Phosphorus-arsenic bonds synthesis

Since several excellent reviews on the chemistry of multiple bonds to silicon [see the chapter written by G. Raabe and J. Michl in a previous volume of this series (1989) ] and also the reviews in Advances in Organometallic Chemistry, Vol. 39 (1995) (e.g. The Chemistry of Silenes by A. G. Brook and M. A. Brook , IminosUanes and Related Compounds—Synthesis and Reactions by I. Hemme and U. Klingebiel, Silicon-Phosphorus and Silicon-Arsenic Multiple Bonds by M. Driess and Chemistry of Stable Disilenes by R. Okazaki and R. West ) have appeared in recent years and as some parts of this chapter will be discussed in detail in related chapters of this book (e.g. Silenes and Iminosilanes by N. Auner and coworkers and Recent Advances in the Chemistry of Disilenes by H. Sakurai ), we will concentrate our attention in this chapter on the chemistry of silicon-chalcogen doubly-bonded compounds. 

The synthesis of stable complexes with transition metal-phosphorus triple bonds is of fundamental importance and opens a novel chapter of a special field of coordination chemistry. The synthesis of analogous complexes with ligands of the heavier homologues like arsenic has partially been carried out [6], while for antimony and bismuth, the elusive M=Sb and M=Bi systems have now moved within reach. Moreover, the experimental and theoretical... 

The chemistry of phospholes and related phospholide anion complexes remains a very active area, which also continues to attract the attentions of the theoretical community. Among recent theoretical contributions are a consideration of the stability, structure and bonding in lithium- and beryl-lium-pentaphospholide systems, the aromaticity of the pentaphospholide anion (and its arsenic analogue) as probed by ring currents,the remarkable influence of fluorine-substitution (either at phosphorus or at a ring carbon) on the electronic and thermochemical properties of phospholes,and the effects of methyl and vinyl substitution at various positions on the geometries, relative stabilities and Diels-Alder reactivities of phospholes. An ab initio approach has been used to reinterprete some spectral and thermochemical properties of IH-phospholes. The synthesis and reactivity of phospholes of reduced... 

Stable compounds containing unsupported double bonds between phosphorus and/or arsenic atoms have been isolated recently. This has been achieved by the use of sterically demanding substituents that ofler a high degree of kinetic and thermodynamic stability. The synthesis of representative examples of these compounds is described in Section 47. Herein are described the preparations of the relevant starting materials. 

For several reasons the development of the chemistry of 6n heteroaromatic arsenic systems, for example arsinine (3), was much less vigorous than that of the phosphinines. While t-butylphos-phaethyne (4) and several other phosphaethynes are important building blocks for the synthesis of six-membered aromatic phosphorus heterocycles with more than one heteroatom, only one compound with a C=As triple bond, the 2,4,6-tri- -butylphenyl derivative (5), has been described <86AG(E)264>, and this has not been thoroughly studied. The only six-membered As-heteroaromatic system with more than one heteroatom is the l,3A -azarsinine (6) <88TL535>. Since pentavalent... 

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