SiNC inorganic heterocycles

At first, N-heterocyclic carbenes 20 look bizarre to the organic chemist, since they are organic/inorganic hybrid compounds. However, borazines, sometimes called inorganic benzene , are isoelectronic with benzene and are therefore extraordinarily stable heterocycles. Exchange of a borane... 

The third contribution in our volume reviews the interesting classes of five-membered heterocyclic rings containing two sulfur and two nitrogen atoms, both as anionic and radical species. This area lies on the border of organic and inorganic chemistry since its inception, in 1977, it made great strides as are now documented by J. M. Rawson, A. J. Banister, and I. Lavender of the University of Durham, UK. 

A second problem of this revision is the vast literature which has grown up in the twenty years since this book was first written. At that time it was possible, at least to aspire, to include all the relevant references. To try to do so now would require a bibliography as large as the book itself. Moreover a number of specialist texts have appeared in which the whole book is devoted to the material which has to be presented here in one chapter, and these already offer the complete documentation that a specialist may need. Thus, two reviews by Katritzky and his coworkers deal exclusively with the group frequencies of heterocyclics and between them cite over 1500 references. Varsanyi has provided a comparable review of the aromatics, Adams of coordination compounds and Bentley et al. of the far infrared. There is also a wide coverage on inorganics by Nakamoto and by Lawson, whilst the supplementary Raman group frequency data has recently been very excellently covered by Dollish, Fateley and Bentley. I have therefore confined myself to those references which are most relevant and contented myself with reference to these more detailed sources where appropriate. 

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