catena-Poly[[diacetonitrile­copper(I)]-μ-dicyanamido]

Oelkers, B.; Stricker, M.; Sundermeyer, J.

doi:10.1107/S1600536811047052

metal-organic compounds

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ISSN: 2056-9890

Volume 67| Part 12| December 2011| Page m1784

https://doi.org/10.1107/S1600536811047052

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catena-Poly[[diacetonitrilecopper(I)]-μ-dicyanamido]

Benjamin Oelkers,^a Marion Stricker ^a and Jörg Sundermeyer ^a ^*

^aPhilipps-Universität Marburg, Fachbereich Chemie, Hans-Meerwein-Strasse, 35032 Marburg, Germany
^*Correspondence e-mail: jsu@staff.uni-marburg.de

(Received 4 November 2011; accepted 7 November 2011; online 19 November 2011)

The crystal structure of the title compound, [Cu(C₂N₃)(C₂H₃N)₂]_n, features zigzag chains along the a axis that consist of alternating [Cu(MeCN)₂] and dicyanamide units, the latter acting as bidentate ligands via both terminal N atoms. The Cu atom shows a slightly distorted tetrahedral coordination sphere. The anionic and neutral ligands lie on different mirror planes (perpendicular to the b and a axis, respectively), while the Cu atom is situated on their intersection. The asymmetric unit comprises one fourth of the formula unit.

Related literature

For ionic liquids (ILs) with dicyanamide anions, see: MacFarlane et al. (2001 ). For copper-based ILs, see: Stricker et al. (2010 ). For solvent-free [Cu(dicyanamide)] and its monoadduct with acetonitrile, see: Bessler et al. (2000 ); Batten et al. (2000 ).

Experimental

Crystal data

[Cu(C₂N₃)(C₂H₃N)₂]
M_r = 211.71
Orthorhombic, P m m n
a = 7.5222 (5) Å
b = 10.5307 (11) Å
c = 5.5378 (4) Å
V = 438.67 (6) Å³
Z = 2
Mo Kα radiation
μ = 2.44 mm⁻¹
T = 100 K
0.45 × 0.27 × 0.12 mm

Data collection

Stoe IPDS 2 diffractometer
Absorption correction: multi-scan (Blessing, 1995 ) T_min = 0.375, T_max = 0.783
4132 measured reflections
528 independent reflections
510 reflections with I > 2σ(I)
R_int = 0.097

Refinement

R[F² > 2σ(F²)] = 0.032
wR(F²) = 0.066
S = 1.13
528 reflections
39 parameters
H-atom parameters constrained
Δρ_max = 0.89 e Å⁻³
Δρ_min = −1.05 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

Cu1—N2	1.974 (2)
Cu1—N3	2.021 (2)
N1—C1	1.312 (3)
N2—C1	1.155 (3)

N2ⁱ—Cu1—N2	110.34 (11)
N2—Cu1—N3	111.79 (4)
N3ⁱ—Cu1—N3	98.91 (11)
C1ⁱⁱ—N1—C1	117.0 (3)
C1—N2—Cu1	172.85 (18)
N2—C1—N1	176.2 (2)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, -y+{\script{3\over 2}}, z]$ ; (ii) $[-x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z]$ .

Data collection: X-AREA (Stoe & Cie, 2001 ); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: DIAMOND (Brandenburg, 2007 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536811047052/hp2020sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811047052/hp2020Isup2.hkl

checkCIF report

Comment top

Salts with dicyanamide (DCA) as anion have gained some interest recently because of their use as ionic liquids (ILs) with low viscosities (MacFarlane et al., 2001). During our ongoing investigations on copper-containing ILs (Stricker et al., 2010), we found that upon heating a mixture of Cu(DCA) and [BMIM](DCA) ([BMIM]⁺ = 1-n-butyl-3-methylimidazolium) in acetonitrile the title compound [Cu(DCA)(MeCN)₂]_∞ is formed instead of the expected product [BMIM][Cu(DCA)₂]. It is interesting to note that slightly different conditions ([Cu(MeCN)₄]ClO₄, (Ph₃P=N=PPh₃)(DCA), acetonitrile/acetone, ambient temperature) lead to the monoadduct [Cu(DCA)(MeCN)]_∞ (Batten et al., 2000), while solvent-free copper(I)-dicyanamide results from reduction of an aqueous solution of Na(DCA) and CuSO₄ with NaHSO₃ (Bessler et al., 2000).

The crystal structure of the title compound features zigzag chains along the a axis that consist of alternating [Cu(MeCN)₂] and dicyanamide units. The latter act as bidentate ligands via both terminal nitrogen atoms, the copper atoms show a slightly distorted tetrahedral coordination sphere (Fig. 1). The anionic and neutral ligands lie on different mirror planes (perpendicular to the b and a axis, respectively) while the metal is situated on their intersection. The asymmetric unit comprises one fourth of the formula unit.

The comparison of the title compound [Cu(DCA)(MeCN)₂]_∞ and the monoadduct [Cu(DCA)(MeCN)]_∞ (Batten et al., 2000) shows similarities in terms of bond lengths and angles. In fact, both structures can locally be related to each other by formally breaking the copper-imide bonds of the latter and replacing them with acetonitrile ligands. The obtained structural motif is then very similar to the one-dimensional polymer building up the title compound (Fig. 2). Thus a partial depolymerization of [Cu(DCA)(MeCN)]_∞ formally leads to the reported structure of [Cu(DCA)(MeCN)₂]_∞ without additional bond breaking.

Related literature top

For ionic liquids (ILs) with dicyanamide anions, see: MacFarlane et al. (2001). For copper-based ILs, see: Stricker et al. (2010). For solvent-free [Cu(DCA)] (DCA is dicyanamide) and its monoadduct with acetonitrile, see: Bessler et al. (2000); Batten et al. (2000).

Experimental top

To a mixture of Cu(DCA) (68 mg, 0.52 mmol) and [BMIM](DCA) (108 mg, 0.53 mmol; [BMIM]⁺ = 1-n-butyl-3-methylimidazolium) acetonitrile (60 ml) was added. Although the mixture was heated to 80 °C for 4.5 h, some amorphous solid remained. Upon slow cooling to room temperature colourless crystals of the title compound formed.

Structure description top

Computing details top

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA (Stoe & Cie, 2001); data reduction: X-AREA (Stoe & Cie, 2001); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2007); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. Molecular structure of the title compound. Displacement ellipsoids are shown for 50% probability. Symmetry codes: (i) 3/2–x, 3/2–y, z; (ii) 1/2–x, 3/2–y, z; (iii) -1 + x, y, x.
	Fig. 2. Packing diagram of the title compound, view along [1 1 10].

catena-Poly[[diacetonitrilecopper(I)]-µ-dicyanamido] top

Crystal data top

[Cu(C₂N₃)(C₂H₃N)₂]	F(000) = 212
M_r = 211.71	D_x = 1.603 Mg m⁻³
Orthorhombic, Pmmn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2a	Cell parameters from 9024 reflections
a = 7.5222 (5) Å	θ = 1.9–27.1°
b = 10.5307 (11) Å	µ = 2.44 mm⁻¹
c = 5.5378 (4) Å	T = 100 K
V = 438.67 (6) Å³	Prism, colourless
Z = 2	0.45 × 0.27 × 0.12 mm

Data collection top

Stoe IPDS 2 diffractometer	528 independent reflections
Radiation source: fine-focus sealed tube	510 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.097
Detector resolution: 6.67 pixels mm^-1	θ_max = 26.7°, θ_min = 3.3°
rotation method scans	h = −8→9
Absorption correction: multi-scan (Blessing, 1995)	k = −13→13
T_min = 0.375, T_max = 0.783	l = −7→6
4132 measured reflections

Refinement top

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)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.066	H-atom parameters constrained
S = 1.13	w = 1/[σ²(F_o²) + (0.0425P)² + 0.0839P] where P = (F_o² + 2F_c²)/3
528 reflections	(Δ/σ)_max < 0.001
39 parameters	Δρ_max = 0.89 e Å⁻³
0 restraints	Δρ_min = −1.05 e Å⁻³

Crystal data top

[Cu(C₂N₃)(C₂H₃N)₂]	V = 438.67 (6) Å³
M_r = 211.71	Z = 2
Orthorhombic, Pmmn	Mo Kα radiation
a = 7.5222 (5) Å	µ = 2.44 mm⁻¹
b = 10.5307 (11) Å	T = 100 K
c = 5.5378 (4) Å	0.45 × 0.27 × 0.12 mm

Data collection top

Stoe IPDS 2 diffractometer	528 independent reflections
Absorption correction: multi-scan (Blessing, 1995)	510 reflections with I > 2σ(I)
T_min = 0.375, T_max = 0.783	R_int = 0.097
4132 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.032	0 restraints
wR(F²) = 0.066	H-atom parameters constrained
S = 1.13	Δρ_max = 0.89 e Å⁻³
528 reflections	Δρ_min = −1.05 e Å⁻³
39 parameters

Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.

The methyl group was modelled using AFIX 133 as a riding group with idealized geometry. As the most favourable conformation was found to be symmetric with respect to a mirror plane, two protons with half occupancy were generated at symmetry-related positions. These two symmetry-dependent protons were combined by eliminating one of them, setting the other one to full occupancy and finally changing the AFIX code to 03 in order to retain the idealized geometry.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cu1	0.7500	0.7500	0.37747 (6)	0.02393 (18)
N1	0.2500	0.7500	0.8017 (5)	0.0267 (5)
N2	0.5346 (3)	0.7500	0.5810 (3)	0.0270 (4)
N3	0.7500	0.8958 (2)	0.1402 (3)	0.0299 (4)
C1	0.3987 (3)	0.7500	0.6779 (4)	0.0226 (4)
C2	0.7500	1.0397 (2)	−0.2413 (4)	0.0318 (5)
H2A	0.7500	0.9863	−0.3861	0.048*
H2B	0.8562	1.0937	−0.2407	0.048*
C3	0.7500	0.95947 (19)	−0.0270 (4)	0.0267 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0242 (3)	0.0252 (2)	0.0224 (3)	0.000	0.000	0.000
N1	0.0233 (12)	0.0342 (13)	0.0224 (12)	0.000	0.000	0.000
N2	0.0241 (9)	0.0312 (9)	0.0256 (8)	0.000	−0.0021 (7)	0.000
N3	0.0348 (11)	0.0268 (10)	0.0281 (11)	0.000	0.000	0.0007 (7)
C1	0.0258 (10)	0.0214 (8)	0.0205 (9)	0.000	−0.0044 (8)	0.000
C2	0.0463 (13)	0.0246 (10)	0.0245 (11)	0.000	0.000	0.0028 (9)
C3	0.0307 (10)	0.0235 (10)	0.0261 (11)	0.000	0.000	−0.0014 (9)

Geometric parameters (Å, º) top

Cu1—N2ⁱ	1.974 (2)	N2—C1	1.155 (3)
Cu1—N2	1.974 (2)	N3—C3	1.143 (3)
Cu1—N3ⁱ	2.021 (2)	C3—C2	1.457 (3)
Cu1—N3	2.021 (2)	C2—H2A	0.9800
N1—C1ⁱⁱ	1.312 (3)	C2—H2B	0.9800
N1—C1	1.312 (3)

N2ⁱ—Cu1—N2	110.34 (11)	C1—N2—Cu1	172.85 (18)
N2ⁱ—Cu1—N3ⁱ	111.79 (4)	C3—N3—Cu1	166.44 (18)
N2—Cu1—N3ⁱ	111.79 (4)	N2—C1—N1	176.2 (2)
N2ⁱ—Cu1—N3	111.79 (4)	C3—C2—H2A	109.5
N2—Cu1—N3	111.79 (4)	C3—C2—H2B	109.5
N3ⁱ—Cu1—N3	98.91 (11)	H2A—C2—H2B	109.6
C1ⁱⁱ—N1—C1	117.0 (3)	N3—C3—C2	179.6 (2)

N2ⁱ—Cu1—N3—C3	117.87 (5)	N3ⁱ—Cu1—N3—C3	0.000 (4)
N2—Cu1—N3—C3	−117.87 (5)

Symmetry codes: (i) −x+3/2, −y+3/2, z; (ii) −x+1/2, −y+3/2, z.

Experimental details

Crystal data
Chemical formula	[Cu(C₂N₃)(C₂H₃N)₂]
M_r	211.71
Crystal system, space group	Orthorhombic, Pmmn
Temperature (K)	100
a, b, c (Å)	7.5222 (5), 10.5307 (11), 5.5378 (4)
V (Å³)	438.67 (6)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	2.44
Crystal size (mm)	0.45 × 0.27 × 0.12

Data collection
Diffractometer	Stoe IPDS 2
Absorption correction	Multi-scan (Blessing, 1995)
T_min, T_max	0.375, 0.783
No. of measured, independent and observed [I > 2σ(I)] reflections	4132, 528, 510
R_int	0.097
(sin θ/λ)_max (Å⁻¹)	0.633

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.032, 0.066, 1.13
No. of reflections	528
No. of parameters	39
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.89, −1.05

Computer programs: X-AREA (Stoe & Cie, 2001), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2007), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top

Cu1—N2	1.974 (2)	N1—C1	1.312 (3)
Cu1—N3	2.021 (2)	N2—C1	1.155 (3)

N2ⁱ—Cu1—N2	110.34 (11)	C1ⁱⁱ—N1—C1	117.0 (3)
N2—Cu1—N3	111.79 (4)	C1—N2—Cu1	172.85 (18)
N3ⁱ—Cu1—N3	98.91 (11)	N2—C1—N1	176.2 (2)

Symmetry codes: (i) −x+3/2, −y+3/2, z; (ii) −x+1/2, −y+3/2, z.

Acknowledgements

Routine data collection was performed by the XRD service department (Dr K. Harms, G. Geiseler and R. Riedel) of the Chemistry Department, Philipps-University, and is gratefully acknowledged.

References

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