A Terminally Bound Niobium Methylidyne
A Terminally Bound Niobium Methylidyne
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末端结合的铌甲基
DOI：
10.1021/jacs.6b00830
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发表时间：
2016
影响因子：
15
通讯作者：
and Daniel J. Mindiola
中科院分区：
文献类型：
--
作者：
Takashi Kurogi;Patrick J. Carroll;and Daniel J. Mindiola
（PNP）Nb（CH 3）2（OAr）（PNP = N[2-PiPr 2 -4-methylphenyl]2-，Ar = 2，6-iPr 2C 6 H3）是由（PNP）NbCl 3先用NaOAr再用2当量H3CMgCl处理而得，它可以用[FeCp 2][OTf]氧化得到（PNP）Nb（CH 3）2（OAr）（OTf）.虽然后者的光解导致形成一种罕见的铌亚甲基，（PNP）Nb CH 2（OAr）（OTf），但用叶立德H2 CPPh 3处理三氟甲磺酸二甲酯前体产生单核5族亚甲基络合物，（PNP）Nb CH（OAr）。在（PNP）Nb·CH 2（OAr）（OTf）中加入Brønsted碱也会导致次甲基的形成。固态结构分析证实了亚甲基和次甲基部分都是末端，分别具有非常短的Nb-C距离1.963（2）和1.820（2）nm。它还表明，（PNP）Nb <$CH（OAr）和NCR（R =叔丁基或1-金刚烷基）之间的氮化物交叉复分解的次甲基导致形成中性和单核铌氮化物，（PNP）Nb <$N（OAr），沿着末端炔HC <$CR。
Complex (PNP)Nb(CH3)2(OAr) (PNP = N[2-PiPr2-4-methylphenyl]2–, Ar = 2,6-iPr2C6H3), prepared from treatment of (PNP)NbCl3with 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)NbCH2(OAr)(OTf), treatment of the dimethyl triflate precursor with the ylide H2CPPh3produced the mononuclear group 5 methylidyne complex, (PNP)NbCH(OAr). Adding a Brønsted base to (PNP)NbCH2(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)NbCH(OAr) and NCR (R =tert-butyl or 1-adamantyl) results in formation of a neutral and mononuclear niobium nitride, (PNP)NbN(OAr), along with the terminal alkyne HCCR.