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 [O2P(PZPY)(2)](-)

The new podand ligand S=P(pzpy)(3) [L-1; pzpy = 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 crysta llographically characterised. Reaction with Cu(II) or Cu(I) resulted i n complexes of the partially-hydrolysed ligand [OSP(pzpy)(2)](-)(L-2), containing two bidentate chelating arms linked by a thiophosphinate f ragment. [Cu-2(L-2)(2)(mu-pzpy)(2)] contains a planar dinuclear copper (II) core with two pyrazolate bridges linking the metal centres, and o ne L-2 ligand attached to each metal by one bidentate arm with the oth er 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 N3S donor set, this co mplex is achiral with a ''side-by-side'' disposition of bridging ligan ds. For comparison purposes we also crystallographically characterised [Cu-2(L-3)(2)], where L-3 is [O2P(pzpy)(2)](-), an analogue of L-2 bu t with a phosphinate rather than thiophosphinate group. This complex i s a dinuclear double helicate in which each ligand acts as an N,N-bide ntate 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 thiophosphi nate S atom of L-2 in coordination that prevents helication from occur ring. (C) 1998 Elsevier Science Ltd. All rights reserved.