Stefan Thum, Jonathan Mai, Neha Patel, Jens Langer, Sjoerd Harder
{"title":"Reduction of CO2 and Related Compounds with a Low-Valent CaI Synthon","authors":"Stefan Thum, Jonathan Mai, Neha Patel, Jens Langer, Sjoerd Harder","doi":"10.1002/ceur.202500080","DOIUrl":null,"url":null,"abstract":"<p>The reduction of CO<sub>2</sub> with low-valent <i>s</i>-block metal complexes is limited to Mg<sup>I</sup> reducing agents. Herein, the reduction of a series of CX<sub>2</sub> reagents (X = O, S, N<i>i</i>Pr) with the Ca<sup>I</sup> synthon [(BDI)Ca(THP)]<sub>2</sub>(N<sub>2</sub>) (<b>VI</b>) is described, which is a Ca<sup>II</sup> complex that reacts like the hypothetical Ca<sup>I</sup> complex (BDI)CaCa(BDI); BDI = HC[(Me)-N(DIPeP)]<sub>2</sub>, DIPeP = 2,6-Et<sub>2</sub>CH-phenyl, THP = tetrahydropyran. Reaction of <b>VI</b> with excess CO<sub>2</sub> led to crystallization of a carbonate complex with a Ca<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub><sup>4+</sup> core. The stabilizing BDI ligands also react by nucleophilic addition of CO<sub>2</sub> at the backbone <i>γ</i>-C atom. Reaction with only two equivalents of CO<sub>2</sub> gave the presumed carbonite (CO<sub>2</sub><sup>2</sup><sup>−</sup>) intermediate, but this could not be confirmed by X-ray diffraction. Reaction with CS<sub>2</sub> gave the first unique <i>s</i>-block metal complex with a CS<sub>2</sub><sup>2</sup><sup>−</sup> anion. This anion bridges between two (BDI)Ca<sup>+</sup> cations by Ca<span></span>C and Ca<span></span>S bonding. The reduction of <i>i</i>PrN=C=N<i>i</i>Pr with <b>VI</b> gave C–C coupling to a [(<i>i</i>PrN)<sub>2</sub>C–C(N<i>i</i>Pr)<sub>2</sub>]<sup>2</sup><sup>−</sup> dianion. An intermediate with a C(N<i>i</i>Pr)<sub>2</sub><sup>2</sup><sup>−</sup> dianion could not be isolated.</p>","PeriodicalId":100234,"journal":{"name":"ChemistryEurope","volume":"3 4","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ceur.202500080","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ChemistryEurope","FirstCategoryId":"1085","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/ceur.202500080","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The reduction of CO2 with low-valent s-block metal complexes is limited to MgI reducing agents. Herein, the reduction of a series of CX2 reagents (X = O, S, NiPr) with the CaI synthon [(BDI)Ca(THP)]2(N2) (VI) is described, which is a CaII complex that reacts like the hypothetical CaI complex (BDI)CaCa(BDI); BDI = HC[(Me)-N(DIPeP)]2, DIPeP = 2,6-Et2CH-phenyl, THP = tetrahydropyran. Reaction of VI with excess CO2 led to crystallization of a carbonate complex with a Ca4(CO3)24+ core. The stabilizing BDI ligands also react by nucleophilic addition of CO2 at the backbone γ-C atom. Reaction with only two equivalents of CO2 gave the presumed carbonite (CO22−) intermediate, but this could not be confirmed by X-ray diffraction. Reaction with CS2 gave the first unique s-block metal complex with a CS22− anion. This anion bridges between two (BDI)Ca+ cations by CaC and CaS bonding. The reduction of iPrN=C=NiPr with VI gave C–C coupling to a [(iPrN)2C–C(NiPr)2]2− dianion. An intermediate with a C(NiPr)22− dianion could not be isolated.