REDETERMINATION OF THE STRUCTURE OF (ACETONITRILE)CHLOROCOPPER(I) [(H3CCN)CUCL] AT 178-K

[Cu(C2H3N)Cl], M(r) = 140.0, orthorhombic, Pnma, a = 8.545 (3), b = 3.8691 (10), c = 12.692 (4) angstrom, V = 419.6 (3) angstrom3, Z = 4, D(x) = 2.217 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 5.6 mm-1, F(000) = 272, T = 178 K, R = 0.022 for 491 reflections. All non-H atoms lie in the mirror planes at y = 0.25. Although the Cu atom displays slightly larger displacement parameters than the Cl atom [U(eq) 0.0317 (2) and 0.0225 (2) angstrom2 for Cu and Cl], there seems no cogent reason to prefer the non-centrosymmetric space group Pna2(1) with the Cu atom displaced from the mirror plane. Zigzag chains -Cu(NCCH3)-Cl- are connected in pairs parallel to the short x axis, and joined by Cu-Cl cross-links to form infinite pleated sheets. The Cu atoms thus attain (somewhat distorted) tetrahedral coordination geometry, with Cu-N 1.935 (3), Cu-Cl 2.399 (1)(x 2), 2.406 (1)angstrom.