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Komplexe mit sterisch anspruchsvollen Liganden, V. Synthese von 4‐ tert ‐Butyl‐1,2‐bis(trimethylsilyl)cyclopentadienyl‐Komplexen des Eisens und Cobalts

1989; Wiley; Volume: 122; Issue: 6 Linguagem: Inglês

10.1002/cber.19891220612

0009-2940

Jun Okuda,

Synthesis and characterization of novel inorganic/organometallic compounds

Complexes with Sterically Demanding Ligands, V. – Synthesis of 4‐ tert ‐Butyl‐1,2‐bis(trimethylsilyl) cyclopentadienyl Complexes of Iron and Cobalt 2‐ tert ‐Butyl‐5,5‐bis(trimethylsilyl)‐2,4‐cyclopentadiene ( 1 ) is prepared in a one‐pot synthesis starting from 1,1‐dimethylfulvene. Deprotonation of 1 with n ‐butyllithium yields the lithium derivative Li[C 5 H 2 (CMe 3 )(SiMe 3 ) 2 ] ( 2 ) which is treated with FeBr 2 · DME and CO to cleanly give [C 5 H 2 (CMe 3 )(SiMe 3 ) 2 ]Fe(CO) 2 Br ( 3 ). Ferrocene and cobaltocenium cation derivatives [C 5 H 2 ‐(CMe 3 )(SiMe 3 ) 2 ] 2 M (M = Fe: 4 ; M = Co ⊕ PF 6 ⊖ : 5 ) have also been synthesized using 2 . Variable‐temperature 1 H‐NMR spectroscopy shows that rotation of the five‐membered ring about the metal‐ring axis is hindered in these metallocenes.