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Updated: Jun 18, 2026
Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Synthesis and Reactivity of Heteroleptic U4+ Alkyl, Benzyl, and Hydride Imidophosphorane Complexes
Haruko Tateyama1, Maximilian G Bernbeck1, Tyler-Rayne Nero1
1School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.
Abstract:
A series of heteroleptic U4+ benzyl, neopentyl, and methyl complexes supported by the imidophosphorane ligand, [N = P(N,N'-ditert-butylethylenediamide)(diethylamide)]1- (NP*), were synthesized from the monoiodide precursor, [UI(NP*)3]. These heteroleptic complexes were synthesized through the selective formation of [UI(NP*)3] under transmetalation conditions in the reaction between [UI4(1,4-dioxane)2] and K[NP*]. Formation of the homoleptic complex [U(NP*)4] was not observed even in the presence of excess K[NP*]. The oxidation and hydrogenolysis reactivity of the neopentyl complex, [U(Npt)(NP*)3] (Npt = neopentyl) was explored. While cyclic voltammetry indicates a potentially isolable U5+ alkyl cation, chemical oxidation of the neopentyl complex results in the isolation of a cationic U4+ complex with a bound diethyl ether in the primary coordination sphere, [U4+(NP*))3(Et2O)][(BArF24)] (BArF24 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate). Notably, hydrogenolysis of [U(Npt)(NP*)3] with H2 gas at -20 °C results in the formation of a terminal hydride intermediate confirmed by in situ NMR spectroscopy and deuterium labeling with D2. The connectivity and structural parameters of this hydride intermediate, [UH(NP*)3], which rapidly thermally decomposes to the homoleptic complex, [U(NP*)4], can be confirmed by single-crystal X-ray diffraction studies of a crystal grown by chilling the reaction mixture. The identity of [U(NP*)4] was confirmed by its direct, bulk synthesis from [U(Me)(NP*)3] and HNP* in a protonolysis reaction.
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