Affiliation: | a CIPM, Universidad de Sonora, Apartado Postal 130, Hermosillo, Sonora, Mexico b Department of Chemistry, University of Arizona, Tuczon, AZ 85721, USA |
Abstract: | Reactions between 1,1′-dibenzyl-4,4′-bipyridinium(2+) (benzylviologen, BzV) chloride and cyanocuprates(I) gave two charge-transfer complexes having different colors: dark brown (BzV)3Cu9(CN)15·H2O and light brown (BzV)Cu(CN)3·2H2O. An X-ray crystal analysis of the former compound showed that nine crystallographically nonequivalent Cu atoms form three kinds of triad ---Cu---(CN)---Cu--- screws, which are linked by CN groups resulting in a unique three-dimensional network structure. Three of the nine Cu atoms have distorted tetrahedral (td) coordination geometries while the others have triangular plane (tp) geometries. Each screw consists of a (-tp-td-tp-)n array. There are three crystallographically nonequivalent viologen molecules. Certain CuCN moieties are located above a viologen ring or by the side of a viologen ring, with close interatomic contacts. These close contacts are characteristic of the charge-transfer complex and are responsible for the deep color of the complex. |