Self assembly of asymmetric tetranuclear Cu(II) [2 × 2] grid-like complexes and of a dinuclear Ni(II) complex from pyridyl-phenol Schiff base ligands

Self assembly of N-salicylidene 2-aminopyridine (L1H) with Cu(NO3)2·3H2O affords [Cu4(L1)4(NO3)3(CH3OH)][Cu(L1)(NO3)2](2-aminopyridinium)(NO3)·5CH3OH (1) which is composed of an asymmetric [2 × 2] grid-like cationic complex that co-crystallizes with a Cu(II) mononuclear anion. This remarkable tetranuclear unit presents three penta-coordinated and one hexa-coordinated Cu(II) sites. This quadruple helicate structure reveals strong anti-ferromagnetic coupling (J = −340(2) cm−1) between Cu(II) ions through a double alkoxo bridge. Reacting L1H with Cu(NO3)2·3H2O in slightly different conditions affords however a more symmetric tetranuclear grid-like complex: [Cu4(L1)4(NO3)2(OH)2](2-aminopyridinium)(OH)·CH3OH) (2). A dinuclear Ni(II) complex, [Ni2(L2)2(L2H)2(NCS)2(CH3OH)2]·2CH3OH (3), obtained with another related donor ligand (L2H = N-salicylidene 3-aminomethylpyridine) was also prepared.

Self assembly of pyridyl-phenol Schiff base ligands affords asymmetric Cu(II) [2 × 2] grid-like complexes thanks to diverse coordination spheres, displaying also strong anti-ferromagnetic coupling through a double alkoxo bridge.Figure optionsDownload as PowerPoint slide