Six-coordinate CoIII and four-coordinate MII (M = Co, Zn) mixed-valence dimers supported by a deprotonated pyridine amide ligand: magnetism of a CoIIICoII complex and C–H⋯O/Cl/Br interactions

Using a pyridine amide ligand 4-methyl-2-{N-(2-pyridyl)carbamoyl}pyridine (HL), in its deprotonated form, binuclear mixed-valence homonuclear bimetallic complexes [CoIII,II2(L)3(X)]X·S [X = Cl (1); X = Br, S = CH3OH (2)] and heteronuclear bimetallic complex [CoIIIZnII(L)3(Cl)]Cl·CH3OH·5H2O (3) have been synthesized. Structural analysis revealed that trivalent cobalt is in distorted octahedral and bivalent cobalt/zinc is in distorted tetrahedral environment. Three L(−) ligands provide six-coordination by utilizing three pyridine amide units (pyridine N and amide N donor set) in a facial mode, which in turn places three 4-methylpyridine nitrogens to coordinate to another metal center, which c…