The singlet states of diarylcarbenes are thought to insert into the 0-H bonds of alcohols and to add stereospecifically to olefins. By contrast, their triplet ground states are thought to be efficient hydrogen abstracting agents and are believed to add non-stereospecifically to olefins.1-12 The experimental data supporting these hypotheses are equivocal. For example, optical absorption spectra due to the triplet states of diphenyl~arbene,~~~,~~ fluoreny1idene,'l*l2 and 1 - ...