Synthesis, crystal structure and catalytic activity in reductive amination of dichlorido(η6-p-cymene)(2′-dicyclohexylphosphanyl-2,6-dimethoxybiphenyl-κP)ruthenium(II)

Abstract

The title compound, [RuCl2(C10H14)(C26H35O2P)] (I), crystallizes in the monoclinic space group P21/c with two crystallographically independent molecules (A and B) in the asymmetric unit. The geometries of both molecules are very similar and distinguished only by the twist angles of the two benzene rings in the phosphine substituents [89.54 (14) and 78.36 (14)° for molecules A and B, respectively]. The Ru atoms have classical pseudo-tetrahedral piano-stool coordination environments. The conformation of each molecule is stabilized by intramolecular C—H...O and C—H...Cl hydrogen bonds and C—H...π interactions. The two molecules are linked by a C—H...Cl hydrogen bond. In the crystal, the molecules are further linked by C—H... π interactions, forming –A–B–A–B– chains propagating along the a-axis direction. Complex I is an active catalyst for reductive amination reaction. The catalytic activity of this complex can be explained by the lability of the p-cymene ligand, which can be replaced by two-electron ligands such as CO or amine.

Keywords

• crystal structure
• ruthenium(II)
• η6-arene complex
• phosphine complex
• reductive amination
• carbon monoxide
• synchrotron radiation
• hydrogen bonding
• C—H...π interactions