Trimethylantimony(V) tetraphenyldichalcogenoimidodiphosphinates:: crystal structure of Me3Sb[O-PPh2=N-PPh2=S]2, a compound containing true O-monometallic monoconnective phosphorus ligands with XPNPY skeleton

Reactions between Me3SbCl2 and K[(SPPh2)(2)N], using 1:1 and 1:2 molar ratios, have been investigated. In both cases Me-SPPh2=N-PPh2=S (1) was isolated, as a result of the migration of a methyl group from antimony to sulfur. The S-Me ester was identified by NMR spectroscopy and its solid-state molecular structure was determined. Reaction of Me3SbCl2 and K[(OPPh2)(SPPh2)N] in 1:2 molar ratio gave Me3Sb[O-PPh2=N-PPh2=S](2) (2), isolated as a white solid and characterized by IR and NMR (H-1, C-13, P-31) spectroscopy. The molecular structure of 2 was investigated by X-ray diffraction. The crystal consists of discrete molecules, with two monothio ligands bound to the metal center only through oxygen atoms, thus resulting in a trigonal bipyramidal C3SbO2 core. The SbC3 unit is planar [Sigma(C-Sb-C angles) 360degrees] and the angle between the axial Sb-O bonds is 173.4(2)degrees. The coordination of the monothioimododiphosphinato ligand in the O-monometallic monoconnective mode is unique; such ligands usually exhibiting chelate or bridging coordination through both oxygen and sulfur atoms. (C) 2003 Elsevier Ltd. All rights reserved.