Poly[[diaquadi-μ₂-cyanido-bis­(μ₂-pyrazine-2-carboxyl­ato)dicopper(I)copper(II)] dihydrate]

Abstract

In the title compound, {[Cu^IICu^I ₂(C₅H₃N₂O₂)₂(CN)₂(H₂O)₂]·2H₂O}_n, the Cu^II atom lies on an inversion centre and is octa­hedrally coordinated by two N atoms and two O atoms from opposing pyrazine-2-carboxyl­ate (2-pac) ligands and two water O atoms. The Cu^I atom has a triangular geometry, coordinated by one N atom and one C atom from two bridging cyanide ligands, and another N atom from the 2-pac ligand. The three-dimensional structure features a succession of two-dimensional sheets containing [Cu(CN)]_n chains linked by Cu(2-pac)₂(H₂O)₂ groups. The coordinated and free water mol­ecules are involved in an extended three-dimensional hydrogen-bond network with the 2-pac ligands.

Related literature

For applications of metal-organic frameworks (MOFs), see: Klein et al. (1982 ▶); Li et al. (2004 ▶); Plater et al. (2001 ▶); Thomas (1978 ▶). For a related structure, see: Fan et al. (2006 ▶).

Experimental

Crystal data

• [Cu₃(C₅H₃N₂O₂)₂(CN)₂(H₂O)₂]·2H₂O

• M _r = 560.91

• Monoclinic,

• a = 13.8297 (4) Å

• b = 9.4906 (3) Å

• c = 7.1272 (3) Å

• β = 100.768 (3)°

• V = 918.99 (6) ų

• Z = 2

• Mo Kα radiation

• μ = 3.50 mm⁻¹

• T = 296 K

• 0.10 × 0.08 × 0.05 mm

Data collection

• Bruker SMART APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) ▶ T _min = 0.721, T _max = 0.845

• 4141 measured reflections

• 1615 independent reflections

• 1269 reflections with I > 2σ(I)

• R _int = 0.022

Refinement

• R[F ² > 2σ(F ²)] = 0.029

• wR(F ²) = 0.095

• S = 0.99

• 1615 reflections

• 145 parameters

• 6 restraints

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.36 e Å⁻³

• Δρ_min = −0.36 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL/PC (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL/PC.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Cu1—O1	1.978 (2)
Cu1—N1	2.003 (3)
Cu1—O3	2.378 (3)
Cu2—C6	1.865 (3)
Cu2—N3i	1.886 (4)
Cu2—N2	2.163 (3)

Symmetry code: (i) .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H4A⋯O2	0.86 (2)	2.08 (3)	2.910 (5)	160 (7)
O3—H3B⋯O1ii	0.82 (2)	2.11 (2)	2.883 (3)	156 (4)
O3—H3A⋯O2iii	0.84 (2)	1.94 (2)	2.783 (4)	172 (4)

Symmetry codes: (ii) ; (iii) .

supplementary crystallographic information

Comment

Single crystal diffraction has revealed that complex (I) crystallizes in the monoclinic space group P2₁/c featuring two-dimensional networks through chain-like [Cu(CN)]_n units linked by Cu(2-pac)₂(H₂O)₂. As shown in Fig. 1, there are two crystallographic inequivalent copper atoms. The Cu(1) atom is divalent and Cu(2) is monovalent. Cu(1) adopts a distorted octahedral geometry by two N and two O atoms from the 2-pac ligands in the equatorial plane whereas the axial positions are occupied by two water molecules with 1.9781 (17)Å for Cu1—O1; 2.002 (2)Å for Cu1—N1; 2.371 (2)Å for Cu1—O3. Each Cu(2) atom has a triangular geometry, coordinated to one N atom and one C atom from two bridging cyanide ligands and another N atom from Cu(2-pac)₂(H₂O)₂, with 1.860 (3)Å for Cu2—C6; 1.885 (3)Å for Cu2—N3; 2.163 (2)Å for Cu2—N2.

Fig. 2 shows the independent cyanide ligands bridging Cu(2) to form a zigzag chain of [Cu(CN)]_n units. Such chains are interconnected through two Cu(2-pac)₂(H₂O)₂ N donor ligands giving rise to a two-dimensional sheet network. Furthermore, an extensive hydrogen bonding network is formed, which involves the coordinated, free water molecules and the 2-pac ligand substituents, affording a three-dimensional network, as shown in Fig. 3. It is noted that one proton of the free water molecule has no apparent hydrogen acceptor atom.

The present structure is quite different from the mixed-valence copper complex [Cu^IICu^I(2-pac)₂(NO₃)(H₂O)]_n reported by Fan et al. (2006). In the latter structure the coordination number of monovalent Cu atom is 4, but for the present structure the coordination number is 3.

Experimental

Red crystals from complex (I) were obtained by hydrothermal synthesis of a mixture of Cu(NO₃)₂.3H₂O (0.1241 g, 0.5 mmol), 0.4 ml H₃PO₃ and 2-pac (0.0673 g, 0.5 mmol) in 6 ml H₂O, sealed in a Teflon-lined stainless container, heated at 363 K for 24 h and slowly cooled to room temperature.

Refinement

All H atoms attached to C atoms from the organic ligands were generated in idealized positions and constrained to ride on their parent atoms, with d(C—H) = 0.93 Å, U_iso=1.2U_eq (C). The water H-atoms were located in a different Fourier map, and the geometry of the two water molecules was restrained to its ideal geometry by in total six restraints on angles and bond distances.

Figures

Fig. 1.

A view of the molecular structure of (I) with the atom-labeling scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii. Symmetry code for A: 1-x, -y, -z; B: –x, -0.5+y, 0.5-z.

Fig. 2.

Two-dimensional sheet structure for complex (I). Hydrogen atoms have been omitted for clarity.

Fig. 3.

Three-dimensional stacking diagram for complex (I) along the c axis.

Crystal data

[Cu3(C5H3N2O2)2(CN)2(H2O)2]·2H2O	F(000) = 558
Mr = 560.91	Dx = 2.027 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 117 reflections
a = 13.8297 (4) Å	θ = 2.5–19.1°
b = 9.4906 (3) Å	µ = 3.50 mm−1
c = 7.1272 (3) Å	T = 296 K
β = 100.768 (3)°	Block, red
V = 918.99 (6) Å3	0.10 × 0.08 × 0.05 mm
Z = 2

Data collection

Bruker SMART APEXII CCD diffractometer	1615 independent reflections
Radiation source: fine-focus sealed tube	1269 reflections with I > 2σ(I)
graphite	Rint = 0.022
φ and ω scans	θmax = 25.1°, θmin = 3.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −16→16
Tmin = 0.721, Tmax = 0.845	k = −11→11
4141 measured reflections	l = −7→8

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.095	H atoms treated by a mixture of independent and constrained refinement
S = 0.99	w = 1/[σ2(Fo2) + (0.0484P)2 + 1.5206P] where P = (Fo2 + 2Fc2)/3
1615 reflections	(Δ/σ)max < 0.001
145 parameters	Δρmax = 0.36 e Å−3
6 restraints	Δρmin = −0.36 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	0.5000	0.0000	0.0000	0.0296 (2)
Cu2	0.03571 (3)	0.00934 (4)	0.21527 (8)	0.0366 (2)
O1	0.45839 (17)	0.1989 (2)	−0.0394 (4)	0.0316 (6)
O2	0.33417 (17)	0.3429 (2)	−0.0167 (4)	0.0356 (6)
O3	0.5540 (2)	0.0613 (3)	0.3263 (4)	0.0433 (7)
H3A	0.588 (3)	−0.001 (4)	0.393 (6)	0.065*
H3B	0.524 (3)	0.113 (4)	0.390 (6)	0.065*
C5	0.3724 (2)	0.2253 (3)	−0.0104 (5)	0.0258 (7)
N1	0.3627 (2)	−0.0237 (3)	0.0479 (5)	0.0297 (7)
N2	0.1722 (2)	−0.0069 (3)	0.1101 (5)	0.0330 (7)
N3	−0.0012 (2)	0.3197 (4)	0.2534 (5)	0.0422 (8)
C1	0.3146 (2)	0.0996 (3)	0.0357 (5)	0.0253 (7)
C4	0.3148 (3)	−0.1381 (4)	0.0874 (6)	0.0401 (10)
H4	0.3458	−0.2254	0.0941	0.048*
C2	0.2195 (2)	0.1067 (3)	0.0676 (5)	0.0293 (8)
H2	0.1877	0.1935	0.0591	0.035*
C6	0.0122 (2)	0.2013 (3)	0.2401 (5)	0.0288 (8)
C3	0.2199 (3)	−0.1284 (4)	0.1185 (6)	0.0405 (10)
H3	0.1881	−0.2100	0.1463	0.049*
O4	0.1922 (3)	0.5271 (4)	0.1144 (8)	0.0884 (13)
H4A	0.229 (4)	0.457 (5)	0.093 (11)	0.133*
H4B	0.133 (2)	0.495 (7)	0.108 (13)	0.133*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cu1	0.0222 (3)	0.0210 (3)	0.0499 (4)	0.0014 (2)	0.0178 (3)	0.0025 (2)
Cu2	0.0345 (3)	0.0214 (3)	0.0572 (4)	−0.00078 (17)	0.0176 (2)	−0.0008 (2)
O1	0.0256 (12)	0.0243 (12)	0.0487 (16)	−0.0007 (10)	0.0170 (11)	0.0041 (11)
O2	0.0297 (12)	0.0217 (13)	0.0564 (18)	0.0009 (10)	0.0109 (12)	0.0014 (11)
O3	0.0502 (17)	0.0366 (16)	0.0452 (18)	0.0128 (13)	0.0138 (14)	−0.0037 (13)
C5	0.0267 (17)	0.0226 (17)	0.029 (2)	−0.0009 (13)	0.0070 (15)	−0.0010 (14)
N1	0.0240 (14)	0.0234 (15)	0.0449 (19)	0.0010 (12)	0.0147 (14)	0.0007 (13)
N2	0.0267 (15)	0.0260 (16)	0.050 (2)	−0.0008 (11)	0.0173 (15)	0.0018 (13)
N3	0.0386 (17)	0.042 (2)	0.050 (2)	0.0022 (15)	0.0172 (16)	0.0012 (16)
C1	0.0251 (16)	0.0212 (17)	0.031 (2)	0.0003 (13)	0.0079 (14)	−0.0012 (14)
C4	0.036 (2)	0.0215 (18)	0.068 (3)	0.0060 (15)	0.023 (2)	0.0058 (18)
C2	0.0248 (17)	0.0225 (18)	0.042 (2)	−0.0004 (14)	0.0106 (16)	−0.0012 (15)
C6	0.0322 (18)	0.0183 (17)	0.039 (2)	0.0033 (14)	0.0139 (16)	−0.0011 (15)
C3	0.0326 (19)	0.0267 (19)	0.068 (3)	−0.0008 (16)	0.0245 (19)	0.0055 (19)
O4	0.082 (3)	0.077 (3)	0.115 (4)	0.013 (2)	0.043 (3)	−0.001 (3)

Geometric parameters (Å, °)

Cu1—O1i	1.978 (2)	C5—C1	1.507 (4)
Cu1—O1	1.978 (2)	N1—C4	1.329 (4)
Cu1—N1i	2.003 (3)	N1—C1	1.340 (4)
Cu1—N1	2.003 (3)	N2—C3	1.324 (5)
Cu1—O3i	2.378 (3)	N2—C2	1.326 (4)
Cu1—O3	2.378 (3)	N3—C6	1.146 (5)
Cu2—C6	1.865 (3)	N3—Cu2iv	1.886 (4)
Cu2—N3ii	1.886 (4)	C1—C2	1.377 (5)
Cu2—N2	2.163 (3)	C4—C3	1.375 (5)
Cu2—Cu2iii	3.0481 (11)	C4—H4	0.9300
O1—C5	1.269 (4)	C2—H2	0.9300
O2—C5	1.232 (4)	C3—H3	0.9300
O3—H3A	0.844 (19)	O4—H4A	0.86 (2)
O3—H3B	0.824 (19)	O4—H4B	0.87 (2)
O1i—Cu1—O1	180.00 (14)	O2—C5—O1	125.6 (3)
O1i—Cu1—N1i	82.62 (10)	O2—C5—C1	118.9 (3)
O1—Cu1—N1i	97.38 (10)	O1—C5—C1	115.5 (3)
O1i—Cu1—N1	97.38 (10)	C4—N1—C1	117.8 (3)
O1—Cu1—N1	82.62 (10)	C4—N1—Cu1	130.8 (2)
N1i—Cu1—N1	180.00 (3)	C1—N1—Cu1	111.5 (2)
O1i—Cu1—O3i	86.28 (10)	C3—N2—C2	117.1 (3)
O1—Cu1—O3i	93.72 (10)	C3—N2—Cu2	120.4 (2)
N1i—Cu1—O3i	89.72 (11)	C2—N2—Cu2	121.4 (2)
N1—Cu1—O3i	90.28 (11)	C6—N3—Cu2iv	173.8 (3)
O1i—Cu1—O3	93.72 (10)	N1—C1—C2	120.7 (3)
O1—Cu1—O3	86.28 (10)	N1—C1—C5	115.4 (3)
N1i—Cu1—O3	90.28 (11)	C2—C1—C5	124.0 (3)
N1—Cu1—O3	89.72 (11)	N1—C4—C3	120.6 (3)
O3i—Cu1—O3	180.00 (14)	N1—C4—H4	119.7
C6—Cu2—N3ii	150.28 (16)	C3—C4—H4	119.7
C6—Cu2—N2	106.34 (13)	N2—C2—C1	121.7 (3)
N3ii—Cu2—N2	103.29 (12)	N2—C2—H2	119.2
C6—Cu2—Cu2iii	97.07 (12)	C1—C2—H2	119.2
N3ii—Cu2—Cu2iii	91.27 (11)	N3—C6—Cu2	178.9 (4)
N2—Cu2—Cu2iii	77.67 (9)	N2—C3—C4	122.2 (3)
C5—O1—Cu1	114.9 (2)	N2—C3—H3	118.9
Cu1—O3—H3A	115 (3)	C4—C3—H3	118.9
Cu1—O3—H3B	126 (3)	H4A—O4—H4B	107 (4)
H3A—O3—H3B	113 (3)

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

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4A···O2	0.86 (2)	2.08 (3)	2.910 (5)	160 (7)
O3—H3B···O1v	0.82 (2)	2.11 (2)	2.883 (3)	156 (4)
O3—H3A···O2vi	0.84 (2)	1.94 (2)	2.783 (4)	172 (4)

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