Kinetics of the Same Reaction Monitored over Nine Orders of Magnitude in Concentration: When Are Unique Subensemble and Single‐Turnover Reactivity Displayed?

Abstract: Essentially no information is known about the behavior of individual molecular catalysts under reaction conditions. This is a result of the averaging inherent to traditional analytical techniques. Herein, a combined fluorescence microscopy and 1H NMR spectroscopy study reveals that unique (that is, non‐ensemble averaged) distributions and time‐variable kinetics from molecular ruthenium catalysts within growing polynorbornene occur and are detectable between 10−9  m and 10−6  m of substrate, surprisingly just 1000‐fold less concentrated than a typical laboratory bench‐scale reaction. The kinetic states governing single‐turnover events are determinable by overlay of the signal arising from individual monomer insertion reactions with that from polymer growth from neighboring catalysts. [ABSTRACT FROM AUTHOR]