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

In this study, two [PCP] pincer silylene cobalt(i) complexes [((Ph2POCH2)(2)CH)Co(PMe3)(SiCl(((NBu)-Bu-t)(2)CAr))] (Ar = Ph (2) and 4-MePh (3)) were synthesized through the substitution reaction of the [PCP] pincer cobalt(i) complex [((Ph2POCH2)(2)CH)Co(PMe3)(2)] (1) with silylene ligands: SiCl(((NBu)-Bu-t)(2)CAr) (Ar = Ph (L1) and 4-MePh (L2)). The reaction of complex 2 with CO afforded the carbonyl silylene cobalt(i) complex [((Ph2POCH2)(2)CH)Co(CO)(SiCl(((NBu)-Bu-t)(2)CPh))] (4), while complex 2 reacted with CH3I to give rise to cobalt(ii) iodide [((Ph2POCH2)(2)CH)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.