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 [L 3 Ln 3 (μ 2 -Me) 2 (μ 3 -Me)(μ 3 -η 1:η 2:η 2 -PC 6 H 4 - o )] (L = [PhC(NC 6 H 4 i Pr 2 -2,6) 2 ] −, Ln = Y ( 1a ), Lu ( 1b )) with phenylacetylene, CO 2, diisopropyl carbodiimide, isocyanide, or PhSSPh lead to the formation of a series of phosphorus-containing products. The reaction of 1 with CS 2 yields two novel P -methyl-phosphindole-2,3-dithiolate dianion complexes, revealing an unusual tandem desulfurization/coupling/cyclization reaction mode of CS 2 . A possible reaction pathway was determined by density functional theory calculations. This emphasizes the key role of the reduction power of the formal P 2– part of the phosphinidene in the C–S bond cleavage.