LOW-TEMPERATURE STRUCTURES OF CATENA-(BIPYRIMIDINE-N,N')BIS(THIOCYANATO)COPPER(II) AND POLY-(MU-BIPYRIMIDINE-N,N',N'',N''')TETRAKIS(THIOCYANATO)DICOPPER(II)

Compound (1), catena-poly[(2,2'-bipyrimi-dine-kappa2N,N')copper(II)-bis-mu-(thiocyanato-kappaN:kappaS)], [Cu(NCS)2(C8H6N4)]n, M(r) = 337.9, monoclinic, C2/c, a = 11.403 (2), b = 13.943 (3), c = 7.722 (2) angstrom, beta = 93.93 (2)-degrees, V = 1224.9 (4) angstrom3, Z = 4, D(x) = 1.832 g cm-3, lambda(Mo Kalpha) = 0.71069 angstrom, mu = 21.1 cm F(000) = 676, T = 153 K, final R = 0.025 and wR = 0.032 for 1241 reflections with I > 3sigma(I). (2), poly[copper(Il)-mu-(2,2'-bipyrimidine-1 kappa2N1,N1: 2kappa2N2,N2')-Copper(II)-tetrakis-mu-(thiocyanato-kappaN:kappaS)], [Cu2(NCS)4(C8H6N4)]n, M(r) = 517.6, orthorhombic, Fddd, a = 12.676(2), b = 22.171(3), c = 24.490 (3) angstrom, V = 6883 (2) angstrom3, Z = 16, D(x) 1.998 g cm-3, lambda(Mo Kalpha) = 0.71069 angstrom, mu 29.6 cm-1 F(000) = 4096, T = 153 K, final R = 0.033 and wR = 0.042 for 1634 reflections with I > 3sigma(I). The structure of (1) consists of one-dimensional chains, in which the thiocyanate group bridges the [Cu(bpm)]2+ (bpm = bipyrimidine) units in an end-to-end fashion. The structure of (2) consists of [Cu(bpm)Cu]4+ units which are linked by thiocyanate groups acting in an end-to-end bridging fashion. In both complexes, the copper(II) ion displays a distorted octahedral coordination. There is a significant distortion towards tetrahedral coordination in (1) which is not observed in (2). The bipyrimidine group acts as a bidentate and bis-bidentate ligand in (1) and (2), respectively.