Impact of variations in design of flexible bitopic bis(pyrazolyl)methane ligands and counterions on the structures of silver(I) complexes: dominance of cyclic dimeric architecture.

The new ligands 1,1,4,4-tetra(1-pyrazolyl)butane [CH(pz)(2)(CH(2))(2)CH(pz)(2), L2] and 1,1,5,5-tetra(1-pyrazolyl)pentane [CH(pz)(2)(CH(2))(3)CH(pz)(2), L3] have been prepared to determine the structural changes in silver(I) complexes, if any, that accompany the lengthening of the spacer group between two linked bis(pyrazolyl)methane units. Silver(I) complexes of both ligands with BF(4)(-) and SO(3)CF(3)(-) as the counterion have the formula [Ag(2)(micro-L)(2)](counterion)(2). These complexes have a cyclic dimeric structure in the solid state previously observed with the shorter linked ligand CH(pz)(2)CH(2)CH(pz)(2). Similar chemistry starting with AgNO(3) for L2 yields a complex of the empirical formula [Ag(2)[micro-CH(pz)(2)(CH(2))(2)CH(pz)(2)](3)](NO(3))(2) that retains the cyclic dimeric structure, but bonding of an additional ligand creates a coordination polymer of the cyclic dimers. In contrast, coordination of the nitrate counterion to silver in the complex of L3 leads to the formation of the coordination polymer of the empirical formula [Ag(micro-CH(pz)(2)(CH(2))(3)CH(pz)(2))]NO(3). All six new complexes have extended supramolecular structures based on noncovalent interactions supported by the counterions and the functional groups designed into the ligands.