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Acta Cryst. (2007). E63, m2053    [ doi:10.1107/S1600536807031108 ]

Jahn-Teller distorted copper(II) in poly[bis([mu]-4,4'-bipyridine)tetra-[mu]-cyanido-copper(II)disilver(I)]

J. Maher and R. E. Sykora

Abstract top

The title compound, [Ag2Cu(CN)4(C10H8N2)2]n, contains a three-dimensional doubly penetrating framework structure composed of copper(II) bridged by 4,4'-bipyridine and dicyanoargentate groups. The Cu atom is located on an inversion center and is coordinated by six N atoms in a distorted tetragonal-bipyramidal geometry as a result of a significant Jahn-Teller distortion. The equatorial plane of Cu is coordinated by two bridging bipyridine ligands and two N-bound dicyanoargentate anions, while the axial positions are occupied by two N atoms from bridging dicyanoargentate anions. A three-coordinate Ag atom is present, due to two Ag-C bonds and one longer Ag-N interaction.

Comment top

Numerous dicyanoargentates have been prepared in recent years due to their interesting structural and magnetic properties (Černák et al., 2002; Lefebvre & Leznoff, 2005). By incorporating various amine ligands along with Cu2+ cations and dicyanoargentate anions, structure types containing molecular units, Cu(pn)2Ag2(CN)4 (pn = 1,2-diaminopropane) (Triščíková et al., 2004), one-dimensional chains, Cu(bpy)2Ag2(CN)4.H2O (bpy = 2,2'-bipyridine) (Černák et al., 1993), two-dimensional sheets, [Cu(en)2][Ag2(CN)3][Ag(CN)2] (en = ethylenediamine) (Shorrock et al., 2002), and three-dimensional networks, [Cu2(C4H12N2)2{Ag(CN)2}4(NH3)].2H2O (Potočňák et al., 2003) have all been prepared. Numerous other metal organic compounds containing various transition metal cations, amine ligands, and dicyanoargentate anions have also been prepared. One such structure-type type containing 4,4'-bipyridine (bpy), M(bpy)2[Ag(CN)2]2, where M is Mn (Dong et al., 2003), Fe (Niel et al., 2002), or Cd (Soma et al., 1994) has been prepared. This structure contains a distorted octahedral coordination polyhedron for the M(II) cations, bridging 4,4'-bipyridine ligands, and a three coordinate Ag atom. The title compound, bis(µ-4,4'-bipyridine)bis[µ-dicyanoargentate(I)]copper(II), was prepared in order to determine (1) if the same structure was possible with copper(II) and (2) to probe the effects on the structure.

There is one symmetrically unique copper atom in the structure of Cu(bpy)2[Ag(CN)2]2 and it is located on an inversion center. The coordination geometry around the Cu atoms (Fig. 1) is composed of six nitrogen atoms in a tetragonal bipyramidal arrangement. Two bridging bipyridine ligands and two nitrogen-bound dicyanoargentate anions account for the nitrogen atoms located in the equatorial plane, while the apical positions are occupied by two nitrogen atoms from bridging dicyanoargentate anions. A significant Jahn-Teller distortion is evident in the lengthened Cu—N distance (2.563 (3) Å) of the apical nitrogen atoms as compared to the equatorial Cu—N distances (1.961 (3) and 2.056 (3) Å). In the previously reported Mn, Fe, and Cd structures, the coordination geometries of these metals can be described as distorted octahedral and the M—N bond distances showed much less variation. In Cd(bpy)2[Ag(CN)2]2 the three unique Cd—N bond distances are 2.288, 2.369, and 2.377 Å, in Fe(bpy)2[Ag(CN)2]2 the three Fe—N bond distances are 2.129, 2.188, and 2.248 Å, and in Mn(bpy)2[Ag(CN)2]2 the three Mn—N bond distances are 2.193, 2.264, and 2.320 Å.

There are no unusual features in the bond distances found in the dicyanoargentate anions in Cu(bpy)2[Ag(CN)2]2, although there is a significant bond angle decrease from linearity, C1—Ag1—C2 angle of 157.40 (13)°, as also observed in the previous Mn, Fe, and Cd structures, which have angles of 153.9°, 154.2°, and 153.6°, respectively. The three-dimensional double penetrating framework (Fig 2.) (Soma et al., 1994) built up by the bridging 4,4'-bipyridine and dicyanoargentate anions is preserved in the structure of Cu(bpy)2[Ag(CN)2]2.

Related literature top

For related literature, see: Dong et al. (2003); Lefebvre & Leznoff (2005); Niel et al. (2002); Potočňák et al. (2003); Shorrock et al. (2002); Soma et al. (1994); Triščíková et al. (2004); Černák et al. (1993, 2002).

Experimental top

A methanolic solution of 4,4'-bipyridine (0.25 ml, 1.0 M) and aqueous KAg(CN)2 (2.5 ml, 0.2 M) were added to an aqueous solution of CuSO4 (2.5 ml, 0.1 M). This resulted in the precipitation of a blue powder, which was then dissolved by the addition of 2.5 ml of a concentrated NH3 (26%) solution. The solution was left for 5 days, resulting in dark blue crystals of the title compound suitable for single-crystal X-ray analysis.

Refinement top

H atoms were placed in calculated positions and allowed to ride during subsequent refinement, with Uiso(H) = 1.2Ueq(C) and C—H distances of 0.93 Å.

Computing details top

Data collection: CAD-4-PC Software (Enraf–Nonius, 1993); cell refinement: CAD-4-PC Software; data reduction: XCAD4PC (Harms, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: publCIF (Westrip, 2007).

Figures top
[Figure 1] Fig. 1. Part of the structure of Cu(bpy)2[Ag(CN)2]2, with atom labeling for the independent atoms. Displacement ellipsoids are shown at the 50% probability level. H atoms are shown as spheres of arbitrary size.
[Figure 2] Fig. 2. The packing diagram of the three-dimensional network in Cu(bpy)2[Ag(CN)2]2. The hydrogen atoms have been omitted for clarity.
poly[bis(µ-4,4'-bipyridine)tetra-µ-cyanido-copper(II)disilver(I)] top
Crystal data top
[Ag2Cu(CN)4(C10H8N2)2]F(000) = 678
Mr = 695.73Dx = 1.873 Mg m−3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 25 reflections
a = 8.9056 (9) Åθ = 8.7–12.0°
b = 11.4712 (10) ŵ = 2.46 mm−1
c = 12.5918 (11) ÅT = 290 K
β = 106.484 (8)°Irregular prism, dark blue
V = 1233.5 (2) Å31.00 × 0.51 × 0.42 mm
Z = 2
Data collection top
Enraf–Nonius CAD-4
diffractometer		1969 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.022
graphiteθmax = 25.4°, θmin = 2.5°
θ/2θ scansh = 0→10
Absorption correction: ψ scan
(North et al., 1968)		k = 0→13
Tmin = 0.255, Tmax = 0.353l = −15→14
2418 measured reflections3 standard reflections every 120 min
2267 independent reflections intensity decay: none
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.025H-atom parameters constrained
wR(F2) = 0.065 w = 1/[σ2(Fo2) + (0.0257P)2 + 1.3204P]
where P = (Fo2 + 2Fc2)/3
S = 1.11(Δ/σ)max = 0.001
2267 reflectionsΔρmax = 0.45 e Å−3
161 parametersΔρmin = −0.38 e Å−3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0043 (4)
Crystal data top
[Ag2Cu(CN)4(C10H8N2)2]V = 1233.5 (2) Å3
Mr = 695.73Z = 2
Monoclinic, P21/nMo Kα radiation
a = 8.9056 (9) ŵ = 2.46 mm−1
b = 11.4712 (10) ÅT = 290 K
c = 12.5918 (11) Å1.00 × 0.51 × 0.42 mm
β = 106.484 (8)°
Data collection top
Enraf–Nonius CAD-4
diffractometer		1969 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)		Rint = 0.022
Tmin = 0.255, Tmax = 0.353θmax = 25.4°
2418 measured reflections3 standard reflections every 120 min
2267 independent reflections intensity decay: none
Refinement top
R[F2 > 2σ(F2)] = 0.025H-atom parameters constrained
wR(F2) = 0.065Δρmax = 0.45 e Å−3
S = 1.11Δρmin = −0.38 e Å−3
2267 reflectionsAbsolute structure: ?
161 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Ag10.17340 (3)0.82881 (2)0.67239 (2)0.04213 (12)
Cu10.00001.00001.00000.04178 (18)
N10.0760 (3)0.9291 (3)0.8833 (2)0.0374 (6)
N20.1216 (4)1.1913 (3)0.9593 (3)0.0479 (7)
N30.2061 (3)0.9593 (3)1.1172 (2)0.0395 (6)
N40.9171 (3)0.8550 (3)1.5329 (2)0.0475 (7)
C10.1135 (4)0.8918 (3)0.8110 (3)0.0370 (7)
C20.1904 (4)1.2467 (3)0.9156 (3)0.0408 (8)
C30.3430 (4)0.9961 (4)1.1058 (3)0.0510 (10)
H3A0.34371.03571.04150.061*
C40.4829 (4)0.9777 (4)1.1853 (3)0.0492 (9)
H4A0.57541.00531.17410.059*
C50.4869 (4)0.9184 (3)1.2819 (3)0.0373 (7)
C60.3451 (4)0.8779 (3)1.2912 (3)0.0427 (8)
H6A0.34150.83551.35330.051*
C70.2092 (4)0.9001 (3)1.2089 (3)0.0432 (8)
H7A0.11520.87261.21760.052*
C80.6358 (4)0.8986 (3)1.3694 (3)0.0349 (7)
C90.7772 (4)0.8921 (3)1.3440 (3)0.0394 (8)
H9A0.78090.90301.27160.047*
C100.9128 (4)0.8692 (3)1.4276 (3)0.0459 (9)
H10A1.00630.86341.40890.055*
C110.7813 (4)0.8638 (4)1.5570 (3)0.0474 (9)
H11A0.78210.85601.63070.057*
C120.6401 (4)0.8835 (3)1.4798 (3)0.0423 (8)
H12A0.54830.88671.50100.051*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ag10.04338 (18)0.04940 (19)0.03717 (17)0.00608 (12)0.01719 (12)−0.00403 (11)
Cu10.0309 (3)0.0685 (4)0.0239 (3)0.0119 (3)0.0044 (2)−0.0064 (3)
N10.0332 (14)0.0481 (17)0.0309 (14)0.0011 (12)0.0091 (12)−0.0005 (13)
N20.0454 (17)0.0549 (19)0.0482 (18)−0.0031 (15)0.0213 (15)0.0052 (15)
N30.0309 (14)0.0556 (18)0.0306 (14)0.0032 (13)0.0064 (12)−0.0008 (13)
N40.0367 (16)0.063 (2)0.0383 (16)0.0033 (14)0.0038 (13)0.0012 (14)
C10.0333 (16)0.0432 (19)0.0343 (17)0.0037 (14)0.0094 (14)0.0011 (14)
C20.0380 (17)0.049 (2)0.0346 (17)−0.0039 (16)0.0096 (15)0.0002 (16)
C30.0386 (19)0.073 (3)0.0389 (19)0.0012 (18)0.0075 (15)0.0181 (19)
C40.0309 (17)0.067 (3)0.046 (2)−0.0084 (17)0.0056 (15)0.0126 (18)
C50.0349 (17)0.0399 (18)0.0344 (17)−0.0007 (14)0.0054 (14)0.0018 (14)
C60.0362 (17)0.056 (2)0.0340 (17)−0.0029 (16)0.0070 (14)0.0093 (16)
C70.0292 (16)0.062 (2)0.0390 (18)−0.0035 (16)0.0106 (14)0.0030 (16)
C80.0321 (16)0.0333 (17)0.0358 (17)−0.0029 (13)0.0038 (14)−0.0007 (13)
C90.0382 (17)0.049 (2)0.0296 (16)−0.0027 (15)0.0069 (14)−0.0025 (14)
C100.0336 (18)0.060 (2)0.043 (2)0.0023 (16)0.0098 (15)−0.0037 (17)
C110.0406 (19)0.067 (2)0.0318 (18)0.0020 (17)0.0055 (15)0.0057 (17)
C120.0335 (17)0.056 (2)0.0363 (18)0.0006 (15)0.0078 (14)0.0032 (16)
Geometric parameters (Å, °) top
Ag1—C2i2.086 (4)C3—H3A0.9300
Ag1—C12.093 (3)C4—C51.385 (5)
Ag1—N4ii2.472 (3)C4—H4A0.9300
Cu1—N1iii1.961 (3)C5—C61.381 (5)
Cu1—N11.961 (3)C5—C81.481 (4)
Cu1—N3iii2.056 (3)C6—C71.376 (5)
Cu1—N32.056 (3)C6—H6A0.9300
Cu1—N22.563 (3)C7—H7A0.9300
N1—C11.138 (4)C8—C91.386 (5)
N2—C21.128 (4)C8—C121.391 (5)
N3—C71.333 (5)C9—C101.384 (5)
N3—C31.336 (5)C9—H9A0.9300
N4—C101.325 (5)C10—H10A0.9300
N4—C111.332 (5)C11—C121.372 (5)
N4—Ag1iv2.472 (3)C11—H11A0.9300
C2—Ag1v2.086 (4)C12—H12A0.9300
C3—C41.375 (5)
C2i—Ag1—C1157.40 (13)C4—C3—H3A118.7
C2i—Ag1—N4ii103.67 (12)C3—C4—C5120.5 (3)
C1—Ag1—N4ii98.52 (12)C3—C4—H4A119.8
N1—Cu1—N1iii180C5—C4—H4A119.8
N1—Cu1—N3iii89.09 (11)C6—C5—C4116.3 (3)
N1iii—Cu1—N3iii90.91 (11)C6—C5—C8122.2 (3)
N1—Cu1—N390.91 (11)C4—C5—C8121.5 (3)
N1iii—Cu1—N389.09 (11)C7—C6—C5120.3 (3)
N3iii—Cu1—N3180C7—C6—H6A119.9
N1—Cu1—N2iii92.88 (11)C5—C6—H6A119.9
N1iii—Cu1—N2iii87.12 (11)N3—C7—C6123.0 (3)
N3iii—Cu1—N2iii89.78 (11)N3—C7—H7A118.5
N3—Cu1—N2iii90.22 (11)C6—C7—H7A118.5
N1—Cu1—N287.12 (11)C9—C8—C12117.1 (3)
N1iii—Cu1—N292.88 (11)C9—C8—C5121.1 (3)
N3iii—Cu1—N290.22 (11)C12—C8—C5121.8 (3)
N3—Cu1—N289.78 (11)C10—C9—C8119.3 (3)
N2iii—Cu1—N2180C10—C9—H9A120.4
C1—N1—Cu1175.9 (3)C8—C9—H9A120.4
C7—N3—C3117.3 (3)N4—C10—C9123.8 (3)
C7—N3—Cu1122.2 (2)N4—C10—H10A118.1
C3—N3—Cu1120.5 (2)C9—C10—H10A118.1
C10—N4—C11116.6 (3)N4—C11—C12124.0 (3)
C10—N4—Ag1iv119.0 (2)N4—C11—H11A118.0
C11—N4—Ag1iv124.2 (2)C12—C11—H11A118.0
N1—C1—Ag1176.9 (3)C11—C12—C8119.2 (3)
N2—C2—Ag1v172.6 (3)C11—C12—H12A120.4
N3—C3—C4122.7 (3)C8—C12—H12A120.4
N3—C3—H3A118.7
Symmetry codes: (i) −x+1/2, y−1/2, −z+3/2; (ii) x−1, y, z−1; (iii) −x, −y+2, −z+2; (iv) x+1, y, z+1; (v) −x+1/2, y+1/2, −z+3/2.
Acknowledgements top

Start-up funds supplied by the University of South Alabama supported this research. The authors also gladly acknowledge the Department of Energy and Oak Ridge National Laboratory for the loan of an Enraf–Nonius CAD-4 X-ray diffractometer.

references
References top

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