Bis[1,1-di­methyl­biguanide(1–)-κ²N²,N⁵]copper(II) monohydrate

The crystal structure of the title compound, [Cu(C₄H₁₀N₅)₂]·H₂O, contains two independent copper N,N-di­methyl­biguanide complex units, each with square-planar coordination of the Cu atom by four N atoms. The two complexes have different symmetry, with one Cu atom lying on an inversion centre and the other on a twofold rotation axis. The Cu—N bond lengths are 1.923 (2) and 1.950 (2) Å in the centrosymmetric complex, and 1.928 (2) and 1.938 (2) Å in the non-centrosymmetric complex. The crystal structure is stabilized by N—H...O, O—H...N and N—H...N hydrogen bonds; each water mol­ecule forms four hydrogen bonds involving three different Cu complexes.

S1. Comment

An N-substituted derivative of biguanide, N,N-dimethylbiguanide, is a powerful oral antihyperglycaemic drug that has been used in many countries for over 40 years for treating diabetic patients with non-insulin-dependent diabetes mellitus. This compound forms complexes with many metal ions (Ray, 1961; Viossat et al., 1995; Lemoine et al., 1996; Bentefrit et al., 1997; Zhu et al., 2002a,b,c). We report here the structure of a new copper(II) complex, (I), of N,N-dimethylbiguanide.

The asymmetric unit of (I) contains two copper N,N-dimethylbiguanide complexes and two water molecules (Fig. 1). The copper N,N-dimethylbiguanide complexes have square-planar coordination of the metal ion through the formation of four Cu—N bonds with two bidentate ligands. The two ligands form a slightly distorted plane, with the Cu atom at the center. The dimethyl groups of the two ligands have a trans configuration. These properties agree with those of other copper N,N-dimethylbiguanide complexes (Viossat et al., 1995; Lemoine et al., 1996; Zhu et al., 2002b). However, in (I), the two copper N,N-dimethylbiguanide complexes have different symmetry. Atom Cu1 lies on an inversion centre, while atom Cu2 lies on a twofold rotation axis. The Cu—N bond lengths in the complexes are also slightly different (Table 1).

The crystal structure is stabilized by N—H···O, O—H···N and N—H···N hydrogen bonds (Table 2 and Fig. 2). The water molecule forms four hydrogen bonds involving three different copper N,N-dimethylbiguanide complexes, viz. two hydrogen bonds with one copper N,N-dimethylbiguanide complex (containing atom Cu2) and one hydrogen bond with each of the neighboring complexes (containing atom Cu1). The complexes containing atoms Cu1 and Cu2 are connected to one another by N—H···N hydrogen bonds and by N—H···O and O—H···N hydrogen bonds. Neighbouring complexes containing atoms Cu1 or Cu2 are linked indirectly by N—H···O and O—H···N hydrogen bonds via the water molecules. The antiparallel zigzag hydrogen-bond chains [N7—H···O···H—N1···H–]_n run throughout the crystal.

S2. Experimental

All solvents and chemicals were commercially available (reagent grade) and were used without further purification. An aqueous solution of CuCl₂2H₂O was added dropwise to a 0.1 M KOH solution of the ligand, in the molar ratio 1:1, with stirring. The resulting red–purple solution was filtered and the filtrate was left to stand at room temperature. Red–purple crystals formed after a few days.

S3. Refinement

H atoms attached to C atoms were placed in idealized positions, with Csp³—H distances of 0.96 Å, and constrained to ride on their parent atoms, with U_iso(H) values of 1.5U_eq(C). H atoms attached to O and N atoms were located from difference Fourier maps and their U_iso values were refined?, O—H distances set at 0.786 and 0.0.834 Å and N—H distances in the range 0.847–0.850 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. The structure of the title compound, with displacement ellipsoids drawn at the 40% probability level for non-H atoms. [Symmetry codes: (A) 0.5 − x, 0.5 − y, −z; (B) 1 − x, y, 0.5 − z.]
	Fig. 2. The hydrogen-bond network of the title compound. [Symmetry codes: (A) 0.5 − x, 0.5 − y, −z; (B) x, y − 1, z; (C) x, −y, z − 0.5; (E) 0.5 − x, −0.5 − y, −z; (F) 0.5 − x, y − 0.5, 0.5 − z; (G) = x, −y, 0.5 + z.]

Bis(1,1-dimethylbiguanido)copper(II) hydrate

Crystal data

[Cu(C4H10N5)2]·H2O	F(000) = 1416
Mr = 337.90	Dx = 1.605 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 10688 reflections
a = 30.535 (6) Å	θ = 2.8–27.5°
b = 7.055 (1) Å	µ = 1.58 mm^−1
c = 13.746 (3) Å	T = 173 K
β = 109.18 (3)°	Block, red–purple
V = 2796.9 (10) Å^3	0.45 × 0.20 × 0.15 mm
Z = 8

Data collection

Bruker SMART 1K CCD area-detector diffractometer	3155 independent reflections
Radiation source: fine-focus sealed tube	2423 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.000
ϕ and ω scans	θmax = 27.5°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	h = 0→39
Tmin = 0.537, Tmax = 0.798	k = 0→9
3155 measured reflections	l = −17→16

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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.094	H atoms treated by a mixture of independent and constrained refinement
S = 0.95	w = 1/[σ^2(Fo^2) + (0.05P)^2] where P = (Fo^2 + 2Fc^2)/3
3155 reflections	(Δ/σ)max < 0.001
188 parameters	Δρmax = 0.66 e Å^−3
0 restraints	Δρmin = −0.38 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	0.2500	0.2500	0.0000	0.01991 (13)
Cu2	0.5000	0.29791 (7)	0.2500	0.02119 (13)
N1	0.31106 (8)	0.2578 (3)	−0.01147 (19)	0.0275 (5)
H1	0.3224	0.1593	−0.0293	0.034 (3)*
N2	0.37393 (8)	0.3976 (3)	−0.04268 (17)	0.0265 (5)
H2A	0.3691	0.3125	−0.0887	0.034 (3)*
H2B	0.3866	0.5022	−0.0489	0.034 (3)*
N3	0.33272 (7)	0.5781 (3)	0.03514 (15)	0.0212 (4)
N4	0.26313 (7)	0.4972 (3)	0.06671 (16)	0.0249 (5)
H4D	0.2471	0.5376	0.1023	0.034 (3)*
N5	0.30861 (8)	0.7569 (3)	0.14611 (17)	0.0240 (5)
N6	0.43376 (8)	0.3067 (4)	0.21996 (16)	0.0299 (5)
H6	0.4157	0.3256	0.1589	0.034 (3)*
N7	0.36293 (7)	0.3251 (4)	0.24842 (16)	0.0269 (5)
H7D	0.3478	0.2805	0.2852	0.034 (3)*
H7E	0.3493	0.3181	0.1838	0.034 (3)*
N8	0.42703 (8)	0.2668 (3)	0.38706 (16)	0.0209 (4)
N9	0.50589 (8)	0.2880 (3)	0.39462 (16)	0.0245 (5)
H9	0.5339	0.2964	0.4332	0.034 (3)*
N10	0.48579 (8)	0.2216 (3)	0.54053 (17)	0.0242 (5)
C1	0.33637 (8)	0.4096 (4)	−0.00690 (18)	0.0214 (5)
C2	0.30003 (8)	0.6044 (4)	0.08241 (18)	0.0210 (5)
C3	0.35429 (9)	0.8427 (4)	0.1826 (2)	0.0305 (6)
H3A	0.3775	0.7463	0.1914	0.046*
H3B	0.3586	0.9045	0.2473	0.046*
H3C	0.3570	0.9341	0.1331	0.046*
C4	0.27487 (10)	0.8180 (4)	0.1937 (2)	0.0327 (6)
H4A	0.2447	0.8242	0.1423	0.049*
H4B	0.2833	0.9409	0.2239	0.049*
H4C	0.2743	0.7291	0.2462	0.049*
C5	0.41001 (9)	0.2982 (4)	0.28458 (19)	0.0209 (5)
C6	0.47343 (9)	0.2605 (3)	0.43752 (19)	0.0210 (5)
C7	0.45316 (10)	0.2181 (4)	0.5971 (2)	0.0302 (6)
H7A	0.4238	0.2671	0.5544	0.045*
H7B	0.4648	0.2948	0.6579	0.045*
H7C	0.4493	0.0901	0.6165	0.045*
C8	0.53434 (9)	0.2073 (4)	0.6041 (2)	0.0270 (6)
H8A	0.5509	0.1349	0.5683	0.041*
H8B	0.5366	0.1455	0.6678	0.041*
H8C	0.5475	0.3320	0.6181	0.041*
O1	0.34525 (7)	−0.1056 (3)	−0.08042 (15)	0.0302 (5)
H1A	0.3439	−0.1880	−0.0380	0.031*
H1B	0.3709	−0.1160	−0.0800	0.031*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0177 (2)	0.0225 (2)	0.0194 (2)	−0.00157 (16)	0.00588 (17)	−0.00191 (17)
Cu2	0.0207 (2)	0.0284 (3)	0.0160 (2)	0.000	0.00804 (17)	0.000
N1	0.0240 (13)	0.0225 (11)	0.0390 (14)	−0.0014 (9)	0.0145 (11)	−0.0079 (10)
N2	0.0265 (12)	0.0260 (12)	0.0303 (12)	−0.0042 (9)	0.0141 (10)	−0.0050 (10)
N3	0.0207 (11)	0.0223 (11)	0.0209 (11)	−0.0013 (8)	0.0074 (9)	−0.0014 (9)
N4	0.0230 (11)	0.0297 (12)	0.0249 (11)	−0.0007 (9)	0.0116 (9)	−0.0067 (10)
N5	0.0233 (12)	0.0250 (12)	0.0240 (11)	−0.0015 (9)	0.0080 (9)	−0.0067 (9)
N6	0.0260 (12)	0.0477 (15)	0.0167 (11)	0.0031 (11)	0.0082 (9)	0.0052 (10)
N7	0.0213 (11)	0.0413 (14)	0.0182 (10)	0.0026 (10)	0.0066 (9)	0.0057 (10)
N8	0.0217 (11)	0.0261 (11)	0.0162 (10)	0.0016 (9)	0.0079 (8)	0.0029 (9)
N9	0.0188 (11)	0.0378 (14)	0.0167 (10)	−0.0015 (9)	0.0056 (8)	0.0005 (9)
N10	0.0197 (11)	0.0357 (13)	0.0178 (10)	0.0012 (9)	0.0070 (9)	0.0024 (9)
C1	0.0188 (12)	0.0269 (13)	0.0173 (12)	0.0015 (10)	0.0045 (10)	0.0022 (10)
C2	0.0209 (13)	0.0227 (13)	0.0181 (12)	0.0034 (10)	0.0046 (10)	0.0016 (10)
C3	0.0304 (15)	0.0335 (16)	0.0277 (14)	−0.0080 (12)	0.0099 (12)	−0.0085 (12)
C4	0.0324 (16)	0.0355 (16)	0.0326 (15)	−0.0004 (13)	0.0140 (12)	−0.0136 (13)
C5	0.0219 (13)	0.0209 (12)	0.0204 (12)	0.0006 (10)	0.0076 (10)	−0.0001 (10)
C6	0.0219 (13)	0.0215 (12)	0.0194 (12)	0.0018 (10)	0.0066 (10)	−0.0005 (10)
C7	0.0247 (15)	0.0439 (17)	0.0244 (13)	0.0046 (12)	0.0114 (11)	0.0041 (12)
C8	0.0236 (14)	0.0366 (15)	0.0189 (12)	0.0007 (11)	0.0042 (10)	0.0021 (11)
O1	0.0347 (11)	0.0283 (10)	0.0312 (10)	0.0085 (8)	0.0161 (9)	0.0052 (9)

Geometric parameters (Å, º)

Cu1—N1^i	1.923 (2)	N7—H7D	0.8500
Cu1—N1	1.923 (2)	N7—H7E	0.8492
Cu1—N4^i	1.950 (2)	N8—C5	1.350 (3)
Cu1—N4	1.950 (2)	N8—C6	1.358 (3)
Cu2—N6^ii	1.928 (2)	N9—C6	1.324 (3)
Cu2—N6	1.928 (2)	N9—H9	0.8467
Cu2—N9	1.938 (2)	N10—C6	1.368 (3)
Cu2—N9^ii	1.938 (2)	N10—C7	1.452 (3)
N1—C1	1.310 (3)	N10—C8	1.456 (3)
N1—H1	0.8484	C3—H3A	0.9600
N2—C1	1.391 (3)	C3—H3B	0.9600
N2—H2A	0.8493	C3—H3C	0.9600
N2—H2B	0.8494	C4—H4A	0.9600
N3—C1	1.342 (3)	C4—H4B	0.9600
N3—C2	1.371 (3)	C4—H4C	0.9600
N4—C2	1.315 (3)	C7—H7A	0.9600
N4—H4D	0.8469	C7—H7B	0.9600
N5—C2	1.357 (3)	C7—H7C	0.9600
N5—C3	1.451 (3)	C8—H8A	0.9600
N5—C4	1.455 (3)	C8—H8B	0.9600
N6—C5	1.320 (3)	C8—H8C	0.9600
N6—H6	0.8500	O1—H1A	0.8341
N7—C5	1.371 (3)	O1—H1B	0.7859
N1^i—Cu1—N1	180.00 (14)	N1—C1—N3	127.8 (2)
N1^i—Cu1—N4^i	87.59 (9)	N1—C1—N2	118.4 (2)
N1—Cu1—N4^i	92.41 (9)	N3—C1—N2	113.6 (2)
N1^i—Cu1—N4	92.41 (9)	N4—C2—N5	122.4 (2)
N1—Cu1—N4	87.59 (9)	N4—C2—N3	124.2 (2)
N4^i—Cu1—N4	180.00 (13)	N5—C2—N3	113.4 (2)
N6^ii—Cu2—N6	176.31 (16)	N5—C3—H3A	109.5
N6^ii—Cu2—N9	92.54 (10)	N5—C3—H3B	109.5
N6—Cu2—N9	87.60 (10)	H3A—C3—H3B	109.5
N6^ii—Cu2—N9^ii	87.60 (10)	N5—C3—H3C	109.5
N6—Cu2—N9^ii	92.54 (10)	H3A—C3—H3C	109.5
N9—Cu2—N9^ii	175.87 (14)	H3B—C3—H3C	109.5
C1—N1—Cu1	126.31 (18)	N5—C4—H4A	109.5
C1—N1—H1	113.1	N5—C4—H4B	109.5
Cu1—N1—H1	120.0	H4A—C4—H4B	109.5
C1—N2—H2A	110.2	N5—C4—H4C	109.5
C1—N2—H2B	115.9	H4A—C4—H4C	109.5
H2A—N2—H2B	120.8	H4B—C4—H4C	109.5
C1—N3—C2	120.0 (2)	N6—C5—N8	127.0 (2)
C2—N4—Cu1	128.65 (17)	N6—C5—N7	119.5 (2)
C2—N4—H4D	109.8	N8—C5—N7	113.5 (2)
Cu1—N4—H4D	120.3	N9—C6—N8	125.2 (2)
C2—N5—C3	120.9 (2)	N9—C6—N10	119.9 (2)
C2—N5—C4	120.6 (2)	N8—C6—N10	115.0 (2)
C3—N5—C4	117.6 (2)	N10—C7—H7A	109.5
C5—N6—Cu2	128.62 (19)	N10—C7—H7B	109.5
C5—N6—H6	110.4	H7A—C7—H7B	109.5
Cu2—N6—H6	120.9	N10—C7—H7C	109.5
C5—N7—H7D	116.3	H7A—C7—H7C	109.5
C5—N7—H7E	117.7	H7B—C7—H7C	109.5
H7D—N7—H7E	115.2	N10—C8—H8A	109.5
C5—N8—C6	121.2 (2)	N10—C8—H8B	109.5
C6—N9—Cu2	129.18 (19)	H8A—C8—H8B	109.5
C6—N9—H9	118.7	N10—C8—H8C	109.5
Cu2—N9—H9	112.0	H8A—C8—H8C	109.5
C6—N10—C7	123.6 (2)	H8B—C8—H8C	109.5
C6—N10—C8	121.0 (2)	H1A—O1—H1B	102.0
C7—N10—C8	114.8 (2)

Symmetry codes: (i) −x+1/2, −y+1/2, −z; (ii) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1	0.85	2.19	3.035 (3)	175
N2—H2B···N8^iii	0.85	2.38	3.193 (3)	160
N7—H7D···O1^iv	0.85	2.24	3.010 (3)	150
N7—H7E···N1	0.85	2.59	3.432 (3)	174
O1—H1A···N3^v	0.83	2.02	2.838 (3)	167
O1—H1B···N8^vi	0.79	2.19	2.909 (3)	153

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