Nickel and Palladium Complexes of a PP(O)P Pincer Ligand Based upon a peri-Substituted Acenaphthyl Scaffold and a Secondary Phosphine Oxide

A PP­(O)­P pincer ligand based upon a peri-substituted acenaphthyl (Ace) scaffold and a secondary phosphine oxide, (5-Ph2P-Ace-6-)2P­(O)­H, was prepared and fully characterized including a neutron diffraction study. The reaction with [Ni­(H2O)6]­Cl2 and PdCl2 produced ionic metal­(II) complexes [κ3-P,P’,P’’((5-Ph2P-Ace-6-)2P­(OH))­MCl]­Cl, which upon addition of Et3N gave rise to zwitterionic metal­(II) complexes κ3-P,P’,P’’((5-Ph2P-Ace-6-)2P­(O))­MCl (M = Ni, Pd). The reaction with Ni­(COD)2 (COD = cyclooctadiene) provided the η3-cyclooctenyl Ni­(II) complex κ3-P,P’,P’’((5-Ph2P-Ace-6-)2P­(O))­Ni­(η3-C8H13). A detailed complementary bonding analysis of the P–H, P–O, and P–M interactions was carried out (M = Ni, Pd).