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The new podand ligand SP(pzpy)3 [L1; pzypy = 3-(2-pyridyl)-pyrazol-1-yl], containing three bidentate pyrazolyl-pyridine arms linked to an apical PS group via the pyrazolyl N1 atoms, was prepared and crystallographically characterised. Reaction with Cu(II) or Cu(I) resulted in complexes of the partially-hydrolysed ligand [OSP(pzpy)2]− (L2), containing two bidentate chelating arms linked by a thiophosphinate fragment. [Cu2(L2)2(μ-pzpy)2] contains a planar dinuclear copper(II) core with two pyrazolate bridges linking the metal centres, and one L2 ligand attached to each metal by one bidentate arm with the other arm pendant. In [Cu2(L2)2] each ligand L2 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 complex is achiral with a “side-by-side” disposition of bridging ligands. For comparison purposes we also crystallographically characterised [Cu2(L3)2], where L3 is [O2P(pzpy)2]−, an analogue of L2 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 [Cu2(L2)2] shows that it is the involvement of the thiophosphinate S atom of L2 in coordination that prevents helication from occurring. |
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