%0 Generic %A Harvey, Benjamin G. %A Mayne, Charles L. %A Arif, Atta M. %A Ernst, Richard D. %D 2005 %T Structural and Spectroscopic Demonstration of Agostic C−C Interactions in Electron-Deficient Metallacyclobutanes and Related Cage Complexes:  Possible Implications for Olefin Polymerizations and Metatheses %U https://acs.figshare.com/articles/dataset/Structural_and_Spectroscopic_Demonstration_of_Agostic_C_C_Interactions_in_Electron_Deficient_Metallacyclobutanes_and_Related_Cage_Complexes_Possible_Implications_for_Olefin_Polymerizations_and_Metatheses/3254038 %R 10.1021/ja052287b.s003 %2 https://acs.figshare.com/ndownloader/files/5089408 %K dienyl fragment %K C 8 H 11 ligand %K electron %K PhC 2 SiMe 3 %K C 8 H 11 %K bond %K C 5 H 5 %K allyl %K interaction %K PMe 3 coordinations %K CH 2 group %X The reaction of the half-open titanocene, Ti(C5H5)(c-C8H11)(PMe3) (c-C8H11 = cyclooctadienyl), with two equivalents of PhC2SiMe3 leads to their incorporation and coupling to the dienyl fragment. One alkyne inserts into a C−H bond of the central CH2 group of the c-C8H11 ligand's edge-bridge, while the second undergoes a 5+2 coupling with the dienyl fragment, yielding coordinated σ-allyl and olefin fragments, as demonstrated by X-ray diffraction. Together with the C5H5 and PMe3 coordinations, this leads to a 14-electron count. While the very electron-deficient titanium center passes up potential π coordination of the allyl fragment, it instead engages in interactions with one or two C−C bonds, and perhaps a C−H bond, as revealed from the structural and spectroscopic data. Similar interactions have been found in electron-deficient metallacyclobutane complexes of titanium and zirconium, but not in the 18-electron molybdenum and tungsten analogues. These and other observations may have implications relating to metatheses and polymerizations of olefins. %I ACS Publications