Reaction of a CH3CN solution of [NEt4]2[WSe4] with 1 equiv of lithium (2-thienyl)cyanocuprate, Li[(CN)Cu-(C4H3S)], affords [NEt4]2[μ-WSe4] [(SC4H3)SeCu]2 (1), in which a Se atom from the decomposition of the WSe42− anion formally has been inserted into the 2-thienylcopper bond of Cu(C4H3S) to form the 2-selenothiophene ligand. [NEt4]2[μ-WSe4] [(SC4H3)SeCu]2 crystallizes with four formula units in the tetragonal space group D2d7 − P4̄b2 in a cell of dimensions a = 15.732(2) Å and c = 14.992(3) Å (T = 113 K). Full anisotropic refinement (4934 unique data, 173 variables) of the structure on Fo2 led to a value of R(F) = 0.055 for those 4282 data having Fo2 ≥ 2σ(Fo2). The molecule has a crystallographically imposed 2-fold axis. Four Se atoms are arranged in an almost perfect tetrahedron about the W center; the Se atoms bridge to two Cu atoms, each of which in turn is bonded to a third Se atom in a distorted trigonal planar array. Each of these latter Se atoms is bonded to a thiophene group at the 2-position. The 77Se NMR spectrum of a DMF solution of 1 exhibits two resonances at δ 905.8 and −18.1 ppm. The 13C NMR spectrum displays six peaks at δ 15.5, 52.7, 65.9, 124.5, 127.9, and 131.6 ppm, consistent with the solid-state structure.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry