Crystal and molecular structure and ESR spectra of the 1:1 salt 5-(1-butyl)phenazinium (NBP)-2,2′-(2,3,5,6-tetrafluoro-2,5- cyclohexadiene-1,4-diylidene)-bispropanedinitrile (TCNQF4)

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Abstract
The title compound C28H17F4N6, Mr=513.48, crystallizes in the monoclinic space group P21/c, with a=10.972(2) Å, b=17.557(3) Å, c=13.523(4) Å, β=111.88(2)°, V=2417.36 Å3, z=4, and dc=1.411 Mg m−3. Final refinement yielded residuals of R=0.056 and Rw=0.046. The structure consists of (NBP+)2 and (TCNQF−4)2 dimers stacked in a DDAA sequence along the c axis. The NBP+ and TCNQF−4 ions are planar, with interplanar distances of 3.54(2) Å for a donor pair and 3.15(3) Å for an acceptor pair. The angle between the NBP+ and TCNQF−4 planes is 15.8°. In the ESR experiments, two equivalent species of thermally activated Frenkel triplet spin excitons (TSE), with differently oriented fine structure tensors, are observed. They are located on two TCNQF4 molecular pairs of different orientation. A motion of the TSE in the b direction can be excluded. Additional S=1/2 lines are due to immobile doublet spins on TCNQF−4 radical ions.

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