Transition-Metal-like Behavior of Main Group Elements: Ligand Exchange at a Phosphinidene.

(Phosphino)phosphaketenes (>P-P═C═O) behave as (phosphino)phosphinidene-carbonyl adducts (>P-P←:C═O). CO scrambling was observed using C labeled CO, and exchange reactions with phosphines afford the corresponding (phosphino)phosphinidene-phosphine adducts (>P-P←:PR). The latter react with isonitriles and singlet carbenes giving (phosphino)phosphinidene-isonitrile (>P-P←:CNR) and -carbene adducts (>P-P←:C<). Based on experimental results and DFT calculations, it is shown that these "ligand" exchange reactions occur via an associative mechanism as classically observed with transition metal complexes.