The unique synthesis and reactivity of [(RPNP∗)NiH] complexes (1a,b), based on metal-ligand cooperation (MLC), are presented (RPNP∗ = deprotonated PNP ligand, R = iPr, tBu). Unexpectedly, the dearomatized complexes 1a,b were obtained by reduction of the dicationic complexes [(RPNP)Ni(MeCN)](BF4)2 with sodium amalgam or by reaction of the free ligand with Ni0(COD)2. Complex 1b reacts with CO via MLC, to give a rare case of a distorted-octahedral PNP-based pincer complex, the Ni(0) complex 3b. Complexes 1a,b also react with CO2 via MLC to form a rare example of η1 binding of CO2 to nickel, complexes 4a,b. An unusual CO2 cleavage process by complex 4b, involving C-O and C-P cleavage and C-C bond formation, led to the Ni-CO complex 3b and to the new complex [(PiPr2NC2O2)Ni(P(O)iPr2)] (5b). All complexes have been fully characterized by NMR and X-ray crystallography.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry