Metal-Ligand Cooperation as Key in Formation of Dearomatized Ni^II-H Pincer Complexes and in Their Reactivity toward CO and CO₂.

ABSTRACT: 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 ?¹ 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.

SUBMITTER: Oren D 

PROVIDER: S-EPMC6503609 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature