Chemistry of nickel tetrafluoropyridyl derivatives: their versatile behaviour with Brønsted acids and the Lewis acid BF3 †
作者:Stephen J. Archibald、Thomas Braun、Joseph A. Gaunt、James E. Hobson、Robin N. Perutz
DOI:10.1039/b002333g
日期:——
Treatment of trans-[NiF(2-C5NF4)(PEt3)2] (C5NF4 = tetrafluoropyridyl) (1) with HCl effects the formation of the air stable chloride complex trans-[NiCl(2-C5NF4)(PEt3)2] (2). The reaction of 2 with excess HCl slowly yields 2,3,4,5-tetrafluoropyridine (4). On reaction of 4 with [Ni(COD)(PEt3)2], the C–F activation product trans-[NiF(2-C5NF3H)(PEt3)2] (5) is formed instantly. The bifluoride compound trans-[Ni(FHF)(2-C5NF4)(PEt3)2] (6) is obtained on treatment of 1 with Et3N·3HF. Reaction of 2 with HBF4 yields the binuclear complex [NiClμ-κ2(C,N)-(2-C5NF4)}(PEt3)]2 (7). The X-ray crystal structure of 7 reveals a “butterfly”-shaped dimeric complex with square-planar coordination at both nickel atoms, with Ni–N distances of 1.965(4) and 1.955(4) Å and Ni–C distances of 1.884(5) and 1.875(5) Å. Treatment of 1 with BF3·OEt2 in the presence of acetonitrile yields the cationic compound trans-[Ni(2-C5NF4)(NCMe)(PEt3)2]BF4 (8), while reaction of trans-[Ni(OTf)(2-C5NF4)(PEt3)2] (3) with NaBAr′4 and acetonitrile gives trans-[Ni(2-C5NF4)(NCMe)(PEt3)2]BAr′4 (9) [Ar′ = 3,5-C6H3(CF3)2]. The studies reported in this paper provide methods for the synthesis of tetrafluoropyridines substituted in the 2-position and demonstrate the behaviour of nickel derivatives with Brønsted acids and the Lewis acid BF3.
对转-[NiF(2-C5NF4)(PEt3)2] (C5NF4 = 四氟吡啶基) (1) 进行HCl处理,形成空气稳定的氯化物络合物转-[NiCl(2-C5NF4)(PEt3)2] (2)。与过量HCl反应时,2缓慢生成2,3,4,5-四氟吡啶 (4)。4与[Ni(COD)(PEt3)2]反应时,立即生成C–F活化产物转-[NiF(2-C5NF3H)(PEt3)2] (5)。将1与Et3N·3HF处理,得到双氟化合物转-[Ni(FHF)(2-C5NF4)(PEt3)2] (6)。2与HBF4反应得到双核络合物[NiClμ-κ2(C,N)-(2-C5NF4)}(PEt3)]2 (7)。7的X射线晶体结构显示出一个“蝴蝶”形状的二聚体络合物,两个镍原子的配位均为方形平面,Ni–N距离为1.965(4)和1.955(4) Å,Ni–C距离为1.884(5)和1.875(5) Å。将1与BF3·OEt2在乙腈存在下反应,得到阳离子化合物转-[Ni(2-C5NF4)(NCMe)(PEt3)2]BF4 (8),而转-[Ni(OTf)(2-C5NF4)(PEt3)2] (3)与NaBAr′4和乙腈反应则得到转-[Ni(2-C5NF4)(NCMe)(PEt3)2]BAr′4 (9) [Ar′ = 3,5-C6H3(CF3)2]。本文报告的研究提供了在2位取代的四氟吡啶的合成方法,并展示了镍衍生物与布朗斯特酸及路易斯酸BF3的行为。