One-dimensional coordination polymers with phenyl-carbaborane anions:: Ag(I)/4,4′-bipyridine and 2,3-bis-(2-pyridyl)pyrazine complexes

A series of new silver/4,4'-bipyridine [Ag(I)/bpy] and silver/2,3-bis-(2-pyridyl)pyrazine [Ag(I)/bppz] crystalline complexes with the C-phenyl-carbaborane anion [PhCB9H9](-) and the halogenated C-phenyl-carbaborane (HPC) anions [PhCB9H8Br](-), [BrC6H4CB11H11](-), [PhCB9H4I5](-), and [PhCB11H5I6](-) has been prepared and characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction analysis. While {Ag(bppz)[PhCB9H8Br]} (6) has been isolated as a discrete dimeric complex, all the remaining complexes feature 1D polymeric coordination chains. Among these 1D coordination chains, only [Ag(bpy)][PhCB9H9](CH3CN) (1) and [Ag-2(bppz)(3)][BrC6H4CB11H11](2)(CH3CN) (5) exhibit structures where the carbaborane anions act as simple counteranions and thus are not involved directly in the coordination network. In all the other species, significant framework-construction interaction of the silver center with the {BH} or {BI} units of the carbaborane anions is observed. Interestingly, in complex {Ag(bppz)[PhCB9H9]} (CH3CN)(0.5) (4) the Ag(I) center has an octahedral geometry with two Ag center dot center dot center dot H-B interactions between the silver atom and phenyl-carbaborane anion. The influence of the carbaborane anions on the structural features of coordination chains is analyzed and discussed, and the preparation of the [NEt4](+) salts of the [PhCB9H8Br](-), [BrC6H4CB11H11](-), and [PhCB9H4I5](-) anions is also presented.