TECHNETIUM(III) COMPLEXES WITH THE TETRADENTATE UMBRELLA LIGAND TRIS(O-MERCAPTOPHENYL)PHOSPHINATE - X-RAY STRUCTURAL CHARACTERIZATION OF TC(P(O-C6H4S)3)(CNC3H7) AND TC(P(O-C6H4S)3)(CNC3H7)2

Tris(o-mercaptophenyl)phosphinate (PS3) binds to Tc(III) as a tetradentate ligand to form the formally 14-electron complex Tc(PS3)(CNMe). An X-ray single-crystal structure determination of the isopropyl isocyanide derivative Tc(PS3)(CN-i-Pr) shows that the complex has a trigonal-bipyramidal geometry with the phosphorus and isonitrile carbon in the axial positions and the sulfurs bound in the equatorial plane (crystal data: MF = C22H19NPS3Tc, monoclinic, a = 10.3541 (8) angstrom, b = 13.2274 (6) angstrom, c = 16.437 (1) angstrom, beta = 90.855 (6)-degrees, space group P2(1)/c, Z = 4; final R = 0.049, R(w) = 0.057). In the presence of a large excess of isonitrile, these electron-deficient complexes bind a sixth ligand. The six-coordinate complex Tc(PS3)(CN-i-Pr)2, was also structurally characterized (crystal data: MF = C26H26N2PS3Tc, orthorhombic, a = 18.896 (1) angstrom, b = 13.2815 (8) angstrom, c = 10.3823 (6) angstrom, space group Pna2(1), Z = 4; final R = 0.044, R(w) = 0.048).