Hahn F Ekkehardt, García Plumed César, Münder Marco, Lügger Thomas
Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 36, 48149 Münster, Germany.
Chemistry. 2004 Dec 3;10(24):6285-93. doi: 10.1002/chem.200400576.
The reaction of 2-nitrophenyl isocyanide 2 with [M(CO)5(thf)] (M=Cr, Mo, W) yields the isocyanide complexes [M(CO)5(2)] (3: M=Cr; 4: M=Mo; 5: M=W). Complexes 3-5 react with elemental tin under reduction of the nitro function of the isocyanide ligand to give the complexes with the unstable 2-aminophenyl isocyanide ligand. The coordinated 2-aminophenyl isocyanide ligand in all three complexes reacts spontaneously under intramolecular nucleophilic attack of the primary amine at the isocyanide carbon atom to yield the complexes with the NH,NH-benzimidazol-2-ylidene ligand (6: M=Cr; 7: M=Mo; 8: M=W). An incomplete reduction of the nitro group in 3-5 is observed when hydrazine hydrate is used instead of tin. Here the formation of complexes with a coordinated 2-hydroxylamine-functionalized phenyl isocyanide [(CO)5M-CN-C6H(4-)-2-N(H)-OH] is postulated and this unstable ligand again undergoes intramolecular cyclization to give the NH,NOH-stabilized benzimidazol-2-ylidene complexes 9-11. The tungsten derivative 11 can be allylated stepwise by a deprotonation/alkylation sequence first at the OH and then at the NH position to yield the monoallylated and diallylated species 12 and 13. The molecular structures of 3-5 and 12-13 were established by X-ray crystallography.
2-硝基苯基异腈2与[M(CO)5(thf)]（M = Cr、Mo、W）反应生成异腈配合物[M(CO)5(2)]（3：M = Cr；4：M = Mo；5：M = W）。配合物3 - 5与元素锡反应，异腈配体的硝基官能团被还原，得到含有不稳定的2-氨基苯基异腈配体的配合物。在所有三种配合物中，配位的2-氨基苯基异腈配体在伯胺对异腈碳原子的分子内亲核攻击下自发反应，生成含有NH,NH-苯并咪唑-2-亚基配体的配合物（6：M = Cr；7：M = Mo；8：M = W）。当使用水合肼代替锡时，观察到3 - 5中的硝基不完全还原。在此推测形成了含有配位的2-羟胺官能化苯基异腈[(CO)5M-CN-C6H(4-)-2-N(H)-OH]的配合物，并且这种不稳定的配体再次进行分子内环化，得到NH,NOH稳定的苯并咪唑-2-亚基配合物9 - 11。钨衍生物11可以通过去质子化/烷基化序列依次在OH位然后在NH位进行烯丙基化，得到单烯丙基化和二烯丙基化产物12和13。通过X射线晶体学确定了3 - 5和12 - 13的分子结构。
