Silyl Derivatives of the Mixed Sandwiches Cyclopentadienyl Manganese Benzene and Cyclopentadienyl Manganese Biphenyl, CpMn(C6H6) and CpMn(C6H5-Ph)

Abstract

Mixed manganese sandwich complexes containing a silyl-substituted cyclopentadienyl ring, e. g. (η5 - C5H4 - R)Mn(η6- C6H6) (3a - c) and (η5- C5H4 - R)Mn(η6- C6H5 - Ph) (4a - c); (R = SiMe3 (a), Si2Me5 (b) and SiMe2 tBu (c)), were obtained in low yield via intermediates {(η5 - C5H4 - R)MnCl} and their reaction with phenyl Grignard reagents. Use of the 4-trimethylsilyl-phenyl magnesium halide in the reaction with the intermediate {CpMnCl} led to complexes with silylsubstituted arene rings, CpMn(η6 - C6H5 - R′) (5a) and CpMn(η6 -R′ - C6H5 - C6H5 - R′) (6a); (R′ = SiMe3 (a)). Dilithiation of CpMn6H6) (1) and subsequent reaction with a chlorosilane gave (η5-C5H4 - R)Mn(η6 - C6H5 - R′) (7a,b); (R = R′ = SiMe3 (a), Si2Me5 (b)). A cyclophane 8 in which five- and six-membered ring are linked through a -Me2Si-SiMe2- bridge was obtained using 1,2-dichloro-tetramethyldisilane. The mixed manganese sandw ich complexes were thoroughly characterized by 1H , 13C, 29Si and 55Mn NMR spectroscopy. The 55Mn spectra can be used to detect low-yield side-products.