8-purinyl versus 2-benzimidazolyl carbanions: charge demands of the heterocycles and ligand properties of the bis(heteroaryl)methanes

The characterization of two new purinyl derivatives, 8-benzyl-7methylpurine and bis(7-methylpurin-8-y)methane, was performed and their corresponding carbanions examined in DMSO. The C NMR spectrum reveals the presence of the carbanions of both purinyl derivatives as a mixture of geometric isomers, a conseqence of the high double-bond character along the bond linking the carbanionic carbon to C(8) of the purinyl ring. Results indicate that bis(7-methylpurin-8-yl)methane reacts with metal acetates to produce neutral methanates.