Bis[2-(1H-benzimidazol-2-yl)phenolato]copper(II) dimethyl­formamide disolvate

In the crystal structure of the title compound, [Cu(C₁₃H₉N₂O)₂]·2C₃H₇NO, the Cu^II ion is coordinated by two N and two O atoms from two deprotonated 2-(1H-benzimidazol-2-yl)phenol ligands to give a four-coordinate distorted tetra­hedral geometry. The Cu atom lies on a twofold rotation axis.

Key indicators

• Single-crystal X-ray study
• T = 273 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.043
• wR factor = 0.115
• Data-to-parameter ratio = 16.9

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S1. Comment

Complexes with imidazole-related and imidazole-containing ligands serve as models for metalloproteins and have been studied extensively in recent years (Sundburg & Martin, 1974; Maekawa et al., 1989; Lorosch & Haase, 1985; Benzekri et al., 1991; Crane et al., 1995; Mckee et al., 1981). The bidentate ligand 2-(1H-benzimidazol-2-yl)phenol (Hpbm) is an N,O-bidentate ligand that contains two donor groups of relevance to the coordination of metal centers in biological systems, namely phenolate (tyrosine) and imidazole (histidine). In the present paper, we report the synthesis and crystal structure of the dimethylformamide (DMF) disolvate of the Cu^II complex with two deprotonated ligands, [Cu(pbm)₂]·2DMF, (I).

The structure of (I) is shown in Fig. 1. The molecules of the copper complex are disposed about a twofold symmetry axis. The Cu—O and Cu—N bond lengths are 1.8904 (2) and 1.9487 (2) Å, respectively (Table 1). The Cu atoms adopt a distorted four-coordinate environment, with a dihedral angle of 47.3 (3)° between the two coordinating ligands (as defined by the Cu—N—O planes). The O—Cu—O and N—Cu—N bond angles are 146.96 (2) and 145.50 (2)°, respectively.

The complex forms an N—H···O hydrogen bond between the N2 proton and the carbonyl O atom of the DMF solvent (Table 2).

S2. Experimental

The ligand 2-(1H-benzimidazol-2-yl)phenol was synthesized as follows: a solution of salicylaldehyde (2.32 g, 19 mmol) in EtOH (15 ml) was added to a solution of o-phenylenediamine (2.05 g, 19 mmol) in EtOH (25 ml) with stirring and heating. The resulting orange solution was refluxed for 1 h and then cooled to room temperature. After standing in a refridgerator for 12 h, the orange solution was filtered and ether (15 ml) was added to the solution. Standing in the open air for 2 d yielded orange crystalline needles which were filtered off and air-dried (yield: 60%). The elemental analysis results were completely in agreement with the structural composition of the ligand (m.p. 524–525 K). The title complex was obtained as follows: to a filtered solution of HL (0.420 g, 2 mmol) and KOH (0.112 g, 2 mmol) in methanol (60 ml) at room temperature was added a filtered solution of Cu(OAc)₂·H₂O (0.200 g, 1 mmol) in methanol (20 ml) with stirring. The product began to crystallize from the solution almost immediately. After 1 h, the brown solid was filtered off, washed with methanol and air-dried. X-ray quality single crystals were grown by the vapour diffusion of ether into a DMF solution of the solid above to yield green crystals of the title complex. Analysis calculated for C₃₂H₃₂CuN₆O₄ (%): C 61.18, H 5.13, N 13.38; found (%): C 60.96, H 5.10, N 13.35.

S3. Refinement

C-bound H atoms were treated as riding, with C—H = 0.96 Å and U_iso(H) = 1.5U_eq(C). N-bound H atoms were refined with U_iso(H) = 1.2U_eq(N) and N—H = 0.86 Å.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2000); program(s) used to refine structure: SHELXL97 (Sheldrick, 2000); molecular graphics: SHELXTL/PC (Sheldrick, 1999); software used to prepare material for publication: SHELXTL/PC.

Figures

Fig. 1. A view of the molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level for non-H atoms. H atoms are shown as small spheres of arbitrary radii [symmetry code: (i) −x + 1, y, −z + 1/2].

Bis[2-(1H-benzimidazol-2-yl)phenolato]copper(II) dimethylformamide disolvate

Crystal data

[Cu(C13H9N2O)2]·2C3H7NO	Dx = 1.422 Mg m^−3
Mr = 628.18	Melting point: not measured K
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2ab	Cell parameters from 1684 reflections
a = 16.1964 (9) Å	θ = 2.5–22.3°
b = 8.0465 (4) Å	µ = 0.79 mm^−1
c = 22.5076 (13) Å	T = 273 K
V = 2933.3 (3) Å^3	Flake, green
Z = 4	0.32 × 0.21 × 0.06 mm
F(000) = 1308

Data collection

Bruker SMART CCD area-detector diffractometer	3323 independent reflections
Radiation source: fine-focus sealed tube	2098 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.051
ω scans	θmax = 27.4°, θmin = 2.2°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −20→15
Tmin = 0.785, Tmax = 0.954	k = −10→10
12837 measured reflections	l = −29→27

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.115	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + 0.472P] where P = (Fo^2 + 2Fc^2)/3
3323 reflections	(Δ/σ)max = 0.004
197 parameters	Δρmax = 0.31 e Å^−3
0 restraints	Δρmin = −0.46 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Cu1	0.5000	0.08063 (6)	0.2500	0.03384 (16)
O1	0.39697 (10)	0.0138 (3)	0.28142 (7)	0.0488 (5)
O2	0.48617 (13)	0.3055 (3)	0.53569 (9)	0.0685 (7)
N1	0.54063 (12)	0.1525 (3)	0.32734 (8)	0.0325 (5)
N2	0.53924 (12)	0.2259 (3)	0.42209 (8)	0.0363 (5)
H2A	0.5231	0.2354	0.4583	0.044*
N3	0.51469 (14)	0.3714 (3)	0.63078 (10)	0.0459 (6)
C1	0.61202 (14)	0.2439 (3)	0.33906 (10)	0.0317 (6)
C2	0.67699 (15)	0.2907 (3)	0.30199 (10)	0.0390 (6)
H2	0.6781	0.2603	0.2621	0.047*
C3	0.73946 (16)	0.3837 (4)	0.32686 (12)	0.0450 (7)
H3	0.7837	0.4170	0.3033	0.054*
C4	0.73769 (18)	0.4287 (4)	0.38638 (12)	0.0501 (8)
H4	0.7809	0.4916	0.4017	0.060*
C5	0.67423 (17)	0.3835 (4)	0.42348 (11)	0.0466 (7)
H5	0.6737	0.4137	0.4634	0.056*
C6	0.61128 (15)	0.2908 (3)	0.39857 (10)	0.0354 (6)
C7	0.49829 (14)	0.1445 (3)	0.37818 (9)	0.0305 (5)
C8	0.42009 (15)	0.0589 (3)	0.38639 (10)	0.0326 (6)
C9	0.38969 (16)	0.0319 (4)	0.44429 (10)	0.0421 (7)
H9	0.4190	0.0740	0.4765	0.050*
C10	0.31854 (17)	−0.0544 (4)	0.45449 (11)	0.0476 (7)
H10	0.2999	−0.0712	0.4931	0.057*
C11	0.27428 (17)	−0.1169 (4)	0.40647 (12)	0.0519 (8)
H11	0.2262	−0.1773	0.4130	0.062*
C12	0.30137 (17)	−0.0897 (4)	0.34951 (11)	0.0473 (7)
H12	0.2702	−0.1299	0.3179	0.057*
C13	0.37502 (15)	−0.0026 (3)	0.33753 (10)	0.0359 (6)
C14	0.5303 (2)	0.3673 (4)	0.57331 (13)	0.0555 (8)
H14	0.5793	0.4157	0.5605	0.067*
C15	0.5716 (2)	0.4472 (4)	0.67281 (15)	0.0725 (10)
H15A	0.5906	0.3646	0.7004	0.109*
H15B	0.5438	0.5343	0.6941	0.109*
H15C	0.6179	0.4928	0.6517	0.109*
C16	0.44058 (18)	0.2976 (4)	0.65432 (13)	0.0624 (9)
H16A	0.4102	0.2460	0.6227	0.094*
H16B	0.4072	0.3821	0.6725	0.094*
H16C	0.4550	0.2155	0.6835	0.094*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0333 (3)	0.0456 (3)	0.0227 (2)	0.000	−0.00097 (16)	0.000
O1	0.0430 (11)	0.0733 (15)	0.0301 (9)	−0.0155 (10)	−0.0027 (7)	0.0053 (9)
O2	0.0776 (15)	0.0896 (19)	0.0384 (11)	0.0021 (13)	0.0046 (10)	−0.0165 (11)
N1	0.0345 (12)	0.0350 (13)	0.0279 (10)	−0.0004 (10)	0.0012 (8)	0.0007 (8)
N2	0.0395 (12)	0.0456 (14)	0.0240 (9)	−0.0040 (11)	0.0031 (8)	−0.0020 (9)
N3	0.0509 (15)	0.0499 (15)	0.0368 (12)	0.0056 (11)	0.0042 (10)	−0.0039 (10)
C1	0.0294 (13)	0.0341 (15)	0.0316 (12)	0.0019 (11)	−0.0032 (9)	0.0003 (10)
C2	0.0403 (15)	0.0445 (17)	0.0322 (12)	−0.0019 (13)	0.0039 (10)	0.0003 (11)
C3	0.0380 (16)	0.0498 (18)	0.0473 (15)	−0.0077 (13)	0.0062 (12)	0.0016 (13)
C4	0.0425 (17)	0.059 (2)	0.0489 (16)	−0.0159 (14)	−0.0043 (12)	−0.0050 (13)
C5	0.0505 (17)	0.055 (2)	0.0346 (13)	−0.0092 (14)	−0.0027 (12)	−0.0066 (12)
C6	0.0349 (14)	0.0380 (16)	0.0333 (12)	0.0001 (12)	0.0006 (10)	0.0018 (10)
C7	0.0356 (14)	0.0323 (14)	0.0237 (11)	0.0044 (12)	−0.0016 (10)	0.0018 (9)
C8	0.0305 (13)	0.0328 (15)	0.0344 (12)	0.0021 (11)	0.0038 (9)	0.0035 (10)
C9	0.0418 (16)	0.0507 (19)	0.0337 (13)	0.0001 (13)	0.0011 (11)	0.0022 (11)
C10	0.0464 (18)	0.059 (2)	0.0375 (14)	0.0003 (15)	0.0106 (12)	0.0074 (12)
C11	0.0384 (16)	0.063 (2)	0.0544 (17)	−0.0107 (14)	0.0061 (13)	0.0103 (15)
C12	0.0384 (16)	0.065 (2)	0.0386 (14)	−0.0077 (14)	−0.0043 (11)	0.0026 (12)
C13	0.0348 (14)	0.0418 (17)	0.0313 (12)	0.0020 (12)	0.0005 (10)	0.0060 (11)
C14	0.0606 (19)	0.063 (2)	0.0432 (16)	0.0079 (17)	0.0131 (14)	−0.0051 (14)
C15	0.080 (3)	0.081 (3)	0.0567 (19)	0.002 (2)	−0.0085 (17)	−0.0171 (17)
C16	0.071 (2)	0.063 (2)	0.0526 (17)	0.0043 (18)	0.0151 (15)	0.0039 (15)

Geometric parameters (Å, º)

Cu1—O1	1.8904 (17)	C4—H4	0.9300
Cu1—O1^i	1.8904 (17)	C5—C6	1.382 (3)
Cu1—N1	1.9487 (18)	C5—H5	0.9300
Cu1—N1^i	1.9487 (18)	C7—C8	1.453 (3)
O1—C13	1.319 (3)	C8—C13	1.410 (3)
O2—C14	1.215 (4)	C8—C9	1.410 (3)
N1—C7	1.335 (3)	C9—C10	1.365 (4)
N1—C1	1.396 (3)	C9—H9	0.9300
N2—C7	1.359 (3)	C10—C11	1.391 (4)
N2—C6	1.384 (3)	C10—H10	0.9300
N2—H2A	0.8600	C11—C12	1.373 (4)
N3—C14	1.318 (3)	C11—H11	0.9300
N3—C16	1.440 (3)	C12—C13	1.409 (4)
N3—C15	1.455 (4)	C12—H12	0.9300
C1—C6	1.392 (3)	C14—H14	0.9300
C1—C2	1.395 (3)	C15—H15A	0.9600
C2—C3	1.378 (3)	C15—H15B	0.9600
C2—H2	0.9300	C15—H15C	0.9600
C3—C4	1.388 (4)	C16—H16A	0.9600
C3—H3	0.9300	C16—H16B	0.9600
C4—C5	1.373 (4)	C16—H16C	0.9600
O1—Cu1—O1^i	146.96 (13)	N1—C7—C8	125.4 (2)
O1—Cu1—N1	92.76 (8)	N2—C7—C8	124.1 (2)
O1^i—Cu1—N1	96.92 (8)	C13—C8—C9	119.1 (2)
O1—Cu1—N1^i	96.92 (8)	C13—C8—C7	121.2 (2)
O1^i—Cu1—N1^i	92.76 (8)	C9—C8—C7	119.7 (2)
N1—Cu1—N1^i	145.50 (12)	C10—C9—C8	121.9 (2)
C13—O1—Cu1	128.67 (16)	C10—C9—H9	119.0
C7—N1—C1	106.78 (18)	C8—C9—H9	119.0
C7—N1—Cu1	125.30 (16)	C9—C10—C11	119.2 (2)
C1—N1—Cu1	127.22 (14)	C9—C10—H10	120.4
C7—N2—C6	108.38 (19)	C11—C10—H10	120.4
C7—N2—H2A	125.8	C12—C11—C10	120.2 (3)
C6—N2—H2A	125.8	C12—C11—H11	119.9
C14—N3—C16	120.7 (3)	C10—C11—H11	119.9
C14—N3—C15	121.8 (3)	C11—C12—C13	121.9 (2)
C16—N3—C15	117.5 (3)	C11—C12—H12	119.1
C6—C1—C2	120.6 (2)	C13—C12—H12	119.1
C6—C1—N1	108.5 (2)	O1—C13—C12	117.5 (2)
C2—C1—N1	130.9 (2)	O1—C13—C8	124.9 (2)
C3—C2—C1	117.2 (2)	C12—C13—C8	117.6 (2)
C3—C2—H2	121.4	O2—C14—N3	125.5 (3)
C1—C2—H2	121.4	O2—C14—H14	117.2
C2—C3—C4	121.3 (2)	N3—C14—H14	117.2
C2—C3—H3	119.4	N3—C15—H15A	109.5
C4—C3—H3	119.4	N3—C15—H15B	109.5
C5—C4—C3	122.2 (3)	H15A—C15—H15B	109.5
C5—C4—H4	118.9	N3—C15—H15C	109.5
C3—C4—H4	118.9	H15A—C15—H15C	109.5
C4—C5—C6	116.6 (2)	H15B—C15—H15C	109.5
C4—C5—H5	121.7	N3—C16—H16A	109.5
C6—C5—H5	121.7	N3—C16—H16B	109.5
C5—C6—N2	132.1 (2)	H16A—C16—H16B	109.5
C5—C6—C1	122.0 (2)	N3—C16—H16C	109.5
N2—C6—C1	105.8 (2)	H16A—C16—H16C	109.5
N1—C7—N2	110.5 (2)	H16B—C16—H16C	109.5

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O2	0.86	1.93	2.773 (3)	168