Poly[di-μ-glycinato-copper(II)]: a two-dimensional coordination polymer

The title coordination polymer, [Cu(C₂H₄NO₂)₂]_n, is two-dimensional and consists of a distorted octa­hedral copper coordination polyhedron with two bidentate glycine ligands chelating the metal through the O and N atoms in a trans-square-planar configuration. The two axial coordination sites are occupied by carbonyl O atoms of neighbouring glycine mol­ecules. The Cu—O distances for the axial O atoms [2.648 (2) and 2.837 (2) Å] are considerably longer than both the Cu—O [1.9475 (17) and 1.9483 (18) Å] and Cu—N [1.988 (2) and 1.948 (2) Å] distances in the equatorial plane, which indicates a strong Jahn–Teller effect. In the crystal, the two-dimensional networks are arranged parallel to (001) and are linked via N—H...O hydrogen bonds, forming a three-dimensional arrangement.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.032
• wR factor = 0.075
• Data-to-parameter ratio = 16.2

checkCIF/PLATON results

No syntax errors found



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 ....          ?
PLAT128_ALERT_4_G Alternate Setting of Space-group P21/c   .......      P21/n

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 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
   1 ALERT type 4 Improvement, methodology, query or suggestion
   2 ALERT type 5 Informative message, check

---

S1. Comment

Different metal glycine complexes and polymeric structures have been known since the 1960's. The first work on a cadmium glycinato complexe was done by (Low et al., 1959), and further studies were reported by (Barrie et al., 1993). Mixed metal glycinato complexes with copper(II) were investigated by (Papavinasam, 1991; Davies et al., 2003; Low et al., 1959).

The complexation of simple copper salts to amino acids is a well investigated reaction and various complexes and clusters have been reported (Low et al., 1959; Davies et al., 2003; Aromi et al., 2008; Bi et al., 2006; Zhang et al., 2005). A three-dimensional copper-glycinate coordination polymer has been reported on by (Chen et al., 2009).

While redissolving the copper cluster [NaCu₆(gly)₃(ClO₄)₃(H₂O)]_n (ClO₄)_2n (Aromi et al., 2008) in DMSO, blue crystals of the title compound were obtained and were characterized by X-ray diffraction.

The title compound is a two-dimensional coordination polymer (Fig. 1). It consists of a distorted octahedral copper coordination polyhedron with two bidentate glycine ligands chelating the metal through the oxygen and nitrogen atoms (O1, O3, N1, N2) in a trans square planar configuration. The two axial coordination sites are occupied by carbonyl oxygen atoms of the neighbouring glycine molecules (O2 and O4). The Cu—O distances are 2.648 (2) Å (Cu1—O2ⁱ) and 2.837 (2) Å (Cu1—O4ⁱⁱ) for the axial oxygen atoms [symmetry codes: (i) -x-1/2, y+1/2, -z+1/2; (ii) -x+1/2, y-1/2, -z+1/2]. In the equatorial plane the Cu-O distances are 1.9474 (15) and 1.9483 (16) Å for Cu1—O1 and Cu1—O3, respectively, while the Cu—N distances are 1.9883 (19) and 1.948 (2) Å for Cu1-N1 and Cu1—N2, respectively. These bond length differences indicate a strong Jahn-Teller effect.

In the crystal the two dimensional networks are linked via N-H···O hydrogen bonds to form a three-dimensional arrangement (Table 1 and Fig. 2).

Related literature

For the first work on cadmium glycinato complexes, see: Low et al. (1959). For similar mixed-metal glycinato complexes with copper(II), see: Papavinasam (1991); Davies et al. (2003); Low et al. (1959); Bi et al. (2006); Zhang et al. (2005). For further studies on cadmium–glycinato complexes, see: Barrie et al. (1993). For the properties and structure of a three-dimensional copper–glycinate polymer, see: Chen et al. (2009). For the synthesis of [NaCu₆(gly)₃(ClO₄)₃(H₂O)]_n(ClO₄)_2n, see: Aromi et al. (2008).

S2. Experimental

The title compound was prepared by dissolving 20 mg of [NaCu₆(gly)₃(ClO₄)₃(H₂O)]_n (ClO₄)_2n (Aromi et al., 2008) in 5 ml DMSO. Crystals could be grown out of the blue solution by slow diffusion of THF.

S3. Refinement

The NH-atoms were located in difference electron-density maps and were freely refined. The C-bound H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.97 Å, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: X-AREA (Stoe & Cie, 2009); cell refinement: X-AREA (Stoe & Cie, 2009); data reduction: X-RED (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. Part of the polymeric structure of the title compound, showing the numbering scheme and the displacement ellipsoids drawn at the 50% probability level [H atoms have been omitted for clarity; symmetry codes: (i) -x-1/2, y+1/2, -z+1/2; (ii) -x+1/2, y-1/2, -z+1/2].
	Fig. 2. A view along the x-axis of the three-dimensional hydrogen bonded network of the title compound built up from the two-dimenional nets. The N-H···O hydrogen bonds are shown as dashed lines (see Table 1 for details; H-atoms not involved in these reactions have been omitted for clarity).

Poly[di-µ-glycinato-copper(II)]

Crystal data

[Cu(C2H4NO2)2]	F(000) = 428
Mr = 211.66	Dx = 2.195 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 5867 reflections
a = 9.4265 (19) Å	θ = 2.3–30.5°
b = 5.1159 (10) Å	µ = 3.37 mm^−1
c = 13.912 (3) Å	T = 298 K
β = 107.36 (3)°	Block, blue
V = 640.4 (2) Å^3	0.21 × 0.15 × 0.09 mm
Z = 4

Data collection

Stoe IPDS 2 diffractometer	1876 independent reflections
Radiation source: fine-focus sealed tube	1561 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.048
Detector resolution: 6.67 pixels mm^-1	θmax = 30.0°, θmin = 2.3°
rotation method scans	h = −13→13
Absorption correction: integration (X-SHAPE and X-RED; Stoe & Cie, 2009)	k = −7→6
Tmin = 0.549, Tmax = 0.692	l = −19→17
9012 measured reflections

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)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.075	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0447P)^2] where P = (Fo^2 + 2Fc^2)/3
1876 reflections	(Δ/σ)max = 0.001
116 parameters	Δρmax = 0.42 e Å^−3
0 restraints	Δρmin = −0.58 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles

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	−0.00228 (3)	0.02678 (5)	0.26465 (2)	0.0301 (1)
O1	−0.17587 (17)	−0.1989 (3)	0.21922 (12)	0.0270 (4)
O2	−0.3924 (2)	−0.2410 (4)	0.10081 (14)	0.0408 (6)
O3	0.17471 (18)	0.2461 (3)	0.30307 (13)	0.0317 (4)
O4	0.41730 (18)	0.2283 (4)	0.38098 (15)	0.0392 (5)
N1	−0.1151 (2)	0.2642 (4)	0.15535 (16)	0.0283 (5)
N2	0.1137 (2)	−0.2140 (4)	0.37098 (17)	0.0302 (6)
C1	−0.2742 (2)	−0.1247 (4)	0.13882 (17)	0.0260 (6)
C2	−0.2384 (3)	0.1181 (4)	0.08778 (17)	0.0304 (6)
C3	0.2916 (2)	0.1351 (4)	0.36051 (16)	0.0253 (5)
C4	0.2694 (2)	−0.1268 (4)	0.40529 (17)	0.0282 (6)
H1A	0.112 (5)	−0.378 (10)	0.340 (3)	0.076 (13)*
H1B	0.082 (4)	−0.233 (7)	0.418 (3)	0.045 (9)*
H2A	−0.21240	0.06770	0.02790	0.0360*
H2B	−0.32560	0.22930	0.06700	0.0360*
H3A	−0.153 (4)	0.393 (7)	0.184 (2)	0.045 (9)*
H3B	−0.061 (4)	0.342 (8)	0.124 (3)	0.061 (11)*
H4A	0.33140	−0.25670	0.38670	0.0340*
H4B	0.30110	−0.11300	0.47810	0.0340*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0249 (1)	0.0214 (1)	0.0380 (2)	−0.0026 (1)	−0.0001 (1)	0.0078 (1)
O1	0.0262 (7)	0.0191 (7)	0.0334 (8)	−0.0016 (5)	0.0052 (6)	0.0030 (6)
O2	0.0375 (9)	0.0391 (10)	0.0389 (10)	−0.0142 (7)	0.0010 (7)	0.0043 (7)
O3	0.0277 (7)	0.0216 (7)	0.0408 (9)	−0.0028 (6)	0.0028 (6)	0.0046 (6)
O4	0.0275 (8)	0.0350 (9)	0.0510 (11)	−0.0060 (7)	0.0057 (7)	0.0016 (8)
N1	0.0274 (9)	0.0214 (8)	0.0340 (10)	−0.0019 (7)	0.0062 (7)	0.0055 (7)
N2	0.0291 (9)	0.0253 (9)	0.0331 (11)	−0.0023 (7)	0.0046 (8)	0.0068 (8)
C1	0.0282 (10)	0.0234 (9)	0.0262 (10)	−0.0011 (7)	0.0080 (8)	−0.0020 (8)
C2	0.0351 (11)	0.0263 (10)	0.0264 (11)	−0.0053 (8)	0.0041 (8)	0.0017 (8)
C3	0.0267 (9)	0.0238 (9)	0.0246 (10)	−0.0018 (7)	0.0066 (8)	−0.0025 (7)
C4	0.0279 (10)	0.0272 (10)	0.0272 (11)	0.0017 (8)	0.0049 (8)	0.0043 (8)

Geometric parameters (Å, º)

Cu1—O1	1.9475 (17)	N2—C4	1.471 (3)
Cu1—O3	1.9483 (18)	N1—H3B	0.86 (4)
Cu1—N1	1.988 (2)	N1—H3A	0.90 (4)
Cu1—N2	1.984 (2)	N2—H1A	0.94 (5)
Cu1—O2^i	2.648 (2)	N2—H1B	0.80 (4)
Cu1—O4^ii	2.837 (2)	C1—C2	1.518 (3)
O1—C1	1.279 (3)	C3—C4	1.518 (3)
O2—C1	1.234 (3)	C2—H2A	0.9700
O3—C3	1.284 (3)	C2—H2B	0.9700
O4—C3	1.229 (3)	C4—H4A	0.9700
N1—C2	1.463 (3)	C4—H4B	0.9700
O1—Cu1—O3	176.59 (8)	H3A—N1—H3B	105 (4)
O1—Cu1—N1	84.73 (8)	C4—N2—H1A	107 (3)
O1—Cu1—N2	95.55 (8)	Cu1—N2—H1A	106 (3)
O1—Cu1—O2^i	92.26 (7)	Cu1—N2—H1B	115 (3)
O1—Cu1—O4^ii	80.68 (7)	C4—N2—H1B	111 (3)
O3—Cu1—N1	94.41 (8)	H1A—N2—H1B	108 (4)
O3—Cu1—N2	85.22 (8)	O2—C1—C2	119.5 (2)
O2^i—Cu1—O3	91.07 (7)	O1—C1—O2	123.9 (2)
O3—Cu1—O4^ii	96.01 (7)	O1—C1—C2	116.60 (19)
N1—Cu1—N2	178.27 (9)	N1—C2—C1	111.24 (19)
O2^i—Cu1—N1	92.22 (8)	O3—C3—O4	124.2 (2)
O4^ii—Cu1—N1	89.04 (8)	O3—C3—C4	116.60 (18)
O2^i—Cu1—N2	89.48 (8)	O4—C3—C4	119.3 (2)
O4^ii—Cu1—N2	89.32 (8)	N2—C4—C3	112.39 (18)
O2^i—Cu1—O4^ii	172.69 (7)	N1—C2—H2A	109.00
Cu1—O1—C1	115.30 (14)	N1—C2—H2B	109.00
Cu1^iii—O2—C1	113.23 (15)	C1—C2—H2A	109.00
Cu1—O3—C3	114.93 (14)	C1—C2—H2B	109.00
Cu1^iv—O4—C3	120.10 (16)	H2A—C2—H2B	108.00
Cu1—N1—C2	108.68 (14)	N2—C4—H4A	109.00
Cu1—N2—C4	109.16 (15)	N2—C4—H4B	109.00
C2—N1—H3A	108 (2)	C3—C4—H4A	109.00
Cu1—N1—H3A	107.6 (18)	C3—C4—H4B	109.00
Cu1—N1—H3B	114 (3)	H4A—C4—H4B	108.00
C2—N1—H3B	113 (3)
N1—Cu1—O1—C1	6.99 (16)	N2—Cu1—O2^i—C1^i	−157.43 (17)
N2—Cu1—O1—C1	−171.29 (16)	O1—Cu1—O4^ii—C3^ii	−133.24 (18)
O2^i—Cu1—O1—C1	99.01 (15)	O3—Cu1—O4^ii—C3^ii	47.61 (18)
O4^ii—Cu1—O1—C1	−82.90 (15)	N1—Cu1—O4^ii—C3^ii	141.95 (18)
N1—Cu1—O3—C3	−166.00 (16)	N2—Cu1—O4^ii—C3^ii	−37.51 (18)
N2—Cu1—O3—C3	12.30 (16)	Cu1—O1—C1—O2	−178.31 (18)
O2^i—Cu1—O3—C3	101.69 (16)	Cu1—O1—C1—C2	3.1 (2)
O4^ii—Cu1—O3—C3	−76.51 (16)	Cu1^iii—O2—C1—O1	32.3 (3)
O1—Cu1—N1—C2	−14.98 (16)	Cu1^iii—O2—C1—C2	−149.11 (17)
O3—Cu1—N1—C2	161.71 (16)	Cu1—O3—C3—O4	169.39 (19)
O2^i—Cu1—N1—C2	−107.04 (16)	Cu1—O3—C3—C4	−11.0 (2)
O4^ii—Cu1—N1—C2	65.75 (16)	Cu1^iv—O4—C3—O3	−34.4 (3)
O1—Cu1—N2—C4	166.43 (15)	Cu1^iv—O4—C3—C4	146.03 (16)
O3—Cu1—N2—C4	−10.23 (15)	Cu1—N1—C2—C1	19.8 (2)
O2^i—Cu1—N2—C4	−101.35 (15)	Cu1—N2—C4—C3	7.4 (2)
O4^ii—Cu1—N2—C4	85.86 (15)	O1—C1—C2—N1	−15.8 (3)
O1—Cu1—O2^i—C1^i	−61.90 (17)	O2—C1—C2—N1	165.5 (2)
O3—Cu1—O2^i—C1^i	117.36 (17)	O3—C3—C4—N2	2.1 (3)
N1—Cu1—O2^i—C1^i	22.91 (17)	O4—C3—C4—N2	−178.3 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H1A···O3^v	0.94 (5)	2.12 (5)	3.029 (3)	162 (4)
N2—H1B···O2^vi	0.80 (4)	2.49 (4)	3.223 (3)	154 (4)
N1—H3A···O1^vii	0.90 (4)	2.17 (4)	2.994 (3)	152 (3)
N1—H3A···O1^i	0.90 (4)	2.44 (4)	3.003 (3)	121 (3)
N1—H3B···O4^iv	0.86 (4)	2.41 (4)	3.152 (3)	145 (3)

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