Indium-Bridged [1]Ferrocenophanes

Indium-bridged [1]ferrocenophanes ([1]FCPs) and [1.1]ferrocenophanes ([1.1]FCPs) were synthesized from dilithioferrocene species and indium dichlorides. The reaction of Li(2)fctmeda (fc=(H4C5)(2)Fe) and (Mamx)InCl2 (Mamx=6-(Me2NCH2)-2,4-tBu(2)C(6)H(2)) gave a mixture of the [1]FCP (Mamx)Infc (4(1)), the [1.1]FCP [(Mamx)Infc](2) (4(2)), and oligomers [(Mamx)Infc](n) (4(n)). In a similar reaction, employing the enantiomerically pure, planar-chiral (S-p,S-p)-1,1-dibromo-2,2-diisopropylferrocene (1) as a precursor for the dilithioferrocene derivative Li(2)fc(iPr2), equipped with two iPr groups in the position, gave the inda[1]ferrocenophane 5(1) [(Mamx)Infc(iPr2)] selectively. Species 5(1) underwent ring-opening polymerization to give the polymer 5(n). The reaction between Li(2)fc(iPr2) and ArInCl2 (Ar=2-(Me2NCH2)C6H4) gave an inseparable mixture of the [1]FCP ArInfc(iPr2) (6(1)) and the [1.1]FCP [ArInfc(iPr2)](2) (6(2)). Hydrogenolysis reactions (BP86/TZ2P) of the four inda[1]ferrocenophanes revealed that the structurally most distorted species (5(1)) is also the most strained [1]FCP.