Silicon compounds catenated

Recently some bicyclo and cage structures based on P—P bonds have been obtained by reacting a mixture of RPCl and PCI3 with magnesium. Only the phosphorus skeletons are shown (Fig. 4.12). These discoveries show that the chemistry of catenated phosphorus derivatives, like that of catenated silicon compounds, is much more diverse than was imagined even ten years ago. 

There is then no significant formal difference between some series of catenated carbon compounds and catenated silicon compounds. 

Baumgartner J, Grogger C (2013) Catenated silicon compounds (cyclic and acyclic). In Chivers T (ed) Comprehensive inorganic chemistry II, Elsevier... 

Poly(hydrosilane)s are stable compounds and can be manipulated in the air only for a short period since they are oxygen-sensitive. The oxidized products obtained from poly(phenylhydrosilane) exposed to the air contain the units 119-122 without the formation of silyl hydroperoxides and peroxides. In particular, units 119,120, and 121+122 were present in the relative percentages of 27,54, and 19%, respectively, which means that more than 70% of the catenated silicons are altered. 

Poly(hydrosilane)s are stable compounds and can be manipulated in the air only for a short period since they are oxygen sensitive. In order to study the oxidation products, a xylene solution of poly(phenylhydrosilane)(Mw = 2340, Mw/Mn = 1.72) was refluxed (140 °C) for 12 h in a system exposed to the air [15]. Only minor changes were observed by GPC analysis whereas FTIR showed characteristic absorptions due to siloxane-type structures on the polymer backbone. A detailed NMR analysis, based on H NMR, Si INEPT and H- Si HMQC spectroscopies, indicated that the oxidized material contains the units 7-10 shown in Scheme 8.2. In particular, units 7,8 and 9+10 were present in relative percentages of 27%, 54% and 19%, respectively, which mean that more than 70% of the catenated silicons were altered. It has also been reported that silyl hydroperoxides and peroxides are not found as products in the autoxidation of poly(phenylhy-drosilane) [16]. 

Further complications with silanes arise from lack of convenient syntheses and difficulties in separation. Nevertheless, compounds from n = I to n = 8 have been isolated, including both straight-chain and branched-chain compounds We should nol judge silicon s tendency to catenate by looking at these hydrides, however, since a much dilfereni result is obtained when substituents other than hydrogen are present.7 Flutters other than inherent Si—Si bond strength must be involved because it is possible to isolate a large number of polysilane polymers 8... 

Catenated Organic Compounds of Silicon, Germanium, Tin, and Lead Henry Gilman, William H. Atwell, and Frank K. Cartledge Cyclobutadiene-Metal Complexes P. M. Maitlis Organoarsenic Chemistry W. R. Cullen... 

The term catenation is used to describe the tendency for covalent bond formation between atoms of a given element to form chains, cycles, layers, or 3D frameworks. Catenation is common in carbon compounds, but it only occurs to a limited extent in silicon chemistry. The reason can be deduced from the data listed in Table 14.4.1. 

Germanium forms a wide range of compounds with hydrogen, silicon, the heavier group 14 elements, some main group metals, and transition metals. Catenated hydrides, Ge H2 +2, have already been discussed. The majority have carbon bonded to Ge and are included in the next article (see Germanium Organometallic Chemistry). 

The formation of the Si-Si bond occupies a special position in organosilicon chemistry. Silicon is one of the few elements, which can form stable catenated compounds. Besides high-molecular weight polysilanes, oligomeric polysilanes are a very important class of compounds that are related to silylenes,... 

The direct linking of like atoms, such an essential feature of carbon chemistry, occurs to only a limited extent with other elements. Metal-metal bonds are not uncommon but they are always weak examples are found in the polynuclear carbonyls (p. 306) and compounds such as SugRg and PbgRfi (R = alkyl). Among the other non-metals catenation is displayed by boron, silicon, germanium, phosphorus and sulphur none of the substances... 

Well over 100000 organosilicon compounds have been synthesized. Of these, during the past few decades, silicone oils, elastomers and resins have become major industrial products. Many organosilicon compounds have considerable thermal stability and chemical inertness e.g. SiPha can be distilled in air at its bp 428°, as can PhaSiCl (bp 378°) and Ph2SiCl2 (bp 305°). These, and innumerable similar compounds, reflect the considerable strength of the Si-C bond which is, indeed, comparable with that of the C-C bond (p. 338). A further illustration is the compound SiC which closely resembles diamond in its properties (p. 334). Catenation and the formation of multiple bonds are further similarities with carbon chemistry, though these features are less prominent in organosilicon chemistry and much of the work in these areas is of recent... 

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