Synthesis and experimental electron density of bis(heterocyclic) azines: The case of 6,6 '-bis(chloromethyl)-2,2 '-bipyrazine

The synthesis and reactivity of mono- and bis(chloromethyl)-2,2'-bipyrazine s toward nucleophiles are reported. The reactivity of the bipyrazine ring i s explained in terms of allylic substitution and rearrangement mechanisms. A new family of monofunctionalized bipyrazine derivatives as molecular buil ding blocks for supermolecules has been obtained, opening access to unsymme trical ligands. The low-temperature crystallographic structure and the expe rimental electron density distribution of 6,6'-bis(chloromethyl)-2,2'-bipyr azine have been determined on the basis of high-resolution X-ray diffractio n data. The electron density of the molecule has been accurately analyzed u sing the topological properties of its gradient and Laplacian features. The reactivity of these bidentate molecules in metal complexation is related t o the shape of the atomic basins and may be explained in terms of a key/loc k-type interaction. The results are compared with corresponding data for 2, 2'-dimethyl-6,6'-diphenyl-4,4'-bipyrimidine.