The PNS pincer-type ligand 1 and the novel Ru(PNS) complexes 2-8 were synthesized and characterized. The (PNS)RuH(Cl)CO complex 2 was prepared by reaction of ligand 1 with RuH(Cl)CO(PPh 3) 3. 2 reacted with KHMDS (potassium bis(trimethylsilyl)amide) to form the symmetrical dimeric complex 4 via the intermediacy of the dearomatized complex (PNS*)Ru(H)CO 3, in which deprotonation of the benzylic-S "arm" took place. Reaction of 2 with excess NaH gave the dimeric 4, by a formal intermolecular attack of the benzylic "arm" on a second ruthenium center. Complex 4 underwent spontaneous transformation in solution to the dinuclear complex 5 via C-S bond cleavage, resulting in the loss of a S-bound tBu group. Treatment of 2 with KHMDS in the presence of PEt 3 resulted in the trapping of intermediate 3 in the form of the dearomatized complex 8. Reaction of 2 with LiHBEt 3 gave the trans-dihydride complex 6, which reacted with CO 2 to give the formato complex 7, in which the formato ligand is located trans to the hydride. Complexes 2, 4, and 5 were also investigated as catalysts for the dehydrogenative coupling of alcohols with amines.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry