Synthesis and properties of [PCP] pincer silylene cobalt(i) complexes

Abstract

In this study, two [PCP] pincer silylene cobalt(I) complexes [((Ph₂POCH₂)₂CH)Co(PMe₃)(SiCl((N^tBu)₂CAr))] (Ar = Ph (2) and 4-MePh (3)) were synthesized through the substitution reaction of the [PCP] pincer cobalt(I) complex [((Ph₂POCH₂)₂CH)Co(PMe₃)₂] (1) with silylene ligands: SiCl((N^tBu)₂CAr) (Ar = Ph (L1) and 4-MePh (L2)). The reaction of complex 2 with CO afforded the carbonyl silylene cobalt(I) complex [((Ph₂POCH₂)₂CH)Co(CO)(SiCl((N^tBu)₂CPh))] (4), while complex 2 reacted with CH₃I to give rise to cobalt(II) iodide [((Ph₂POCH₂)₂CH)Co(I)(PMe₃)] (6). With a catalyst loading of 2 mol%, complex 6 displayed efficient catalytic activity for hydrosilylation of alkenes by using Ph₂SiH₂ as the hydrogen source under mild conditions. The molecular structures of complexes 2, 3, 4 and 6 were determined by single crystal X-ray diffraction analysis.