Probing the reactivity of a 2,2′-bipyridyl-3,3′-bis-imine ligand by X-ray crystallography

Abstract

The reactivity of a Schiff-base bis-imine ligand 3 is probed by X-ray diffraction studies. Its susceptibility to hydrolysis, oxidation and nucleophilic addition reactions is demonstrated by the isolation of the methanol adduct 4 and two diazapene heterocycles 5 and 6. This reactivity is also reflected in the molecular structures of two coordination complexes isolated by the reaction of 3 with MIJhfac) 2 salts, to afford ijCuIJ5)-IJhfac)IJtfa)] (8) and ijZnIJ6)IJhfac) 2 ] (9).

3,3′-Di(pyrazinamoyl)-2,2′-bipyridine: rational ligand design for the self-assembly of a 1-D coordination polymer

“…10 A search of the CSD reveals close to 900 complexes of unsubstituted pyrazine ligands bridging two metal ions, forming discrete dinuclear 11 complexes, most famously the Creutz-Taube complex 11a and higher nuclearity 12 molecules, as well as coordination polymers that include 1-D chains, 13 2-D sheets 14 and 3-D networks. 15 Our long-term interest in the exploitation of bipyridine scaffolds to prepare and study new families of polydentate ligands [16][17][18][19][20] began with the coordination chemistry of 3,3′diamino-2,2′-bipyridine, 16 a ligand whose mode of chelation can be tuned by varying the pH of the reaction; additional binding sites have been introduced into this core framework in the form of 2-pyridyl bis-imine (L 1 H 2 ) 17 and bis-amide substituents (L 2 H 2 ). 18,19 The imine ligand is highly reactive in solution and susceptible to both hydrolysis and metal-catalysed rearrangements that render its coordination chemistry particularly challenging.…”