C-F or C-H bond activation and C-C coupling reactions of fluorinated pyridines at rhodium: synthesis, structure and reactivity of a variety of tetrafluoropyridyl complexes.
C-F or C-H bond activation and C-C coupling reactions of fluorinated pyridines at rhodium: synthesis, structure and reactivity of a variety of tetrafluoropyridyl complexes.
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DOI：
10.1039/b414734k
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发表时间：
2004-11
影响因子：
4
通讯作者：
Daniel Noveski;T. Braun;B. Neumann;A. Stammler;H. Stammler
中科院分区：
文献类型：
--
作者：
Daniel Noveski;T. Braun;B. Neumann;A. Stammler;H. Stammler
[RhH（PEt 3）3]（1）或[RhH（PEt 3）4]（2）与五氟吡啶或2，3，5，6-四氟吡啶反应得到活化产物[Rh（4-C5 NF 4）（PEt 3）3]（3）。用CO、13 CO或CNTBu处理3可形成反式-[Rh（4-C5 NF 4）（CO）（PEt 3）2]（4a）、反式-[Rh（4-C5 NF 4）（13 CO）（PEt 3）2]（4 b）和反式-[Rh（4-C5 NF 4）（CNTBu）（PEt 3）2]（5）。铑（III）化合物trans-[RhI（CH 3）（4-C5 NF 4）（PEt 3）2]（6a）和trans-[RhI（13 CH 3）（4-C5 NF 4）（PEt 3）2]（6 b）可通过3与CH 3 I或13 CH 3 I反应得到。在CO或13 CO存在下，这些配合物转化为trans-[RhI（CH 3）（4-C5 NF 4）（CO）（PEt 3）2]（7a）、trans-[RhI（13 CH 3）（4-C5 NF 4）（CO）（PEt 3）2]（7 b）和trans-[RhI（13 CH 3）（4-C5 NF 4）（13 CO）（PEt 3）2]（7 c）。7a-7 c中羰基和甲基配体的反式排列已经通过7 c的13 C NMR谱中的13 C-13 C偶合常数证实。4a或4 b与CH 3 I或13 CH 3 I反应，分别得到酰基化合物trans-[RhI（COCH 3）（4-C5 NF 4）（PEt 3）2]（8a）和trans-[RhI（13 CO 13 CH 3）（4-C5 NF 4）（PEt 3）2]（8b）。配合物8a与更多的CH 3 I缓慢反应，得到[PEt 3 Me][Rh（I）2（COCH 3）（4-C5 NF 4）（PEt 3）]（9）。加热7a的溶液，得到配合物trans-[RhI（CO）（PEt 3）2]（10）和C-C偶合产物4-甲基四氟吡啶（11）。在CO存在下，在高温下，配合物8a也与新的酮4-乙酰基四氟吡啶（12）一起形成10。配合物3、4a、5、6a、8a和9的晶体结构用X射线衍射法测定。6a和8a的19 F-1H HMQC NMR溶液光谱揭示了膦中的甲基与结合在铑上的甲基或酰基配体的紧密接触。
Reactions of [RhH(PEt3)3] (1) or [RhH(PEt3)4] (2) with pentafluoropyridine or 2,3,5,6-tetrafluoropyridine afford the activation product [Rh(4-C5NF4)(PEt3)3] (3). Treatment of 3 with CO, 13CO or CNtBu effects the formation of trans-[Rh(4-C5NF4)(CO)(PEt3)2] (4a), trans-[Rh(4-C5NF4)(13CO)(PEt3)2] (4b) and trans-[Rh(4-C5NF4)(CNtBu)(PEt3)2] (5). The rhodium(III) compounds trans-[RhI(CH3)(4-C5NF4)(PEt3)2] (6a) and trans-[RhI(13CH3)(4-C5NF4)(PEt3)2] (6b) are accessible on reaction of 3 with CH3I or 13CH3I. In the presence of CO or 13CO these complexes convert into trans-[RhI(CH3)(4-C5NF4)(CO)(PEt3)2] (7a), trans-[RhI(13CH3)(4-C5NF4)(CO)(PEt3)2] (7b) and trans-[RhI(13CH3)(4-C5NF4)(13CO)(PEt3)2] (7c). The trans arrangement of the carbonyl and methyl ligand in 7a-7c has been confirmed by the 13C-13C coupling constant in the 13C NMR spectrum of 7c. A reaction of 4a or 4b with CH3I or 13CH3I yields the acyl compounds trans-[RhI(COCH3)(4-C5NF4)(PEt3)2] (8a) and trans-[RhI(13CO13CH3)(4-C5NF4)(PEt3)2] (8b), respectively. Complex 8a slowly reacts with more CH3I to give [PEt3Me][Rh(I)2(COCH3)(4-C5NF4)(PEt3)](9). On heating a solution of 7a, the complex trans-[RhI(CO)(PEt3)2] (10) and the C-C coupled product 4-methyltetrafluoropyridine (11) have been obtained. Complex 8a also forms 10 at elevated temperatures in the presence of CO together with the new ketone 4-acetyltetrafluoropyridine (12). The structures of the complexes 3, 4a, 5, 6a, 8a and 9 have been determined by X-ray crystallography. 19F-1H HMQC NMR solution spectra of 6a and 8a reveal a close contact of the methyl groups in the phosphine to the methyl or acyl ligand bound at rhodium.