A Tertiary Carbon–Iron Bond as an FeICl Synthon and the Reductive Alkylation of Diphosphine-Supported Iron(II) Chloride Complexes to Low-Valent Iron

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• 作者：Aaron M. Tondreau ; Brian L. Scott ; James M. Boncella
• 刊名：Organometallics
• 出版年：2016
• 出版时间：June 13, 2016
• 年：2016
• 卷：35
• 期：11
• 页码：1643-1651
• 全文大小：409K
• 年卷期：0
• ISSN：1520-6041

文摘

Ligand-induced reduction of ferrous alkyl complexes via homolytic cleavage of the alkyl fragment was explored with simple chelating diphosphines. The reactivities of the sodium salts of diphenylmethane, phenyl(trimethylsilyl)methane, or diphenyl(trimethylsilyl)methane were explored in their reactivity with (py)₄FeCl₂. A series of monoalkylated salts of the type (py)₂FeRCl were prepared and characterized from the addition of 1 equiv of the corresponding alkyl sodium species. These complexes are isostructural and have similar magnetic properties. The double alkylation of (py)₄FeCl₂ resulted in the formation of tetrahedral high-spin iron complexes with the sodium salts of diphenylmethane and phenyl(trimethylsilyl)methane that readily decomposed. A bis(cyclohexadienyl) sandwich complex was formed with the addition of 2 equiv of the tertiary alkyl species sodium diphenyl(trimethylsilyl)methane. The addition of chelating phosphines to (py)₂FeRCl resulted in the overall transfer of Fe(I) chloride concurrent with loss of pyridine and alkyl radical. (dmpe)₂FeCl was synthesized via addition of 1 equiv of sodium diphenyl(trimethylsilyl)methane, whereas the addition of 2 equiv of the sodium compound to (dmpe)₂FeCl₂ gave the reduced Fe(0) nitrogen complex (dmpe)₂Fe(N₂). These results demonstrate that iron–alkyl homolysis can be used to afford clean, low-valent iron complexes without the use of alkali metals.