Felix Kracht, Sophie Mayer, Cäcilia Maichle-Mössmer and Reiner Anwander
{"title":"Reactivity of titanium pyrazolates towards CO2, CS2 and N2O†","authors":"Felix Kracht, Sophie Mayer, Cäcilia Maichle-Mössmer and Reiner Anwander","doi":"10.1039/D5DT00957J","DOIUrl":null,"url":null,"abstract":"<p >The tetravalent titanium pyrazolate Ti(pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>4</sub></small> inserts two molecules of carbon dioxide instantly at ambient temperature and 1 bar heteroallene, forming the complex Ti(CO<small><sub>2</sub></small>·pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>2</sub></small>(pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>2</sub></small> (pz<small><sup>Me<small><sub>2</sub></small></sup></small> = 3,5-dimethylpyrazolato). CO<small><sub>2</sub></small> insertion is reversible as proven by thermogravimetric analysis (TGA). Solid Ti(CO<small><sub>2</sub></small>·pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>2</sub></small>(pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>2</sub></small> exhibits an exceptionally high stability at ambient atmosphere but converts in solution over time <em>via</em> deoxygenation into the oxo-bridged species [Ti(CO<small><sub>2</sub></small>·pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>2</sub></small>(pz<small><sup>Me<small><sub>2</sub></small></sup></small>)]<small><sub>2</sub></small>(μ-O) and [Ti(μ-O)<small><sub>2</sub></small>(μ-pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>4</sub></small>(Ti{CO<small><sub>2</sub></small>·pz<small><sup>Me<small><sub>2</sub></small></sup></small>}{pz<small><sup>Me<small><sub>2</sub></small></sup></small>})<small><sub>2</sub></small>]. Treatment of Ti(pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>4</sub></small> with CS<small><sub>2</sub></small> results in a mono-insertion to Ti(CS<small><sub>2</sub></small>·pz<small><sup>Me<small><sub>2</sub></small></sup></small>)(pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>3</sub></small>, which is reversible at 110 °C. Applying similar conditions, trivalent Ti(pz<small><sup><em>t</em>Bu<small><sub>2</sub></small></sup></small>)<small><sub>3</sub></small> inserts also two molecules of CO<small><sub>2</sub></small> to afford Ti(CO<small><sub>2</sub></small>·pz<small><sup><em>t</em>Bu<small><sub>2</sub></small></sup></small>)<small><sub>2</sub></small>(pz<small><sup><em>t</em>Bu<small><sub>2</sub></small></sup></small>) displaying complete de-insertion at 70 °C. At elevated temperatures compound Ti(CO<small><sub>2</sub></small>·pz<small><sup><em>t</em>Bu<small><sub>2</sub></small></sup></small>)<small><sub>2</sub></small>(pz<small><sup><em>t</em>Bu<small><sub>2</sub></small></sup></small>) does neither display redox activity nor engages in a deoxygenation reaction. While tetravalent Ti(pz<small><sup>Me<small><sub>2</sub></small></sup></small>)<small><sub>4</sub></small> does not react with N<small><sub>2</sub></small>O under ambient conditions, trivalent Ti(pz<small><sup><em>t</em>Bu<small><sub>2</sub></small></sup></small>)<small><sub>3</sub></small> converts into oxo-bridged [Ti(pz<small><sup><em>t</em>Bu<small><sub>2</sub></small></sup></small>)<small><sub>3</sub></small>]<small><sub>2</sub></small>(μ-O) <em>via</em> initial N<small><sub>2</sub></small>O insertion and subsequent fast release of N<small><sub>2</sub></small>.</p>","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":" 28","pages":" 10890-10897"},"PeriodicalIF":3.3000,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/dt/d5dt00957j?page=search","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Dalton Transactions","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2025/dt/d5dt00957j","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, INORGANIC & NUCLEAR","Score":null,"Total":0}
引用次数: 0
Abstract
The tetravalent titanium pyrazolate Ti(pzMe2)4 inserts two molecules of carbon dioxide instantly at ambient temperature and 1 bar heteroallene, forming the complex Ti(CO2·pzMe2)2(pzMe2)2 (pzMe2 = 3,5-dimethylpyrazolato). CO2 insertion is reversible as proven by thermogravimetric analysis (TGA). Solid Ti(CO2·pzMe2)2(pzMe2)2 exhibits an exceptionally high stability at ambient atmosphere but converts in solution over time via deoxygenation into the oxo-bridged species [Ti(CO2·pzMe2)2(pzMe2)]2(μ-O) and [Ti(μ-O)2(μ-pzMe2)4(Ti{CO2·pzMe2}{pzMe2})2]. Treatment of Ti(pzMe2)4 with CS2 results in a mono-insertion to Ti(CS2·pzMe2)(pzMe2)3, which is reversible at 110 °C. Applying similar conditions, trivalent Ti(pztBu2)3 inserts also two molecules of CO2 to afford Ti(CO2·pztBu2)2(pztBu2) displaying complete de-insertion at 70 °C. At elevated temperatures compound Ti(CO2·pztBu2)2(pztBu2) does neither display redox activity nor engages in a deoxygenation reaction. While tetravalent Ti(pzMe2)4 does not react with N2O under ambient conditions, trivalent Ti(pztBu2)3 converts into oxo-bridged [Ti(pztBu2)3]2(μ-O) via initial N2O insertion and subsequent fast release of N2.
期刊介绍：
Dalton Transactions is a journal for all areas of inorganic chemistry, which encompasses the organometallic, bioinorganic and materials chemistry of the elements, with applications including synthesis, catalysis, energy conversion/storage, electrical devices and medicine. Dalton Transactions welcomes high-quality, original submissions in all of these areas and more, where the advancement of knowledge in inorganic chemistry is significant.
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