CRYSTAL-STRUCTURE OF [(C2H5)3NCH3]CU3CL7 - A NEW STRUCTURAL VARIANT OF THE CUCL2 STRUCTURE

Triethylmethylammonium heptachlorotricuprate, [(C2H5)3NCH3]Cu3Cl7, M(r) = 555.0, triclinic, P1BAR, a = 7.917(5), b = 11.131(7), c = 11.664(7) angstrom, alpha = 65.71 (3), beta = 86.86 (3), gamma = 73.28 (3)-degrees, V = 894.8 (9) angstrom, Z 2, D(x) = 2.060 g cm-3, Mo Kalpha, lambda = 0.71073 angstrom, mu = 45.6 cm-1, F(000) = 546, T = 293 K, wR = 0.0675 for 1222 observed [Absolute value of F > 3sigma(F)] reflections and 164 parameters. The compound consists of two-dimensional anionic (Cu3Cl7-)infinity sheets separated by the organic cations. The sheets are made up of alternating metal halide rows. One half of the rows are infinite bibridged (CuCl2)infinity chains. Interspersed between these rows are rows of discreet bibridged Cu2Cl62- dimers. Adjacent rows are linked by long semi-coordinate Cu...Cl bonds. Adjacent dimers along the rows are separated by holes corresponding to the absence Of CuCl2 units. The cations sit directly above and below these holes to compensate for the loss in charge, with the methyl groups pointed toward the holes. The anionic sheets can be viewed as being derived from the ferrodistortive layers found in the parent CuCl2 structure. A discussion of structures related to the CuCl2 Structure is given, with emphasis on the role that the cations and additional ligands have in developing these structures.