Electron Density-Matching Diamido Ligands to 1st Row Transition Metals: Coordination and Reactivity Trends

Amido-based ligands can employ a variable R-group which can be used to “tune” the steric and electronic properties of the resulting metal complex, targeting bond activation and catalytic applications. This thesis explored how the chelating diamido ligand {(tBuNSiMe2)2O}2- interacts with the early transition metals scandium(III), titanium(III) and vanadium(III), to discern how the number of d-electrons affects the coordination and reactivity of the complexes. The coordination motif is oxidation state-dependent, and structural differences are observed as the number of d-electrons changes. Alkylation yielded interesting results: the vanadium complex formed the dinitrogen species {[(tBuNSiMe2)2O]VR}2(μ-N2) (R = CH2SiMe3, CH2Ph), while scandium produced the expected complex, {[tBuNSiMe2]2O}ScCH2SiMe3•THF. Concurrently, a diamido ligand containing electron-withdrawing –CF3 groups, {[3,5-(CF3)2PhNSiMe2]2O}2-, was examined to probe how the altered electronic profile affects the overall coordination and reactivity of later transition metal iron(III) and cobalt(II) complexes. Unusual structural motifs indicated that this ligand warrants additional research.