Competitive Carbon-Sulfur vs Carbon-Carbon Bond Activation of 2-Cyanothiophene with [Ni(dippe)H]2
Competitive Carbon-Sulfur vs Carbon-Carbon Bond Activation of 2-Cyanothiophene with [Ni(dippe)H]2
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DOI：
10.1021/ja104158h
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发表时间：
2010-09-08
影响因子：
15
通讯作者：
Jones, William D.
中科院分区：
文献类型：
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作者：
Grochowski, Matthew R.;Li, Ting;Jones, William D.
用均相有机金属化合物[Ni(Dippe)H](2)(1)研究了C-C和C-S键的断裂过程。当1与2-氰基噻吩室温反应时，氰基取代的C-S键发生断裂，生成镍金属环络合物(Dippe)Ni(kappa(2)-S，C-SCH=CHCH=C(CN))(2a)，其结构经核磁共振谱和X射线衍射法确证。当在溶液中加热时，2A转化为C CN裂解产物(Dippe)Ni(CN)(2-噻吩基)(3)。进一步观察，在低温下用P-31核磁共振波谱观察到了另外四个中间体。通过独立合成、理论计算、化学表征和实验先例相结合，阐明了中间体的结构。动力学产物(DIPPE)Ni(kappa(2)-S，C-Sc(CN)=CHCH=CH)(2b)由未取代的C S键裂解而成，还生成了Ni(0)eta(2)-腈中间体(Dippe)Ni(eta(2)-C，N-2-氰基噻吩基)(4)和双核混合Ni(0)Ni(II)产物(6b)。对该体系进行了完整的密度泛函分析，揭示了两个键断裂过渡态的比较细节。
The processes of C C and C S bond cleavage have been studied with the homogeneous organometallic compound [Ni(dippe)H](2) (1). When 1 is reacted with 2-cyanothiophene at room temperature, cleavage of the nitrile-substituted C S bond occurs, forming the Ni-metallacycle complex (dippe)Ni(kappa(2)-S,C-SCH=CHCH=C(CN)) (2a), which has been fully characterized by NMR spectroscopy and X-ray diffraction. 2a was converted to the C CN cleavage product (dippe)Ni(CN)(2-thiophenyl) (3) when heated in solution. On closer inspection, four other intermediates were observed by P-31 NMR spectroscopy at low temperature. Structures for the intermediates were elucidated through a combination of independent synthesis, theoretical calculations, chemical characterization, and experimental precedent. A kinetic product (dippe)Ni(kappa(2)-S,C-SC(CN)=CHCH=CH) (2b) was formed from cleavage of the nonsubstituted C S bond, as well as a Ni(0) eta(2)-nitrile intermediate, (dippe)Ni(eta(2)-C,N-2-cyanothiophene) (4), and a dinuclear mixed Ni(0) Ni(II) product (6b). A complete DFT analysis of this system has been carried out to reveal comparative details about the two bond cleavage transition states.