Abstract:

Metal(0) complexes L(Cr, Mo, W)(CO)(5) have been prepared from 1,3-bis(2,6-diisopropylphenyl)-2-(4-methylphenyl)-3-aza-1(lambda(3),sigm a(2))-phosphapropene and 1,3-bis(2,6-diisopropylphenyl)-2-(4-methoxy-phenyl)-3-aza-1(lambda(3),si gma(2))-phosphapropene using standard methods. Full characterization of four products and crystal structures of these complexes as well as the methoxyphenyl-phosphapropene are reported. The ligands coordinate kappa P, common for simple phosphaalkenes, despite the strongly-perturbing amino substitution at the double bond C atoms. Analyses of the NMR and vibrational spectroscopic data reveal that the complexes have very similar character to similarly-coordinated phosphaalkenes, with strong sigma-donor character. The presence of some net pi-interactions (acceptor or donor) is indicated by structures in which the ligands coordinate fully eclipsed with the M-CO groups. The synthetic and structural results have been augmented by B3PW91/LANL2DZ calculations that reproduce the structures of the Cr complexes accurately. The calculated vibrational spectra are used to confirm the assignment of the nu(C=O) vibrational data. Detailed orbital interaction diagrams based on DFT calculations are reported for the title complexes as well as for the Cr(CO)(5) complex of Mes-P-CPh2. The electronic absorption spectra of the title complexes have intense low-energy absorptions ranging from 24 500 to 25 300 cm(-1), which can be interpreted qualitatively using the DFT results.