Syntheses and molecular structures of Co3+–Na+ and Co3+–K+ coordination polymers constructed using mono- and bis-chelated cobalt(III) complexes of bis(2-pyridylcarbonyl)amide ion

Four new hetero-bimetallic Co3+–Na+ and Co3+–K+ coordination polymers having the molecular formulae [Na(H2O)Co(L)(N3)3]n (1), [Na2Co(L)(N3)3(H2O)5][Co(L)(N3)3] (2), K[Co(L)(NCS)3]·H2O (3) and K[Co(L)2][Co(NCS)4]·0.5H2O (4), were synthesized. Compounds 1–4 were characterized by single crystal X-ray diffraction, IR, UV–Vis, and thermogravimetric methods. These bimetallic systems have EE, EO azide bridge (1, 2) as well as bent (1, 2, 3) and linear (1, 4) aquo bridges. Important features observed among them were: a Z-shaped and diamond-shaped Co2Na2 clusters in 1, a centrosymmetric double ladder like polymer based on Na4 cluster in 2, and a linear KOK core having paddle-wheel structure in 4.