45, 304 (1973). The thermodynamic functions given for KCN and NaCN in thls paper are incorrect. (1 5) An attempt to use silver vaporized under identical conditions, Including using the same effuslon cell, to check our values of ku, kD, and kT failed because there is no reliable means to estimate the relatlve cross sections, e.g., uA,+uW In fact, comparison of our KCN and Ag data suggests that uA,+(gM x uD i= uT) = 5.0 f 0.2 at 20 eV.This large ratio is understandable on the basis that fragmentation to Kt Is much more probable than forming the ions we monitored. Table I data clearly support this idea. (16) D. 0. Welch, 0.The behavior of polymeric iron phthalocyanine catalysts during the cathodic reduction of oxygen in sulfuric acid was studied by labeling central iron atoms with 5?Fe. Moreover, in order to get an insight into the interaction between iron polyphthalocyanines and carbon supports, Mossbauer spectroscopic investigations have been undertaken. The experiments showed that iron polyphthalocyanine electrocatalysts, which are built in carbon-teflon electrodes, could be classified in (a) phthalocyanine molecules with low stability and large quadrupole splitting which have only a low influence on the electrochemical operation of the electrode and (b) phthalocyanine molecules with high stability and low quadrupole splitting which are decisive in electrocatalysis.In agreement with the mechanism of long-life electrocatalytic operation and deactivation, derived from these experiments, carbon-teflon cathodes with polymeric iron polyphthalocyanine catalysts could be constructed which are characterized by a high stability during continuous operation in 6 N HzS04 up to 3000 h. Experimental Section1. Electrochemical Measurements. The electrocatalytic properties of polymeric iron phthalocyanines that are being discussed in this paper have been tested in teflon-bonded porous electrodes. For details of synthesis see, e.g., ref 22

A membrane osmometer with a short response time based on a previously developed concentric design with a capillary-shaped membrane has been applied as an online SEC detector for absolute molar mass detection in combination with a concentration detector. The flow cell volume is 12.2 µL, the response time approximately 15 s, and the molar mass cutoff is below 5 kg/mol. The performance has been tested with polystyrene standards in toluene under realistic SEC conditions.

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Zwischen der elektrokatalytischen Aktivität der in Brennstoffzellen eingebauten Phthalocyaninkatalysatoren und deren Leitfähigkeit bestehen verschiedene Zusammenhänge: Unter anderem wird die Elektrokatalyse der Sauerstoffreduktion durch die am besten leitenden Polymere der Fe‐ oder Co‐Phthalocyaningruppe am stärksten aktiviert. Auch wird ein Einfluß der Leitfähigkeit und der mit dieser verbundenen Katalaseaktivität auf die Stabilität länger belasteter Sauerstoffkathoden festgestellt. Die an Fe‐Polyphthalocyaninen beobachtete Störung der pi‐Elektronendelokalisation (Rubikonjugation) und der Nachweis einer Beziehung zwischen Leitfähigkeit einerseits und Elektrokatalyse sowie Katalaseaktivität andererseits führt zu einer die Elektrokatalyse der Sauerstoffreduktion beschreibenden Modellvorstellung. Nach diesem Modell, das u. a. die überragende elektrokatalytische Eignung der Fe‐Polyphthalocyanine erklären kann, spielen bei der Elektrokatalyse sowohl Donatorzustände für die Reduktion des Sauerstoffs als auch Akzeptorzustände für die Zersetzung des H2O2 eine entscheidende Rolle.

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