Synthesis and structure of uranium(III) complexes with dihydrobis(pyrazolyl)borates

Abstract

The synthesis of the novel uranium(III) complexes [UI₂{H₂B(3^tBu,5Me-pz)₂}(THF)₂] 1, [UI₂{H₂B(3^tBu,5Me-pz)₂}(OPPh₃)₂] 2 (3^tBu,5Me-pz = 3-tert-butyl-5-methylpyrazolyl) and [U{Ph₂B(pz)₂}₃] 3 are reported. The molecular structures have been determined by single crystal X-ray diffraction. In monomeric complexes 1 and 2 the U^III is seven-co-ordinated by the two pyrazolyl nitrogens, the two iodides and two oxygen atoms of the neutral ligands and by an agostic B–H· · ·U interaction. In monomeric 3 the uranium is six-co-ordinated by the nitrogen atoms of the chelating Ph₂B(pz)₂ ligands which are arranged in a trigonal prismatic geometry around the uranium.