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Complexes of silver(I), thallium(I),lead(II) and barium(II) withbis[3-(2-pyridyl)pyrazol-1-yl]phosphinate: one-dimensional helicalchains and discrete mononuclear complexes

Elefteria Psillakis, Jon A McCleverty, John C Jeffery, Michael D War

Πλήρης Εγγραφή

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Περίληψη

Reaction of 3-(2-pyridyl)pyrazole with POBr 3 in toluene–NEt 3 afforded not the expected tris(pyrazolyl)phosphine oxide but the partially hydrolysed compound bis[3-(2-pyridyl)pyrazol-1-yl]phosphinate (as its triethylammonium salt). This compound has two potentially chelating N,N′-bidentate arms linked by an apical PO 2 - group. Reaction with AgNO 3 , Tl(O 2 CMe), Pb(NO 3 ) 2 or Ba(NO 3 ) 2 in dry MeCN followed by recrystallisation afforded crystals of the complexes [AgL]·2H 2 O, [TlL]·MeOH, [PbL 2 ]·H 2 O and [(BaL 2 ) 3 ]·6MeCN·2H 2 O respectively, all of which have been crystallographically characterised. The compound [AgL]·2H 2 O contains infinite helical chains (AgL) ∞ in which each ligand donates one N,N′-bidentate arm to each of two metals and each metal ion is four-co-ordinated by two arms from different ligands. The strands are held together in the crystal by a complex network of hydrogen bonds involving lattice water molecules and also by aromatic π-stacking interactions. The compound [TlL]·MeOH is likewise a one-dimensional helical polymer of TlL units, with each ligand bridging two metals and each Tl ion in a ‘2 + 3’ co-ordination geometry with two short bonds to ligands (<2.71 Å) and three longer, weak bonds (>2.87 Å): there is an obvious gap in the co-ordination sphere due to a stereochemically active lone pair. A combination of interstrand aromatic π-stacking interactions and hydrogen-bonding interactions involving the lattice MeOH molecule is present.

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