The 3,5-dimethyl-4-nitropyrazole ligand in the construction of supramolecular networks of silver(I) complexes

Three new ionic silver complexes based on the 3,5-dimethyl-4-nitropyrazole ligand (Hpz(NO2)) and 1:2 or 1:3 (Ag: Hpz(NO2)) stoichiometries, [Ag(HPZ(NO2))2][BF4], [Ag(Hpz(NO2) )(3)] [SbF6] and [Ag(Hpz(NO2))(3)] [PO2F2] center dot Hpz(NO2) have been prepared and structurally characterised. The linear or trigonal metallic coordination environment, the NO2 groups on the pyrazole ligand as well as the presence of counteranions of the type AX(n)(-)as BF4-1 SbF6- or PF6- (the latter one evolving to PO2F2-) were strategically selected to produce molecular assemblies established on the basis of hydrogen-bonds (N-H center dot center dot center dot X) and pi center dot center dot center dot pi or coordinative interactions involving the NO2 group. The complex [Ag(Hpz(NO2))(2)] [BF4] exhibited polymeric N-H center dot center dot center dot F hydrogen-bonded chains which were assembled in a 3D network by weaker coordinative Ag center dot center dot center dot O(NO2) and pi(NO2)center dot center dot center dot Tu(NO2) interactions. In the complex [Ag(Hpz(NO2))(3)] [SbF6], consistent with the three-coordinated molecular environment, the interactions were extended to give rise an open 3D cationic sub-network in which the counteranions SbF6- were encapsulated. By contrast, in the related complex [Ag(Hpz NO2),] [PO2F2] - Hpz(NO2) the presence of a fourth non-coordinated pyrazole Hpz(NO2) avoided the formation of a 3D network giving rise to a double-chained ID structure. (c) 2007 Elsevier B.V. All rights reserved.