Synthesis and characterization of uranium(III) compounds supported by the hydrotris(3,5-dimethyl-pyrazolyl)borate ligand: Crystal structures of [U(Tp Me2) 2(X)] complexes (X = OC 6H 2-2,4,6-Me 3, dmpz, Cl)

Abstract

Reaction of [U(Tp Me2) 2(NR 2)] (R = Ph, SiMe 3) with protic substrates such as 2,4,6-trimethylphenol (HOC 6H 2-2,4,6-Me 3), 3,5-dimethylpyrazole (Hdmpz), 2-mercaptopyridine (HSC 5H 4N) and phenylacetylene (HCCPh) afforded the corresponding [U(Tp Me2) 2(OAr)] (Ar = C 6H 2-2,4,6-Me 3) ( 1), [U(Tp Me2) 2(dmpz)] ( 2), [U(Tp Me2) 2(η 2-SC 5H 4N)] ( 3), and [U(Tp Me2) 2(CCPh)] ( 4) compounds. Reaction of [U(Tp Me2) 2(NR 2)] with Me 3SnCl or Me 3SiBr gave [U(Tp Me2) 2Cl] ( 5) and [U(Tp Me2) 2Br] ( 6), respectively, in high yield. The amido precursors failed to react with cyclopentadiene, but metathesis of [U(Tp Me2) 2I] with NaCp yielded [U(κ 3-Tp Me2)(κ 2-Tp Me2)(η 5-Cp)] ( 7). Thermolysis of 7 resulted in oxidation of the metal centre and redistribution of the ligands, giving [UCp 3(dmpz)] ( 8), pyrazabole ( 9) and [U(Tp Me2)(dmpz) 3] ( 10). The complexes have been fully characterized by spectroscopic methods and the structures of 1, 2, and 5 were confirmed by X-ray crystallographic studies. In the solid state the complexes exhibit distorted pentagonal bipyramidal geometries.