Synthesis and Characterization of the First Sandwich Complex of Trivalent Thorium: A Structural Comparison with the Uranium Analogue

Reduction of the bulky 8-annulene thorium complex [Th{COT(TBS)2}2] (COT(TBS)2 =¿-C8H6(tBuMe2Si)2-1,4) by potassium yields the anionic compound {Th[COT(TBS)2]2}(DME)2, which was crystallographically characterized and is the first sandwich complex of Th(III). EPR spectroscopy indicates that the molecule possesses a 6d1 ground state. A structural comparison is made with the isostructural uranium(III) complex and the thorium(IV) parent compound

Formation of Mono(dithiolene)-Thiocarboxamido Complexes in Reactions of Thio(dithiocarbamato)-Mo/W Complexes and Dimethyl Acetylenedicarboxylate

Reactions of Tp*MS(S2CNEt2) with dimethyl acetylenedicarboxylate in dichloromethane produce olive green/black Tp*M{S2C2(CO2Me)2}(SCNEt2-2S,C) (M = Mo (1), W (2); Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate). The seven-coordinate complexes exhibit pseudo-octahedral (1) and distorted pentagonal bipyramidal (2) coordination spheres comprised of tridentate fac-Tp*, bidentate dithiolene, and thiocarboxamido-2S,C ligands. In the solid state, molecules of 1 exhibit pseudo-Cs symmetry, with the thiocarboxamide NEt2 group in a cleft in the Tp* ligand. Molecules of 2 have C1 symmetry in the solid state; here, the thiocarboxamide unit is orientated along one of the W-S(dithiolene) bonds with its NEt2 group projecting away from the Tp* ligand. Both complexes possess effective Cs symmetry in solution. Reaction of Tp*MoI(CO)3 with AgS2CNEt2 affords olive green Tp*Mo(S2CNEt2)(CO)2 (3), which reacts with propylene sulfide in a new synthesis for Tp*MoS(S2CNEt2), the starting material for 1. Complex 3 exhibits a distorted pentagonal bipyramidal structure, the axial sites being defined by a Tp* nitrogen atom and a carbonyl ligand, the pentagonal plane by the remaining nitrogen and carbonyl donors and the two sulfur atoms of the bidentate dithiocarbamate ligand.Patrick J. Lim, Damian A. Slizys, Edward R. T. Tiekink, and Charles G. Youn