Conformations of heteroferrocenes. Synthesis and crystal and dynamic solution behavior of 2,2′,5,5′-tetrakis(trimethylsilyl)-3,3′,4,4′- tetramethyl-1,1′-distibaferrocene

Article abstract of DOI:10.1021/om00040a019

2,2′,5,5′-Tetrakis(trimethylsilyl)-3,3′,4,4′- tetramethyl-1,1′-distibaferrocene (2) as been obtained from the reaction of 1-phenyl-2,5-bis(trimethylsilyl)-3,4-dimethylstibole with lithium followed by FeCl₂. In a similar manner 2,2′,5,5′-tetrakis(trimethylsilyl)-3,3′,4,4′- tetramethyl-1,1′-dibismaferrocene (3) was obtained from 1-phenyl-2,5-bis(trimethylsilyl)-3,4-dimethylbismole. Dark red crystals of 2 form in the P1 (No. 2) space group with Z = 2, a = 9.243 (2) ?, b = 11.310 (2) ?, c = 17.345 (3) ?, α = 76.51 (1)°, β = 79.23 (2)°, and γ = 73.18 (1)°. A full structure has been determined and shows a ferrocene-like arrangement in which the trimethylsilyl groups are arranged in a staggered fashion. In solution a barrier to ring rotation for both 2 and 3 of ΔG? = 13 kcal/mol can be estimated from variable-temperature ¹H-NMR spectroscopy.