Streamlined Preparation and Coordination Chemistry of Hybrid Phosphine–Phosphaalkene Ligands
datasetposted on 16.03.2016, 20:13 by Kevin W. Magnuson, Shelly M. Oshiro, Joshua R. Gurr, Wesley Y. Yoshida, Milan Gembicky, Arnold L. Rheingold, Russell P. Hughes, Matthew F. Cain
A rationally designed and selective synthesis of hybrid phosphine–phosphaalkene ligands E-1a (Cy2PCH2CHPMes*, Mes* = 2,4,6-tri-tert-butylphenyl) and E-1b (Ph2PCH2CHPMes*) was developed using phospha-Wittig methodology. The new hybrid ligands E-1a and E-1b were used to prepare the Pd and Pt dichloride complexes Pd(Cy2PCH2CHPMes*)Cl2 (2a), Pd(Ph2PCH2CHPMes*)Cl2 (2b), Pt(Cy2PCH2CHPMes*)Cl2 (3a), and Pt(Ph2PCH2CHPMes*)Cl2 (3b). The crystal structures of E-1a, E-1b, 2a·1.33CHCl3, 3a·CH3CN, and 3b were determined. DFT calculations (M06/LACV3P**) on 2a revealed that the π* orbital located on the PC unit is low-lying and accessible. An NBO analysis concluded that the phosphaalkene ligand is a significantly poorer σ donor and a slightly better π acceptor than its tertiary phosphine counterpart, due to the presence of the PC double bond.