A Terminally Bound Niobium Methylidyne

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• 作者：Takashi Kurogi ; Patrick J. Carroll ; Daniel J. Mindiola
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：April 6, 2016
• 年：2016
• 卷：138
• 期：13
• 页码：4306-4309
• 全文大小：348K
• ISSN：1520-5126

文摘

Complex (PNP)Nb(CH₃)₂(OAr) (PNP = N[2-PⁱPr₂-4-methylphenyl]₂^–, Ar = 2,6-ⁱPr₂C₆H₃), prepared from treatment of (PNP)NbCl₃ with NaOAr followed by 2 equiv of H₃CMgCl, can be oxidized with [FeCp₂][OTf] to afford (PNP)Nb(CH₃)₂(OAr)(OTf). While photolysis of the latter resulted in formation of a rare example of a niobium methylidene, (PNP)Nb═CH₂(OAr)(OTf), treatment of the dimethyl triflate precursor with the ylide H₂CPPh₃ produced the mononuclear group 5 methylidyne complex, (PNP)Nb≡CH(OAr). Adding a Brønsted base to (PNP)Nb═CH₂(OAr)(OTf) also resulted in formation of the methylidyne. Solid-state structural analysis confirms both methylidene and methylidyne moieties to be terminal, having very short Nb–C distances of 1.963(2) and 1.820(2) Å, respectively. It is also shown that methylidyne for nitride cross-metathesis between (PNP)Nb≡CH(OAr) and NCR (R = tert-butyl or 1-adamantyl) results in formation of a neutral and mononuclear niobium nitride, (PNP)Nb≡N(OAr), along with the terminal alkyne HC≡CR.