New Tetrathiapentalene-Derived Charge Transfer Salts with Paramagnetic Transition Metal Complex Anion: <i>κ</i>-(EDDH-TTP)<sub>3</sub>[Cr(phen)(NCS)<sub>4</sub>]·2CH<sub>2</sub>Cl<sub>2</sub> and <i>κ</i><sub>21</sub>-(BDH-TTP)<sub>5</sub>[Cr(phen)(NCS)<sub>4</sub>]<sub>2</sub>·2CH<sub>2</sub>Cl<sub>2</sub>
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The preparation, crystal structures, and optical and magnetic properties of two new charge-transfer salts κ-(EDDH-TTP)3[Cr(phen)(NCS)4]·2CH2Cl2 (1) and κ21-(BDH-TTP)5[Cr(phen)(NCS)4]2·2CH2Cl2 (2), where phen = 1,10- phenanthroline, EDDH-TTP = 2-(4,5-ethylenedithio-1,3-dithiol-2-ylidene)-5-(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene, and BDH-TTP = 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene, are reported. Crystal data: (1) monoclinic P21/a, a = 25.0752(5) Å, b = 10.6732(3) Å, c = 28.1601(6) Å, β = 95.195(2)°, Z = 4, R = 0.0585 for 6741 independent reflections with I > 3σ(I); (2) monoclinic P21/a, a = 23.8275(4) Å, b = 9.1015 (2) Å, c = 27.0420(1) Å, β = 99.9297(8)°, Z = 4, R = 0.0530 for 4565 independent reflections with I > 2σ(I). The crystal structures for both compounds consist of alternating organic and inorganic layers. The organic layer in compound 1 is characterized as κ-type, while the organic layer in 2 resembles the κ-type but it contains orthogonal dimers and monomers, and it is therefore called κ21. Compound 1 shows metallic behavior down to low temperature. Salt 2 shows semiconductive behavior, which is explained as the result of either charge ordering owing to the κ21-type structure or Peierls distortion due to the one-dimensional electronic nature. However, weak metallic behavior could be observed at 10 kbar above ca. 150 K and at 15 kbar above 170 K. The magnetic susceptibilities for both compounds show Curie−Weiss behavior, showing that the exchange interactions between the magnetic anions are weak. Polarized reflectance spectra of single crystals were measured over the spectral range from 650 to 7000 cm-1. Moreover, absorption and diffusion reflectance spectra of powdered crystals dispersed in KBr (from 400 to 7000 cm-1) were recorded. Vibrational and electronic features are discussed.
