PREPARATION, STRUCTURE AND THERMAL-PROPERTIES OF THE COMPLEX [(CH3)2C6H5S][CU2(CN)3] WITH SHORT CU(I) ... CU(I) DISTANCE (2.655(2) A)

The reaction between K[Cu2(CN)3] and [(CH3)2(C6H5)S]ClO4 in aqueous solution gives rise to colourless [(CH3)2(C6H5)S][Cu2(CN)3]. This compound crystallizes in the monoclinic space group P21/n, its lattice parameters being a = 8.582(5), b = 12.979(5), c = 11.745(6) angstrom, beta = 101.10(4)degrees and Z = 4. The structure comprises an isolated [(CH3)2(C6H5)S]+ cation and polymer [Cu2(CN)3]- anion. This anion consists of distorted planes which are cross-linked in the third direction through a long Cu(2)-C(1) bond (2.419(2) angstrom). The planes are composed of distorted hexagons in which two different copper atoms (vertices) are joined with the bridged cyano groups (edges). The Cu(1) atoms exhibit trigonal coordination while the Cu(2) atoms display distorted tetrahedral coordination. The distance between two Cu(2) atoms (in adjacent planes) is very short, i.e. 2.655(2) angstrom. The pyramidal sulfonium cations are situated between the planes and are disordered in two positions, the occupation factors of which are in the ratio 68:32. The final value of R for 1244 observed diffractions (F(o) greater-than-or-equal-to 4-sigma(F(o)) is 0.0544. The thermal decomposition was investigated derivatographically in argon atmosphere. The compound starts to decompose at 200-degrees-C and CH3SC6H5 and CH3CN are liberated. At 470-degrees-C the liberation of (CN)2 begins.