Tungsten coupling constants with

The 31P NMR chemical shifts of compounds 36-38 are also in line with the expected trends previously reported for S P within group 6 metal carbonyl-phosphine complexes. The 31P NMR spectra of compound 38 also exhibit the tungsten (183W) satellites around the resonance of P-2 and the typical 1J P-W coupling constants for y/digated [W(CO)s]-phosphine complexes. 

A comparative analysis of the F NMR parameters of tungsten(VI) complexes with 0,N-two-center ligands, amides [13,14] and ketimides [39] leads to the conclusion that the transition from the octahedral shape of the coordination compound to the pentagonal-bipyramidal structure is accompanied by a change in the mutual positions of the signals from equatorial fluorine atoms (Fa, Fc, or Fm), and by a considerable increase in the magnitude of the 7( Fa— Fc) and /( Fa— Fm) coupling constants [15, p. 115] (Table 3.4). 

Oxidation tests have been carried out under xenon lamp heating and natural convection of air, where weight loss under constant temperature was monitored. The temperature was monitored by an infrared thermo-viewer and was calibrated with that of the tungsten-rhenium or platinum-rhodium thermo-couples. Temperature range examined was from 600 to 2300°C. Main features of this apparatus are that a large size specimen can be exposed and equilibrium constant temperature is rapidly attained (about 20s). 

The resistance of n-CdSe to photodecomposition varies with solwnt in the following order AN PC > DMF > EtOH MeOH > HzO . Methanol/ [Fe(CN)gf was chosen for subsequent stability tests because of the high rates of electron transfer and its transparence to most of the solar spectrum. The conversion efficiency for the photo-anode at 85 mW/cm (tungsten-halogen illumination) is reported to be 3.5% at a constant current density of 6mA/cm and the fill factor is 0.56 The anode was completely stabilized by the redox couple and no deterioration of the surface or degradation of the photoresponse were observed Specific adsorption at the electrode surface and ion pairs in the bulk solution limit the maximum short-circuit current to 17.5 mA/cm in stirred and 7.5 mA/cm in unstirred solutions Purity of the solvent is essential... 

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