Synthesis and Characterization of a 1,2,4-Diazarsolide Anion

Cyclopentadienyl anions ([Cp]-) are pervasive ligands in coordination chemistry. In contrast, heavy-element derivatives of these ligands, particularly those that feature arsenic, are not as well developed. In this work, a new arsenic-based heterocycle with a structure analogous to [Cp]- is presented. Reaction of K3As7 with benzyl azide (BnN3) leads to fragmentation of the [As7]3- core and C-H activation of two [BnN] units to give the five-membered arsenic heterocycle [As(NC(Ph))2]-. This arsenic heterocycle was studied by nuclear magnetic resonance and UV-vis spectroscopy, X-ray diffraction, and its electronic structure was investigated computationally.