Copper(II)-templated assembly of tetranuclear grid-like complexes from simple pyridine–pyrazole ligands

Reaction of Cu(O 2 CMe) 2 ·H 2 O with HL 1 [3-(2-pyridyl)pyrazole] or HL 2 [6-(3-pyrazolyl)-2,2′-bipyridine] and NH 4 PF 6 followed by crystallisation of the crude products from dmf–ether affords [Cu 4 L 1 6 (dmf) 2 ][PF 6 ] 2 1 and [Cu 4 L 2 4 (dmf) 4 ]- [PF 6 ] 4 2 respectively, in which the deprotonated pyrazolyl groups act as bridging ligands and the 2 × 2 grid–like architectures are a result of the preference of the Cu II ions for elongated square-pyramidal coordination geometries.