4,4'-bis(2-picolinimino)-2,2'-bibenzimidazoles: a new class of dinucleating ligands which allow for a tuning of the metal-metal distance. Structure and properties of a dicopper(II) complex and of two oxygenation products of a dicopper(I) complex: a tentative coordination chemical modeling of hemocyanin

The 4,4'-bis(2-picolinimino)-2,2'-bibenzimidazoles (L) are synthesized from 1,1'-disubstituted 4,4'-diamino-2,2'-bibenzimidazoles and 2-pyridinecarboxaldehyde as models for type 3 sites of hemocyanin and tyrosinase. Tuning of metal-metal distance occurs through polymethylene bridge in the ligand's backbone. The resulting complex exhibits an open conformation with distinct (4 + 2) copper coordination. Two oxygenation products dicopper complexes, Cu(II)4(H2(L3)O2(super 2-))2(ClO4)4 and (Cu(I)2(L3')2)(ClO4)2 are synthesized and the structures are analyzed.