Sterically directed functionalization of the redox-active bis(imino)acenaphthene ligand class: an experimental and theoretical investigation.

The synthesis, characterization, and theoretical study of the sterically directed functionalization of the redox-active bis(imino)acenaphthene (BIAN) ligand class has been explored. With dependence on the steric congestion encompassing the N-C-C-N fragment of the Ar-BIAN ligand, functionalization can be directed to proceed either via a radical backbone dearomatization or a nucleophilic imine C-alkylation pathway. The structures of the Ar-BIAN derivatives 14-19 were determined by means of single-crystal X-ray diffraction. The reaction pathways involved in Ar-BIAN functionalization were monitored by means of EPR spectroscopy. The experimental results and observations were examined in conjunction with DFT-D calculations in order to explain the driving forces that direct the pathways leading to Ar-BIAN functionalization.