Aromatic Carbon-Carbon Bond Cleavage Using Tungsten Complexes. A DFT Computational Study

作者：Miscione Gian Pietro^*; Angels Carvajal Maria; Bottoni Andrea

来源：Organometallics, 2011, 30(18): 4924-4934.

DOI：10.1021/om2005029

The mechanism of aromatic C-C bond cleavage in quinoxaline (QoxH) catalyzed by the tungsten complexes W(PMe(3))(4)(eta(2)-CH(2)PMe(2))H has been theoretically investigated at the DFT level. The mononuclear species (eta(2)(N,C)-Qox)W(PMe(3))(4)H (experimentally isolated and characterized) is directly involved in the formation of the final product [kappa(2)(C(2))-C(6)H(4)(NC)(2)]W(PMe(3))(4), where the aromatic C-C bond of quinoxaline has been broken. The mechanism requires a double insertion of the metal into two quinoxaline C-H bonds, thus affording the "strained" benzyne-type species eta(2)(C(2))-C(6)H(4)(NCCN)W(PMe(3))(4)H(2). After expulsion of H(2) the eta(2)(C(2)) complex leads to the [kappa(2)(C(2))-C(6)H(4)(NC)(2)]W(PMe(3))(4) product, thus relieving the structural strain of the small WCC cycle in eta(2)(C(2)). Also, the theoretical investigation shows the existence of a stable (eta(4)(C(2)N(2))-QoxH)W(PMe(3))(3)H(2) complex (an unprecedented example of eta(4) coordination), in agreement with its experimental observation and characterization by X-ray diffraction.

• 出版日期2011-9-26