catena-Poly[[[(diethyl­enetriamine-κ3 N,N′,N′′)­copper(II)]-μ-cyanido-κ2 C:N] perchlorate]

Peter W R Corfield; Sylvia C Yang

doi:10.1107/S1600536812023987

. 2012 Jun 13;68(Pt 7):m872–m873. doi: 10.1107/S1600536812023987

catena-Poly[[[(diethylenetriamine-κ³ N,N′,N′′)copper(II)]-μ-cyanido-κ² C:N] perchlorate]

Peter W R Corfield ^a,^*, Sylvia C Yang ^b

PMCID: PMC3393153 PMID: 22807721

Abstract

The structure of the title salt, {[Cu(CN)(C₄H₁₃N₃)]ClO₄}_n, is composed of copper-containing cations and perchlorate anions. The Cu^II atom shows a square-pyramidal coordination, with equatorial positions occupied by the cyanide C atom [Cu—C = 1.990 (3) Å] and the N atoms of the diethylenetriamine ligand (average Cu—N = 2.033 Å), while the axial position is occupied by the N atom of a c-glide-related cyanide group. The axial Cu—N distance of 2.340 (3) Å is longer than the equatorial distances, reflecting Jahn–Teller distortion. The Cu^II cations are linked by the cyanide groups into infinite chains along the c-axis direction. The refinement included a three-component disordered model for the perchlorate ion. Each minor site is stabilized by hydrogen bonds to N—H donors from four surrounding cations, while one O atom of the major perchlorate site forms hydrogen bonds to three of these cations.

Related literature

There is a growing body of literature on self-assembled polymers involving copper cyanide moieties, with many examples of one- two- and three-dimensional networks, see, for example: Roof et al. (1968 ▶); Chestnut et al. (2001 ▶); Kim et al. (2005 ▶); Lim et al. (2008 ▶). Most of these structures involve Cu^I atoms bridged by cyanide ligands, while a smaller number are mixed-valence compounds with cyanide linkages between Cu^I and Cu^II atoms. The present structure was prepared as a model for CN⁻ binding to copper-containing proteins (Fager & Alben, 1972 ▶), and is a rare example of a Cu^II cyanide-bridged linear polymer, similar to the linear polymer reported by Zhan et al. (2007 ▶). For the CN stretching frequency, see: Alben & Farrier (1972 ▶).

Experimental

Crystal data

[Cu(CN)(C₄H₁₃N₃)]ClO₄
M _r = 292.18
Monoclinic,
a = 6.7767 (8) Å
b = 21.5081 (16) Å
c = 8.3635 (12) Å
β = 118.109 (9)°
V = 1075.2 (2) Å³
Z = 4
Cu Kα radiation
μ = 5.29 mm⁻¹
T = 295 K
0.32 × 0.17 × 0.07 mm

Data collection

Picker four-circle diffractometer
Absorption correction: integration (Busing & Levy, 1957a ▶) T _min = 0.394, T _max = 0.697
3044 measured reflections
1752 independent reflections
1625 reflections with I > 2σ(I)
R _int = 0.024
6 standard reflections every 200 reflections intensity decay: none

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.085
S = 1.09
1752 reflections
158 parameters
H-atom parameters constrained
Δρ_max = 0.59 e Å⁻³
Δρ_min = −0.35 e Å⁻³

Data collection: locally modified program (Corfield, 1972 ▶); cell refinement: locally modified program (Corfield, 1972 ▶); data reduction: cell refinements and data reduction follow procedures in Corfield et al. (1967 ▶) and Corfield & Shore (1973 ▶); standard deviations of intensities include an ignorance factor (Busing & Levy, 1957b ▶) set here to 0.06; program(s) used to solve structure: local superposition program (Corfield, 1972 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPII (Johnson, 1976 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812023987/pk2408sup1.cif

e-68-0m872-sup1.cif^{(23KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812023987/pk2408Isup2.hkl

e-68-0m872-Isup2.hkl^{(86.3KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Cu—C8	1.990 (3)
Cu—N1	2.023 (2)
Cu—N4	2.034 (2)
Cu—N7	2.040 (3)
Cu—N8ⁱ	2.340 (3)
C8—N8	1.139 (4)

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Symmetry code: (i) Inline graphic .

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1B⋯O3ⁱⁱ	0.90	2.38	3.215 (5)	154
N4—H4⋯O3ⁱⁱⁱ	0.91	2.42	3.214 (5)	145
N7—H7A⋯O3ⁱ	0.90	2.23	3.092 (4)	161
N1—H1A⋯O4′	0.90	2.17	2.771 (17)	124
N1—H1B⋯O3′ⁱⁱ	0.90	2.04	2.913 (15)	164
N4—H4⋯O1′ⁱⁱⁱ	0.91	2.30	3.139 (19)	154
N7—H7A⋯O3′ⁱ	0.90	2.14	3.040 (16)	173
N1—H1A⋯O1′′	0.90	2.21	3.06 (4)	156
N1—H1B⋯O4′′ⁱⁱ	0.90	2.51	3.21 (3)	135
N4—H4⋯O3′′ⁱⁱⁱ	0.91	2.12	2.99 (3)	160
N7—H7A⋯O3′′ⁱ	0.90	2.45	3.24 (3)	147
N7—H7B⋯O4′′	0.90	2.50	3.04 (3)	119

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

We acknowledge gratefully the provision of a crystalline sample by James O. Alben and N. J. Farrier, as well as partial support from the National Science Foundation through equipment grant GP8534 awarded to the Ohio State University, where the experimental work was carried out.

supplementary crystallographic information

Comment

The title compound, [Cu(dien)CN]ClO₄, (Fig. 1), was originally prepared as a simple model for CN^- binding to copper-containing proteins, with the expectation that structural data would supplement information from infra-red studies on cyanide binding to the proteins. (Fager and Alben, 1972) The structure is reported now in light of current interest in cyanide-bridged copper polymers.

The crystal structure consists of cyanidodiethylenetriaminecopper(II) cations and perchlorate anions. The cyanide groups link c-glide related copper atoms to form infinite chains along the c axis, as shown in Fig. 2. The coordination of the copper atoms is square pyramidal, with the terdentate diethylenetriamine ligand and the carbon atom of the cyanide group in equatorial positions, and the nitrogen atom of a symmetry-related cyanide group in the axial position.

Atom O4 of the perchlorate group would occupy the sixth coordination site of the Cu^II atom if the Cu—O4 distance of 2.956 (4) Å represented a chemical bond, making the copper atom octahedrally coordinated. Perchlorate anions rarely coordinate, however, and we prefer the square pyramidal designation, in view of the long Cu—O4 distance, and the displacement of the copper atom by 0.237 (1) Å towards the axial nitrogen atom and away from the perchlorate O4 atom. Furthermore, the O4 atom has similar U_eq values to the other perchlorate oxygen atoms, and is disordered in the same way, whereas bonding to the Cu atom would be expected to localize the atom O4.

The Cu—C—N angle at the cyanide carbon atom is close to linear, at 175.9 (3)°, but the C—N—Cu angle at the bridging cyanide nitrogen atom is 146.5 (2)°, significantly different from 180°. The C—N bond length is 1.139 (4) Å, similar to the terminal bond length of 1.129 Å in K₃Cu(CN)₄, (Roof et al., 1968).

In the diethylenetriamine ligand, the carbon atoms in each chelate ring lie on opposite sides of the corresponding CuN₂ plane. The Cu—N1—C2—C3—N4 chelate ring has the λ conformation, with torsional angle N1—C2—C3—N4 equal to -51.9 (3) °, while the other chelate ring has the δ conformation, with the N4—C5—C6—N7 torsional angle equal to +51.9 (3) °.

Two minor alternative orientations for the perchlorate anion were refined, related to the major orientation by rotation about the Cl—O2 bond, by 34° in one direction, and 25° in the other. (Fig. 3) Each minor site is stabilized by hydrogen bonds to N—H donors from four surrounding cations, while atom O3 of the major perchlorate site forms hydrogen bonds to three of these cations.

Experimental

The compound was prepared by addition of stoichiometric amounts of diethylenetriamine and potassium cyanide to a solution of copper(II) perchlorate. Calculated elemental analysis, based upon C₅H₁₃ClCuN₄O₄: C, 20.55%; H, 4.48%; N, 19.18%. Found: C, 20.60, 20.66%; H, 4.98, 4.58%; N, 19.02%. The CN stretching frequency was 2141.4 cm^-1 (Alben and Farrier, 1972).