Electronic Structure and Reactivity of a Well-Defined Mononuclear Complex of Ti(II)

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• 作者：Gayan B. Wijeratne ; Eva M. Zolnhofer ; Skye Fortier ; Lauren N. Grant ; Patrick J. Carroll ; Chun-Hsing Chen ; Karsten Meyer ; J. Krzystek ; Andrew Ozarowski ; Timothy A. Jackson ; Daniel J. Mindiola ; Joshua Telser
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：November 2, 2015
• 年：2015
• 卷：54
• 期：21
• 页码：10380-10397
• 全文大小：873K
• ISSN：1520-510X

文摘

A facile and high-yielding protocol to the known Ti(II) complex trans-[(py)₄TiCl₂] (py = pyridine) has been developed. Its electronic structure has been probed experimentally using magnetic susceptibility, magnetic circular dichroism, and high-frequency and high-field electron paramagnetic resonance spectroscopies in conjunction with ligand-field theory and computational methods (density functional theory and ab initio methods). These studies demonstrated that trans-[(py)₄TiCl₂] has a p>3p>E_g ground state (d_xyp class="stack">1p>d_xz,yzp class="stack">1p> orbital occupancy), which, as a result of spin鈥搊rbit coupling, yields a ground-state spinor doublet that is EPR active, a first excited-state doublet at 鈭?0 cmp>鈥?p>, and two next excited states at 鈭?20 cmp>鈥?p>. Reactivity studies with various unsaturated substrates are also presented in this study, which show that the Ti(II) center allows oxidative addition likely via formation of [Ti(畏p>2p>-R₂E₂)Cl₂(py)_n] E = C, N intermediates. A new Ti(IV) compound, mer-[(py)₃(畏p>2p>-Ph₂C₂)TiCl₂], was prepared by reaction with Ph₂C₂, along with the previously reported complex trans-(py)₃Ti鈺怤Ph(Cl)₂, from reaction with Ph₂N₂. Reaction with Ph₂CN₂ also yielded a new dinuclear Ti(IV) complex, [(py)₂(Cl)₂Ti(渭₂:畏p>2p>-N₂CPh₂)₂Ti(Cl)₂], in which the two Ti(IV) ions are inequivalently coordinated. Reaction with cyclooctatetraene (COT) yielded a new Ti(III) complex, [(py)₂Ti(畏p>8p>-COT)Cl], which is a rare example of a mononuclear 鈥減iano-stool鈥?titanium complex. The complex trans-[(py)₄TiCl₂] has thus been shown to be synthetically accessible, have an interesting electronic structure, and be reactive toward oxidation chemistry.