Silenes chemistry

It may well be that activity in the area of silene chemistry has peaked. Certainly, the number of papers currently published is lower than it was a few years ago. This may be due, at least in part, to the fact that many of the easier and more obvious experiments have been attempted. However, only the discovery of important applications is required for the field to be revitalized. In particular, the successful synthesis of useful polymers... 

Most of the pioneering and fundamental work of the last thirty years in silene chemistry has been conducted in the gas phase under thermolytic or photolytic conditions. The results of the last ten years in this area of silene chemistry are summarized together with related earlier reports in the next sections of the chapter. For more complete information, which includes the literature before 1987, the interested reader is referred in addition to the previous reviews by Raabe and Michl7,8 and to references given therein. 

Like the first stable disilene, the first isolable silene was prepared photochemically. This produced a flurry of activity and opened a new chapter in silene chemistry. These developments have been reviewed in Reference 2. 

In the early days of silene chemistry most of the structural data for simple siienes came from IR, and microwave studies . By 1997 only three... 

X-ray studies of stable siienes had been published and much of the information about structure and bonding in siienes came from ab initio molecular orbital calculatious. These data are well summarized in several review articles by Brook and Brook and by Michl and Raabe . The important role which ab initio calculations play in this field is outlined in the comprehensive review by Apeloig and by Kami and Apeloig. We will therefore emphasize in this paragraph the new important findings and we will outline the general trends of structural silene chemistry. Some stmctural data and original references are summarized in Table 12. 

This fundamental discovery dramatically affected the whole chemistry of main-group elements. Subsequently, a series of new compounds with silicon element multiple bonds has been introduced. Within only a few years, stable silenes (silaethenes with a Si = C double bond) [8-11], silaimines Si = N [12-14], and silaphosphenes Si = P [15] were synthesized. As a pacemaker, silicon chemistry has exerted a strong influence on further areas of main-group chemistry a variety of stable molecules with Ge = Ge [16], P = P [17], As = As [18], P = C and P = C [19-22] bonds were subsequently isolated, and systems with cumulated double bonds P = C = P [23-25] are also known today. 

During recent years, fascinating developments have occurred in the area of r 2-silene complexes, which opened up to totally new chemistry. Some of the highlights will be presented in this section. The first investigations of coordination compounds of silenes were carried out by means of matrix isolation techniques at very low temperatures. In particular, photochemical methods proved to be most effective... 

Brook, Adrian, G., and Brook, Michael, A., The Chemistry of Silenes. 

Prior to 1985, much had been learned about the chemistry of the silicon-carbon double bond through the study of the reactions of silenes with a wide variety of reactants. Thus it was known that all silenes studied reacted readily with alcohols (particularly methanol) by regiospecific addition across the ends of the Si=C bond in which the MeO group became attached to silicon and the alcoholic H to carbon, as in Eq. (22). 

---