cis-β-Ruthenium Complexes with Sterically Bulky Salen Ligands: Enantioselective Intermolecular Carbene Insertion into Si–H Bonds and X-ray Crystal Structure of cis-β-[RuII(salen)(CO)(CPh2)] Complex

The synthesis, spectroscopy, crystal structure, and electrochemical behavior of cis-β- Ru II (CO) 2, cis-β- Ru II (CO)(H 2 O), and cis-β- Ru II (CO)(carbene) complexes supported by sterically bulky salen ligands are described, along with the catalytic activity of chiral cis-β -[Ru II (salen)(CO) 2 ] complexes toward enantioselective carbene Si–H insertion using N 2 C(Ar)CO 2 R as the carbene source under light irradiation with product yields up to 96% and ee up to 84%. The cis-β- Ru II (CO)(H 2 O) complex was isolated by using a binaphthyl salen ligand bearing bulky CPh 3 substituents with the H 2 O molecule coordinated at the site trans to an N imine atom of the salen ligand. Light irradiation of a cis-β -Ru II (CO) 2 complex, supported by a binaphthyl salen ligand with t Bu substituents, followed by treatment with N 2 CAr 2 (Ar = Ph, p -ClC 6 H 4 ) gave cis-β- [Ru II (salen)(CO)(CAr 2 )], which features a coordinated carbene ligand trans to a salen N imine atom and undergoes carbene transfer to nitrosobenzene to give the corresponding nitrone product. These findings and related HR-ESI-MS studies provide evidence for the involvement of salen-supported cis-β- Ru II (CO)(C(Ar)CO 2 R) active species in the intermolecular carbene Si–H insertion reaction catalyzed by cis-β -[Ru II (salen)(CO) 2 ] complexes.