Novel C-H···C contacts involving 3,5-dimethylpyrazole ligands in a tetracoordinate Co(II) complex.

A violet-blue cobalt(II) complex [Co(4-nbz)(2)(DMP)(2)] (1), where 4-nbz = 4-nitrobenzoate and DMP = 3,5-dimethylpyrazole, has been prepared at room temperature. Crystallographic studies on 1·0.5H(2)O reveal that the molecules of 1 are linked by a variety of non-covalent bonds including a novel type of C-H···C contact forming, with assistance from N-H···O, C-H···O and C-H···π interactions, an intricate 3-D supramolecular network. Theoretical calculations suggest that the observed C-H···C interactions are energetically quite significant. This journal is © The Royal Society of Chemistry 2011