Synthesis and structural characterisation of a Co(II) coordination polymer incorporating a novel dicarboxy-Trogers base/bis-pyrazole mixed ligand system

Abstract: A cobalt(II) coordination polymer, [Co(L1)(H(2)L2)]center dot 2.5H(2)O, 1, has been prepared via the hydrothermal reaction of cobalt(II) chloride with the novel dicarboxy-Troger s base ligand 2,8-dicarboxy-6H,12H-5,11-methano-dibenzo[b,f][1,5]diazocine, H(2)L1, and the bis-pyrazole ligand 4,4 -methylenebis-(3,5-dimethylpyrazole),H(2)L2. The structure of 1 contains 2D (4,4) networks showing 2D -> 3D parallel interpenetration, whereby adjacent 2D sheets interlock through the apertures defined by the cleft-like Troger s base ligand, to realise an overall 3D entanglement. The interlocking also forms one-dimensional solvent filled channels which are easily disturbed on drying resulting in framework collapse. The crystal structure of H(2)L1 is also reported, and represents a rare example of homochiral hydrogen bonded [6,4] dia networks interpenetrated by their enantiomeric partner frameworks.