Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States.
J Am Chem Soc. 2016 Apr 6;138(13):4306-9. doi: 10.1021/jacs.6b00830. Epub 2016 Mar 24.
Complex (PNP)Nb(CH3)2(OAr) (PNP = N[2-P(i)Pr2-4-methylphenyl]2(-), Ar = 2,6-(i)Pr2C6H3), 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.
复杂的（PNP）Nb（CH3）2（OAr）（PNP = N[2-P（i）Pr2-4-甲基苯基]2（-），Ar = 2,6-（i）Pr2C6H3），由（PNP）NbCl3与 NaOAr 处理后再与 2 当量的 H3CMgCl 反应制得，可被[FeCp2][OTf]氧化，得到（PNP）Nb（CH3）2（OAr）（OTf）。虽然后者的光解导致了一种罕见的铌亚甲基的形成，（PNP）Nb═CH2（OAr）（OTf），但用叶立德 H2CPPh3处理二甲基三氟甲磺酸酯前体产生了单核第 5 族亚甲基配合物，（PNP）Nb≡CH（OAr）。向（PNP）Nb═CH2（OAr）（OTf）中添加布朗斯台德碱也导致了亚甲基的形成。固态结构分析证实，两个亚甲基和亚甲基部分都是末端的，具有非常短的 Nb-C 距离分别为 1.963（2）和 1.820（2）Å。还表明，亚甲基与氮化物交叉复分解反应之间的（PNP）Nb≡CH（OAr）和 NCR（R = 叔丁基或 1-金刚烷基）结果形成了一个中性和单核铌氮化物，（PNP）Nb≡N（OAr），以及末端炔烃 HC≡CR。
