Consecutive introduction of Ag(i) to an anionic homoleptic Co(iii) complex: variable Ag(i) coordination mode

Abstract

Although the pyridine-2,6-diamide ligand is widely reported, coordination chemistry of the analogous pyrazine-2,6-diamide ligand has not been reported to date. To study the complexation behavior, we have synthesized N,N′-dibenzylpyrazine-2,6-dicarboxamide and the heterometallic complexes were in a stepwise manner. After dimerisation with Co(III) complexation, two ring nitrogen atoms are freely available. These two free pyrazine nitrogen atoms were studied for their coordination with Ag(I), resulting in three heterometallic complexes, C₄₀H₃₄AgCoN₈O₅, C₄₂H₃₈Ag₃CoN₁₀O₁₁ and C₄₂H₅₃AgCoN₉O₁₃. The mode of coordination could be controlled by varying the metal to ligand ratio and varying the counter anion. Moreover, we found conditions that make the ligand to either coordinate or not coordinate to Ag⁺. Some of these complexes also display the rare organometallic (C–Ag) bond.