Charge and Spin Confinement to the Amine Site in 3-Connected Triarylamine Vinyl Ruthenium Conjugates

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• 作者：Walther Polit ; Philipp M眉cke ; Evelyn Wuttke ; Thomas Exner ; Rainer F. Winter
• 刊名：Organometallics
• 出版年：2013
• 出版时间：October 14, 2013
• 年：2013
• 卷：32
• 期：19
• 页码：5461-5472
• 全文大小：505K
• 年卷期：v.32,no.19(October 14, 2013)
• ISSN：1520-6041

文摘

The triarylamine vinyl ruthenium conjugate (4-OMeC₆H₄)₂N{C₆H₄-3-CH鈺怌H-RuCl(CO)(PⁱPr₃)₂} (m-1) has been prepared and investigated in its neutral and one-electron-oxidized states. Comparison with tris(4-anisylamine), An₃N, and the related 4-methoxystyryl complex 4-OMeC₆H₄-CH鈺怌H-RuCl(CO)(PⁱPr₃)₂, 2, shows that the intrinsic formal potentials of the two nonidentical redox-active subunits of complex m-1 (triarylamine and vinyl ruthenium) are very similar. Complex m-1 is oxidized in two consecutive one-electron waves with a half-wave potential splitting of 320 mV. Detailed investigations of the one-electron-oxidized radical cation m-1^鈥? by IR and EPR spectroscopy and by quantum chemical calculations as well as comparison to An₃N^鈥? and 2^鈥? indicate that the charge and the unpaired spin of m-1^鈥? are dominantly located on the triarylamine site. This is in stark contrast to the previously published para isomer p-1^鈥?, which, despite the nonidentical redox sites, is a fully delocalized mixed-valent system of Class III. As a consequence of partial charge localization, the low-energy absorption bands in the near-infrared assume the character of ruthenium or styryl ruthenium to triarylamine intervalence charge-transfer (IVCT) transitions with significantly diminished absorptivities compared to the highly intense charge resonance bands of p-1^鈥?. Hush analysis of the IVCT bands indicates that m-1^鈥? is a significantly coupled mixed-valent system of Class II. The crystallographically determined structures of complexes m-1 and 2 and of the amine precursor (4-OMeC₆H₄)₂N(C₆H₄Br-3) (An₂N-Br) are also reported.