Trimethylantimony(V) tetraphenyldichalcogenoimidodiphosphinates: crystal structure of Me 3Sb[O-PPh 2N-PPh 2S] 2, a compound containing true O-monometallic monoconnective phosphorus ligands with XPNPY skeleton

Abstract

Reactions between Me 3SbCl 2 and K[(SPPh 2) 2N], using 1:1 and 1:2 molar ratios, have been investigated. In both cases Me-S-PPh 2N-PPh 2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 Me 3SbCl 2 and K[(OPPh 2)(SPPh 2)N] in 1:2 molar ratio gave Me 3Sb[O-PPh 2N-PPh 2S] 2 ( 2), isolated as a white solid and characterized by IR and NMR ( 1H, 13C, 31P) 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 C 3SbO 2 core. The SbC 3 unit is planar [Σ(CSbC angles) 360°] and the angle between the axial SbO bonds is 173.4(2)°. 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.