10.1021/ja052287b.s003
Benjamin G. Harvey
Benjamin G.
Harvey
Charles L. Mayne
Charles L.
Mayne
Atta M. Arif
Atta M.
Arif
Richard D. Ernst
Richard D.
Ernst
Structural and Spectroscopic Demonstration of Agostic C−C
Interactions in Electron-Deficient Metallacyclobutanes and
Related Cage Complexes: Possible Implications for Olefin
Polymerizations and Metatheses
American Chemical Society
2005
dienyl fragment
C 8 H 11 ligand
electron
PhC 2 SiMe 3
C 8 H 11
bond
C 5 H 5
allyl
interaction
PMe 3 coordinations
CH 2 group
2005-11-30 00:00:00
Dataset
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
The reaction of the half-open titanocene, Ti(C<sub>5</sub>H<sub>5</sub>)(<i>c-</i>C<sub>8</sub>H<sub>11</sub>)(PMe<sub>3</sub>) (<i>c-</i>C<sub>8</sub>H<sub>11</sub> = cyclooctadienyl),
with two equivalents of PhC<sub>2</sub>SiMe<sub>3</sub> leads to their incorporation and coupling to the dienyl fragment. One
alkyne inserts into a C−H bond of the central CH<sub>2</sub> group of the <i>c-</i>C<sub>8</sub>H<sub>11</sub> 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 C<sub>5</sub>H<sub>5</sub> and PMe<sub>3</sub> 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.