PtS-Related {[CuI(F4TCNQII-)]-}∞ Networks

A series of compounds of composition A[Cu-I(F-4-TCNQ(II-))] (A = a quaternary ammonium or phosphonium cation, F(4)TCNQ(II-) = the dianionic form of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) have been synthesized and structurally characterized. In each structure, an anionic [Cu-I(F(4)TCNQ(II-))](-) framework possessing the topology of PtS is formed with the Cu(I) center serving as a tetrahedral 4-connecting center and the F(4)TCNQ(2-) anion acting as a planar 4-connecting unit Although a PtS topology is observed for six different compounds, the anionic framework shows significant geometric variation depending upon the identity of the cation. Very similar structures are obtained when the organic cation is NMe4+, NMe2Pr2+, or NMe2Bu2+. A distorted anionic structure possessing the same connectivity is generated when the cation is NEt4+, and anionic frameworks with a different connectivity, but still related to PtS, are obtained when the much larger quaternary phosphonium cations are employed. Of interest in the structures containing quaternary phosphonium cations are pi-stacking interactions involving phenyl groups of the cation and F(4)TCNQ(2-) ligands. These face-to-face interactions between the electron-rich F(4)TCNQ(2-) ligands and a phenyl group of the cation appear to be responsible for the color exhibited by these compounds.