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Amidophosphine complexes of early and late transition elements

University of British Columbia

Expanding on the work of previously reported amidophosphine ligand frameworks, novel coordination chemistry and dinitrogen functionalization of transition metal complexes was pursued, utilizing both early and late transition-metals. A variety of group 5 (V, Nb, Ta) and group 9 (Co, Rh) amidophosphine complexes are described and characterized using NMR spectroscopy and X-ray crystallography. A tantalum dinitrogen complex containing a modified amidophosphine ligand was used to examine further functionalization of the dinitrogen unit. Hydrosilylation of the modified tantalum dinitrogen complex generated a novel dinitrogen-functionalized tantalum species. Dinitrogen functionalization of amidophosphine complexes of niobium and vanadium was explored via treatment with various electrophiles and oxidants. The formation of numerous paramagnetic niobium and vanadium complexes are described, although the desired outcome of producing oxidized dinitrogen species or cleavage and functionalization of the dinitrogen moiety was often challenged by loss of the dinitrogen unit entirely. Reactivity of a paramagnetic niobium dinitrogen complex with an oxygen-containing radical reagent resulted in generation of a novel diamagnetic niobium dinitrogen complex, incorporating a bridging oxo ligand and altered binding of the dinitrogen unit. Paramagnetic amidophosphine cobalt complexes were examined for reactivity, in relation to previously reported work with paramagnetic cobalt species, leading to formation of an oxidized-phosphine species and a cobalt iodide complex. Synthesis of cobalt alkyl complexes was accomplished via treatment of a cobalt iodide complex with alkyllithium and Grignard reagents. Attempts to generate a cobalt hydride complex yielded regeneration of the antecedent amidophosphine cobalt complex. The synthesis of diamagnetic amidophosphine complexes of rhodium was investigated and the reactivity of these novel rhodium complexes with alkyl halides and H2 was explored, in order to observe their ability to undergo oxidative addition. Several rhodium iodide and rhodium hydride species are described. Synthesis of rhodium carbonyl complexes was accomplished via ligand exchange using CO gas.

Text

2020-04-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/74129

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/