({[2-(1H-Benz­imid­azol-2-yl)­ethyl]­imino­methyl}­phenolato)­chlorido­copper(II)

In the title compound, [Cu(C₁₆H₁₄N₃O)Cl], the Cu^II ion exhibits a distorted tetra­hedral geometry. The coordination environment of the Cu^II ion is composed of one benzimidazole N atom, one imino N atom, one phenolato O atom and one Cl⁻ anion. Inter­molecular N—H...O hydrogen bonds play key roles in stabilizing the crystal packing.

Key indicators

• Single-crystal X-ray study
• T = 571 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.047
• wR factor = 0.096
• Data-to-parameter ratio = 13.1

checkCIF/PLATON results

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Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.50 Ratio
PLAT153_ALERT_1_C The su's on the Cell Axes   are Equal (x 100000)        300 Ang.
PLAT154_ALERT_1_C The su's on the Cell Angles are Equal  (x 10000)        400 Deg.

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cu1         (2)       2.13

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
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S1. Comment

The aggregation of the amyloid-beta peptide to form senile plaques is a key event in Alzheimer's disease (Masters et al., 1985). Complexation of copper and zinc with the amyloid-beta peptide induces aggregation of the peptide (Atwood et al., 1998; Bush et al., 1994; Syme et al., 2004). Detailed knowledge of the metal- Amyloid-beta coordination environment could aid in the development of compounds with more effective and specific metal chelating properties as eventual treatments in Alzheimer's disease. As our efforts to develop model complexes as mimics of the metal site, we report a novel copper complex in this paper.

A displacement ellipsoid drawing of (I) is shown in Fig. 1. Selected bond lengths and angles are listed in Table 1. Cu(II) ion exhibits a distorted tetrahedral geometry. The coordination sphere of Cu(II) ion is composed of one benzoimidazole N atom, one imino N atom, one phenolato O atom and one Cl anion. As shown in Fig. 2, intermolecular N—H···O hydrogen bonds play key roles in stabilizing the crystal packing. The detailed hydrogen bond information is listed in Table 2.

Related literature

For related literature, see: Atwood et al. (1998); Masters et al. (1985); Maurya et al. (2006); Syme et al. (2004).

For related literature, see: Bush et al. (1994).

S2. Experimental

All chemicals were of reagent grade and commercially available from the Beijing Chemical Reagents Company of China, and were used without further purification.

At room temperature, a methanol solution of CuCl₂.2H₂O (0.5 mmol, 5 ml) and a methanol solution of N-salicylidine-2-aminoethylbenzimidazole (0.5 mmol, 10 ml, Maurya et al., 2006) were mixed together. The mixture was stirred for about six hours and then filtered. The filtrate was allowed to evaporate at room temperature, affording the green crystal (I).

S3. Refinement

H atoms attached to C atoms were placed in geometrically idealized positions, with Csp³—H=0.970 Å and constrained to ride on their parent atoms, with U_iso(H) = 1.5_Ueq(C), and with Csp² = 0.930 Å, constrained to ride on their parent atoms, with U_iso(H) = 1.2_Ueq(C). The H atom on N atom was located in a difference Fourier map and its position and isotropic displacement parameters were refined, with N—H distance was fixed at 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, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The structure of the title compound in 30% probability ellipsoids.
	Fig. 2. A packing diagram, viewed down the b axis. Hydrogen bonds are indicated by dashed lines. [Symmetry code: (A) x - 1, y, z]

({[2-(1H-Benzimidazol-2-yl)ethyl]iminomethyl}phenolato)chloridocopper(II)

Crystal data

[Cu(C16H14ON3)Cl]	Z = 2
Mr = 363.29	F(000) = 370
Triclinic, P1	Dx = 1.606 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.009 (3) Å	Cell parameters from 1643 reflections
b = 9.303 (3) Å	θ = 2.2–26.6°
c = 10.192 (3) Å	µ = 1.64 mm^−1
α = 87.815 (4)°	T = 571 K
β = 87.548 (4)°	Block, green
γ = 82.267 (4)°	0.20 × 0.20 × 0.10 mm
V = 751.3 (4) Å^3

Data collection

Bruker SMART CCD diffractometer	2599 independent reflections
Radiation source: fine-focus sealed tube	2293 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
ω scans	θmax = 25.0°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→9
Tmin = 0.736, Tmax = 0.854	k = −9→11
3708 measured reflections	l = −11→12

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.096	H-atom parameters constrained
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0324P)^2 + 0.4537P] where P = (Fo^2 + 2Fc^2)/3
2599 reflections	(Δ/σ)max < 0.001
199 parameters	Δρmax = 0.42 e Å^−3
0 restraints	Δρmin = −0.39 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	0.32075 (6)	0.15770 (6)	0.09550 (4)	0.03379 (17)
Cl1	0.45923 (12)	0.15497 (12)	−0.09963 (9)	0.0441 (3)
O1	0.4966 (3)	0.2340 (3)	0.1815 (2)	0.0364 (7)
N1	0.2375 (4)	0.0735 (3)	0.2598 (3)	0.0310 (7)
N2	−0.1942 (4)	0.2427 (4)	0.0546 (3)	0.0371 (8)
H16	−0.2948	0.2365	0.0852	0.045*
N3	0.0840 (4)	0.2006 (3)	0.0333 (3)	0.0319 (7)
C1	0.5099 (4)	0.2481 (4)	0.3089 (4)	0.0323 (9)
C2	0.6238 (5)	0.3345 (5)	0.3519 (4)	0.0398 (10)
H2	0.6862	0.3832	0.2901	0.048*
C3	0.6470 (5)	0.3500 (5)	0.4830 (4)	0.0464 (11)
H3	0.7257	0.4076	0.5081	0.056*
C4	0.5554 (5)	0.2816 (5)	0.5775 (4)	0.0486 (11)
H4	0.5720	0.2921	0.6662	0.058*
C5	0.4401 (5)	0.1984 (4)	0.5393 (4)	0.0412 (10)
H5	0.3776	0.1526	0.6032	0.049*
C6	0.4126 (4)	0.1795 (4)	0.4062 (4)	0.0310 (9)
C7	0.2891 (5)	0.0901 (4)	0.3741 (4)	0.0339 (9)
H7	0.2419	0.0391	0.4433	0.041*
C8	0.1105 (5)	−0.0237 (4)	0.2442 (4)	0.0385 (10)
H8A	0.0996	−0.0822	0.3242	0.046*
H8B	0.1461	−0.0886	0.1731	0.046*
C9	−0.0580 (5)	0.0634 (5)	0.2148 (4)	0.0385 (10)
H9A	−0.1376	−0.0032	0.1986	0.046*
H9B	−0.0996	0.1173	0.2919	0.046*
C10	−0.0531 (4)	0.1680 (4)	0.0993 (4)	0.0326 (9)
C11	−0.1515 (4)	0.3313 (4)	−0.0485 (4)	0.0335 (9)
C12	−0.2493 (5)	0.4289 (4)	−0.1289 (4)	0.0414 (10)
H12	−0.3660	0.4461	−0.1172	0.050*
C13	−0.1657 (5)	0.4988 (5)	−0.2260 (4)	0.0459 (11)
H13	−0.2267	0.5662	−0.2814	0.055*
C14	0.0094 (5)	0.4713 (5)	−0.2444 (4)	0.0462 (11)
H14	0.0618	0.5184	−0.3135	0.055*
C15	0.1063 (5)	0.3762 (5)	−0.1626 (4)	0.0412 (10)
H15	0.2231	0.3608	−0.1735	0.049*
C16	0.0237 (4)	0.3041 (4)	−0.0634 (4)	0.0324 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0250 (3)	0.0526 (3)	0.0254 (3)	−0.0124 (2)	0.00124 (19)	0.0014 (2)
Cl1	0.0364 (6)	0.0643 (7)	0.0292 (6)	−0.0022 (5)	0.0072 (4)	0.0041 (5)
O1	0.0271 (14)	0.0581 (19)	0.0260 (15)	−0.0135 (13)	0.0011 (11)	−0.0011 (13)
N1	0.0277 (17)	0.0395 (19)	0.0265 (18)	−0.0078 (14)	0.0012 (14)	0.0013 (14)
N2	0.0208 (16)	0.054 (2)	0.037 (2)	−0.0087 (15)	0.0039 (14)	−0.0036 (17)
N3	0.0222 (16)	0.044 (2)	0.0303 (18)	−0.0092 (14)	−0.0028 (14)	0.0037 (15)
C1	0.0231 (19)	0.041 (2)	0.031 (2)	0.0026 (17)	−0.0003 (16)	−0.0013 (18)
C2	0.037 (2)	0.050 (3)	0.034 (2)	−0.0128 (19)	0.0034 (19)	−0.0034 (19)
C3	0.044 (3)	0.056 (3)	0.042 (3)	−0.014 (2)	−0.009 (2)	−0.009 (2)
C4	0.058 (3)	0.064 (3)	0.025 (2)	−0.012 (2)	−0.006 (2)	−0.004 (2)
C5	0.047 (3)	0.046 (3)	0.029 (2)	−0.008 (2)	−0.002 (2)	0.0062 (19)
C6	0.030 (2)	0.035 (2)	0.028 (2)	−0.0023 (17)	−0.0016 (17)	0.0015 (17)
C7	0.032 (2)	0.037 (2)	0.031 (2)	−0.0021 (17)	0.0067 (17)	0.0044 (17)
C8	0.040 (2)	0.042 (2)	0.036 (2)	−0.0136 (19)	0.0014 (19)	0.0020 (19)
C9	0.029 (2)	0.054 (3)	0.035 (2)	−0.0156 (19)	0.0030 (18)	0.0022 (19)
C10	0.026 (2)	0.049 (3)	0.024 (2)	−0.0129 (18)	0.0025 (16)	−0.0055 (17)
C11	0.027 (2)	0.040 (2)	0.035 (2)	−0.0071 (17)	−0.0018 (17)	−0.0057 (18)
C12	0.030 (2)	0.045 (3)	0.049 (3)	−0.0022 (19)	−0.008 (2)	−0.007 (2)
C13	0.046 (3)	0.042 (3)	0.049 (3)	−0.004 (2)	−0.014 (2)	0.004 (2)
C14	0.041 (2)	0.050 (3)	0.050 (3)	−0.015 (2)	−0.007 (2)	0.013 (2)
C15	0.028 (2)	0.053 (3)	0.045 (3)	−0.0143 (19)	−0.0027 (19)	0.008 (2)
C16	0.027 (2)	0.038 (2)	0.034 (2)	−0.0082 (17)	−0.0031 (17)	−0.0045 (18)

Geometric parameters (Å, º)

Cu1—O1	1.918 (3)	C5—C6	1.404 (5)
Cu1—N1	1.951 (3)	C5—H5	0.9300
Cu1—N3	2.009 (3)	C6—C7	1.431 (5)
Cu1—Cl1	2.2347 (12)	C7—H7	0.9300
O1—C1	1.321 (4)	C8—C9	1.514 (5)
N1—C7	1.274 (5)	C8—H8A	0.9700
N1—C8	1.466 (5)	C8—H8B	0.9700
N2—C10	1.333 (5)	C9—C10	1.501 (5)
N2—C11	1.371 (5)	C9—H9A	0.9700
N2—H16	0.8600	C9—H9B	0.9700
N3—C10	1.327 (4)	C11—C12	1.384 (5)
N3—C16	1.406 (5)	C11—C16	1.395 (5)
C1—C2	1.389 (5)	C12—C13	1.365 (6)
C1—C6	1.420 (5)	C12—H12	0.9300
C2—C3	1.372 (6)	C13—C14	1.397 (6)
C2—H2	0.9300	C13—H13	0.9300
C3—C4	1.375 (6)	C14—C15	1.376 (5)
C3—H3	0.9300	C14—H14	0.9300
C4—C5	1.360 (6)	C15—C16	1.385 (5)
C4—H4	0.9300	C15—H15	0.9300
O1—Cu1—N1	92.21 (12)	N1—C7—H7	116.9
O1—Cu1—N3	145.14 (13)	C6—C7—H7	116.9
N1—Cu1—N3	90.28 (12)	N1—C8—C9	110.3 (3)
O1—Cu1—Cl1	93.09 (8)	N1—C8—H8A	109.6
N1—Cu1—Cl1	155.59 (10)	C9—C8—H8A	109.6
N3—Cu1—Cl1	98.78 (9)	N1—C8—H8B	109.6
C1—O1—Cu1	127.4 (2)	C9—C8—H8B	109.6
C7—N1—C8	119.2 (3)	H8A—C8—H8B	108.1
C7—N1—Cu1	126.2 (3)	C10—C9—C8	114.3 (3)
C8—N1—Cu1	114.5 (2)	C10—C9—H9A	108.7
C10—N2—C11	108.3 (3)	C8—C9—H9A	108.7
C10—N2—H16	125.8	C10—C9—H9B	108.7
C11—N2—H16	125.8	C8—C9—H9B	108.7
C10—N3—C16	104.9 (3)	H9A—C9—H9B	107.6
C10—N3—Cu1	125.4 (2)	N3—C10—N2	112.6 (3)
C16—N3—Cu1	127.2 (2)	N3—C10—C9	126.3 (3)
O1—C1—C2	119.2 (3)	N2—C10—C9	121.1 (3)
O1—C1—C6	123.4 (4)	N2—C11—C12	131.5 (3)
C2—C1—C6	117.4 (4)	N2—C11—C16	105.6 (3)
C3—C2—C1	121.9 (4)	C12—C11—C16	122.9 (4)
C3—C2—H2	119.0	C13—C12—C11	116.6 (4)
C1—C2—H2	119.0	C13—C12—H12	121.7
C2—C3—C4	120.9 (4)	C11—C12—H12	121.7
C2—C3—H3	119.6	C12—C13—C14	121.6 (4)
C4—C3—H3	119.6	C12—C13—H13	119.2
C5—C4—C3	118.9 (4)	C14—C13—H13	119.2
C5—C4—H4	120.5	C15—C14—C13	121.6 (4)
C3—C4—H4	120.5	C15—C14—H14	119.2
C4—C5—C6	122.0 (4)	C13—C14—H14	119.2
C4—C5—H5	119.0	C14—C15—C16	117.7 (4)
C6—C5—H5	119.0	C14—C15—H15	121.2
C5—C6—C1	118.8 (4)	C16—C15—H15	121.2
C5—C6—C7	118.6 (3)	C15—C16—C11	119.7 (4)
C1—C6—C7	122.6 (3)	C15—C16—N3	131.7 (3)
N1—C7—C6	126.3 (3)	C11—C16—N3	108.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H16···O1^i	0.86	1.90	2.753 (4)	170

Symmetry code: (i) x−1, y, z.