Preparation of the new podand ligand SP(pzpy) 3 [pzpy = 3-(2-pyridyl)-pyrazol-1-yl], and the syntheses and crystal structures of copper(II) and copper(I) complexes of its hydrolysis product [OSP(pzpy) 2] −, and a double helical copper(I) complex of [O 2P(pzpy) 2] −

Abstract

The new podand ligand SP(pzpy) 3 [L 1; pzypy = 3-(2-pyridyl)-pyrazol-1-yl], containing three bidentate pyrazolyl-pyridine arms linked to an apical PS group via the pyrazolyl N 1 atoms, was prepared and crystallographically characterised. Reaction with Cu(II) or Cu(I) resulted in complexes of the partially-hydrolysed ligand [OSP(pzpy) 2] − (L 2), containing two bidentate chelating arms linked by a thiophosphinate fragment. [Cu 2(L 2) 2(μ-pzpy) 2] contains a planar dinuclear copper(II) core with two pyrazolate bridges linking the metal centres, and one L 2 ligand attached to each metal by one bidentate arm with the other arm pendant. In [Cu 2(L 2) 2] each ligand L 2 acts as an N, N-donor to one metal ion and an N, S-donor to the other with a non-coordinated pyridyl group, such that each metal ion has an N 3 S donor set; this complex is achiral with a “side-by-side” disposition of bridging ligands. For comparison purposes we also crystallographically characterised [Cu 2(L 3) 2], where L 3 is [O 2P(pzpy) 2] −, an analogue of L 2 but with a phosphinate rather than thiophosphinate group. This complex is a dinuclear double helicate in which each ligand acts as an N, N-bidentate chelate to each metal ion. Comparison of this with the structure of [Cu 2(L 2) 2] shows that it is the involvement of the thiophosphinate S atom of L 2 in coordination that prevents helication from occurring.