Silylenes triplet

Phosphinidenes (R-P) differ from other low-coordinate organophosphorus compounds, such as phosphaalkynes (R-C=P), phosphaalkenes (R2C=PR), and phosphaaromatics, in that the phosphorus atom carries only a single a-bonded substituent [7-9]. They relate to carbenes, nitrenes, and silylenes and likewise can exist as singlet and triplet species. The advances that led to stable carbenes [10, 11] and silylenes [12] stimulated an exploration of the chemistry of phosphinidenes. 

Holthausen, M. C., Koch, W., Apeloig, Y., 1999, Theory Predicts Triplet Ground-State Organic Silylenes , J. Am. 

STRUCTURES OF SILYLENES AND GERMYLENES 3.1. Singlet and Triplet States... 

While carbenes are found with both singlet and triplet ground electronic states, only singlet silylenes and germylenes are well documented. 

One alternative route to the observed disilane derivatives could be via the silylenes by hydrogen abstraction and dimerization. This process, although we consider it to be less likely, might be one pathway anticipated if triplet silylenes are generated in the reaction media. 

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