21 January 2000
Vol 287, Issue 5452

About The Cover

Cover image expansion

COVER Model of a neutral single-component nickel complex that polymerizes ethylene in the presence of organic functional groups that are detrimental to conventional systems. The high activity and efficiency of this neutral catalyst complex were realized through modular ligand modification. The ligand [attached through the nitrogen (purple) and oxygen (red) atoms] surrounds the metal center (orange), preventing side reactions and decomposition. See page 460 [Image: T. R. Younkin, J. I. Henderson, O. A. Scherman]