COORDINATION CHEMISTRY OF A TRIPODAL S2ON LIGAND - SYNTHESES, STRUCTURES, AND REACTIVITY OF THE MOLYBDENUM(VI) AND NICKEL(II) COMPLEXES OF BIS(2-MERCAPTOETHYL)-2-AMINO-4-METHYLPHENOL (H(3)BTAP) AND COMPARISON TO (VO)-O-V(BTAP)

The tripodal tetradentate ligand H(3)btap coordinates to V-V, Mo-VI, a nd Ni-II via three different bonding modes to yield three complexes wi th unique ligand-based oxidation chemistry. For V-V and Mo-VI (1), all four of the heteroatom donors are coordinated to the metal ion formin g a trigonal bipyramidal complex with the oxovanadium(V) ion, (VO3+)-O -V, and an octahedral complex with the cis-dioxomolybdenum(VI) ion, [M oO2](2+). Only three of the heteroatom donors of H(3)btap are used to coordinate to Ni-II (2), two thiolate sulfurs and the amine nitrogen, yielding a dimeric structure in which each nickel(II) ion has NS3 coor dination. The ability of (VO)-O-V(btap) to form eta(2)-sulfenates, whi le [MoO2(btap)](-) does not form stable eta(2)-sulfenates, has been as cribed to the electron-deficient, pi-accepting nature of (VO3+)-O-V re lative to [(MoO2)-O-VI](2+). Crystal data for 1 (C11H16NO4S2KMo): spac e group Pbcn, a = 6.6596(9) Angstrom, b = 13.7446(9) Angstrom, c = 32. 992(2) Angstrom, alpha = beta = gamma = 90 degrees, Z = 8. Crystal dat a for 2 (C24H38N2O4S4Ni): space group Pbcn, a 12.0841(3) Angstrom, b = 14.4948(4) Angstrom, c = 16.7751(4) Angstrom, alpha = beta = gamma = 90 degrees, Z = 4.