Bis(μ-1,2,4-triazole-κ²N¹:N²)­bis­[diaqua­(oxalato-κ²O,O′)copper(II)]

The crystal structure of the title compound, [Cu₂(C₂O₄)₂(C₂H₃N₃)₂(H₂O)₄], consists of dimeric neutral entities with D₂ (222) point symmetry. The two Cu^II atoms (site symmetry 2) are linked by two symmetry-related N¹,N²-bidentate 1,2,4-triazole bridges (one of the N atoms has site symmetry 2). The distorted octahedral coordination around each Cu atom is completed by two O donor atoms from a terminal bidentate oxalate ligand in the equatorial plane, and two trans-coordinated water mol­ecules occupying the apical positions with longer metal–oxy­gen distances. The complete solid-state structure can be described as a three-dimensional supramolecular framework, stabilized by extensive hydrogen-bonding interactions involving the water mol­ecules, the non-coordinated oxalate O atoms and the protonated N atom of the triazole ligands. The thermal degradation of the title compound was carried out in air between 298 and 873 K.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.041
• wR factor = 0.116
• Data-to-parameter ratio = 18.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT250_ALERT_2_C Large U3/U1 ratio for average U(i,j) tensor ....       2.11
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C1     -   C1_c     =       1.56 Ang.
PLAT432_ALERT_2_C Short Inter X...Y Contact  C1     ..  C1       =       3.15 Ang.

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2003); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Bis(µ-1,2,4-triazole-κ²N¹:N²)bis[aqua(oxalato-κ²O,O')copper(II)]

Crystal data

[Cu2(C2O4)2(C2H3N3)2(H2O)4]	Dx = 2.064 Mg m^−3 Dm = 2.05 (1) Mg m^−3 Dm measured by flotation in a mixture of carbon tetrachloride and bromoform
Mr = 513.35	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I41/acd	Cell parameters from 13778 reflections
Hall symbol: -I 4bd 2c	θ = 2.5–25.8°
a = 16.596 (1) Å	µ = 2.66 mm^−1
c = 11.996 (2) Å	T = 293 K
V = 3304.0 (6) Å^3	Prism, blue
Z = 8	0.42 × 0.20 × 0.08 mm
F(000) = 2064

Data collection

Xcalibur diffractometer	652 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.070
ω scans	θmax = 30.0°, θmin = 3.2°
Absorption correction: numerical CrysAlis RED (Oxford Diffraction, 2003)	h = −23→23
Tmin = 0.534, Tmax = 0.809	k = −23→23
13778 measured reflections	l = −16→16
1212 independent reflections

Refinement

Refinement on F^2	Primary atom site location: heavy-atom method
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.041	Hydrogen site location: difference Fourier map
wR(F^2) = 0.116	H-atom parameters not refined
S = 0.98	w = 1/[σ^2(Fo^2) + (0.0549P)^2] where P = (Fo^2 + 2Fc^2)/3
1212 reflections	(Δ/σ)max = 0.001
65 parameters	Δρmax = 0.50 e Å^−3
0 restraints	Δρmin = −0.55 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	0.91613 (2)	0.16613 (2)	0.1250	0.0264 (2)
O1	0.7976 (1)	0.1593 (1)	0.1352 (2)	0.0290 (6)
O2	0.7013 (1)	0.0664 (1)	0.1278 (2)	0.0309 (6)
O3w	0.9167 (2)	0.1755 (2)	−0.0816 (2)	0.0336 (6)
N1	1.0363 (2)	0.1557 (2)	0.1219 (3)	0.0208 (6)
N3	1.1525 (2)	0.0975 (2)	0.1250	0.0250 (9)
C1	0.7718 (2)	0.0882 (2)	0.1279 (3)	0.0245 (7)
C2	1.0740 (2)	0.0864 (2)	0.1199 (3)	0.0286 (8)
H2	1.047	0.041	0.127	0.05*
H3	1.186	0.064	0.1250	0.05*
H31	0.969	0.157	−0.112	0.05*
H32	0.892	0.129	−0.095	0.05*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0157 (2)	0.0157 (2)	0.0477 (4)	−0.0014 (3)	0.0003 (2)	−0.0003 (2)
O1	0.018 (1)	0.017 (1)	0.052 (2)	−0.000 (1)	0.001 (1)	0.001 (1)
O2	0.018 (1)	0.023 (1)	0.051 (2)	−0.004 (1)	−0.002 (1)	0.002 (1)
O3w	0.029 (2)	0.032 (2)	0.040 (2)	−0.002 (1)	0.000 (1)	0.001 (1)
N1	0.017 (1)	0.013 (1)	0.033 (2)	−0.002 (1)	0.001 (1)	0.000 (1)
N3	0.019 (1)	0.019 (1)	0.037 (2)	0.010 (2)	−0.003 (2)	−0.003 (2)
C1	0.023 (2)	0.021 (2)	0.029 (2)	−0.002 (1)	0.000 (2)	0.005 (2)
C2	0.024 (2)	0.018 (2)	0.044 (2)	0.002 (1)	−0.005 (2)	−0.003 (2)

Geometric parameters (Å, º)

Cu1—O1	1.975 (2)	O3w—H32	0.89
Cu1—N1	2.002 (3)	N1—N1^ii	1.364 (5)
Cu1—O3w	2.483 (3)	N1—C2	1.309 (4)
Cu1—O1^i	1.975 (2)	N3—C2	1.318 (4)
Cu1—N1^i	2.002 (3)	N3—C2^ii	1.318 (4)
Cu1—O3w^i	2.483 (3)	C1—C1^i	1.560 (7)
O1—C1	1.259 (4)	C2—H2	0.88
O2—C1	1.224 (4)	N3—H3	0.78
O3w—H31	0.99
O1—Cu1—O1^i	83.7 (1)	N1^i—Cu1—O3w^i	89.1 (1)
O1—Cu1—N1	171.4 (1)	N1^i—Cu1—O3w	87.5 (1)
O1—Cu1—N1^i	88.3 (1)	H31—O3w—H32	93.9
O1—Cu1—O3w	94.0 (1)	O1—C1—O2	127.0 (3)
O1—Cu1—O3w^i	90.1 (1)	O1—C1—C1^i	115.2 (2)
N1—Cu1—N1^i	100.0 (1)	O2—C1—C1^i	117.8 (2)
N1—Cu1—O3w	89.1 (1)	N1—C2—N3	110.5 (3)
N1—Cu1—O3w^i	87.5 (1)	C2—N1—N1^ii	106.5 (2)
O3w—Cu1—O3w^i	174.6 (1)	C2—N3—C2^ii	106.1 (4)
O1^i—Cu1—N1^i	171.4 (1)	N1—C2—H2	121.0
O1^i—Cu1—N1	88.3 (1)	C2—N3—H3	127.0
O1^i—Cu1—O3w^i	94.0 (1)	C2^ii—N3—H3	127.0
O1^i—Cu1—O3w	90.1 (1)	N3—C2—H2	127.6

Symmetry codes: (i) y+3/4, x−3/4, −z+1/4; (ii) −y+5/4, −x+5/4, −z+1/4.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3···O2^iii	0.78	2.18	2.838 (4)	142
N3—H3···O2^iv	0.78	2.18	2.838 (4)	142
O3w—H32···O2^v	0.89	1.91	2.724 (3)	152
O3w—H31···O3w^vi	0.99	1.88	2.822 (4)	157

Symmetry codes: (iii) x+1/2, −y, z; (iv) y+5/4, −x+3/4, −z+1/4; (v) −x+3/2, y, −z; (vi) −y+5/4, x−3/4, −z−1/4.