Electronic structures of nickel(II)-bis(indanyloxazoline)-dihalide catalysts: Understanding ligand field contributions that promote C(sp2)–C(sp3) cross-coupling

21 June 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


NiII(IB) dihalide [IB = (3aR,3a'R,8aS,8a'S)-2,2'-(cyclopropane-1,1-diyl)bis(3a,8a-dihydro-8H-indeno[1,2-d]-oxazole)] complexes are representative of a growing class of first-row transition metal catalysts for the enantioselective reductive cross-coupling of C(sp2) and C(sp3) electrophiles. Recent mechanistic studies highlight the complexity of these ground state cross-couplings, but also illuminate new reactivity pathways stemming from one-electron redox and their significant sensitivities to reaction conditions. For the first time, a diverse array of spectroscopic methods coupled to electrochemistry has been applied to NiII-based pre-catalysts to evaluate specific ligand field effects governing key Ni-based redox potentials. We also experimentally demonstrate DMA solvent coordination to catalytically-relevant Ni complexes. Coordination is shown to favorably influence key redox-based reaction steps and prevent other deleterious Ni-based equilibria. Combined with electronic structure calculations, we further provide a direct correlation between reaction intermediate frontier molecular orbital energies and cross-coupling yields. Considerations developed herein demonstrate the use of synergic spectroscopic and electrochemical methods to provide concepts for catalyst ligand design and rationalization of reaction condition optimization.


frontier molecular orbitals

Supplementary materials

Supporting Information
Materials and methods, NMR spectra, additional UV-vis-NIR, CD, and MCD spectra, additional voltammetry and spectroelectrochemistry data, X-ray crystallographic parameters, and DFT and CASSCF/CASPT2 input parameters and results.


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