Tables of 1 H and 13 C NMR chemical shifts have been compiled for common organic compounds often used as reagents or found as products or contaminants in deuterated organic solvents. Building upon the work of Gottlieb, Kotlyar, and Nudelman in the Journal of Organic Chemistry, signals for common impurities are now reported in additional NMR solvents (tetrahydrofuran-d 8 , toluene-d 8 , dichloromethane-d 2 , chlorobenzene-d 5 , and 2,2,2-trifluoroethanol-d 3 ) which are frequently used in organometallic laboratories. Chemical shifts for other organics which are often used as reagents or internal standards or are found as products in organometallic chemistry are also reported for all the listed solvents.
The selective transformation of ubiquitous but inert C H bonds to other functional groups has far-reaching practical implications, ranging from more efficient strategies for fine chemical synthesis to the replacement of current petrochemical feedstocks by less expensive and more readily available alkanes. The past twenty years have seen many examples of C-H bond activation at transition-metal centres, often under remarkably mild conditions and with high selectivity. Although profitable practical applications have not yet been developed, our understanding of how these organometallic reactions occur, and what their inherent advantages and limitations for practical alkane conversion are, has progressed considerably. In fact, the recent development of promising catalytic systems highlights the potential of organometallic chemistry for useful C-H bond activation strategies that will ultimately allow us to exploit Earth's alkane resources more efficiently and cleanly.
A new class of coordinatively unsaturated, monomeric organoscandium compounds, Cp*2Sc-R (Cp* = (rj5-C5Me5); R = halide, hydride, alkyl, alkenyl, alkynyl, aryl), has been prepared. Cp*2Sc-Cl is obtained from reaction of ScCl3(THF)3 (THF = tetrahydrofuran) with LiCp*, and Cp*2Sc-R (R = CH3, C6H5, C6H4CH3, CH2C6H5) from treatment of Cp*2Sc-Cl with the appropriate organoalkali reagent. These organoscandium compounds react with dihydrogen rapidly to yield R-H and Cp*2Sc-H. The tetrahydrofuran adducts Cp*2ScX(THF) (X = Cl, H, CH3) are obtained upon treatment of Cp*2Sc-X with tetrahydrofuran. Rapid exchange of dihydrogen with the hydride ligands of Cp*2Sc-H and Cp*2ScH(THF) occurs even at low temperatures. Other alkyl derivatives may be conveniently prepared by treatment of Cp*2Sc-H (or Cp*2ScH(THF)) with -olefins, e.g., Cp*2ScCH2CH3 from Cp*2Sc-H and ethylene. Aliene and Cp*2Sc-H afford Cp*2Sc(7j3-C3H5). Cp*2Sc-R (R = H, CH3, aryl) reacts with pyridine to yield Cp*2Sc(C, N-j;2-C5H4N), which crystallizes in the orthorhombic space group
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