Characterization and electrochemical study of bis(ferrocenes) with a furan spacer and ferrocenophanes prepared from α-bromoacetyl substituted ferrocenes

The bis(ferrocene) derivative 3-bromo-2,4-bis(ferrocenyl)furan (3) was prepared from α-bromoacetylferrocene (1) by basic treatment. The heterotrimetallic complex 7 containing two ferrocene moieties and Pd(II) was synthesized by oxidative addition of 3 with a zerovalent palladium precursor. These stable solids were characterized throroughly by spectroscopic means and electrochemical methods (CV and DPV). The new [4]-ferrocenophane (8), with all sp2C bridges was prepared easily from 1,1′-bis(α-bromoacetyl)ferrocene (2) by treatment with KtBuO whereas the reaction with Na2S provides a mixture of 3-thia-[5]ferrocenophane (9), as the major product, and [5,5]ferrocenophane (10), as the minor product.