N,N'-Dimethyl­ethylenediammonium dioxalatocuprate(II)

The asymmetric unit of the title salt, (C₄H₁₄N₂)[Cu(C₂O₄)₂], consists of one complex anion and two cationic half-mol­ecules, the other halves being generated by inversion symmetry. The Cu^II atom in the anion is coordinated by two bidentate oxalate ligands in a distorted square-planar geometry. Inter­molecular hydrogen bonds, involving the NH groups as donors and O atoms as acceptors, are observed, which lead to the formation of a three-dimensional network structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.024
• wR factor = 0.070
• Data-to-parameter ratio = 13.2

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT919_ALERT_3_B Reflection # Likely Affected by the Beamstop ...          1
PLAT934_ALERT_3_B Number of (Iobs-Icalc)/SigmaW .gt. 10 Outliers .          2

Alert level C
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         20
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         23

Alert level G
PLAT004_ALERT_5_G Info: Polymeric Structure Found with Dimension .          1
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT154_ALERT_1_G The su's on the Cell Angles are Equal ..........    0.00100 Deg.
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K
PLAT232_ALERT_2_G Hirshfeld Test Diff (M-X)  Cu1    --  O1      ..        5.5 su
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........         14

   0 ALERT level A = Most likely a serious problem - resolve or explain
   2 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   7 ALERT level G = General information/check it is not something unexpected

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   2 ALERT type 5 Informative message, check

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S1. Comment

The title salt, (C₄H₁₄N₂)[Cu(C₂O₄)₂], was obtained as an unexpected product by reaction of the employed ligand (C₆H₁₀N₂O₂)_n, in a methanolic medium. The hydrolytically unstable cyclic ligand apparently is oxidatively hydrolyzed in the presence of metal ions, leading to the oxalate dianion (Diallo et al., 2008; Kelly et al., 2005). This species, which is generated in situ, acts with copper(II) ions resulting in the formation of the title compound. A similar reaction was found elsewhere (Zhang et al., 2009).

The structure exhibits an ion-pair complex comprising two cationic half-molecules (the other halves being generated by inversion symmetry) and a [Cu(C₂O₄)₂]^2- dianion (Fig. 1). The Cu^II ion is four-coordinated in a slightly distorted square–planar CuO₄ environment, comprising four O donor atoms from two oxalate ligands [Cu–O, 1.9128 (13), 1.9163 (13), 1.9184 (13) and 1.9572 (13) Å]. The O(1)—Cu—O(2 A) and O(2)—Cu—O(1 A) angles are 179.52 (5) and 178.10 (5)°, respectively, which are slightly smaller than those observed in the complex [K₂Cu(ox)₂]^.4H₂O (180 °), where ox is oxalate (Fan et al., 2001). The other two oxygen atoms of each oxalate group are not involved in coordination. The two oxalate anions deviate slightly from planarity, with torsion angles of O(1)—C(1)—C(2)—O(2), O(4)—C(1)—C(2)—O(3), O(1A)—C(1A)—C(2A)—O(2A) and O(4A)—C(1A)—C(2A)—O(3A) -2.5 (2), -3.4 (3), 2.8 (2) and 3.8 (2)°, respectively. These values are similar to those found in [Cu(bpy)(C₂O₄)(H₂O)]^.H₂C₂O₄ (Androš et al., 2010), where bpy is bipyridine.

N—H···O hydrogen-bonding interactions, part of which are bifurcated, between the cations and the complex anions lead to the formation of a three-dimensional network structure (Table 2; Figs. 2, 3).

Related literature

For background to decomposition reactions leading to oxalate anions, see: Kelly et al. (2005); Diallo et al. (2008). For related structures, see: Androš et al. (2010); Fan et al. (2001); Zhang et al. (2009).

S2. Experimental

In a 50 ml round bottom flask dimethyl oxalate (2.36 g, 0.020 mol), dissolved in ethanol (10 ml), was reacted with N,N'-dimethyl-1,2-diaminoethane (1.77 g, 0.020 mol) in ethanol (10 ml), to yield immediately a quantitative precipitate. The white solid formed was separated by filtration, washed with methanol and ether and dried under vacuum (yield 3.32 g, 58.5%); m.p.= 513 K. ¹ H NMR in CDCl₃, δ (p.p.m.): 3.1, s, 12H, –CH3; 3.5, s, 8H, –CH₂–. ¹³C NMR in CDCl₃, δ (p.p.m.): 34.86, N—CH₃, 46.12, N—CH₂, 157.56, C=O. IR (cm^-1) 1598 (C=O), 1284 (C—N). Anal. Calc. for C₁₂H₂₀N₄O₄ (%): C, 50.62; H, 7.11; N, 19.68. Found: C, 50.60; H, 7.09; N, 19.71. Mass spectrum (m/z) 284, 162, 134, 106, 78. Into a methanolic solution (5 ml) of copper chloride dihydrate (0.2131 g, 1.25 mmol) was added a methanolic solution (10 ml) of the ligand prepared as described above (0.3554 g, 1.25 mmol). The resulting mixture was heated at 333 K for thirty minutes. The green solution was filtered and then allowed to evaporate slowly in open atmosphere. After one week, blue crystals suitable for X-ray analysis were obtained. The crystals were separated, washed with cold methanol and dried (yield: 65%); Anal. Calc. for (C₄H₁₄N₂)[Cu(C₂O₄)₂](%): C, 29.14; H, 4.28; N, 8.50. Found: C, 29.16; H, 4.26; N, 8.46. Selected IR data (cm^-1, KBr pellet): 3300, 1637, 1600, 1582, 1197, 764.

S3. Refinement

All H atoms were located from the Fourier electron density maps, then placed according to their geometrical environment and refined isotropically. They were refined using a riding model with 0.96 Å for methyl H atoms and U_iso(H) = 1.5U_eq(C), with 0.97 Å for methylene H atoms and U_iso(H) = 1.2U_eq(C), and with 0.90 Å for ammonium H atoms and U_iso(H) = 1.2U_eq(N). In addition, a rotating-group model was applied for methyl groups.

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. An ORTEP view of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are plotted at the 50% probability level. [Symmetry codes: *) -x + 1, -y + 1, -z; **) -x + 1, -y, -z + 1].
	Fig. 2. Projection of the structure along the b axis showing the anions connected by organics cations. Broken lines stand for hydrogen bonds.
	Fig. 3. Projection of the structure along the a axis showing the anions connected by organics cations. Broken lines stand for hydrogen bonds.

N,N'-Dimethylethylenediammonium dioxalatocuprate(II)

Crystal data

(C4H14N2)[Cu(C2O4)2]	Z = 2
Mr = 329.75	F(000) = 338
Triclinic, P1	Dx = 1.916 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.7734 (5) Å	Cell parameters from 2192 reflections
b = 8.4127 (7) Å	θ = 1.7–26.4°
c = 12.5623 (11) Å	µ = 1.95 mm^−1
α = 90.443 (1)°	T = 293 K
β = 100.715 (1)°	Prism, blue
γ = 107.188 (1)°	0.15 × 0.13 × 0.10 mm
V = 571.46 (8) Å^3

Data collection

Bruker SMART CCD diffractometer	Rint = 0.014
Graphite monochromator	θmax = 26.4°, θmin = 1.7°
ω scans	h = −7→7
4558 measured reflections	k = −10→10
2292 independent reflections	l = −15→15
2192 reflections with I > 2σ(I)

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)] = 0.024	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.07	H-atom parameters constrained
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0412P)^2 + 0.2106P] where P = (Fo^2 + 2Fc^2)/3
2292 reflections	(Δ/σ)max < 0.001
174 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.43 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	0.81900 (4)	0.08511 (2)	0.071311 (15)	0.02027 (10)
O1	0.7688 (2)	−0.09898 (16)	0.16179 (10)	0.0236 (3)
O2	0.9414 (3)	0.22323 (16)	0.20393 (11)	0.0273 (3)
O3	0.9874 (3)	0.1983 (2)	0.38225 (12)	0.0400 (4)
O4	0.8221 (3)	−0.14792 (19)	0.33674 (12)	0.0346 (3)
O1A	0.7045 (2)	−0.05261 (16)	−0.06558 (10)	0.0244 (3)
O2A	0.8699 (3)	0.27099 (16)	−0.01838 (11)	0.0274 (3)
O3A	0.7987 (3)	0.32433 (18)	−0.19228 (12)	0.0325 (3)
O4A	0.6466 (2)	−0.01666 (17)	−0.24263 (10)	0.0271 (3)
C1	0.8324 (3)	−0.0538 (2)	0.26338 (15)	0.0230 (4)
C2	0.9307 (3)	0.1394 (2)	0.28879 (15)	0.0249 (4)
C1A	0.7074 (3)	0.0373 (2)	−0.14883 (14)	0.0201 (3)
C2A	0.8000 (3)	0.2289 (2)	−0.11968 (15)	0.0221 (4)
C1S	0.5705 (4)	0.5131 (2)	0.05810 (18)	0.0323 (4)
H1S1	0.7161	0.4764	0.0631	0.039*
H1S2	0.6244	0.6309	0.0809	0.039*
N1S	0.4111 (3)	0.4180 (2)	0.13069 (15)	0.0328 (4)
H2S1	0.2785	0.4547	0.1272	0.039*
H2S2	0.3564	0.3094	0.1074	0.039*
C2S	0.4947 (4)	−0.0903 (3)	0.50540 (16)	0.0302 (4)
H3S1	0.6487	−0.1056	0.4941	0.036*
H3S2	0.4737	−0.1213	0.578	0.036*
N2S	0.2872 (3)	−0.1980 (2)	0.42503 (13)	0.0329 (4)
H4S1	0.313	−0.1731	0.3578	0.039*
H4S2	0.1467	−0.177	0.4324	0.039*
C3S	0.5449 (4)	0.4354 (3)	0.24519 (18)	0.0394 (5)
H1S3	0.6805	0.3899	0.25	0.059*
H1S4	0.434	0.3762	0.2898	0.059*
H1S5	0.6069	0.5512	0.2698	0.059*
C4S	0.2574 (5)	−0.3766 (3)	0.4373 (2)	0.0484 (6)
H2S3	0.4075	−0.3993	0.4303	0.073*
H2S4	0.124	−0.4417	0.382	0.073*
H2S5	0.2213	−0.4051	0.5075	0.073*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.02469 (14)	0.01821 (14)	0.01732 (14)	0.00556 (9)	0.00424 (9)	0.00003 (9)
O1	0.0270 (7)	0.0220 (6)	0.0214 (6)	0.0065 (5)	0.0054 (5)	0.0008 (5)
O2	0.0344 (7)	0.0231 (6)	0.0228 (7)	0.0070 (6)	0.0046 (5)	−0.0023 (5)
O3	0.0505 (9)	0.0451 (9)	0.0212 (7)	0.0126 (7)	0.0027 (6)	−0.0065 (6)
O4	0.0398 (8)	0.0394 (8)	0.0268 (7)	0.0139 (7)	0.0089 (6)	0.0120 (6)
O1A	0.0326 (7)	0.0193 (6)	0.0194 (6)	0.0060 (5)	0.0034 (5)	−0.0003 (5)
O2A	0.0389 (8)	0.0198 (6)	0.0229 (7)	0.0069 (6)	0.0075 (6)	0.0005 (5)
O3A	0.0419 (8)	0.0299 (7)	0.0280 (7)	0.0139 (6)	0.0071 (6)	0.0104 (6)
O4A	0.0284 (7)	0.0331 (7)	0.0189 (7)	0.0097 (6)	0.0022 (5)	−0.0022 (5)
C1	0.0189 (8)	0.0285 (9)	0.0243 (9)	0.0101 (7)	0.0063 (7)	0.0032 (7)
C2	0.0221 (9)	0.0290 (9)	0.0236 (9)	0.0092 (7)	0.0024 (7)	−0.0032 (7)
C1A	0.0160 (8)	0.0235 (9)	0.0226 (9)	0.0084 (7)	0.0047 (6)	0.0006 (7)
C2A	0.0212 (8)	0.0224 (8)	0.0254 (9)	0.0095 (7)	0.0063 (7)	0.0033 (7)
C1S	0.0270 (10)	0.0234 (9)	0.0457 (12)	0.0029 (8)	0.0135 (9)	−0.0064 (8)
N1S	0.0272 (8)	0.0244 (8)	0.0462 (10)	0.0054 (7)	0.0098 (7)	−0.0023 (7)
C2S	0.0294 (10)	0.0409 (12)	0.0210 (9)	0.0130 (9)	0.0028 (7)	0.0028 (8)
N2S	0.0340 (9)	0.0379 (9)	0.0244 (8)	0.0084 (7)	0.0039 (7)	0.0050 (7)
C3S	0.0414 (12)	0.0311 (11)	0.0445 (13)	0.0124 (9)	0.0032 (10)	−0.0025 (9)
C4S	0.0696 (17)	0.0385 (12)	0.0354 (12)	0.0118 (12)	0.0131 (11)	0.0060 (10)

Geometric parameters (Å, º)

Cu1—O1	1.9128 (13)	C1S—H1S2	0.97
Cu1—O2	1.9163 (13)	N1S—C3S	1.485 (3)
Cu1—O2A	1.9184 (13)	N1S—H2S1	0.90
Cu1—O1A	1.9572 (13)	N1S—H2S2	0.90
O1—C1	1.282 (2)	C2S—N2S	1.473 (3)
O2—C2	1.284 (2)	C2S—C2S^ii	1.511 (4)
O3—C2	1.218 (2)	C2S—H3S1	0.97
O4—C1	1.218 (2)	C2S—H3S2	0.97
O1A—C1A	1.295 (2)	N2S—C4S	1.474 (3)
O2A—C2A	1.275 (2)	N2S—H4S1	0.90
O3A—C2A	1.220 (2)	N2S—H4S2	0.90
O4A—C1A	1.209 (2)	C3S—H1S3	0.96
C1—C2	1.564 (3)	C3S—H1S4	0.96
C1A—C2A	1.558 (2)	C3S—H1S5	0.96
C1S—N1S	1.486 (3)	C4S—H2S3	0.96
C1S—C1S^i	1.513 (4)	C4S—H2S4	0.96
C1S—H1S1	0.97	C4S—H2S5	0.96
O1—Cu1—O2	85.90 (5)	C3S—N1S—H2S1	109.2
O1—Cu1—O2A	179.52 (5)	C1S—N1S—H2S1	109.2
O2—Cu1—O2A	93.63 (6)	C3S—N1S—H2S2	109.2
O1—Cu1—O1A	95.12 (5)	C1S—N1S—H2S2	109.2
O2—Cu1—O1A	178.10 (5)	H2S1—N1S—H2S2	107.9
O2A—Cu1—O1A	85.36 (5)	N2S—C2S—C2S^ii	110.15 (19)
C1—O1—Cu1	113.02 (11)	N2S—C2S—H3S1	109.6
C2—O2—Cu1	112.98 (12)	C2S^ii—C2S—H3S1	109.6
C1A—O1A—Cu1	111.82 (11)	N2S—C2S—H3S2	109.6
C2A—O2A—Cu1	113.52 (11)	C2S^ii—C2S—H3S2	109.6
O4—C1—O1	125.29 (18)	H3S1—C2S—H3S2	108.1
O4—C1—C2	120.57 (17)	C2S—N2S—C4S	112.34 (17)
O1—C1—C2	114.14 (15)	C2S—N2S—H4S1	109.1
O3—C2—O2	125.64 (18)	C4S—N2S—H4S1	109.1
O3—C2—C1	120.45 (17)	C2S—N2S—H4S2	109.1
O2—C2—C1	113.90 (15)	C4S—N2S—H4S2	109.1
O4A—C1A—O1A	125.21 (17)	H4S1—N2S—H4S2	107.9
O4A—C1A—C2A	120.46 (16)	N1S—C3S—H1S3	109.5
O1A—C1A—C2A	114.33 (15)	N1S—C3S—H1S4	109.5
O3A—C2A—O2A	125.78 (17)	H1S3—C3S—H1S4	109.5
O3A—C2A—C1A	119.40 (17)	N1S—C3S—H1S5	109.5
O2A—C2A—C1A	114.82 (15)	H1S3—C3S—H1S5	109.5
N1S—C1S—C1S^i	110.2 (2)	H1S4—C3S—H1S5	109.5
N1S—C1S—H1S1	109.6	N2S—C4S—H2S3	109.5
C1S^i—C1S—H1S1	109.6	N2S—C4S—H2S4	109.5
N1S—C1S—H1S2	109.6	H2S3—C4S—H2S4	109.5
C1S^i—C1S—H1S2	109.6	N2S—C4S—H2S5	109.5
H1S1—C1S—H1S2	108.1	H2S3—C4S—H2S5	109.5
C3S—N1S—C1S	112.06 (16)	H2S4—C4S—H2S5	109.5
O2—Cu1—O1—C1	0.30 (12)	O1—C1—C2—O3	176.97 (17)
O1A—Cu1—O1—C1	178.68 (12)	O4—C1—C2—O2	177.15 (17)
O1—Cu1—O2—C2	−1.77 (13)	O1—C1—C2—O2	−2.5 (2)
O2A—Cu1—O2—C2	178.14 (13)	Cu1—O1A—C1A—O4A	179.71 (14)
O1—Cu1—O1A—C1A	178.09 (11)	Cu1—O1A—C1A—C2A	0.11 (17)
O2A—Cu1—O1A—C1A	−1.83 (12)	Cu1—O2A—C2A—O3A	175.09 (15)
O2—Cu1—O2A—C2A	−178.11 (13)	Cu1—O2A—C2A—C1A	−4.23 (19)
O1A—Cu1—O2A—C2A	3.51 (13)	O4A—C1A—C2A—O3A	3.8 (3)
Cu1—O1—C1—O4	−178.63 (15)	O1A—C1A—C2A—O3A	−176.58 (16)
Cu1—O1—C1—C2	0.99 (18)	O4A—C1A—C2A—O2A	−176.83 (16)
Cu1—O2—C2—O3	−176.78 (17)	O1A—C1A—C2A—O2A	2.8 (2)
Cu1—O2—C2—C1	2.64 (19)	C1S^i—C1S—N1S—C3S	178.0 (2)
O4—C1—C2—O3	−3.4 (3)	C2S^ii—C2S—N2S—C4S	−175.9 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1S—H2S1···O3A^i	0.90	2.22	2.939 (2)	137
N1S—H2S2···O1A^iii	0.90	2.13	3.018 (2)	169
N2S—H4S1···O4A^iii	0.90	2.15	2.939 (2)	145
N2S—H4S1···O3A^iii	0.90	2.31	3.004 (2)	134
N2S—H4S2···O4^iv	0.90	2.11	2.861 (2)	140
N2S—H4S2···O3^ii	0.90	2.58	3.131 (2)	120

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