Organochromium π-complexes—VI. The preparation of Cp′(η3-allyl)2Cr compounds and their reactions with donor ligands
摘要:
The title compounds have been prepared by reacting a Cp'CrCl2 or a (eta3-allyl)2CrCl species with either an allylmagnesium halide or a substituted cyclopentadienyllithium derivative. The compounds react further at room temperature to give the dinuclear species [Cp'(mu-eta3-allyl)Cr]2, and with P-donor ligands with reductive coupling of the allyl groups to give Cp'(eta2,eta2-1,5-hexadiene)CrPR3 species. Diene exchange is observed upon reacting the hexadiene compounds with butadiene or cyclohexadiene. The crystal structures of [Cp'(mu-eta3-C3H5)Cr]2, [(eta5-indenyl)(mu-eta3-C3H5)Cr]2, (eta5-indenyl) (eta2,eta2-1,5-hexadiene)CrP(OMe)3 and three compounds containing a 1,3-diene, viz. Cp(eta4-1,3-C4H6)CrPMe3, (eta5-Me5C5)(eta4-1,3-C4H6)CrCO and Cp(eta4-1,3-cyclohexadiene) CrP(OMe), have been established by X-ray diffraction.
Organochromium π-complexes—VI. The preparation of Cp′(η3-allyl)2Cr compounds and their reactions with donor ligands
摘要:
The title compounds have been prepared by reacting a Cp'CrCl2 or a (eta3-allyl)2CrCl species with either an allylmagnesium halide or a substituted cyclopentadienyllithium derivative. The compounds react further at room temperature to give the dinuclear species [Cp'(mu-eta3-allyl)Cr]2, and with P-donor ligands with reductive coupling of the allyl groups to give Cp'(eta2,eta2-1,5-hexadiene)CrPR3 species. Diene exchange is observed upon reacting the hexadiene compounds with butadiene or cyclohexadiene. The crystal structures of [Cp'(mu-eta3-C3H5)Cr]2, [(eta5-indenyl)(mu-eta3-C3H5)Cr]2, (eta5-indenyl) (eta2,eta2-1,5-hexadiene)CrP(OMe)3 and three compounds containing a 1,3-diene, viz. Cp(eta4-1,3-C4H6)CrPMe3, (eta5-Me5C5)(eta4-1,3-C4H6)CrCO and Cp(eta4-1,3-cyclohexadiene) CrP(OMe), have been established by X-ray diffraction.
The compounds (eta-RC5H4)(eta3-C3H5)2Cr (R = H, Me, t-C4H9) and (eta5-indenyl)(eta3-C3H5)2Cr react with alkynes (RC2R) with displacement of 1,5-hexadiene to give Cp'(eta6-R6C6)Cr species. Treatment with cyclooctatetraene gives compounds containing an eta6-C8H8 group while the final product of the reaction with cycloheptatriene contains an eta7-cycloheptatrienyl fragment. 1,3-Butadiene reacts with dimerization to give the diamagnetic, dinuclear species (Cp'Cr)2(mu-eta3,eta3-C8H12). The molecular structures Cp(eta6-Me6C6)Cr, (eta5-indenyl)(eta6-Me6C6)Cr and Cp(eta6-C8H8)Cr have been confirmed by X-ray diffraction.