SYNTHESES AND STRUCTURAL CHARACTERIZATIONS OF 6-COORDINATE OXO-M(V) COMPLEXES (M=TC, RE) CONTAINING A TETRADENTATE P2N2-PHOSPHINO-AMIDO LIGAND

Reaction of the potentially tetradentate ligand N,N'-bis[2-(diphenylphosphino)phenyl]propane-1,3-diamine (H(2)dppd) with [MO(4)](-) (M = Tc, Re) (via reduction-substitution) or [ReOCl4](-) (via ligand-exchange) produces neutral and stable six-coordinate oxo-M(V) complexes of the type [TcO(dppd)X] (X = Cl (1), OH (2), OMe (3), Oft (4), O2CCF3 (5)) and [ReO(dppd)X] (X = Cl (6), OH (7), OMe (8), OEt(9), O2CCF3 (10)). The P2N2 donor atoms of dppd coordinate in the equatorial plane orthogonal to the M = O linkage; a mononegative unidentate nucleophile completes the distorted octahedral geometry. Compound 3 crystallizes in the monoclinic space group P2(1)/m with cell constants a = 9.157(2) Angstrom, b = 20.391(3) Angstrom, c = 9.948(1) Angstrom, beta = 114.76(1)degrees, and Z = 2. Refinement of 3224 observed reflections and 221 parameters yields R = 0.033 and R(W) = 0.041. Compound 8 crystallizes in the monoclinic space group P2(1)/m with cell constants a = 9.175(1) Angstrom, b = 20.415(3) Angstrom, c = 9.946(2) Angstrom, beta = 114.84(1)degrees, and Z = 2. Refinement of 2176 observed reflections and 221 parameters yields R = 0.053 and R(W) = 0.062. Compound 10 crystallizes in the monoclinic space group P2(1)/c with cell constants a = 12.866(3) Angstrom, b = 31.416(6) Angstrom, c = 9.729(2) Angstrom, beta = 111.53(3)degrees, and Z = 4. The refinement converges to a conventional R of 0.030 and R(W) of 0.043 for 3070 observations with 350 parameters.