Synthesis and characterization of covalent organometallic tetrahydroborates and bis-cyclopentadienyl uranium(IV) complexes

Attempts to prepare (C5H5)2UCl2 from UCl4 and Tl(C5H5) in various solvents are described. The known compound (C5H5)3UCl always resulted as one of the products in these reactions. Solvents studied include DME, toluene, and tetrahydrofuran. The preparation of CH2(C5H4)2UCl2 . THF and (CH3)2 Si(C5H4)2UCl2 . THF as models for (C5H5)2UCl2 is also described. Vibrational spectroscopy was used to distinguish between monodentate, bidentate, and tridentate hydrogen-bridged metal-BH4 interactions for covalent organo-transition metal and actinide tetrahydroborates. The metals studied include V, Nb, Ti, Hf, Zr and Ta. The characterization of the compounds was performed by ir and NMR