HYDROTRIS(3,5-DIMETHYLPYRAZOL-1-YL)BORATE CARBOXYLATE COMPLEXES OF URANIUM AND THORIUM - X-RAY CRYSTAL-STRUCTURE OF U(O2CCH3)3[HB(3,5-ME2PZ)3]

The complexes M(O2CR)3[HB(3,5-Me2Pz)3] (R = CH3 and Ph for M = U(IV) a nd R = CH3 for M = Th(IV)) were produced by reactions of MCl3[HB(3,5-M e2Pz)3](thf) with three equivalents of NaO2CR. The compounds MClCp(O2C R)[HB(3,5-Me2Pz)3], obtained by addition of the sodium carboxylates to MCl2Cp[HB(3,5-Me2Pz)3], are also reported. The complexes were charact erized by standard techniques and on the basis of IR data a bidentate, chelating and/or bridging mode for the carboxylate moieties is assign ed for all the complexes, except in the case of UClCp(O2CR)[HB(3,5-Me2 Pz)3] for which a monodentate bonding is assigned. The crystal and mol ecular structure of U(O2CCH3)3[HB(3,5-Me2Pz)3], determined by X-ray di ffraction, is also reported.