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.