Yongqiang Zhang

Synthesis and characterization of new germylferrocenyl, germylferrocenophane and polymeric germyleneferrocenylene systems

Abstract New germanium-bridged [1]ferrocenophanes Fe(η5-C5H4)2GeClR (1), (R=Me (1a), t-Bu (1b), Ph (1c)) were prepared by the reaction of Fe(η5-C5H4Li)2·TMEDA (TMEDA=tetramethylethylenediamine) with the corresponding chlorogermanes, RGeCl3 (R=Me, t-Bu, Ph). Ring-opening addition of HCl to 1c resulted in the formation of (η5-C5H4)Fe(η5-C5H5)GeCl2Ph (2) which was reacted with dilithioferrocene·TMEDA to form Fe(η5-C5H4)2FcPhGe (3). All complexes were characterized by 13C and 1H NMR, and the structure of Fe(η5-C5H4)2GeClPh was determined by single-crystal X-ray diffraction analysis and exhibits a dihedral angle between the planes of the cyclopentadienyl rings of 18.4°. Cyclic voltammetric analysis of 1a, 1b, and 1c in CH2Cl2 revealed that each ferrocenophane exhibits a reversible, one-electron oxidation, at a higher oxidation potential than that of ferrocene. The voltammogram of 3 shows two reversible redox processes, one for the ferrocenophane moiety and a second for the pendant ferrocene group. Thermal ring-opening of 3 produced good yields of the corresponding polymer [Fe(η5-C5H4)2FcPhGe]n.

Photochemistry of bridged disilyldiiron complexes (SiMe2)[(η5-C5H4)Fe(CO) 2SiMe2SiMe2R]2, R=Me, Ph

Photochemical irradiation of the new bimetallic disilyliron complexes (SiMe 2 )[(η 5 -C 5 H 4 )Fe(CO) 2 SiMe 2 SiMe 2 R] 2 , R=Me, Ph, results in silylene elimination chemistry, as observed for the mono-metallic analogs, resulting in the formation of complexes (SiMe 2 )[(η 5 -C 5 H 4 )Fe(CO) 2 SiMe 2 R] 2 . The intermediate silyl(silylene) complexes can be intercepted with HMPA. Apart from a very reactive minor product that we have been unable to identify at this time, the proximity of the two transition metal centers has little impact upon the observed chemistry.