Synthesis of the New Chiral (R)- and (S)-Aminodiphosphine Ligands sec-Butylbis(2-(diphenylphosphino)ethyl)amine, sec-Butylbis(2-(dicyclohexylphosphino)ethyl)amine, and (α-Methylbenzyl)bis(2-(dicyclohexylphosphino)ethyl)amine and Their Organometallic Chemistry When Combined with Iridium

Abstract

The new chiral aminodiphosphine ligands (R)- and (S)-sec-butylbis(2-(diphenylphosphino)ethyl)amine, (R)- and (S)-sec-butylbis(2-(dicyclohexylphosphino)ethyl)amine, and (R)- and (S)-(α-methylbenzyl)bis(2-(dicyclohexylphosphino)ethyl)amine have been synthesized from optically pure (R)-(−)- and (S)-(+)-sec-butylamine or (R)-(+)- and (S)-(−)-(α-methylbenzyl)amine. The reactions between these PNP* ligands and [Ir(COD)(OMe)]2 have been investigated in either aprotic or protic solvents (COD = cycloocta-1,5-diene). Depending on the substituents at either the carbon stereocenter or the phosphorus donors, iridium products with different structures and/or stabilities are obtained. Among the new complexes, there are monohydride, dihydride, and trihydride species. It is observed that (i) cyclohexyl substituents on the phosphorus donors favor the formation of complexes where the PNP* ligand adopts a meridional conformation; (ii) phenyl groups attached to the carbon stereocenter lead to the formation of thermodynamicall...