Influence of electronic factors on the structure and stability of uranium compounds. Tri-tert-butyl methoxide uranium(IV) complexes

Article abstract of DOI:10.1016/0022-328X(91)83281-8

The complexes (tritox)UCl3(THF)x (I) and (tritox)2UCl2(THF)2 (II) (tritox=^tBu3CO, THF=tetrahydrofuran) have been prepared by treating UCl4 with (tritox)Li.Compound II was a precursor for a series of (tritox)2UX2 compounds (X=BH4, CH3COCHCOCH3, η-C3H5, CH2Ph).The uranium borohydride derivative (tritox)U(BH4)3(THF) (IX) was isolated from the reaction of U(BH4)4(THF)2 with (tritox)H and was successively transformed into (tritox)2U(BH4)2 (IV) and (tritox)3U(BH4) (XI) by treatment with (tritox)Li.The crystal structures of the trigonal bipyramidal compound IX and thepseudo tetrahedral complex XI provide clear evidence of the strong O?->U contribution to the metal-oxygen bonds.The structure and stability of these tritox compounds are quite different from those of the isosteric cylopentadienyl analogues, and reveal the determining role of the electronic factors.