metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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

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[MacFarlane, D. R., Golding, J., Forsyth, M. & Deacon, G. B. (2001). Chem. Commun. pp. 1430-1431.]). For copper-based ILs, see: Stricker et al. (2010[Stricker, M., Linder, T., Oelkers, B. & Sundermeyer, J. (2010). Green Chem. 12, 1589-1598.]). For solvent-free [Cu(dicyanamide)] and its monoadduct with acetonitrile, see: Bessler et al. (2000[Bessler, K. E., Romualdo, L. L., Deflon, V. M. & Hagenbach, A. (2000). Z. Anorg. Allg. Chem. 626, 1942-1945.]); Batten et al. (2000[Batten, S. R., Harris, A. R., Jensen, P., Murray, K. S. & Ziebell, A. (2000). J. Chem. Soc. Dalton Trans. pp. 3829-3835.]).

[Scheme 1]

Experimental

Crystal data
  • [Cu(C2N3)(C2H3N)2]

  • Mr = 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[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.]) Tmin = 0.375, Tmax = 0.783

  • 4132 measured reflections

  • 528 independent reflections

  • 510 reflections with I > 2σ(I)

  • Rint = 0.097

Refinement
  • R[F2 > 2σ(F2)] = 0.032

  • wR(F2) = 0.066

  • S = 1.13

  • 528 reflections

  • 39 parameters

  • H-atom parameters constrained

  • Δρmax = 0.89 e Å−3

  • Δρmin = −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[Stoe & Cie (2001). X-AREA and X-RED. Stoe & Cie, Darmstadt, Germany.]); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SIR92 (Altomare et al., 1993[Altomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl. Cryst. 26, 343-350.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND (Brandenburg, 2007[Brandenburg, K. (2007). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


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.

Refinement top

Hydrogen atoms of the methyl groups were placed on idealized positions and refined using a riding model with Uiso(H) = 1.5 × Ueq(C) and C–H bond lengths of 0.98 Å.

Structure description 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.

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).

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
[Figure 1] 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.
[Figure 2] 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
Mr = 211.71Dx = 1.603 Mg m3
Orthorhombic, PmmnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2aCell parameters from 9024 reflections
a = 7.5222 (5) Åθ = 1.9–27.1°
b = 10.5307 (11) ŵ = 2.44 mm1
c = 5.5378 (4) ÅT = 100 K
V = 438.67 (6) Å3Prism, colourless
Z = 20.45 × 0.27 × 0.12 mm
Data collection top
Stoe IPDS 2
diffractometer
528 independent reflections
Radiation source: fine-focus sealed tube510 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.097
Detector resolution: 6.67 pixels mm-1θmax = 26.7°, θmin = 3.3°
rotation method scansh = 89
Absorption correction: multi-scan
(Blessing, 1995)
k = 1313
Tmin = 0.375, Tmax = 0.783l = 76
4132 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.032Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.066H-atom parameters constrained
S = 1.13 w = 1/[σ2(Fo2) + (0.0425P)2 + 0.0839P]
where P = (Fo2 + 2Fc2)/3
528 reflections(Δ/σ)max < 0.001
39 parametersΔρmax = 0.89 e Å3
0 restraintsΔρmin = 1.05 e Å3
Crystal data top
[Cu(C2N3)(C2H3N)2]V = 438.67 (6) Å3
Mr = 211.71Z = 2
Orthorhombic, PmmnMo Kα radiation
a = 7.5222 (5) ŵ = 2.44 mm1
b = 10.5307 (11) ÅT = 100 K
c = 5.5378 (4) Å0.45 × 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)
Tmin = 0.375, Tmax = 0.783Rint = 0.097
4132 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0320 restraints
wR(F2) = 0.066H-atom parameters constrained
S = 1.13Δρmax = 0.89 e Å3
528 reflectionsΔρmin = 1.05 e Å3
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
xyzUiso*/Ueq
Cu10.75000.75000.37747 (6)0.02393 (18)
N10.25000.75000.8017 (5)0.0267 (5)
N20.5346 (3)0.75000.5810 (3)0.0270 (4)
N30.75000.8958 (2)0.1402 (3)0.0299 (4)
C10.3987 (3)0.75000.6779 (4)0.0226 (4)
C20.75001.0397 (2)0.2413 (4)0.0318 (5)
H2A0.75000.98630.38610.048*
H2B0.85621.09370.24070.048*
C30.75000.95947 (19)0.0270 (4)0.0267 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.0242 (3)0.0252 (2)0.0224 (3)0.0000.0000.000
N10.0233 (12)0.0342 (13)0.0224 (12)0.0000.0000.000
N20.0241 (9)0.0312 (9)0.0256 (8)0.0000.0021 (7)0.000
N30.0348 (11)0.0268 (10)0.0281 (11)0.0000.0000.0007 (7)
C10.0258 (10)0.0214 (8)0.0205 (9)0.0000.0044 (8)0.000
C20.0463 (13)0.0246 (10)0.0245 (11)0.0000.0000.0028 (9)
C30.0307 (10)0.0235 (10)0.0261 (11)0.0000.0000.0014 (9)
Geometric parameters (Å, º) top
Cu1—N2i1.974 (2)N2—C11.155 (3)
Cu1—N21.974 (2)N3—C31.143 (3)
Cu1—N3i2.021 (2)C3—C21.457 (3)
Cu1—N32.021 (2)C2—H2A0.9800
N1—C1ii1.312 (3)C2—H2B0.9800
N1—C11.312 (3)
N2i—Cu1—N2110.34 (11)C1—N2—Cu1172.85 (18)
N2i—Cu1—N3i111.79 (4)C3—N3—Cu1166.44 (18)
N2—Cu1—N3i111.79 (4)N2—C1—N1176.2 (2)
N2i—Cu1—N3111.79 (4)C3—C2—H2A109.5
N2—Cu1—N3111.79 (4)C3—C2—H2B109.5
N3i—Cu1—N398.91 (11)H2A—C2—H2B109.6
C1ii—N1—C1117.0 (3)N3—C3—C2179.6 (2)
N2i—Cu1—N3—C3117.87 (5)N3i—Cu1—N3—C30.000 (4)
N2—Cu1—N3—C3117.87 (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]
Mr211.71
Crystal system, space groupOrthorhombic, Pmmn
Temperature (K)100
a, b, c (Å)7.5222 (5), 10.5307 (11), 5.5378 (4)
V3)438.67 (6)
Z2
Radiation typeMo Kα
µ (mm1)2.44
Crystal size (mm)0.45 × 0.27 × 0.12
Data collection
DiffractometerStoe IPDS 2
Absorption correctionMulti-scan
(Blessing, 1995)
Tmin, Tmax0.375, 0.783
No. of measured, independent and
observed [I > 2σ(I)] reflections
4132, 528, 510
Rint0.097
(sin θ/λ)max1)0.633
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.066, 1.13
No. of reflections528
No. of parameters39
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)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—N21.974 (2)N1—C11.312 (3)
Cu1—N32.021 (2)N2—C11.155 (3)
N2i—Cu1—N2110.34 (11)C1ii—N1—C1117.0 (3)
N2—Cu1—N3111.79 (4)C1—N2—Cu1172.85 (18)
N3i—Cu1—N398.91 (11)N2—C1—N1176.2 (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

First citationAltomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl. Cryst. 26, 343–350.  CrossRef Web of Science IUCr Journals Google Scholar
First citationBatten, S. R., Harris, A. R., Jensen, P., Murray, K. S. & Ziebell, A. (2000). J. Chem. Soc. Dalton Trans. pp. 3829–3835.  Web of Science CSD CrossRef Google Scholar
First citationBessler, K. E., Romualdo, L. L., Deflon, V. M. & Hagenbach, A. (2000). Z. Anorg. Allg. Chem. 626, 1942–1945.  Web of Science CSD CrossRef CAS Google Scholar
First citationBlessing, R. H. (1995). Acta Cryst. A51, 33–38.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationBrandenburg, K. (2007). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
First citationMacFarlane, D. R., Golding, J., Forsyth, M. & Deacon, G. B. (2001). Chem. Commun. pp. 1430–1431.  Web of Science CrossRef Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationStoe & Cie (2001). X-AREA and X-RED. Stoe & Cie, Darmstadt, Germany.  Google Scholar
First citationStricker, M., Linder, T., Oelkers, B. & Sundermeyer, J. (2010). Green Chem. 12, 1589–1598.  Web of Science CSD CrossRef CAS Google Scholar

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