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Title: Effects of the Counteranion on the Pyrazole-Nitrile Coupling Reaction Mediated by Nickel(II) Ions
Authors: Hsieh, Chang-Chih;Lee, Chia-Jung;Horng, Yih-Chern
Contributors: 化學系
Date: 2009-09
Issue Date: 2013-01-07T02:15:58Z
Publisher: American Chemical Society
Abstract: The reaction of Ni(ClO4)2 with 4 equiv of pyrazole (pzH) in MeCN leads to [Ni(pzH)2(HNd
C(Me)pz)2](ClO4)2 via the intermediate [Ni(MeCN)2(pzH)4](ClO4)2, which is the first pyrazole-nitrile
coupling reaction activated by a Ni(II) complex. The reaction is also successfully conducted with other
nitriles RCN bearing an electron-donating group (R=Et, Bz) and is counteranion-specific. The reaction
proceedsmore quickly withNO3
-as counteranion than withClO4
-, andBF4
-is found to be unsatisfactory for
the coupling reaction. As for the X-ray crystal structures, [Ni(MeCN)2(pzH)4](ClO4)2 possesses stronger
pyrazolyl NH3 3 3 anion hydrogen-bonding interactions than does [Ni(MeCN)2(pzH)4](BF4)2. The same
trend is also observed by solution IR(pyrazolylNH) analysis. The supramolecular structure of the complex
[Ni(pzH)2(HNdC(Me)pz)2](ClO4)2 displays a two-dimensional network dominated by cooperative face-toface
π-π stacking and edge-to-face CH3 3 3 π bonding interactions. In addition, a mechanism based on
anion-mediated/hydrogen-bonding-driven proton transfer for the coupling reaction is proposed.
Relation: Organometallics, 28(17): 4923-4928
Appears in Collections:[化學系] 期刊論文

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