Oxidative Decarbonylation of m-Terphenyl Isocyanide Complexes of Molybdenum and Tungsten: Precursors to Low-Coordinate Isocyanide Complexes

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• 作者：Treffly B. Ditri ; Curtis E. Moore ; Arnold L. Rheingold ; Joshua S. Figueroa
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：October 17, 2011
• 年：2011
• 卷：50
• 期：20
• 页码：10448-10459
• 全文大小：1299K
• 年卷期：v.50,no.20(October 17, 2011)
• ISSN：1520-510X

文摘

Synthetic studies are presented addressing the oxidative decarbonylation of molybdenum and tungsten complexes supported by the encumbering m-terphenyl isocyanide ligand CNAr^Dipp2 (Ar^Dipp2 = 2,6-(2,6-(i-Pr)b>2b>Cb>6b>Hb>3b>)b>2b>Cb>6b>Hb>3b>). These studies represent an effort to access halide or pseudohalide M/CNAr^Dipp2 species (M = Mo, W) for use as precursors to low-coordinate, low-valent group 6 isocyanide complexes. The synthesis and structural chemistry of the tetra- and tricarbonyl tungsten complexes trans-W(CO)b>4b>(CNAr^Dipp2)b>2b> and trans-W(NCMe)(CO)b>3b>(CNAr^Dipp2)b>2b> are reported. The acetonitrile adducts trans-M(NCMe)(CO)b>3b>(CNAr^Dipp2)b>2b> (M = Mo, W) react with Ib>2b> to form divalent, diiodide complexes in which the extent of decarbonylation differs between Mo and W. In the molybdenum example, the diiodide, dicarbonyl complex MoIb>2b>(CO)b>2b>(CNAr^Dipp2)b>2b> is generated, which has an S = 1 ground state in solution. Paramagnetic group 6 MXb>2b>Lb>4b> complexes are rare, and the structure of MoIb>2b>(CO)b>2b>(CNAr^Dipp2)b>2b> is discussed in relation to other diamagnetic and Cb>2vb>-distorted MXb>2b>Lb>4b> complexes. Diiodide MoIb>2b>(CO)b>2b>(CNAr^Dipp2)b>2b> reacts further with Ib>2b> to effect complete decarbonylation, producing the paramagnetic tetraiodide complex trans-MoIb>4b>(CNAr^Dipp2)b>2b>. The reactivity of the trans-M(NCMe)(CO)b>3b>(CNAr^Dipp2)b>2b> (M = Mo, W) complexes toward benzoyl peroxide is also surveyed, and it is shown that dicarboxylate complexes can be obtained by oxidative or salt-elimination routes. The reduction behavior of the tetraiodide complex trans-MoIb>4b>(CNAr^Dipp2)b>2b> toward Mg metal and sodium amalgam is studied. In benzene solution under Nb>2b>, trans-MoIb>4b>(CNAr^Dipp2)b>2b> is reduced by Na/Hg to the 畏⁶-arene-dinitrogen complex, (畏⁶-Cb>6b>Hb>6b>)Mo(Nb>2b>)(CNAr^Dipp2)b>2b>. The diiodide-畏⁶-benzene complex (畏⁶-Cb>6b>Hb>6b>)MoIb>2b>(CNAr^Dipp2)b>2b> is an isolable intermediate in this reduction reaction, and its formation and structure are discussed in context of putative low-coordinate, low-valent molybdenum isocyanide complexes.