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 (HpzNO2)(HpzNO2) and 1:2 or 1:3 (Ag:HpzNO2)(Ag:HpzNO2) stoichiometries, [Ag(HpzNO2)2][BF4][Ag(HpzNO2)2][BF4], [Ag(HpzNO2)3][SbF6][Ag(HpzNO2)3][SbF6] and [Ag(HpzNO2)3][Ag(HpzNO2)3][PO2F2]·HpzNO2[PO2F2]·HpzNO2 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 View the MathML sourceAXn-as View the MathML sourceBF4-, View the MathML sourceSbF6- or View the MathML sourcePF6- (the latter one evolving to View the MathML sourcePO2F2-) were strategically selected to produce molecular assemblies established on the basis of hydrogen-bonds (N–H⋯X) and π⋯π or coordinative interactions involving the NO2 group. The complex [Ag(HpzNO2)2][BF4][Ag(HpzNO2)2][BF4] exhibited polymeric N–H⋯F hydrogen-bonded chains which were assembled in a 3D network by weaker coordinative Ag⋯O(NO2) and π(NO2)⋯π(NO2) interactions. In the complex [Ag(HpzNO2)3][SbF6][Ag(HpzNO2)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 View the MathML sourceSbF6- were encapsulated. By contrast, in the related complex [Ag(HpzNO2)3][Ag(HpzNO2)3][PO2F2]·HpzNO2[PO2F2]·HpzNO2 the presence of a fourth non-coordinated pyrazole HpzNO2HpzNO2 avoided the formation of a 3D network giving rise to a double-chained 1D structure.