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large molecules at low temperature (ca. 225 K) and much smaller oligocadmium molecules at high temperature (ca. 340 K).3. The Ii3Cd and 13C NMR spectra are consistent with vertex-linked adamantanoid cages as the structure type for the aggregates in solution. The postulated aggregate structures in SOlution are fragments of the known crystal structures. 4. The low ionic conductivity and the 'I3Cd NMR data indicate that some ligand disproportionation occurs in solution, such that the larger oligoadamantanoid aggregates have small negative charges with SAr and DMF ligands distributed over peripheral terminal Cd coordination sites.5. The aggregates in solution are electrophilic toward halide and thiolate ligands. Experimental SectionPreparations and Crystallizations. The compounds were prepared as previously described, and purified by recrystallization from DMF by addition of ethanoL4 NMR. The II3Cd spectra were measured at natural abundance in DMF, at 66.6 MHz with a Bruker CXP300 spectrometer, using IO-mm tubes in a multinuclear probe locked to acetone-d6 in an insert. Proton decoupling was not used. Typical spectra required 3000-6000 pulses (20 ws; tip angle ca. 75') with recycle delays of 1 2 s. Relaxation times TI were estimated by tests with variable recycle delay periods, in order to ensure that the relative intensities of resonances were not significantly distorted by saturation. All solutions were deoxygenated by sparging with N,. Temperatures in the sample tube were controlled to *l O and were calibrated by replacement with a sample tube containing a platinum thermometer. Chemical shifts are referenced to external 0.1 M aqueous Cd(NO,)* as zero: this reference resonates at -5 ppm relative to aqueous Cd(C104)2 at infinite dilution.I3C NMR spectra were measured on a JEOL FX-100 instrument at 25.05 MHz, with proton decoupling, and referenced to TMS. Small proportions of acetone were added to the DMF solutions for the lowest temperature measurements.Conductivity. Conductivity measurements were obtained at 25 OC on solutions of Cd(SPh),, (Me4N)2[Cd4(SPh)lo], and Bu4NI in DMF. Concentrations were varied through the range 0.1 to 5 X Molecular Weight. Because DMF is a very difficult solvent for molecular weight determinations by cryoscopic or osmometric methods (ebullioscopic data would not be relevant to the temperature range of the NMR data), cryoscopic measurements were made in HMPA. The low values of 290 f 50 Da revealed that HMPA completely disrupted the aggregates and could not be regarded as comparable with DMF. Attempts to use the Signer isothermal distillation method in DMF are in progress.Acknowledgment. Cyclic voltammetry, DPV, and electronic spectroscopy are used to study the reaction between thionyl chloride and cobalt phthalocyanine. SOC12 reacts with [Co'TnPc(2-)]-and Co"TnPc(2-) to give two-electron-oxidized species. Implications for Li/S0Cl2 batteries are discussed. Thionyl chloride also forms a SOC12 monoadduct with Co"TnPc(2-). Driving forces (AE values) have been calculated for CoTnPc amproportio...

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This paper presents in situ measurements of a newly developed current density measurement system for proton exchange membrane fuel cells (PEMFC). While the functional principle and technical evaluation of the measurement system were presented in a previous paper, this paper analyzes the influence of various operation parameters, including multiple start-stop operation, at the anode, cathode and cooling locations on the distribution and long-term development of the current density. The system was operated for 500 h over two years with long periods of inactivity between measurements. The measurement results are evaluated and provide additional information on how to optimize the operation modes of fuel cells, including the start and stop of such systems as well as the water balance.