Synthesis and crystal structure of a copper(I) complex containing tetrathiomolybdate and dihydrobis(3,5-dimethylpyrazolyl)borate ligands:: [Et4N]2[(Bp′)CuMoS4Cu2(μ-Bp′)2Cu2MoS4Cu(Bp′)] (Bp′ = H2B(3,5-Me2Pz)2) and crystal structure of [(Bp′)2Cu]

Complex (1), [Et4N](2)[(Bp')CuMoS4Cu2(mu -Bp')(2)Cu2MoS4Cu(Bp')], was synthesised in acetone by substituting Cl- ligands of [MoS4(CuCl)(3)](2-) by bidentate Bp' ligands. It crystallises as a centrosymmetric dimeric anion, containing MoS42- and Bp' units coordinated to Cu(I) atoms to form a novel structure. Bis(pyrazolyl)borate ligands are both bridging and terminal chelating. The copper(I) atoms have two different geometries: 3-coordinate by two S of thiomolybdate and one N of bridging Bp', and 4-coordinate by two S of thiomolybdate and two N of terminal Bp'. An acetornitrile solution of complex (1) is unstable in air and deposits crystals of (2), [(Bp')(2)Cu]. [n complex (2), the Cu(II) atom resides on an inversion centre with square planar co-ordination. The crystal structure and molecular geometry of (2) are similar to those of its fluorinated analogue [H2B(3,5(CF3)(2)Pz)(2)](2)Cu. (C) 2001 Elsevier Science B.V. All rights reserved.