STRUCTURE AND STEREODYNAMICS OF FE(CO)4L COMPLEXES (L = P(O-TOLYL)3, AS(O-TOLYL)3, P(O-TOLYL)2CH2PH, (O-TOLYL)2PP(O-TOLYL)2)

The crystal structures and variable-temperature NMR spectra of (CO)4FeP(o-tolyl)3, (CO)4FeAs(o-tolyl)3, (CO)4FeP-(o-tolyl)2CH2Ph, and (CO)4Fe(o-tolyl)2PP(o-tolyl)2 (1a-d) are reported. In the solid state, complexes 1a-c contain the phosphine in an axial position of the trigonal bipyramid; complex 1d is equatorially substituted in the solid state but exists as an axial/equatorial mixture in solution. All complexes exhibit P-C restricted rotation, which in the case of 1a may be linked to axial/equatorial CO exchange. Crystallographic data: 1a, C25H21FeO4P, monoclinic, P2(1)/n, a = 10.188(3) angstrom, b = 10.429(2) angstrom, c = 21.755(6) angstrom, beta = 99.79(2)degrees, Z = 4; 1b, C25H21AsFeO4, monoclinic, P2(1)/n, a = 10.265(2) angstrom, b = 10.517(1) angstrom, c = 21.679(3) angstrom, beta = 99.16(2)degrees, Z = 4; 1c, C25H21FeO4P, triclinic, P1BAR, a = 9.618(3) angstrom, b = 15.282(3) angstrom, c = 17.130(5) angstrom, alpha = 66.92(2)degrees, beta = 79.51(2)degrees, gamma = 86.42(2)degrees, Z = 4; 1d, C32H38FeO4P2, orthorbombic, Pbca, a = 15.947(6) angstrom, b = 20.009(3) angstrom, c = 15.470(4) angstrom, Z = 8.