BIS[HYDROTRIS(PYRAZOLYL)BORATE] THORIUM(IV) COMPLEXES - SYNTHESIS AND CHARACTERIZATION OF ALKYL, THIOLATE, ALKOXIDE AND ARYLOXIDE DERIVATIVES AND THE X-RAY CRYSTAL-STRUCTURE OF TH(HBPZ3)2(OPH)2

The complexes Th(HBPz3)2XnCl2-n (where PZ = pyrazolyl, X = OPr(i), OBu(t), OPh, OPh-2,3,5-Me3, OPh-2,4,6-Me3 for n = 1 or 2 and X = CH2SiMe3, SBu(t) for n = 2) have been prepared by reaction of Th(HBPz3)2Cl2 with the appropriate MX reagent (M = Na or Li for X = CH2SiMe3) and were characterized by C, H, N elemental analysis, IR and H-1 NMR spectroscopies and in the case of Th(HBPZ3)2(OPh)2, by single crystal X-ray diffraction. The coordination polyhedron around the thorium is square antiprismatic. distorted towards dodecahedral. Variable temperature H-1 NMR studies of the complexes in solution revealed that they are fluxional, probably due to a facile interconversion of the common eight-coordinate polyhedra; these H-1 NMR studies also showed hindered rotation of the bulky OPh-2,4,6-Me3 groups in the complexes containing these ligands.