Jan Cok - Academia.edu (original) (raw)
Papers by Jan Cok
![Research paper thumbnail of New cation-anion interaction motifs, electronic band structure, and electrical behavior in .beta.-(ET)2X salts [ET = bis(ethylenedithio)tetrathiafulvalene; X = dichloroiodide, chlorobromoiodide]](https://attachments.academia-assets.com/96722418/thumbnails/1.jpg)
](Journal of the American Chemical Society, 1986
Two new organic metals, P-(ET),ICI2 and P-(ET),BrICI, were synthesized, and their structures and ... more Two new organic metals, P-(ET),ICI2 and P-(ET),BrICI, were synthesized, and their structures and electronic properties were characterized via X-ray diffraction, ESR studies, and band electronic structure calculations. BEDT-TTF, abbreviated "ET", is bis(ethylenedithio)tetrathiafulvalene, CioS8H8. The packing of the ET molecules within the sheetlike network of these two isostructural salts is significantly different from that of the two-dimensional metals /3-(ET)2X with the larger anions X-= 13-, 12Br-, 1Br2-, and Ad2-, where all but X-= 12Br-are ambient-pressure superconductors. The ESR studies for the P-(ET),ICI2 salt show that it is metallic down to-22 K, at which temperature a metal-insulator transition is observed. The band electronic structures calculated for /3-(ET)21C12 and P-(ET),BrICI reveal that these salts are one-dimensional metals. Comparison of the structures and electronic properties of the P-(ET),X salts with large linear anions (e.g., X-= 13-, 12Br-, IBr2-, and Au12-) vs. those with the small symmetric (C1-I-CI)-and asymmetric (B r-1 4-anions leads us to conclude that the nature of the interactions between ET molecules within a given sheetlike network, and hence the dimensionality of electrical properties, is strongly governed by the packing motif of ET molecules around a particular X-anion. The new synthetic metals B-(BEDT-TTF),X, where X-is a linear monovalent anion and BEDT-TTF (also known as ET) is the radical cation bis(ethy1enedithio)tetrathiafulvalene 1, have (IO) (a) Wang, H. H.
Inorganic Chemistry, 1985
A Test of Superconductivity vs. Molecular Disorder in (BEDT-'ITF)*X Synthetic Metals: Synthesis, ... more A Test of Superconductivity vs. Molecular Disorder in (BEDT-'ITF)*X Synthetic Metals: Synthesis, Structure (298, 120 K), and Microwave/ESR Conductivity of (BEDT-TTF)212Br Sir: For the first time two ambient-pressure synthetic metal superconductors have been reported in a single organic radical-cation donor system, with two different symmetric trihalide anions, and based on BEDT-TTF,' abbreviated "ET". They are P-(ET),I,, with a reported superconducting transition temperature2-6 (T,) of 1.2-1.6 K, and p-(ET)21Br2, with a T, (2.3-2.8 K) t~i c e~-~ that of the 13-derivative. These two systems are isostructural with a characteristic structural motif of an extended "corrugated sheet" network of short interstack S.43 (ds...s < 3.60 A) interaction distances.e11 The S-S orbital overlap within the two-dimensional BEDT-TTF or 'ET" is bis(ethylenedithio)tetrathiafulvalene
Journal of the American Chemical Society, 1986
Two new organic metals, P-(ET),ICI2 and P-(ET),BrICI, were synthesized, and their structures and ... more Two new organic metals, P-(ET),ICI2 and P-(ET),BrICI, were synthesized, and their structures and electronic properties were characterized via X-ray diffraction, ESR studies, and band electronic structure calculations. BEDT-TTF, abbreviated "ET", is bis(ethylenedithio)tetrathiafulvalene, CioS8H8. The packing of the ET molecules within the sheetlike network of these two isostructural salts is significantly different from that of the two-dimensional metals /3-(ET)2X with the larger anions X-= 13-, 12Br-, 1Br2-, and Ad2-, where all but X-= 12Br-are ambient-pressure superconductors. The ESR studies for the P-(ET),ICI2 salt show that it is metallic down to-22 K, at which temperature a metal-insulator transition is observed. The band electronic structures calculated for /3-(ET)21C12 and P-(ET),BrICI reveal that these salts are one-dimensional metals. Comparison of the structures and electronic properties of the P-(ET),X salts with large linear anions (e.g., X-= 13-, 12Br-, IBr2-, and Au12-) vs. those with the small symmetric (C1-I-CI)-and asymmetric (B r-1 4-anions leads us to conclude that the nature of the interactions between ET molecules within a given sheetlike network, and hence the dimensionality of electrical properties, is strongly governed by the packing motif of ET molecules around a particular X-anion. The new synthetic metals B-(BEDT-TTF),X, where X-is a linear monovalent anion and BEDT-TTF (also known as ET) is the radical cation bis(ethy1enedithio)tetrathiafulvalene 1, have (IO) (a) Wang, H. H.
Inorganic Chemistry, 1985
A Test of Superconductivity vs. Molecular Disorder in (BEDT-'ITF)*X Synthetic Metals: Synthesis, ... more A Test of Superconductivity vs. Molecular Disorder in (BEDT-'ITF)*X Synthetic Metals: Synthesis, Structure (298, 120 K), and Microwave/ESR Conductivity of (BEDT-TTF)212Br Sir: For the first time two ambient-pressure synthetic metal superconductors have been reported in a single organic radical-cation donor system, with two different symmetric trihalide anions, and based on BEDT-TTF,' abbreviated "ET". They are P-(ET),I,, with a reported superconducting transition temperature2-6 (T,) of 1.2-1.6 K, and p-(ET)21Br2, with a T, (2.3-2.8 K) t~i c e~-~ that of the 13-derivative. These two systems are isostructural with a characteristic structural motif of an extended "corrugated sheet" network of short interstack S.43 (ds...s < 3.60 A) interaction distances.e11 The S-S orbital overlap within the two-dimensional BEDT-TTF or 'ET" is bis(ethylenedithio)tetrathiafulvalene