Novel Rearrangement Reactions. 2. Thermal Rearrangement Stereospecificity of Complex (Me₂SiSiMe₂)[(η⁵-IndH₄)Fe(CO)]₂(μ-CO)₂

Abstract

The catalytic hydrogenation of the indenyl complex (Me 2 SiSiMe 2 )[(η 5 -Ind)Fe(CO)] 2 (μ-CO) 2 ( 2 ) in CH 2 Cl 2 afforded the tetrahydroindenyl complex (Me 2 SiSiMe 2 )[(η 5 -IndH 4 )Fe(CO)] 2 (μ-CO) 2 ( 3 ), existing as a mixture of cis and trans isomers ( 3c and 3t ), which were separated by column chromatography. When the two isomers were heated in xylene, respectively, the cis substrate 3c rearranged to the trans product [Me 2 Si(η 5 -IndH 4 )Fe(CO) 2 ] 2 ( 4t ), while the trans substrate 3t yielded the cis product [Me 2 Si(η 5 -IndH 4 )Fe(CO) 2 ] 2 ( 4c ). This indicates that the rearrangement reaction is stereospecific, which is consistent with the result observed in the rearrangement of complex (Me 2 SiSiMe 2 )[(η 5 -t-BuC 5 H 3 )Fe(CO)] 2 (μ-CO) 2 ( 5 ). By analogy with the mechanism proposed based on detailed investigations of 5, the pathway for formation of 4 is described. Molecular structures of 3c, 3t, 4t, and 4c were determined by X-ray diffraction.