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.