Organometallic Sulfur Complexes. IV^a. Synthesis and Characterization of [Fe(Bu^tC₅H₄)(CO)₂]₂ and [Fe(1, 3-di-Bu^tC₅H₃)(CO)₂]₂ and the S-Bonded Thiocarboxylate Derivatives, Fe(Bu^tC₅H₄)(CO)₂Scor and Fe(1, 3-di-Bu^tC₅H₃)(CO)₂Scor

Abstract

The new substituted cyclopentadienyl organoiron dimers [Fe- (Bu^tC₅H₄)(CO)₂]₂, I and [Fe(1,3-di-Bu^tC₅H₃)(CO)₂]₂, II, were prepared from the reaction of Fe₂(CO)₉ with t-butylcyclopentadiene, or 1,3-di-t-butylcyclopentadiene. The equilibrium concentration of the trans-geometrical isomer decreases in the order II>I> [FeCp(CO)₂]₂ as a result of increasing bulkiness of Cp-substituents and increasing the steric repulsion in the cis-configurations. The ¹H NMR spectra of I and II showed an anisotropic shielding effect of the bridging metal-carbonyl on the cyclopentadienyl protons.