Study on the intermolecular interactions of alkylcobaloxime complexes (RCo(dmgH)2L, dmgH=dimethylglyoxime, R=alkyl, L=H2O or pyridine)

A series of alkylcobaloxime complexes, [RCo(dmgH)2L, where dmgH=dimethylglyoxime, R=alkyl, L=neutral monodentate axial ligand], i.e. (EtO2C)2C(Me)CH2Co(dmgH)2H2O(1), n-C5H11Co(dmgH)2H2O(2), Br(CH2)4Co(dmgH)2py(3) and Br(CH2)4Co(dmgH)2H2O(4), have been synthesized and characterized. Analysis and comparison of their crystal packing structures with that of our previous reported complexes, COOCH3(CH2)2Co(dmgH)2H2O(5) and c-C6H11Co(dmgH)2H2O(6), disclose that one-dimensional ribbon-like zigzag hydrogen bonded networks in 1, 2 and 4 are sustained and controlled by self-assembly between dimethylglyoxime and coordinated water through O–H⋯O− interactions. And the further formation of different types of hydrogen bond linkages with the variation of the axial groups leads to creation of special 2D or 3D architectures. However, the crystal packing structure of 5 and 6 are absolutely different from 1, 2 and 4 due to conformational isomerism effect. Additionally, different types of the protons attachment at O–H⋯O− bridge are observed in 3 and 4, respectively, which is favorable to the intermolecular interactions.