Molybdenum(V) on an oxide string. Synthesis and structure of the novel linear trinuclear complex {[MoO(TPP)][O-Mo(TPP)-O][MoO(TPP)]}Cl-4

The syntheses and crystallographic characterization of the linear trinuclea r complex [Mo3O4(TPP)(3)]ClO4 and the monomeric precursors [MoO(TPP)(OClO3) ] and [MoO(TPP)(OH2)]ClO4 an described. The crystallographic analyses of [M oO(TPP)(OClO3)] and [MoO(TPP)(OH2)]ClO4 show that these similar complexes a re typical oxomolybdenum(V)-porphyrin complexes whose only significant stru ctural differences are related to their respective axial ligands. [Mo3O4(TP P)(3)]ClO4 is obtained by the controlled hydrolysis of [MoO(TPP)(OClO3)] or by the direct reaction of [MoO(TPP)(OClO3)] with {[MoO(TPP)](2)O}. This hy drolysis product contains the novel [Mo3O4(TPP)(3)](+) ion, which has an un precedented linear [O=Mo-O-Mo-O-Mo=O](7+) unit and three nearly parallel 24 -atom porphyrin mean planes. The central porphyrin is found to be rotated 2 9.3 degrees and 29.7 degrees with respect to the two terminal porphyrin lig ands, which are nearly eclipsed (twist angle 0.44 degrees). The formation o f [Mo3O4(TPP)(3)]ClO4 instead of the mu-hydroxo-bridged binuclear complexes obtained from the hydrolysis of analogous mononuclear metalloporphyrin com plexes is rationalized on the basis of the greater pi-acceptor ability of M o(V). Crystal data for [MoO(TPP)(OClO3). 0.9CH(2)Cl(2): a = 11.437(2) Angst rom, b = 13.567(6) Angstrom, c = 13.764(4) Angstrom, alpha = 89.15(1)degree s, beta = 108.86(1)degrees, gamma = 103.96(2)degrees, triclinic, space grou p P (1) over bar, Z = 2, T = 293(2) K. Crystal data for [MoO(TPP)(OH2)ClO4. 1.5C(7)H(8): a = 13.2138(7) Angstrom, b = 13.5959(12) Angstrom, c = 14.667 6(11) Angstrom, alpha = 74.292(8)degrees, beta = 69.114(8)degrees, gamma = 69.030(5)degrees, triclinic, space group P (1) over bar, Z = 2, T = 127(2) K. Crystal data for [Mo3O4(TPP)(3)]ClO4. C6H14. 3.4CH(2)Cl(2). 4H(2)O: a = 26.428(6) Angstrom, b = 18.683(6) Angstrom, c = 28.697(4) Angstrom, beta = 113.98(2)degrees, monoclinic, space group P2(1)/c, Z = 4, T = 127(2) K.