C鈥揌 Activation of Pyrazolyl Ligands by Ru(II)

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• 作者：Evan E. Joslin ; Brandon Quillian ; T. Brent Gunnoe ; Thomas R. Cundari ; Michal Sabat ; William H. Myers
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：June 16, 2014
• 年：2014
• 卷：53
• 期：12
• 页码：6270-6279
• 全文大小：511K
• 年卷期：v.53,no.12(June 16, 2014)
• ISSN：1520-510X

文摘

Previously, hydridotris(pyrazolyl)borate (Tp) Ru(II) alkyl and aryl complexes of the type TpRu(L)(NCMe)R (R = methyl or aryl; L = charge-neutral two-electron donating ligand) were demonstrated to activate aromatic C鈥揌 bonds. To determine the impact of replacing the anionic Tp ligand with charge-neutral poly(pyrazolyl)alkane ligands, [(C(pz)₄)Ru(P(OCH₂)₃CEt)(NCMe)Me][BAr鈥?sub>4] (pz = pyrazolyl, BAr鈥?sub>4 = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) was prepared. Heating a C₆D₆ solution of [(C(pz)₄)Ru(P(OCH₂)₃CEt)(NCMe)Me][BAr鈥?sub>4] with 1 equiv of NCMe resulted in C鈥揌 activation of the 5-position of a pyrazolyl ring to yield [(魏³-(N,C⁵,N)C(pz)₄)Ru(P(OCH₂)₃CEt)(NCMe)₂][BAr鈥?sub>4] and CH₄. Intramolecular C鈥揌 activation of the 5-position of a pyrazolyl ring also occurred when (畏⁶-p-cymene)Ru(P(OCH₂)₃CEt)(Br)Ph was heated in the presence of C(pz)₄ to yield [(魏³-N,C⁵,N)C(pz)₄]Ru(P(OCH₂)₃CEt)(NCMe)Br and C₆H₆. Density functional theory calculations revealed that the different reactivities of TpRu(P(OCH₂)₃CEt)(NCMe)R and [(C(pz)₄)Ru(P(OCH₂)₃CEt)(NCMe)Me][BAr鈥?sub>4] result from the stronger binding of the Tp pyrazolyl rings to Ru(II) compared to that of C(pz)₄.