251479-69-3Relevant academic research and scientific papers
Novel Rearrangement Reactions. 6. Thermal Rearrangement of Disilyl-Bridged Diiron Complexes Containing Isocyanide Ligands and Stereochemistry of the Rearranged Products
Zhang, Yongqiang,Sun, Xiuli,Wang, Baiquan,Xu, Shansheng,Zhou, Xiuzhong
, p. 4493 - 4500 (1999)
Treatment of (Me2SiSiMe2)[(η5-C5H 3R1)Fe(CO)]2(μ-CO)2 (R1 = H (1), R1 = t-Bu (5)) with R2NC (R2 = C6H11, t-Bu) in benzene afforded isocyanide-substituted complexes [(η5:η5-C5H3R 1-Me2SiSiMe2C5H3R 1)Fe2(CO)(CNR2)(μ-CO)2] (R1 = H, R2 = C6H11 (3), R2 = t-Bu (4); R1 = R2 = t-Bu (6)). Further investigations indicated that the cis substrate 5c afforded only the cis product (6c), while the trans substrate 5t afforded only the trans product (6t). When 3 and 4 were heated respectively in xylene, three different rearranged products [{(Me2Si)(η5-C5H4)-Fe(CO)L 1}{(Me2Si)(η5-C5H 4)Fe(CO)L2}] (L1 = L2 - CO (2); L1 = C6H11NC, L2 = CO (7), L2 = C6H11NC (9); L1 = t-BuNC, L2 = CO (8), L2 = t-BuNC (10)) were obtained. Similarly, thermal treatment of 6t afforded three different cis rearranged products, 11c, 12c, and 13c, while treatment of 6c yielded three different trans rearranged products, 11t, 12t, and 13t. This indicated that the rearrangement still follows the reaction mechanism proposed previously on the basis of the intramolecular nature of this reaction if we only take into account the configuration of two tert-butyl groups on the Cp rings. To explain the formation of three different products, an alternative mechanism involving free ligand exchange to form three different iron-centered radical intermediates is proposed as a supplement to the previous mechanism. The complex stereochemistry in the molecules of 12 and 13 is discussed. Molecular structures of 8, 9t, 12t, and 13c have been determined by single-crystal X-ray diffraction.
