Reactions of a Cyclopentadienyl鈥揂midinate Titanium Benzimidamido Complex

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• 作者：Laura R. Groom ; Adam F. Russell ; Andrew D. Schwarz ; Philip Mountford
• 刊名：Organometallics
• 出版年：2014
• 出版时间：February 24, 2014
• 年：2014
• 卷：33
• 期：4
• 页码：1002-1019
• 全文大小：762K
• 年卷期：v.33,no.4(February 24, 2014)
• ISSN：1520-6041

文摘

We report the first reactivity study of a transition-metal benzimidamido complex, namely Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{NC(Ar<sup>F<sub>5sub>sup>)NO<sup>tsup>Bu} (5, Ar<sup>F<sub>5sub>sup> = C<sub>6sub>F<sub>5sub>). Reaction with CO<sub>2sub> and <sup>tsup>BuNCO gave the cycloaddition products Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{OC(O)N(C{Ar<sup>F<sub>5sub>sup>}NO<sup>tsup>Bu)} and Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{OC(N<sup>tsup>Bu)N(C{Ar<sup>F<sub>5sub>sup>}NO<sup>tsup>Bu)} (10), respectively, whereas with CS<sub>2sub> slow extrusion of Ar<sup>F<sub>5sub>sup>CN from 5 occurred to ultimately form Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{SC(S)N(O<sup>tsup>Bu)}. Reaction of 5 with ArC(O)H (Ar = Ph, 4-C<sub>6sub>H<sub>4sub>Me, 4-C<sub>6sub>H<sub>4sub><sup>tsup>Bu, 4-C<sub>6sub>H<sub>4sub>OMe, 4-C<sub>6sub>H<sub>4sub>NMe<sub>2sub>, 4-C<sub>6sub>H<sub>4sub>CF<sub>3sub>) also gave the isolable metallacyclic complexes Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{N(C{Ar<sup>F<sub>5sub>sup>}NO<sup>tsup>Bu)C(Ar)(H)O} (13) via reversible [2 + 2] cycloaddition reactions. In contrast, reaction with HC(O)NMe<sub>2sub> formed Me<sub>2sub>N{NC(Ar<sup>F<sub>5sub>sup>)NO<sup>tsup>Bu}H (16) within 1 h at room temperature. Upon heating, 10 and 13 also underwent retrocyclization, forming the organic products <sup>tsup>BuNCNC(Ar<sup>F<sub>5sub>sup>)NO<sup>tsup>Bu and ArC{NC(Ar<sup>F<sub>5sub>sup>)NO<sup>tsup>Bu}H (14), respectively. Selected examples of 14 and 16 were studied by DFT and UV鈥搗isible spectroscopy. Addition of isonitriles <sup>tsup>BuNC and XylNC (Xyl = 2,6-C<sub>6sub>H<sub>3sub>Me<sub>2sub>) to Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{NC(Ar)NO<sup>tsup>Bu} (Ar = Ar<sup>F<sub>5sub>sup> (5), 2,6-C<sub>6sub>H<sub>3sub>F<sub>2sub> (Ar<sup>F<sub>2sub>sup>)) afforded the 蟽 adducts Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{NC(Ar)NO<sup>tsup>Bu}(CNR) (Ar = Ar<sup>F<sub>5sub>sup>, R = <sup>tsup>Bu, Xyl (19); Ar = Ar<sup>F<sub>2sub>sup>, R = Xyl). Subsequently, 19 formed Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{NC(NO<sup>tsup>Bu)C<sub>6sub>F<sub>4sub>N(Xyl)C}(F) (20) via C鈥揊 bond activation. Reaction of 5 with 2 equiv of B(Ar<sup>F<sub>5sub>sup>)<sub>3sub> gave Cp*Ti{PhC(N<sup>isup>Pr)<sub>2sub>}{ON(B{Ar<sup>F<sub>5sub>sup>}<sub>3sub>)C(Ar<sup>F<sub>5sub>sup>)N(H)(B{Ar<sup>F<sub>5sub>sup>}<sub>3sub>)} with elimination of 2-methylpropene.