Photofragmentations of Organosilicon and Organogermanium Compounds

Transient grating spectroscopy, photoacoustic spectroscopy and transient 

5 niotolysis of o-Nitrobenzyl Derivatives - The photocleavage reactions of onitrobenzyl ethers, esters and other derivatives continue to find applications in a number of areas. Two mechanistic studies of this type of photocleavage have 

The potential utility of o-nitrobenzyl as a photocleavable nitrogen protecting group for indoles, benzimidazole and 6-chlorouracil has been evaluated. Simple photolyses of the protected molecules at 300 nm afford good yields of the starting materials. Nitrobenzyl-based phosphoramide mustards (94) with various substituents (R, R, R ) have been developed as potential prodrugs for cancer therapy. UV and P NMR spectroscopy showed that the phosphoramide mustard was quickly liberated upon irradiation with mercury arc lamps. 2-Nitro-benzyl quaternary ammonium derivatives of norbutyrylcholine (A,iV-dimethyla-minoethyl butyrate) have been synthesized and assessed as photolabile inhibitors 

Novel photocleavable, o-nitrobenzyl based linkers for solid-phase synthesis have been developed and 7V-(2-nitrobenzyloxycarbonyl) cyclic amines have been synthesized as photobase generating agents for resists.  

Si-Si bond occurs to a significant extent. The charge-transfer state is apparently responsible for the latter reaction. 

Gas-phase photolysis of silacyclopent-3-ene results m clean extrusion of silylene, yielding buta-1,3-diene, which undergoes secondaiy photolysis.It is suggested that this process is suitable for the chemical vapocr deposition of Si/ C/H films. The influence of an external magnetic field on the yields of the photodecomposition products of the 7,7-dimethyl-7-silanorbomadiene derivative (75) has been investigated in laser-pulse photolysis experiments. These experiments reveal the intermediacy of paramagnetic species (biradicals and dimethylsilylene). 

Bis(diisopropylamino)silylene has been generated by photolysis of the precursor (76), and trapped chemically by reaction with triethylvinylsilane and 2,3-dimethylbuta-l,3-diene.Contrary to theoretical prediction, its dimer seems to have a disilene structure and not a bridged structure. 

The photogeneration of germylene (GeH2) from phenylgermane was previously reported to give anomalously low reaction-rate constants in comparison with data for germylene generated from the alternative precursor, 3,4- 

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