Bonding isomerism in the η1-P coordination of the P4X3 (X=S, Se) molecules toward 16e rhodium fragments stabilized by tripodal tetradentate ligands

The reaction of tetraphosphorus trichalcogenides P4X3 (X=S, Se) with the electronically and coordinatively unsaturated 16 electron systems [(EP3)Rh]+ [E=N, NP3=tris(2-diphenylphosphanylethyl)amine, (1); E=P, PP3=tris(2-diphenylphosphanylethyl)phosphane, (2)] in tetrahydrofuran affords new tetraphosphorus trichalcogenide derivatives of formula [(EP3)Rh(P4X3)]CF3 SO3 [E=N; X=Se (3), S (5). E=P; X=Se (4), S (6)]. In the P4Se3 derivatives 3 and 4 the heptatomic cage is bound to the metal through the apical phosphorus atom. The P4S3 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 [(NP3)Rh(η1-P4S3)]CF3SO3 (5) reacts with 1 affording the dimetal compound [{(NP3)Rh}2(μ,η1:1-Papical,-Pbasal-P4S3)](CF3SO3)2, where the cage exhibits both modes of bonding. All of the compounds have been characterized by 31P NMR spectra and elemental analyses.