Silicon entries

This is a good route to compounds that are functionally substituted at silicon (entries 6-10). 

The rotational barrier in methylsilane (Table 3.4, entry 5) is significantly smaller than that in ethane (1.7 versus 2.88 kcal/mol). This reflects the decreased electron-electron rqjulsions in the eclipsed conformation resulting from the longer carbon-silicon bond length (1.87 A) compared to the carbon-carbon bond length (1.54 A) in ethane. 

Commonly employed anion-stabilizing groups are those containing silicon (Table 5.4, Entries 1-5). Magnus et al. reported that epoxysilane 147 could be deproto-nated with t-BuLi, and that the lithiated epoxide 148 thus generated could be trapped with allyl bromide to give epoxysilane 149 in a synthetically useful yield (Scheme 5.34) [55], Iodomethane (88%) and chlorotrimethylsilane (60%) could also be trapped. 

Entries on new materials, including re-cyclate plastics, fullerenes, hard-surfaced polymers, dendrimers, transflective materials, rapid prototyping materials, silicone nitride, supercritical fluids, bulk molding compounds, conversion coatings, folic acid, replacements for chloro-fluorocarbons ... 

Molecular compounds of silicon in a formally zerovalent oxidation state can be stabilized by appropriate transition-metal fragments. An entry to such polyme-tallated complexes of silicon is given by the chlorosilylene compounds 7, 11 as a starting-point. 

Alcohol functions have also been introduced via hydrosilylation reactions, for example, the reaction of T8[OSiMe2H]8 with allyl alcohol and allyloxy ethanol (Table 19). In the first case, it has been postulated that the compound T8[OSiMe2 (CH2)30H]8 is not very stable due to back-biting of the -OH groups on the silicon corners (Figure 31). Nevertheless, it reacts with polymers such as polyvinyl pyrrolidone to give polymer hybrids (Table 19, entries 4 and 5). 

It is not clear why the sp2-hybridized carbon atom of a fluorenylidene germene (entry 3, Table II) is so shielded (8 79.8), unless this chemical shift is from the spectrum of the THF adduct.28 The chemical shift of the silicon atom in the germasilene (entry 4, Table II) and the phosphorus atom in germaphosphenes (entries 6-10, Table II) is deshielded compared to the corresponding silicon analogs. For example, for Mes2M=SiMes2... 

Silicon and Phosphinomethanides A Novel Entry to Hypervalent and Low Valent Organosilicon Chemistry... 

FIGURE 4. Electrochemical reactor composed of a 2 cm3 capacity filter funnel and (A) stainless steel wire, (B, G) stainless steel needles for N2 entry and exit ports, (C) rubber septum, (D) lead foil cathode, (F) fine porosity glass filter, (H) plug of silicone glue and (I) silver wire anode. (Taken from Reference 176.)... 

S-37 (see above) it is also possible to prepare and to matrix-isolate the silicon species 124, 125, and 126, which again exist in a photoequilibrium. Our first entry to 1-silacyclopropenylidene (124) was the pulsed flash pyrolysis of 2-ethynyl-l,l,l-trimethyldisilane (123).71,72 Even though the structure of educt molecule 123 suggests formation of ethynylsilylene (125), the isolated product was 124. Obviously 125 had already thermally isomerized to the most stable isomer 124 before the products were condensed at 10 K. 

See also ANSI entries silicon carbide standards by, 22 537, 538 American Nuclear Society (ANS), 15 767 American oyster, common and scientific names, 3 188t... 

Antimony (Sb), 3 41-56, 56. See also Group Ill-Sb system InAsSb alloy InSb photodiode detectors/arrays Lead-antimony alloys Low antimony lead alloys Stib- entries in babbitts, 24 797 catalyst poison, 5 257t chemical reactions, 3 42—44 in coal, 6 718 economic aspects, 3 47-48 effect of micro additions on silicon particles in Al-Si alloys, 2 311-312 effect on copper resistivity, 7 676t environmental concerns, 3 50 gallium compounds with, 12 360 health and safety factors, 3 51 in pewter, 24 798... 

International standards, 75 755-757 growing role of, 24 262 International Standards Organization (ISO). See also International Organisation for Standardization (ISO) ISO entries reliability and, 26 993 silicon carbide standards by, 22 537, 538 International Sugar Scale, 23 473 International System of Units (SI Units), 7 xi-xxvi 2-26 ix-xxiv. See also SI Units... 

Silicomanganese, 15 556 low carbon, 15 555—556 world production of, 15 550—551t Silicomanganese, 22 519 Silicomanganese furnace, 15 553, 555 Silicomanganese production, 15 555—556 Silicon (Si), 9 731-733, 22 480-501, 502-511. See also Doped silicon re-type (negative) silicon p-type (positive) silicon Ribbon silicon Sheet silicon Amorphous silicon (a-Si) Si-hybrid sealants Silica entries analytical methods for, 22 498—499 in aluminum alloys, 22 508, 509, 510 applications of, 22 499, 508—509 atomic force microscopy of etching, 3 333-337... 

Siloxane compounds, in vitreous silica manufacture, 22 414 Siloxane materials, 20 240 Siloxane oligomers, in silicone polymerization, 22 555-556 Siloxanols, silylation and, 22 703 Silsesquioxane hybrids, 13 549 Silsesquioxanes, 15 188, 22 589-590 SilvaGas process, 3 696, 697 Silver (Ag), 22 636-667. See also Silver compounds. See Ag entries Argentothiosulfate complexes Batch desilverizing Lead-silver alloys Palladium-silver alloy membranes analytical methods for, 22 650-651 applications of, 22 636-637, 657-662 as bactericide, 22 656, 657, 660 barium alloys with, 3 344 in bimetallic monetary system, 22 647-648 in cast dental gold alloys, 8 307t coke formation on, 5 266 colloidal precipitation color, 7 343t colloidal suspensions, 7 275 color, 7 334, 335... 

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