Fe II complexes supported by an iminophosphorane ligand: synthesis and reactivity.

The synthesis of iron complexes supported by a mixed phosphine-lutidine-iminophosphorane (PPyNP) ligand was carried out. While bidentate κ 2 -N,N coordination was observed for FeCl 2 , pincer coordination modes were adopted at cationic iron centers, either through dechlorination of [LFe(PPyNP)Cl 2 ] (1) or direct coordination of PPyNP to Fe(OTf) 2 . Reaction with tert -butylisocyanide gave access to the diamagnetic octahedral complex [Fe(PPyNP)(CN t Bu) 3 ]X 2 (X = OTf (4), Cl (4')). Both 1 and 4 were shown to undergo deprotonation of the phosphinomethyl group, but the resulting complexes were not active for the dehydrogenative coupling of hexan-1-ol. The hydrosilylation of acetophenones was catalyzed at room temperature with 1 mol% of a catalyst generated in situ from cationic PPyNP-supported iron triflate complexes and KHBEt 3 .