Elements of the Crystal Structure of a Solvated 1:1 Charge-Transfer Salt Derived from Tetrathiafulvalene (TTF) and Tetrafluorotetracyano-p-Quinodimethane (TCNQF4), TTF-TCNQF4

The 1:1 charge-transfer salt TTF-TCNQF4 crystallizes (from cyclohexane/acetonitrile) in the monoclinic system, space group P2/m, with a = 16.562(4) Å, b = 10.728(4) Å, c = 7.013(1) Å, β = 97.39(2)°, V = 1235.6 Å3. A structural solution has been obtained by Patterson-Fourier methods and refined (based on 2107 non-zero F 0's) to an R value of 0.18. The crystal structure of solvated TTF-TCNQF4 consists of segregated stacks of donors and acceptors propagating along the c axis. Parallel to these columnar arrays are solvent channels of unresolved composition. Disorder within these solvent channels prevents a detailed description of their contents; the basic elements of the donor and acceptor stacks are, however, well-defined. The TCNQF4 acceptor column is both distance and overlap modulated (eclipsed, dimeric interaction at a mean separation of 3.25 Å, and ring-over-bond, monomeric interaction at 3.43 Å). The TTF donor column shows analogous eclipsed and ring-over-bond overlap patterns; however, the distance alternation (3.49 Å and 3.51 Å, respectively) is within experimental error (±0.02 Å in each case).