Stereoselective Synthesis and Coordination Behavior of Phosphorus-Bridged [1.1]Ferrocenophanes

Chlorination with HCl of a mixture of syn- and anti-P(NEt2)-bridged [1.1]ferrocenophane 3 derived
from [Fe{(η5-C5H4)PCl(NEt2)}2] 2 accompanied facile anti-to-syn conversion to give the syn isomer of
PCl-bridged [1.1]ferrocenophane syn-4 selectively in 90% yield, and treatment of syn-4 with PhLi, Me3SiCH2Li, or p-TolMgBr afforded the corresponding diarylated or dialkylated compounds syn-5 to syn-7.
Reactions of syn-5 with [PdCl2(COD)], [PdMe2(TMEDA)], and NiCl2 gave respectively four-coordinate
[PdCl2(syn-5)], [PdMe2(syn-5)], and [NiCl2(syn-5)] complexes, the former two of which had a distorted
square-planar structure with the latter adopting a tetrahedral geometry. In addition, syn-5 acted as a bridging
ligand toward piano-stool Mn carbonyl complex fragments to give a novel dinuclear complex, [{Cp‘Mn(CO)2}2(μ-syn-5)] (Cp‘ = C5H4CH3).