Charge transfer states under pressure

After the discovery of a SC state under hydrostatic pressure for a charge transfer complex TTF[Ni(dmit)2]2 (and its Pd analog) [56], it was also found that the radical anion salt (CH3)4N[Ni(dmit)2]2 is a superconducting compound at 5 K under an applied pressure of 7 kbar [57]. This is a crucial result, because, for the first time, a radical-ion salt different from the TTF analogs exhibits a SC state it should open a route for synthesizing new series of interesting compounds. 

The results in Refs. 91 and 127 (Table 9.7) also demonstrate that some alkali salts (nitrate, carbonate, hydroxide) give rise to efficiencies similar to the alkali metals as promoters, while others (chlorides) are almost totally inactive, which is in marked contrast to alumina>supported catalysts where the addition of alkali salts has little promoting effect. The active state of the promoter on ruthenium/carbon catalysts is unlikely to be metallic, as the high vapor pressure of the alkali metals would give rise to substantial losses under synthesis conditions. The more probable state is a charge transfer complex with the graphite... 

Under elevated pressures, the rocksalt stmcture transforms into the CsCl structure. Changes in lattice constants and measurements of other physical properties have provided much quantitative information for empirical fits to equations of state. Modem theoretical tools are used for obtaining a deeper understanding of charge being transferred back from the anion towards the cation in the aUcah hahdes. However, as can be seen from calculations of their cohesive properties, even nowadays there are problems to be solved for such simple stmctures. The data for the halide ions, in particular, are quite useful and may be transferred to other halide systems, and give good predictive values for more complex systems. 

PCE was oxidized in a fixed-bed continuous flow reactor. The reactor was a 6-mm-o.d. Pyrex glass tube operated in the down flow mode. A reactant mainly containing air with 30 10,000 ppm of PCE was fed into the reactor charging 60/80 mesh size catalyst at a flow rate of 600 ml/min to avoid mass transfer resistance. The reaction temperatures were maintained at 350 °C under atmospheric pressure as a typical reactor condition [9]. The feed and product streams of the reactor were analyzed by on-line H.P. 5890A gas chromatography (GC) with TCD and FID detectors. The steady-state conversion of PCE was calculated based upon the difference between inlet and outlet concentrations of PCE. It has also been examined that more than 90% of PCE is converted to CO and CO2 by carbon balance. More detailed experimental procedures are described elsewhere [2]. 

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