Synthesis of hexacarbonyl derivatives of group 5 metals and electron-transfer processes. Crystal and molecular structure of tetracarbonyl(1,2-bis(diphenylphosphino)ethane)iodotantalum

Article abstract of DOI:10.1021/om00095a011

Vanadium, niobium, and tantalum hexacarbonylmetalate(-I) derivatives of several heterocyclic nitrogen bases, R_nB[M(CO)₆]_n (R = H, Me; n = 1, 2), have been synthesized. In some cases an electron transfer from the hexacarbonylmetalate to the protonated or methylated BR_nⁿ⁺ cation has been observed. Pyridinium halides react with Na[M(CO)₆] (M = Nb, Ta) in the presence of 1 equiv of 1,2-bis(diphenylphosphino)ethane (diphos) to give high yields of the halo tetracarbonyl derivatives MX(CO)₄(diphos). The red-orange TaI(CO)₄(diphos) complex has been studied by X-ray diffraction methods. Crystal data: space group P2₁/n; M_r 818.3; a = 14.864 (10) ?, b = 9.875 (7) ?, c = 19.335 (13) ?; β = 105.61 (2)°; U = 2733 (3) ?³; Z = 4; D_calcd = 1.988 g cm^-3; F(000) = 1568; μ(Mo Kα) = 52.4 cm^-1. The geometry of the seven-coordinate tantalum atom is best described as a capped trigonal prism with the iodide ligand in the capping position. By reaction of Na[Ta(CO)₆] with 1 equiv of hydrogen chloride and diphos in toluene, the hydride TaH(CO)₄(diphos) has been isolated in good yield.