Unstable fragments

The application of matrix isolation to organometallic chemistry has been extensively described elsewhere (4,5,6,7). Two methods have generally been employed. In the first, based on G.C. Pimentel s original development, the solid matrix environment is a frozen noble gas - usually Ar - at 10-20K and the unstable fragment is generated either by photolysis of a parent molecule already trapped in the matrix, or by cocondensation from the gas phase. In the... 

We conclude that our working hypothesis is valid, and that when ML4 is a sufficiently unstable fragment, both dinuclear elimination and metal-carbon bond homolysis can occur instead of simple reductive elimination of R-R from ML RR. We conclude further that the involvement of a hydride ligand is necessary for dinuclear elimination from such ML RR. On that basis, we propose the above general mechanism to explain the instability of hydridoalkyls of this type. 

PAHs arise from natural and/or anthropogenic processes, but usually from the incomplete combustion of fossil fuel and other organic matter. At high temperature, organic compounds are pyrolyzed into unstable fragments, such as radicals, and then recombine to form relatively stable PAHs. Oil spill accidents and wastewater discharge can also be sources of PAHs (WUcke, 2000 Rivas, 2006). 

The chapter is based on our systematic theoretical studies of organo-metallic compounds using effective core potentials. - We want to point out that in these investigations only mononuclear low-spin (mainly closed-shell) transition metal compounds have been considered. The review is limited to the calculation of stable transition metal compounds that is, molecules that usually obey the 18-electron (sometimes 16-electron) rule (although the prediction of bond energies requires calculations on the respective unstable fragments, which have also been carried out). 

Related CO and PEts complexes of the Ti(CsH7)2 and Ti(3-C6H9)2 fragments have been isolated by the formation of the otherwise apparently unstable fragments in the presence of the appropriate ligand [Eq. (2)]. A structural study of Ti(3-C6H9)2(CO) has revealed the expected 57/i-eclipsed geometry. 

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