ELUCIDATION OF THE STRUCTURES OF THE HYDRIDOTHIOLATO COMPLEXES WH(SC6H2PR3I-2,4,6)(3)(L)(PME(2)PH), L=PME(2)PH OR PYRIDINE, BY NMR AND X-RAY TECHNIQUES

Measurement of the T-1 values of the P-31 nuclei in the unusual capped trigonal bipyramidal complexes WH(tipt)(3)(PMe(2)Ph)(2) (1, tipt = SC 6H2Pr3i-2,4,6) and W(H-2)(tipt)(3)(PMe(2)Ph)(2) allows the determinati on of the phosphorus-hydride distance of 2.2 +/- 0.2 Angstrom and the P-W-H angle of about 62 +/- 7 degrees. An approximate location of the hydride on an S2P face is proposed on the basis of steric interactions . The crystal structure of WH(tipt)(3)-(NC5H5)(PMe(2)Ph) (2) is report ed; the WS3NP core consists of a distorted trigonal bipyramidal system with the phosphine and pyridine ligands axial and the thiolate ligand s equatorial. The hydride ligand was not located by X-ray diffraction but can be positioned on an open S2P face at an angle P-W-H of about 6 5 degrees. The small P-W-H angle results in large (2)J(H,P) coupling f or 1 and 2. The H-1 NMR spectrum of complex 2 is assigned by use of NO E and homodecoupling NMR methods. This complex has the same crowded st ructure in solution as in the crystalline state. The pyridine ligand, which is sandwiched between two tipt aryl groups, is hindered from rot ating around the W-N bond.