Unprecedented Reaction Mode of Phosphorus in Phosphinidene Rare-Earth Complexes: A Joint Experimental-Theoretical Study.

Reactions of trinuclear rare-earth metal complexes bearing functionalized phosphinidene ligand [L3Ln3(μ2-Me)2(μ3-Me)(μ3-η1:η2:η2-PC6H4-o)] (L = [PhC(NC6H4iPr2-2,6)2]-, Ln = Y (1a), Lu (1b)) with phenylacetylene, CO2, diisopropyl carbodiimide, isocyanide, or PhSSPh lead to the formation of a series of phosphorus-containing products. The reaction of 1 with CS2 yields two novel P-methyl-phosphindole-2,3-dithiolate dianion complexes, revealing an unusual tandem desulfurization/coupling/cyclization reaction mode of CS2. A possible reaction pathway was determined by density functional theory calculations. This emphasizes the key role of the reduction power of the formal P2- part of the phosphinidene in the C-S bond cleavage.