Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, USA.
J Am Chem Soc. 2009 Oct 21;131(41):14903-12. doi: 10.1021/ja904436a.
Treatment of the hafnocene complex bearing a strongly activated, side-on bound dinitrogen ligand, (eta(5)-C(5)Me(4)H)(2)Hf(mu(2),eta(2),eta(2)-N(2)), with two equivalents of methyl triflate yielded a mixture of products, one of which was identified as the triflato hafnocene methyl diazenide compound, (eta(5)-C(5)Me(4)H)(2)Hf(OTf)(N(2)(CH(3))), arising from methylation of one of the nitrogen atoms. This reactivity contrasts with that of the zirconocene congener, (eta(5)-C(5)Me(4)H)(2)Zr(mu(2),eta(2),eta(2)-N(2)), where methyl triflate addition yields a variety of products that lack new nitrogen-carbon bonds. The methylated hafnocene product, (eta(5)-C(5)Me(4)H)(2)Hf(OTf)(N(2)(CH(3))) provides a platform for additional transformations for the functionalized dinitrogen core. Treatment with additional methyl triflate results in a second nitrogen-carbon bond formation to yield a rare example of a triflato hafnocene hydrazonato complex. Loss of methane and formation of the hafnocene bis(triflate) accompany the transformation. Isotopic labeling studies and other experiments are consistent with a pathway involving initial methylation of the unsubstituted nitrogen in the methyl diazenido ligand followed by deprotonation by a triflate anion.
处理 Hafnocene 配合物，该配合物具有强烈激活的、侧向结合的二氮配位体 (eta(5)-C(5)Me(4)H)(2)Hf(mu(2),eta(2),eta(2)-N(2))，用两当量的甲基三氟甲磺酸酯处理得到了产物的混合物，其中一种被鉴定为三氟甲磺酸酯 Hafnocene 甲基偶氮化物化合物 (eta(5)-C(5)Me(4)H)(2)Hf(OTf)(N(2)(CH(3)))，这是由其中一个氮原子的甲基化产生的。这种反应性与锆配合物 (eta(5)-C(5)Me(4)H)(2)Zr(mu(2),eta(2),eta(2)-N(2)) 形成对比，其中甲基三氟甲磺酸酯的加成产生了缺乏新的氮-碳键的各种产物。甲基化的 Hafnocene 产物 (eta(5)-C(5)Me(4)H)(2)Hf(OTf)(N(2)(CH(3))) 为功能化二氮核的进一步转化提供了平台。用额外的甲基三氟甲磺酸酯处理导致形成第二个氮-碳键，从而得到罕见的三氟甲磺酸酯 Hafnocene 腙配合物的实例。甲烷的损失和 Hafnocene 双（三氟甲磺酸酯）的形成伴随着转化。同位素标记研究和其他实验与涉及甲基偶氮化物配体中未取代氮的初始甲基化，然后由三氟甲磺酸根阴离子脱质子化的途径一致。
