New vistas in N-heterocyclic silylene (NHSi) transition-metal coordination chemistry: syntheses, structures and reactivity towards activation of small molecules.

This account is a review on the synthesis and transition-metal coordination chemistry of N-heterocyclic silylenes (NHSi's) over the last 20 years till the present time (2012). Recently, fascinating and novel synthetic methods have been developed to access transition-metal-NHSi complexes as an emerging class of compounds with a wealth of intriguing reactivity patterns. The striking influence of coordinating NHSi's to transition-metal complex fragments affording different reactivities to the "free" NHSi is a connecting theme ("leitmotif") throughout the review, and highlights the potential of these compounds which lie at the interface of contemporary main-group and classical organometallic chemistry towards new molecular catalysts for small-molecule activation.