Ahmadreza Nezamzadeh, Jianfeng Zhu and Jens Müller*,
{"title":"具有令人惊讶的 Cp 质子化学位移模式的杂原子桥接卡巴[2]二茂铁","authors":"Ahmadreza Nezamzadeh, Jianfeng Zhu and Jens Müller*, ","doi":"10.1021/acs.organomet.4c00067","DOIUrl":null,"url":null,"abstract":"<p >[2]Ferrocenophanes bridged by a carbon and a heteroatom were targeted in the hope that such an asymmetric bridge gives rise to monomers suitable for ring-opening polymerization. Three strained sandwich compounds with bridging C–Si (<b>13</b><sup><b>SiMe2</b></sup>), C–P (<b>13</b><sup><b>PPh</b></sup>), or C–B (<b>13</b><sup><b>BMes</b></sup>) moieties were prepared using a lithium–bromine exchange followed by a common salt-metathesis reaction. Single-crystal X-ray structural analyses revealed an increase of the degree of Cp ring tilting, commonly expressed as the α angle, from 12.58(9) (<b>13</b><sup><b>SiMe2</b></sup>) to 16.63(2) (<b>13</b><sup><b>PPh</b></sup>) to 19.66(11)° (<b>13</b><sup><b>BMes</b></sup>). Despite being strained, all three species turned out to be resistant toward thermal ring-opening polymerization. The characterization of the three [2]ferrocenophanes by one- and two-dimensional <sup>1</sup>H NMR spectroscopy disclosed that Cp protons in α position to the bridging elements are deshielded relative to Cp protons in the β position. Experimental assignments were supported by DFT calculations of chemical shifts. The determined order of α and β Cp protons is opposite to that known for [1]ferrocenophanes. Using a set of known [<i>n</i>]ferrocenophanes (<i>n</i> = 1, 2) with significant tilted Cp rings, DFT calculations revealed that both families exhibit a different order of Cp peaks in <sup>1</sup>H NMR spectra.</p>","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.5000,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Heteroatom-Bridged Carba[2]ferrocenophanes with a Surprising Chemical Shift Pattern of Cp Protons\",\"authors\":\"Ahmadreza Nezamzadeh, Jianfeng Zhu and Jens Müller*, \",\"doi\":\"10.1021/acs.organomet.4c00067\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >[2]Ferrocenophanes bridged by a carbon and a heteroatom were targeted in the hope that such an asymmetric bridge gives rise to monomers suitable for ring-opening polymerization. Three strained sandwich compounds with bridging C–Si (<b>13</b><sup><b>SiMe2</b></sup>), C–P (<b>13</b><sup><b>PPh</b></sup>), or C–B (<b>13</b><sup><b>BMes</b></sup>) moieties were prepared using a lithium–bromine exchange followed by a common salt-metathesis reaction. Single-crystal X-ray structural analyses revealed an increase of the degree of Cp ring tilting, commonly expressed as the α angle, from 12.58(9) (<b>13</b><sup><b>SiMe2</b></sup>) to 16.63(2) (<b>13</b><sup><b>PPh</b></sup>) to 19.66(11)° (<b>13</b><sup><b>BMes</b></sup>). Despite being strained, all three species turned out to be resistant toward thermal ring-opening polymerization. The characterization of the three [2]ferrocenophanes by one- and two-dimensional <sup>1</sup>H NMR spectroscopy disclosed that Cp protons in α position to the bridging elements are deshielded relative to Cp protons in the β position. Experimental assignments were supported by DFT calculations of chemical shifts. The determined order of α and β Cp protons is opposite to that known for [1]ferrocenophanes. Using a set of known [<i>n</i>]ferrocenophanes (<i>n</i> = 1, 2) with significant tilted Cp rings, DFT calculations revealed that both families exhibit a different order of Cp peaks in <sup>1</sup>H NMR spectra.</p>\",\"PeriodicalId\":56,\"journal\":{\"name\":\"Organometallics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.5000,\"publicationDate\":\"2024-05-09\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Organometallics\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://pubs.acs.org/doi/10.1021/acs.organomet.4c00067\",\"RegionNum\":3,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, INORGANIC & NUCLEAR\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Organometallics","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acs.organomet.4c00067","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, INORGANIC & NUCLEAR","Score":null,"Total":0}
Heteroatom-Bridged Carba[2]ferrocenophanes with a Surprising Chemical Shift Pattern of Cp Protons
[2]Ferrocenophanes bridged by a carbon and a heteroatom were targeted in the hope that such an asymmetric bridge gives rise to monomers suitable for ring-opening polymerization. Three strained sandwich compounds with bridging C–Si (13SiMe2), C–P (13PPh), or C–B (13BMes) moieties were prepared using a lithium–bromine exchange followed by a common salt-metathesis reaction. Single-crystal X-ray structural analyses revealed an increase of the degree of Cp ring tilting, commonly expressed as the α angle, from 12.58(9) (13SiMe2) to 16.63(2) (13PPh) to 19.66(11)° (13BMes). Despite being strained, all three species turned out to be resistant toward thermal ring-opening polymerization. The characterization of the three [2]ferrocenophanes by one- and two-dimensional 1H NMR spectroscopy disclosed that Cp protons in α position to the bridging elements are deshielded relative to Cp protons in the β position. Experimental assignments were supported by DFT calculations of chemical shifts. The determined order of α and β Cp protons is opposite to that known for [1]ferrocenophanes. Using a set of known [n]ferrocenophanes (n = 1, 2) with significant tilted Cp rings, DFT calculations revealed that both families exhibit a different order of Cp peaks in 1H NMR spectra.
期刊介绍:
Organometallics is the flagship journal of organometallic chemistry and records progress in one of the most active fields of science, bridging organic and inorganic chemistry. The journal publishes Articles, Communications, Reviews, and Tutorials (instructional overviews) that depict research on the synthesis, structure, bonding, chemical reactivity, and reaction mechanisms for a variety of applications, including catalyst design and catalytic processes; main-group, transition-metal, and lanthanide and actinide metal chemistry; synthetic aspects of polymer science and materials science; and bioorganometallic chemistry.