82397-22-6Relevant articles and documents
INDENYL AND FLUORENYL TRANSITION METAL COMPLEXES XIII. DETERMINATION OF GEOMETRIC CONFIGURATION OF (9-SUBSTITUTED FLUORENES)CHROMIUM TRICARBONYL COMPLEXES BY ASIS-EFFECT IN 1H NMR SPECTRA
Ustynyuk, N. A.,Novikova, L. N.,Bel'skii, V. K.,Oprunenko, Yu. F.,Malyugina, S. G.,et al.
, p. 31 - 44 (1985)
A method to determine the geometric configuration of chromium tricarbonyl complexes of 9-substituted fluorenes (η6-9-RC13H9)Cr(CO)3 which allows one to distinguish between exo-isomers (IIIa-e) and endo-isomers (Va-e) is proposed; a, R = CH3; b, R = CH2C6H5, c, R = D; d, R = t-C4H9; e, R = C6H5.This method is based on measuring chemical shifts induced in 1H NMR spectra by aromatic solvents when passing from CDCl3 to C6D6 solutions (ASIS effect).The validity of the criterion is confirmed by X-ray analysis of IIIb.Exo-isomers, IIIb,c were obtained by alkylation of the η6-fluorenylchromium tricarbonyl anion (I) with the corresponding halides RX in tetrahydrofuran (THF) at low temperature.Endo-isomers (Vb,c) have been obtained by alkylation of the η5-fluorenylchromium tricarbonyl anion (II) with subsequent thermal rearrangement of intermediate ?-organometal derivatives (IV) without their isolation.Endo-isomers, Vd,e have been formed by stereoselective protonation of substituted complex anions 6-9-RC13H8)Cr(CO)3>-.
INDENYL AND FLUORENYL TRANSITION METAL COMPLEXES. VII. INNERSPHERE RICOCHET REARRANGEMENTS ON ALKYLATION OF η5-INDENYL- AND η5-FLUORENYLTRICARBONYLCHROMATE ANIONS
Nesmeyanov, A. N.,Ustynyuk, N. A.,Novikova, L. N.,Andrianov, V. G.,Struchkov, Yu. T.
, p. 239 - 250 (2007/10/02)
Alkylation of K5-C9H7Cr(CO)3> (Xa) with CH3I and C6H5CH2Br leads to o-alkyl derivatives of η5-C9H7Cr(CO)3Alk type.These complexes undergo innersphere ricochet rearrangement, with the alkyl group being shifted to the endo position at C(1) and the chromium tricarbonyl group shifted to the benzene nucleus.The structure of the product of such a rearrangement in the case of η5-C9H7(CO)3CrCH2C6H5, i.e. (1-benzyl-3a,4-7,7a-η6-indene)chromium tricarbonyl (XVIII), is established by a low temperature X-ray study, indicating an endo position for the benzyl radical.On alkylation of equilibrium tautomeric mixtures of η5- and η6-fluorenyl-chromium tricarbonyl anions XIa XIb under similar conditions, the η5-anion (Xa) yields a ?-alkyl derivative, which is rearranged to (9-endo-alkyl-1-4,4a,9a-η6-fluorene)chromium tricarbonyl.Electrophilic attack of the η6-anion (XIb) takes place on the outer side at C(9) and leads to a corresponding 9-exo-alkyl derivative.
