An oxalato-bridged copper(II) complex

In the coordination complex μ-oxalato-bis­[(iso­cyanato-N)(tetra­methyl­ethyl­enedi­amine)copper(II)], [Cu₂(NCO)₂(C₂O₄)(C₆H₁₆N₂)₂], the Cu^II ions are five-coordinated. One Cu^II ion bridges to another centrosymmetry-related Cu^II ion through C₂O₄²⁻, forming a plane with an r.m.s. deviation of 0.059 Å. The O—Cu—O angle is 79.33 (8)° and the Cu...Cu separation is 5.14 Å.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.039
• wR factor = 0.090
• Data-to-parameter ratio = 20.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_369  Alert C Long   C(sp2)-C(sp2) Bond  C(1)   -   C(1)a  =       1.54 Ang.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

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S1. Comment

Magnetic studies of oxalate-bridged metal complexes are well documented (Julve, Verdaguer et al., 1984; Julve, Faus et al., 1984; Kahn et al., 1985). Presently, this study is mainly concentrated on one-dimensional/two-dimensional systems having alternating bridging ligands, i.e. systems where more than one bridging ligand (Vicente et al., 1996). Recently, Ribas et al. (1998) designed a strategy for having Ni^II and Cu^II as central atom with the aim of combining oxalate and azide super-exchange pathways in the same compound. To get the desired compound, they replaced the water molecule in [L(H₂O)M-ox-M(H₂O)L]²⁺ [M = Cu^II(Vicente et al., 1997), L = diamine; M = Ni^II (Escuer et al., 1994), L = diamine or triamine] with a bridging azide ligand. Using the same strategy, we tried to synthesize a µ-oxalato-µ-cyanato-dicopper(II) alternating chain. Surprisingly, due to the lesser bridging tendency of the cyanate ion compared to azide, we did not get the desired one-dimensional alternating chain but instead obtained a dinuclear copper(II) oxalate-bridged complex with a pendant cyanate ligand in the fifth position of each copper(II) in a trans fashion. The coordination geometry about each Cu atom is distorted trigonal–bipyrimidal, with with N2, N3, O2 and Cu atoms in the equatorial plane of the bipyramid (r.m.s. deviation 0.019 Å); N1 and O1 are on the axial apices. The µ-oxalato chelate is shared by of the two centrosymmetry-related Cu^II ions. Several similiar oxalato-briging structures of Cu^II coordination complex with aqua instead of isocyanato have been reported (Julve, Verdaguer et al., 1984; Julve, Faus et al., 1984; Sletten, 1983).

S2. Experimental

N,N,N',N'-Tetramethylethane-1,2-diamine (0.3 ml, 2 mmol) was added slowly to copper nitrate trihydrate (483.2 mg, 2 mmol) dissolved in water (10 ml). To the deep-blue solution, an aqueous solution (10 ml) of potassium cyanate (162.6 mg, 2 mmol) was poured drop-by-drop with constant stirring and a blue crystalline compound separated out. An aqueous solution (10 ml) of sodium oxalate (134 mg, 1 mmol) was added slowly with vigorous stirring and a deep-blue solution was obtained. This was filtered and the filtrate was kept in a desiccator. After a few days, single crystals suitable for X-ray crystal structure analysis were obtained.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SHELXTL (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. ORTEP drawing of the title complex. Atoms labeled with a prime are centrosymmetrically related to those without prime. The coordination bonds are hollow.

µ-oxalato-bis[(isocyanato-N)(tetramethylethylenediamine)copper(II)]

Crystal data

[Cu2(NCO)2(C2O4)(C6H16N2)2]	F(000) = 552
Mr = 531.06	Dx = 1.543 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.4943 (9) Å	Cell parameters from 25 reflections
b = 14.5660 (17) Å	θ = 2.4–28.3°
c = 10.8812 (13) Å	µ = 1.90 mm^−1
β = 105.655 (2)°	T = 296 K
V = 1143.8 (2) Å^3	Rectangular plate, blue
Z = 2	0.23 × 0.10 × 0.10 mm

Data collection

CCD area detector diffractometer	2734 independent reflections
Radiation source: fine-focus sealed tube	2367 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.032
ϕ and ω scans	θmax = 28.3°, θmin = 2.4°
Absorption correction: empirical (using intensity measurements) (North et al., 1968)	h = −9→9
Tmin = 0.646, Tmax = 0.827	k = −15→18
7265 measured reflections	l = −14→14

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.090	H-atom parameters constrained
S = 1.16	w = 1/[σ^2(Fo^2) + (0.115P)^2 + 0.612P] where P = (Fo^2 + 2Fc^2)/3
2734 reflections	(Δ/σ)max < 0.001
136 parameters	Δρmax = 0.37 e Å^−3
1 restraint	Δρmin = −0.51 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	0.01552 (4)	0.05732 (2)	0.76424 (3)	0.03128 (11)
O1	0.1048 (3)	−0.04496 (12)	0.88738 (19)	0.0418 (5)
C1	−0.0525 (4)	0.04310 (16)	1.0118 (3)	0.0341 (6)
O2	−0.0791 (3)	0.10586 (12)	0.93093 (18)	0.0432 (5)
N1	−0.0582 (3)	0.17153 (15)	0.6555 (2)	0.0347 (5)
N2	0.2833 (3)	0.10567 (16)	0.8003 (2)	0.0400 (5)
N3	−0.1915 (4)	−0.01432 (19)	0.6664 (3)	0.0578 (7)
C2	−0.2965 (4)	−0.0685 (2)	0.6242 (3)	0.0446 (7)
O3	−0.4076 (4)	−0.1258 (2)	0.5775 (3)	0.0987 (11)
C3	0.2787 (4)	0.1884 (2)	0.7196 (3)	0.0483 (7)
H3A	0.2916	0.1706	0.6365	0.058*
H3B	0.3803	0.2291	0.7593	0.058*
C4	0.0967 (4)	0.23676 (19)	0.7049 (3)	0.0431 (7)
H4A	0.0905	0.2608	0.7868	0.052*
H4B	0.0864	0.2879	0.6463	0.052*
C5	−0.2319 (4)	0.2123 (2)	0.6696 (3)	0.0461 (7)
H5A	−0.2195	0.2252	0.7580	0.069*
H5B	−0.3321	0.1700	0.6385	0.069*
H5C	−0.2570	0.2683	0.6214	0.069*
C6	−0.0820 (5)	0.1523 (3)	0.5184 (3)	0.0565 (8)
H6A	0.0297	0.1257	0.5070	0.085*
H6B	−0.1083	0.2085	0.4708	0.085*
H6C	−0.1830	0.1102	0.4884	0.085*
C7	0.3592 (5)	0.1307 (3)	0.9364 (3)	0.0649 (10)
H7A	0.2829	0.1772	0.9589	0.097*
H7B	0.4831	0.1536	0.9500	0.097*
H7C	0.3608	0.0774	0.9887	0.097*
C8	0.4017 (5)	0.0342 (3)	0.7662 (4)	0.0641 (10)
H8A	0.3529	0.0177	0.6781	0.096*
H8B	0.4037	−0.0190	0.8187	0.096*
H8C	0.5254	0.0574	0.7798	0.096*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.03512 (18)	0.02876 (17)	0.03108 (18)	−0.00039 (13)	0.01084 (12)	0.00284 (12)
O1	0.0592 (13)	0.0313 (10)	0.0426 (11)	0.0108 (8)	0.0269 (9)	0.0056 (8)
C1	0.0405 (14)	0.0253 (13)	0.0383 (14)	0.0000 (10)	0.0134 (11)	0.0022 (10)
O2	0.0631 (13)	0.0294 (10)	0.0425 (11)	0.0084 (9)	0.0233 (9)	0.0074 (8)
N1	0.0362 (11)	0.0357 (11)	0.0325 (11)	−0.0001 (9)	0.0096 (9)	0.0044 (9)
N2	0.0337 (12)	0.0414 (13)	0.0444 (13)	0.0014 (10)	0.0098 (10)	0.0085 (10)
N3	0.0497 (16)	0.0456 (16)	0.072 (2)	−0.0114 (13)	0.0065 (14)	−0.0049 (14)
C2	0.0430 (16)	0.0385 (16)	0.0496 (17)	0.0046 (13)	0.0078 (13)	0.0008 (13)
O3	0.079 (2)	0.0691 (19)	0.124 (3)	−0.0270 (16)	−0.0129 (18)	−0.0185 (18)
C3	0.0399 (16)	0.0479 (18)	0.0601 (19)	−0.0059 (13)	0.0189 (14)	0.0139 (14)
C4	0.0456 (16)	0.0304 (14)	0.0537 (17)	−0.0019 (12)	0.0143 (13)	0.0083 (12)
C5	0.0376 (15)	0.0477 (17)	0.0507 (17)	0.0088 (13)	0.0078 (13)	0.0084 (14)
C6	0.070 (2)	0.065 (2)	0.0338 (15)	0.0010 (17)	0.0125 (15)	0.0078 (14)
C7	0.058 (2)	0.075 (2)	0.0505 (19)	−0.0179 (18)	−0.0045 (16)	0.0048 (18)
C8	0.0485 (19)	0.062 (2)	0.089 (3)	0.0177 (16)	0.0297 (19)	0.0132 (19)

Geometric parameters (Å, º)

Cu1—N3	1.933 (3)	C3—C4	1.505 (4)
Cu1—O1	1.9946 (19)	C3—H3A	0.9700
Cu1—N1	2.030 (2)	C3—H3B	0.9700
Cu1—N2	2.062 (2)	C4—H4A	0.9700
Cu1—O2	2.2330 (19)	C4—H4B	0.9700
O1—C1^i	1.261 (3)	C5—H5A	0.9600
C1—O2	1.247 (3)	C5—H5B	0.9600
C1—O1^i	1.261 (3)	C5—H5C	0.9600
C1—C1^i	1.540 (5)	C6—H6A	0.9600
N1—C5	1.476 (4)	C6—H6B	0.9600
N1—C6	1.480 (4)	C6—H6C	0.9600
N1—C4	1.484 (3)	C7—H7A	0.9600
N2—C8	1.479 (4)	C7—H7B	0.9600
N2—C7	1.482 (4)	C7—H7C	0.9600
N2—C3	1.486 (4)	C8—H8A	0.9600
N3—C2	1.122 (4)	C8—H8B	0.9600
C2—O3	1.191 (4)	C8—H8C	0.9600
N3—Cu1—O1	92.33 (11)	C4—C3—H3B	110.0
N3—Cu1—N1	93.99 (11)	H3A—C3—H3B	108.4
O1—Cu1—N1	173.19 (9)	N1—C4—C3	109.7 (2)
N3—Cu1—N2	152.15 (12)	N1—C4—H4A	109.7
O1—Cu1—N2	89.69 (9)	C3—C4—H4A	109.7
N1—Cu1—N2	85.91 (9)	N1—C4—H4B	109.7
N3—Cu1—O2	103.58 (11)	C3—C4—H4B	109.7
O1—Cu1—O2	79.23 (7)	H4A—C4—H4B	108.2
N1—Cu1—O2	96.78 (8)	N1—C5—H5A	109.5
N2—Cu1—O2	104.09 (9)	N1—C5—H5B	109.5
C1^i—O1—Cu1	116.23 (16)	H5A—C5—H5B	109.5
O2—C1—O1^i	124.8 (2)	N1—C5—H5C	109.5
O2—C1—C1^i	118.2 (3)	H5A—C5—H5C	109.5
O1^i—C1—C1^i	117.1 (3)	H5B—C5—H5C	109.5
C1—O2—Cu1	108.40 (16)	N1—C6—H6A	109.5
C5—N1—C6	108.1 (2)	N1—C6—H6B	109.5
C5—N1—C4	109.3 (2)	H6A—C6—H6B	109.5
C6—N1—C4	110.9 (2)	N1—C6—H6C	109.5
C5—N1—Cu1	112.21 (17)	H6A—C6—H6C	109.5
C6—N1—Cu1	111.86 (19)	H6B—C6—H6C	109.5
C4—N1—Cu1	104.48 (15)	N2—C7—H7A	109.5
C8—N2—C7	109.2 (3)	N2—C7—H7B	109.5
C8—N2—C3	110.1 (3)	H7A—C7—H7B	109.5
C7—N2—C3	109.4 (3)	N2—C7—H7C	109.5
C8—N2—Cu1	109.3 (2)	H7A—C7—H7C	109.5
C7—N2—Cu1	111.4 (2)	H7B—C7—H7C	109.5
C3—N2—Cu1	107.35 (17)	N2—C8—H8A	109.5
C2—N3—Cu1	167.3 (3)	N2—C8—H8B	109.5
N3—C2—O3	179.0 (4)	H8A—C8—H8B	109.5
N2—C3—C4	108.6 (2)	N2—C8—H8C	109.5
N2—C3—H3A	110.0	H8A—C8—H8C	109.5
C4—C3—H3A	110.0	H8B—C8—H8C	109.5
N2—C3—H3B	110.0
N3—Cu1—O1—C1^i	−95.2 (2)	O2—Cu1—N2—C8	138.9 (2)
N2—Cu1—O1—C1^i	112.6 (2)	N3—Cu1—N2—C7	−155.2 (3)
O2—Cu1—O1—C1^i	8.2 (2)	O1—Cu1—N2—C7	−60.8 (2)
O1^i—C1—O2—Cu1	−173.8 (2)	N1—Cu1—N2—C7	114.0 (2)
C1^i—C1—O2—Cu1	6.6 (4)	O2—Cu1—N2—C7	18.0 (2)
N3—Cu1—O2—C1	81.9 (2)	N3—Cu1—N2—C3	85.0 (3)
O1—Cu1—O2—C1	−7.89 (18)	O1—Cu1—N2—C3	179.4 (2)
N1—Cu1—O2—C1	177.70 (18)	N1—Cu1—N2—C3	−5.8 (2)
N2—Cu1—O2—C1	−94.84 (19)	O2—Cu1—N2—C3	−101.76 (19)
N3—Cu1—N1—C5	67.7 (2)	O1—Cu1—N3—C2	−6.5 (14)
N2—Cu1—N1—C5	−140.25 (19)	N1—Cu1—N3—C2	176.1 (14)
O2—Cu1—N1—C5	−36.53 (19)	N2—Cu1—N3—C2	87.3 (14)
N3—Cu1—N1—C6	−54.0 (2)	O2—Cu1—N3—C2	−85.9 (14)
N2—Cu1—N1—C6	98.0 (2)	C8—N2—C3—C4	151.4 (3)
O2—Cu1—N1—C6	−158.2 (2)	C7—N2—C3—C4	−88.5 (3)
N3—Cu1—N1—C4	−174.06 (19)	Cu1—N2—C3—C4	32.5 (3)
N2—Cu1—N1—C4	−21.99 (18)	C5—N1—C4—C3	166.9 (2)
O2—Cu1—N1—C4	81.74 (18)	C6—N1—C4—C3	−74.0 (3)
N3—Cu1—N2—C8	−34.3 (3)	Cu1—N1—C4—C3	46.7 (3)
O1—Cu1—N2—C8	60.1 (2)	N2—C3—C4—N1	−54.3 (3)
N1—Cu1—N2—C8	−125.1 (2)

Symmetry code: (i) −x, −y, −z+2.