Theoretical and experimental study of the factors influencing regio- and stereochemical control in the reactions of nucleophiles with metal carbonyl complexes

The factors influencing the regio- and stereochemical control of reactions between phosphines and phosphites with (A) a series of tricarbonyl(eta(7)-tropylium)metal cations (M = Cr, Mo, W) and (B) a series of tricarbonyl(eta(6)-substituted arene)manganese cations (substituent = Cl, Me, p-Me(2), 1,3,5-Me(3)) are examined theoretically using the interaction determinant method of calculating interaction energies and experimentally using low-temperature infrared and H-1 NMR spectroscopy to identify the nature of the initial attack site in the substrate. In all cases the reactions are predicted to be orbitally controlled and agreement is found between calculated site-nucleophile interaction energies and observed initial attack site both in terms of stereochemistry, e.g. exo ring attack is predicted correctly over endo ring attack, and regioselectivity, e.g. P(OMe)(3) is predicted correctly to give metal attack with the molybdenum and tungsten tropylium complexes.