... ROBERT A. MCCLELLAND AND N. ESTHER SEAMAN Departmerlt of Chemistry. Univer.sip of Toronto, Toronto, Otlr., Cnnadtr M5S /A1 AND JAMES M. DUFF AND R. E. BRANSTON Xerox Research Centre of Canadti, 2660 Speaktnat~ Drive. ... [Traduit par le journal] ... J. CHEM. ...