Synthesis of a rhodium(I) carbonyl complex with a chiral aminodiphosphine ligand and its immobilization onto aminopropyl functionalized silica gel

Abstract

The reaction of [Rh(CO)₂(µ-Cl)]₂ with two molar equivalents of a chiral ligand, (R)-N,N-bis(2-diphenylphosphinoethyl)-1-phenylethylamine(PNP*) yield a mono-carbonyl complex, [Rh(CO)Cl(η²-P,P-PNP*)] (1), in which the potentially tridentate PNP* ligand coordinates in a bidentate fashion through P,P bonding. The complex was characterized by elemental analysis, FAB mass, IR, UV-Vis, ¹H- and ³¹P{¹H}-NMR spectroscopy. Variable temperature (223–298 K) ³¹P{¹H}-,NMR spectra of 1 showed a mixture of cis and trans isomers in the solution with the trans predominating at room temperature and the cis at lower temperature. Complex 1 was immobilized on silica through axial coordination of amine from 3-aminopropyltriethoxysilane functionalized silica. The immobilized materials were characterized by elemental analysis (N₂), FTIR, DTA–TGA, N₂-adsorption, XRD, and SEM analysis.

Keywords:

• Rhodium(I) complex
• Chiral PNP ligand
• Variable temperature ³¹P{¹H}-NMR
• Immobilization
• Silica functionalization

Acknowledgments

The Department of Science and Technology, India, and the Ministry of Education and Research, Ukraine, are gratefully acknowledged for the joint research project (DST/INT/UKR/P-7/06) under Indo-Ukraine cooperation in science and technology. The services of SAIF, CDRI, Lucknow and CIF, IIT Guwahati, are gratefully acknowledged for different analytical facility. We also gratefully acknowledge the UGC, New Delhi, for providing FTIR to the Department under SAP DRS-I program.