@article {MIYAZAKI2021128986, title = {UV photochemistry of 1,3-cyclohexadiene isolated in solid parahydrogen}, journal = {Journal of Molecular Structure}, volume = {1224}, year = {2020}, pages = {128986}, abstract = {

1,3-cyclohexadiene was isolated in solid parahydrogen, and its photochemical reactions were studied via irradiation with 193 nm photons from an ArF excimer laser. Photoproducts were identified using Fourier-transform infrared spectroscopy supported by density functional theory calculations. Photolysis with 193 nm light caused the formation of two well-characterized conformers of 1,3,5-hexatriene, tZt-1,3,5-hexatriene and tEt-1,3,5-hexatriene. A third initial photoproduct was identified as the conformer cZc-1,3,5-hexatriene, and its infrared spectrum was characterized for the first time. In addition, the bicyclo[2.2.0]hex-2-ene and 1-methyl-bicyclo[2.1.0]pent-2-ene were also found to be a minor products from photo-induced ring-closure reactions, where the latter further converts to 2-methyl-cyclopentadiene. The reaction mechanisms and stability of these products are discussed using infrared spectroscopy and density functional theory calculations.

}, keywords = {1, 3-CYCLOHEXADIENE, Density functional theory calculations, Infrared spectroscopy, Matrix isolation, Solid parahydrogen, UV photochemistry}, issn = {0022-2860}, doi = {https://doi.org/10.1016/j.molstruc.2020.128986}, url = {http://www.sciencedirect.com/science/article/pii/S0022286020313090}, author = {Jun Miyazaki and Shin Yi Toh and Brendan Moore and Pavle Djuricanin and Takamasa MOMOSE} } @article {2027, title = {Transformations of cyclic olefins mediated by tungsten nitrosyl complexes}, journal = {Organometallics}, volume = {27}, number = {18}, year = {2008}, note = {ISI Document Delivery No.: 348URTimes Cited: 3Cited Reference Count: 35Buschhaus, Miriam S. A. Pamplin, Craig B. Blackmore, Ian J. Legzdins, Peter}, month = {Sep}, pages = {4724-4738}, type = {Article}, abstract = {This report describes investigations that have elucidated the nature, extent, and mechanism of the cyclic-olefin oligomerization effected by a series of tungsten precatalysts, with particular focus on Cp*W(NO)(CH2CMe3)(2) (1) and Cp*W(NO)(CH2SiMe3)(eta(2)-CPhCH2) (2). Upon thermolysis, these precatalysts oligomerize simple cyclic olefins, from cyclopentene to cyclooctene, into ring-retaining oligomers as high as dodecamers (depending on the substrate) with remaining sites of unsaturation. Precatalyst initiation involves the coupling of one equivalent of the substrate with the reactive 16e intermediate thermally generated by the precatalyst (i.e., an alkylidene by 1 or an eta(2)-alkyne complex by 2), followed by rearrangement of the coupled ligand in the metal{\textquoteright}s coordination sphere either to an olefin or to a diene (with concomitant loss of two hydrogen atoms). The rearranged ligand is displaced from the metal center as two equivalents of substrate coordinate to form a putative bis-olefin complex, Cp*W(NO)(cyclic olefin)2, that represents the convergent entry point to the catalytic cycle for the precatalysts. The coordinated olefins undergo metal-mediated coupling to form a metallacyclopentane complex. The metallacycle then undergoes beta-hydrogen activation and reductive elimination to generate an eta(2)-cyclic-olefin dimer. Further incorporation of substrate leads to formation of trimers and higher oligomers. Alternatively, expulsion of any coordinated oligomer from the tungsten center regenerates the reactive bis-olefin complex. Finally, decomposition of the tungsten catalyst species is consistent with a bimetallic pathway. All new organometallic complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of several compounds have been established by X-ray crystallographic analyses.}, keywords = {1, 3-CYCLOHEXADIENE, ALKYLIDENE COMPLEXES, C-H ACTIVATION, CATALYTIC-ACTIVITY, CRYSTAL-STRUCTURES, CYCLOHEXENE, METATHESIS, MOLYBDENACYCLOBUTANES, MOLYBDENUM, REACTIVITY}, isbn = {0276-7333}, url = {://000259236100022}, author = {Buschhaus, M. S. A. and Pamplin, C. B. and Blackmore, I. J. and Legzdins,Peter} }