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 ¹³C labeled CO, and exchange reactions with phosphines afford the corresponding (phosphino)­phosphinidene–phosphine adducts (>PP←:PR₃). 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