Bonding isomerism in the η 1-P coordination of the P 4X 3 (X=S, Se) molecules toward 16e rhodium fragments stabilized by tripodal tetradentate ligands

Abstract

The reaction of tetraphosphorus trichalcogenides P 4X 3 (X=S, Se) with the electronically and coordinatively unsaturated 16 electron systems [(EP 3)Rh] + [E=N, NP 3=tris(2-diphenylphosphanylethyl)amine, ( 1); E=P, PP 3=tris(2-diphenylphosphanylethyl)phosphane, ( 2)] in tetrahydrofuran affords new tetraphosphorus trichalcogenide derivatives of formula [(EP 3)Rh(P 4X 3)]CF 3 SO 3 [E=N; X=Se ( 3), S ( 5). E=P; X=Se ( 4), S ( 6)]. In the P 4Se 3 derivatives 3 and 4 the heptatomic cage is bound to the metal through the apical phosphorus atom. The P 4S 3 derivatives 5 and 6 are obtained as pairs of coordination isomers, with the cage linked to the metal either through the apical or through one of the basal P atoms; the former isomer is predominant and its amount depends on the nature of the trans-disposed apical donor (N or P) of the tripodal ligand. The monometal species [(NP 3)Rh(η 1-P 4S 3)]CF 3SO 3 ( 5) reacts with 1 affording the dimetal compound [{(NP 3)Rh} 2(μ,η 1:1-P apical,-P basal-P 4S 3)](CF 3SO 3) 2, where the cage exhibits both modes of bonding. All of the compounds have been characterized by 31P NMR spectra and elemental analyses.