Synthesis and characterization of a large bite angle xantphos iridium complex

Abstract

The xantphos iridium complex [Ir(xantphos)(H)(CO)(PPh₃)] CH₂Cl₂ (3) was synthesized and structurally characterized by NMR, IR, and single-crystal X-ray diffraction. Complex 3 crystallizes with two molecules (A,B) in the asymmetric unit. The coordination around Ir is trigonal bipyramidal with all three P groups occupying equatorial positions. The carbonyl and hydride occupy axial sites. This mode of bonding results in a complex that exhibited large bite (P1–Ir–P2) angles of 109.12(6) and 110.50(6)° for the A and B molecules, respectively. NMR data further support the structural elucidation of 3 and IR data confirm the presence of Ir bound to both a carbonyl and a hydride. Thermal analyses of 3 indicate that it is thermally stable up to >400 °C under nitrogen.

Keywords:

• Xantphos
• Diphosphine
• Iridium complex
• Bite angle
• Catalyst

Acknowledgments

We wish to thank Dr. Manuel Fernandes (University of the Witwatersrand) for crystal data collection, SASOL, THRIP, and the University of KwaZulu-Natal for the financial support. We gratefully acknowledge Johnson Matthey for a loan of iridium trichloride.