0.1937 (3)	0.03068 (4)	0.33940 (17)	0.0256 (3)
H16A	0.0561	0.0212	0.3058	0.031*
C17	0.2624 (3)	0.04247 (4)	0.49654 (17)	0.0255 (3)
H17A	0.1694	0.0410	0.5685	0.031*
C18	0.2220 (3)	0.22512 (4)	1.67256 (18)	0.0270 (3)
C19	0.2687 (3)	0.02115 (4)	0.06860 (17)	0.0227 (3)
C20	1.1140 (3)	0.12547 (5)	0.88075 (19)	0.0287 (4)
H20A	1.1895	0.1500	0.8920	0.043*
H20B	1.0729	0.1192	0.7695	0.043*
H20C	1.2046	0.1051	0.9337	0.043*
C21	0.7745 (3)	0.16266 (4)	0.87814 (18)	0.0274 (4)
H21A	0.8507	0.1870	0.8986	0.041*
H21B	0.6466	0.1638	0.9222	0.041*
H21C	0.7381	0.1584	0.7650	0.041*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0265 (8)	0.0254 (6)	0.0199 (6)	−0.0005 (5)	0.0037 (5)	−0.0025 (5)
N2	0.0282 (8)	0.0233 (6)	0.0222 (6)	−0.0009 (5)	0.0070 (5)	−0.0030 (5)
N3	0.0335 (10)	0.0336 (8)	0.0379 (8)	0.0006 (6)	0.0099 (7)	−0.0063 (6)
N4	0.0268 (8)	0.0305 (7)	0.0270 (6)	−0.0013 (6)	0.0071 (6)	−0.0028 (5)
C1	0.0282 (9)	0.0186 (7)	0.0219 (7)	−0.0002 (6)	0.0011 (6)	−0.0015 (5)
C2	0.0257 (9)	0.0222 (7)	0.0244 (7)	−0.0010 (6)	0.0028 (6)	0.0011 (5)
C3	0.0230 (9)	0.0247 (7)	0.0193 (6)	0.0030 (6)	0.0015 (6)	−0.0003 (5)
C4	0.0319 (10)	0.0203 (7)	0.0234 (7)	0.0002 (6)	0.0034 (6)	−0.0040 (5)
C5	0.0275 (9)	0.0212 (7)	0.0222 (7)	−0.0033 (6)	0.0037 (6)	−0.0006 (5)
C6	0.0236 (9)	0.0214 (7)	0.0168 (6)	0.0013 (6)	0.0002 (6)	0.0006 (5)
C7	0.0232 (9)	0.0225 (7)	0.0206 (6)	−0.0012 (6)	0.0019 (6)	0.0007 (5)
C8	0.0250 (9)	0.0235 (7)	0.0244 (7)	0.0015 (6)	0.0029 (6)	−0.0025 (5)
C9	0.0232 (9)	0.0200 (7)	0.0220 (6)	0.0002 (6)	0.0059 (6)	−0.0009 (5)
C10	0.0275 (9)	0.0234 (7)	0.0191 (6)	0.0005 (6)	0.0056 (6)	−0.0007 (5)
C11	0.0286 (10)	0.0193 (7)	0.0218 (7)	0.0010 (6)	0.0095 (6)	0.0000 (5)
C12	0.0277 (9)	0.0152 (6)	0.0214 (6)	0.0012 (6)	0.0063 (6)	0.0000 (5)
C13	0.0234 (9)	0.0226 (7)	0.0240 (7)	−0.0016 (6)	0.0058 (6)	−0.0023 (5)
C14	0.0269 (9)	0.0225 (7)	0.0226 (7)	−0.0003 (6)	0.0101 (6)	−0.0013 (5)
C15	0.0266 (9)	0.0161 (6)	0.0211 (6)	0.0020 (6)	0.0051 (6)	−0.0004 (5)
C16	0.0256 (9)	0.0258 (7)	0.0257 (7)	−0.0031 (6)	0.0054 (6)	−0.0004 (6)
C17	0.0274 (10)	0.0289 (8)	0.0227 (7)	−0.0025 (7)	0.0107 (6)	0.0002 (6)
C18	0.0300 (10)	0.0236 (7)	0.0268 (7)	0.0002 (7)	0.0037 (7)	−0.0020 (6)
C19	0.0240 (9)	0.0199 (7)	0.0253 (7)	0.0007 (6)	0.0075 (6)	0.0000 (5)
C20	0.0284 (10)	0.0290 (8)	0.0309 (8)	−0.0013 (7)	0.0112 (7)	−0.0014 (6)
C21	0.0306 (10)	0.0242 (7)	0.0274 (7)	0.0020 (7)	0.0053 (7)	0.0009 (6)

Geometric parameters (Å, º) top

N1—C7	1.2687 (18)	C9—C21	1.532 (2)
N1—C8	1.459 (2)	C9—C10	1.539 (2)
N2—C11	1.264 (2)	C10—H10A	0.9700
N2—C10	1.4576 (17)	C10—H10B	0.9700
N3—C18	1.143 (2)	C11—C12	1.4786 (19)
N4—C19	1.1486 (19)	C11—H11A	0.9300
C1—C2	1.380 (2)	C12—C17	1.391 (2)
C1—C6	1.395 (2)	C12—C13	1.396 (2)
C1—H1A	0.9300	C13—C14	1.379 (2)
C2—C3	1.398 (2)	C13—H13A	0.9300
C2—H2A	0.9300	C14—C15	1.392 (2)
C3—C4	1.389 (2)	C14—H14A	0.9300
C3—C18	1.444 (2)	C15—C16	1.392 (2)
C4—C5	1.379 (2)	C15—C19	1.446 (2)
C4—H4A	0.9300	C16—C17	1.389 (2)
C5—C6	1.396 (2)	C16—H16A	0.9300
C5—H5A	0.9300	C17—H17A	0.9300
C6—C7	1.476 (2)	C20—H20A	0.9600
C7—H7A	0.9300	C20—H20B	0.9600
C8—C9	1.536 (2)	C20—H20C	0.9600
C8—H8A	0.9700	C21—H21A	0.9600
C8—H8B	0.9700	C21—H21B	0.9600
C9—C20	1.529 (2)	C21—H21C	0.9600

C7—N1—C8	115.55 (14)	N2—C10—H10B	109.4
C11—N2—C10	117.85 (13)	C9—C10—H10B	109.4
C2—C1—C6	120.21 (13)	H10A—C10—H10B	108.0
C2—C1—H1A	119.9	N2—C11—C12	121.33 (14)
C6—C1—H1A	119.9	N2—C11—H11A	119.3
C1—C2—C3	119.66 (15)	C12—C11—H11A	119.3
C1—C2—H2A	120.2	C17—C12—C13	119.54 (13)
C3—C2—H2A	120.2	C17—C12—C11	120.10 (14)
C4—C3—C2	120.41 (14)	C13—C12—C11	120.36 (15)
C4—C3—C18	119.30 (14)	C14—C13—C12	120.32 (15)
C2—C3—C18	120.29 (15)	C14—C13—H13A	119.8
C5—C4—C3	119.66 (14)	C12—C13—H13A	119.8
C5—C4—H4A	120.2	C13—C14—C15	119.65 (14)
C3—C4—H4A	120.2	C13—C14—H14A	120.2
C4—C5—C6	120.45 (15)	C15—C14—H14A	120.2
C4—C5—H5A	119.8	C16—C15—C14	120.88 (13)
C6—C5—H5A	119.8	C16—C15—C19	120.37 (15)
C1—C6—C5	119.60 (14)	C14—C15—C19	118.75 (14)
C1—C6—C7	122.45 (13)	C17—C16—C15	118.87 (16)
C5—C6—C7	117.95 (14)	C17—C16—H16A	120.6
N1—C7—C6	123.57 (15)	C15—C16—H16A	120.6
N1—C7—H7A	118.2	C16—C17—C12	120.73 (14)
C6—C7—H7A	118.2	C16—C17—H17A	119.6
N1—C8—C9	113.72 (13)	C12—C17—H17A	119.6
N1—C8—H8A	108.8	N3—C18—C3	178.73 (19)
C9—C8—H8A	108.8	N4—C19—C15	177.74 (17)
N1—C8—H8B	108.8	C9—C20—H20A	109.5
C9—C8—H8B	108.8	C9—C20—H20B	109.5
H8A—C8—H8B	107.7	H20A—C20—H20B	109.5
C20—C9—C21	109.99 (12)	C9—C20—H20C	109.5
C20—C9—C8	107.02 (13)	H20A—C20—H20C	109.5
C21—C9—C8	110.40 (12)	H20B—C20—H20C	109.5
C20—C9—C10	110.25 (12)	C9—C21—H21A	109.5
C21—C9—C10	109.88 (13)	C9—C21—H21B	109.5
C8—C9—C10	109.26 (11)	H21A—C21—H21B	109.5
N2—C10—C9	111.35 (11)	C9—C21—H21C	109.5
N2—C10—H10A	109.4	H21A—C21—H21C	109.5
C9—C10—H10A	109.4	H21B—C21—H21C	109.5

C6—C1—C2—C3	0.6 (2)	C21—C9—C10—N2	64.21 (16)
C1—C2—C3—C4	0.2 (2)	C8—C9—C10—N2	−174.52 (13)
C1—C2—C3—C18	−179.80 (14)	C10—N2—C11—C12	−179.43 (12)
C2—C3—C4—C5	−0.6 (2)	N2—C11—C12—C17	176.85 (14)
C18—C3—C4—C5	179.36 (15)	N2—C11—C12—C13	−3.1 (2)
C3—C4—C5—C6	0.3 (2)	C17—C12—C13—C14	−0.6 (2)
C2—C1—C6—C5	−0.8 (2)	C11—C12—C13—C14	179.35 (13)
C2—C1—C6—C7	178.55 (14)	C12—C13—C14—C15	−0.4 (2)
C4—C5—C6—C1	0.4 (2)	C13—C14—C15—C16	0.9 (2)
C4—C5—C6—C7	−179.02 (14)	C13—C14—C15—C19	−179.39 (13)
C8—N1—C7—C6	−178.95 (13)	C14—C15—C16—C17	−0.5 (2)
C1—C6—C7—N1	1.7 (2)	C19—C15—C16—C17	179.79 (14)
C5—C6—C7—N1	−178.92 (14)	C15—C16—C17—C12	−0.4 (2)
C7—N1—C8—C9	−119.58 (14)	C13—C12—C17—C16	1.0 (2)
N1—C8—C9—C20	176.60 (12)	C11—C12—C17—C16	−178.95 (13)
N1—C8—C9—C21	56.91 (17)	C4—C3—C18—N3	−19 (9)
N1—C8—C9—C10	−64.04 (16)	C2—C3—C18—N3	161 (9)
C11—N2—C10—C9	−134.31 (14)	C16—C15—C19—N4	149 (5)
C20—C9—C10—N2	−57.17 (17)	C14—C15—C19—N4	−31 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C20—H20B···N2	0.96	2.57	2.923 (2)	102
C21—H21C···Cg1ⁱ	0.96	2.95	3.7193 (16)	138

Symmetry code: (i) x, y, z−1.

Experimental details

Crystal data
Chemical formula	C₂₁H₂₀N₄
M_r	328.41
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	6.3833 (2), 34.0679 (8), 8.5190 (2)
β (°)	100.654 (2)
V (Å³)	1820.65 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.07
Crystal size (mm)	0.42 × 0.20 × 0.19

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker 2005)
T_min, T_max	0.970, 0.986
No. of measured, independent and observed [I > 2σ(I)] reflections	21813, 5329, 3711
R_int	0.046
(sin θ/λ)_max (Å⁻¹)	0.707

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.056, 0.139, 1.04
No. of reflections	5329
No. of parameters	228
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.20

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C20—H20B···N2	0.9600	2.5700	2.923 (2)	102.00
C21—H21C···Cg1ⁱ	0.9600	2.95	3.7193 (16)	138

Symmetry code: (i) x, y, z−1.

Footnotes

‡Additional correspondence author, e-mail: hadi_kargar@yahoo.com.

§Additional correspondence author, e-mail: zsrkk@yahoo.com.

Acknowledgements

HKF and RK thank the Malaysian Government and Universiti sains Malaysia for Science Fund Grant No. 305/PFIZIK/613312. RK thanks Universiti Sains Malaysia for a post-doctoral research fellowship. HK thanks PNU for financial support.

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