Pub Date : 2024-09-20DOI: 10.1021/acs.organomet.4c00215
Thomas E. Shoopman, Andrew T. Morehead, Jr., Andrew L. Sargent
In contrast to the more common rhodium-catalyzed hydroacylation reaction, which is widely accepted to proceed via a low-spin singlet mechanism that passes through the familiar steps of oxidative addition → alkene insertion → reductive elimination, the cobalt-catalyzed hydroacylation reaction of dienes reported by Dong et al. ( J. Am. Chem. Soc., 2014) has been calculated to proceed via a high-spin triplet mechanism. The initial minimum energy pathway evaluated was the singlet, as two prior studies had also examined that pathway. The use of nudged elastic band methods enabled location of additional intermediates relative to the previous studies but also revealed that the isomeric product distribution was not accurately reproduced and that at least one intermediate appeared to prefer a different geometry. Subsequent examination of the triplet minimum energy pathway showed the intermediates are accompanied by geometries not typically associated with the singlet mechanism, which facilitates a very different pathway that involves oxidative cyclization and a direct reductive hydrogen atom transfer, thus avoiding the metal-hydride intermediates and reductive elimination steps that characterize the singlet pathway entirely.
{"title":"Alternate Geometries in the Cobalt-Catalyzed Hydroacylation of Dienes Facilitate a High Spin Mechanism: A Density Functional Theory Study","authors":"Thomas E. Shoopman, Andrew T. Morehead, Jr., Andrew L. Sargent","doi":"10.1021/acs.organomet.4c00215","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00215","url":null,"abstract":"In contrast to the more common rhodium-catalyzed hydroacylation reaction, which is widely accepted to proceed via a low-spin singlet mechanism that passes through the familiar steps of oxidative addition → alkene insertion → reductive elimination, the cobalt-catalyzed hydroacylation reaction of dienes reported by Dong et al. ( <cite><i>J. Am. Chem. Soc.</i></cite>, <span>2014</span>) has been calculated to proceed via a high-spin triplet mechanism. The initial minimum energy pathway evaluated was the singlet, as two prior studies had also examined that pathway. The use of nudged elastic band methods enabled location of additional intermediates relative to the previous studies but also revealed that the isomeric product distribution was not accurately reproduced and that at least one intermediate appeared to prefer a different geometry. Subsequent examination of the triplet minimum energy pathway showed the intermediates are accompanied by geometries not typically associated with the singlet mechanism, which facilitates a very different pathway that involves oxidative cyclization and a direct reductive hydrogen atom transfer, thus avoiding the metal-hydride intermediates and reductive elimination steps that characterize the singlet pathway entirely.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1021/acs.organomet.4c00233
Sebastian Weske, Thomas Auth, Finn Kraft, Arne Winkler, Selina Schneider, Konrad Koszinowski
Despite the frequent use of magnesium organocuprates derived from Grignard reagents in organic synthesis, the molecular composition of these important reagents is poorly understood. To achieve a better understanding of their speciation in solution, we apply here a combination of electrospray-ionization mass spectrometry, gas-phase fragmentation experiments, and quantum chemical calculations. For solutions of CuCl/2RMgCl (R = Ph, 2-thienyl, Bu, and Me3SiCH2) in tetrahydrofuran, we find anions of the type [CunRn+1]−, n = 1–6. Changing the copper precursor, increasing the amount of the Grignard reagent, and adding Me2S have only relatively minor effects. Gas-phase fragmentation of the [CunRn+1]− anions results in deaggregation reactions. In addition, [CunBun+1]− and [Cu(CH2SiMe3)2]− undergo β-hydrogen and β-methyl eliminations, respectively, as well. Presumably, these decomposition pathways (as well as unknown processes) also occur in solution and explain the depletion of organyl substituents in the observed [CunRn+1]− anions. The behavior of the magnesium cuprates deviates from that of the well-studied lithium cuprates, which display a higher tendency to form heteronuclear species. Our quantum chemical calculations for LiCuPh2·LiCl and MgClCuPh2·MgCl2 in THF show that the absence of analogous heteronuclear complexes in the case of the magnesium cuprates results from higher relative Gibbs energies of these species.
{"title":"Association and Aggregation of Magnesium Organocuprates","authors":"Sebastian Weske, Thomas Auth, Finn Kraft, Arne Winkler, Selina Schneider, Konrad Koszinowski","doi":"10.1021/acs.organomet.4c00233","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00233","url":null,"abstract":"Despite the frequent use of magnesium organocuprates derived from Grignard reagents in organic synthesis, the molecular composition of these important reagents is poorly understood. To achieve a better understanding of their speciation in solution, we apply here a combination of electrospray-ionization mass spectrometry, gas-phase fragmentation experiments, and quantum chemical calculations. For solutions of CuCl/2RMgCl (R = Ph, 2-thienyl, Bu, and Me<sub>3</sub>SiCH<sub>2</sub>) in tetrahydrofuran, we find anions of the type [Cu<sub><i>n</i></sub>R<sub><i>n</i>+1</sub>]<sup>−</sup>, <i>n</i> = 1–6. Changing the copper precursor, increasing the amount of the Grignard reagent, and adding Me<sub>2</sub>S have only relatively minor effects. Gas-phase fragmentation of the [Cu<sub><i>n</i></sub>R<sub><i>n</i>+1</sub>]<sup>−</sup> anions results in deaggregation reactions. In addition, [Cu<sub><i>n</i></sub>Bu<sub><i>n</i>+1</sub>]<sup>−</sup> and [Cu(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>]<sup>−</sup> undergo β-hydrogen and β-methyl eliminations, respectively, as well. Presumably, these decomposition pathways (as well as unknown processes) also occur in solution and explain the depletion of organyl substituents in the observed [Cu<sub><i>n</i></sub>R<sub><i>n</i>+1</sub>]<sup>−</sup> anions. The behavior of the magnesium cuprates deviates from that of the well-studied lithium cuprates, which display a higher tendency to form heteronuclear species. Our quantum chemical calculations for LiCuPh<sub>2</sub>·LiCl and MgClCuPh<sub>2</sub>·MgCl<sub>2</sub> in THF show that the absence of analogous heteronuclear complexes in the case of the magnesium cuprates results from higher relative Gibbs energies of these species.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1021/acs.organomet.4c00187
Giorgia Zanchin, Alessia Amodio, Alessandro Piovano, Virginia Guiotto, Giuseppe Leone, Laura Falivene, Elena Groppo
Investigations into iminopyridine chromium complexes have unveiled their potential as precatalysts for the polymerization of (di)olefins (Organometallics2018, 37, 4827–4840). A Cr-to-ligand electron transfer, with the ligand (L) in the monoanionic radical state and Cr in a physical trivalent oxidation state, proved to be fundamental for facilitating ethylene polymerization by the complex with the unsubstituted aldimine (Cr-pH, where X = H). In the absence of structural data, we embarked on a detailed study by ultraviolet–visible–near-infrared (UV–vis–NIR) spectroscopy and density functional theory to elucidate the structural and electronic features driving electron transfer in Cr-pH. The Cr-to-L electron transfer is facilitated by the presence of two tetrahydrofurans in the metal’s coordination sphere in the monoligated form or by the formation of a bis-ligated species. The UV–vis–NIR spectra of Cr-pH, coupled with electrospray ionization mass spectroscopy data, indicate the coexistence of multiple species. Successively, we enlarged the library of chromium complexes by appending different substituents (i.e., CH3, OCH3, and CF3) at the p-N-aryl 4-position. While Cr-pCH3 and Cr-pOCH3 display electronic features analogous to those of Cr-pH, Cr-pCF3 stands out as an exception, likely containing only monoligated species. Cr-pCF3 emerged as the most active catalyst, producing ultra-high-molecular weight poly(ethylene) with a unimodal and narrow molecular weight distribution event at 40 °C.
{"title":"p-Aryl-Substituted Iminopyridine Chromium Complexes as Precatalysts for Ethylene Polymerization: The Question of the Physical Oxidation State Examined by Experimental and Density Functional Study in the Absence of Structural Data","authors":"Giorgia Zanchin, Alessia Amodio, Alessandro Piovano, Virginia Guiotto, Giuseppe Leone, Laura Falivene, Elena Groppo","doi":"10.1021/acs.organomet.4c00187","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00187","url":null,"abstract":"Investigations into iminopyridine chromium complexes have unveiled their potential as precatalysts for the polymerization of (di)olefins (<i>Organometallics</i> <b>2018</b>, <i>37</i>, 4827–4840). A Cr-to-ligand electron transfer, with the ligand (L) in the monoanionic radical state and Cr in a physical trivalent oxidation state, proved to be fundamental for facilitating ethylene polymerization by the complex with the unsubstituted aldimine (<b>Cr</b>-<i>p</i><b>H</b>, where X = H). In the absence of structural data, we embarked on a detailed study by ultraviolet–visible–near-infrared (UV–vis–NIR) spectroscopy and density functional theory to elucidate the structural and electronic features driving electron transfer in <b>Cr</b>-<i>p</i><b>H</b>. The Cr-to-L electron transfer is facilitated by the presence of two tetrahydrofurans in the metal’s coordination sphere in the monoligated form or by the formation of a bis-ligated species. The UV–vis–NIR spectra of <b>Cr</b>-<i>p</i><b>H</b>, coupled with electrospray ionization mass spectroscopy data, indicate the coexistence of multiple species. Successively, we enlarged the library of chromium complexes by appending different substituents (i.e., CH<sub>3</sub>, OCH<sub>3</sub>, and CF<sub>3</sub>) at the <i>p</i>-<i>N</i>-aryl 4-position. While <b>Cr</b>-<i>p</i><b>CH</b><sub><b>3</b></sub> and <b>Cr</b>-<i>p</i><b>OCH</b><sub><b>3</b></sub> display electronic features analogous to those of <b>Cr</b>-<i>p</i><b>H</b>, <b>Cr</b>-<i>p</i><b>CF</b><sub><b>3</b></sub> stands out as an exception, likely containing only monoligated species. <b>Cr</b>-<i>p</i><b>CF</b><sub><b>3</b></sub> emerged as the most active catalyst, producing ultra-high-molecular weight poly(ethylene) with a unimodal and narrow molecular weight distribution event at 40 °C.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1021/acs.organomet.4c00351
R. Noah Sladek, Nattamai Bhuvanesh, Oleg V. Ozerov
The new alane/bis(phosphine) PAlP pincer-type ligands 2-Me and 2-Et have been prepared by protolysis reactions of N-(diisopropylphoshino)acetamide with Me3Al or Et3Al in a 2:1 ratio. Upon reaction with a “RhCl” source and pyridine, 2-Me gave rise to a (PAlP)RhMe(py) compound (4-Me), while 2-Et led to the analogous hydride complex (PAlP)RhH(py) (4-H), with a migration of the chloride from Rh to Al. 4-Me and 4-H possess the shortest Rh–Al bonds to date.
{"title":"Flash Communication: Rhodium Complexes of Acetamide-Derived PAlP Pincer","authors":"R. Noah Sladek, Nattamai Bhuvanesh, Oleg V. Ozerov","doi":"10.1021/acs.organomet.4c00351","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00351","url":null,"abstract":"The new alane/bis(phosphine) PAlP pincer-type ligands <b>2-Me</b> and <b>2-Et</b> have been prepared by protolysis reactions of <i>N</i>-(diisopropylphoshino)acetamide with Me<sub>3</sub>Al or Et<sub>3</sub>Al in a 2:1 ratio. Upon reaction with a “RhCl” source and pyridine, <b>2-Me</b> gave rise to a (PAlP)RhMe(py) compound (<b>4-Me</b>), while <b>2-Et</b> led to the analogous hydride complex (PAlP)RhH(py) (<b>4-H</b>), with a migration of the chloride from Rh to Al. <b>4-Me</b> and <b>4-H</b> possess the shortest Rh–Al bonds to date.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1021/acs.organomet.4c00292
Oliver S. King, Benjamin J. Hofmann, Aran E. Boakye-Smith, Amy J. Managh, Tameryn Stringer, Rianne M. Lord
This work presents the synthesis of five new functionalized (benz)imidazolium N-heterocyclic (NHC) ligands (L) and four new (benz)imidazole silver(I) NHC (Ag(I)-NHC) complexes of mononuclear [Ag(L)2](PF6) or binuclear [Ag2(L)2](PF6)2 type. The complexes have been fully characterized, including single crystal X-ray diffraction of three new structures. The complexes and their corresponding free NHC ligands have been screened against breast cancer and noncancerous cell lines, showing the mononuclear benzimidazole complex has the highest activity, while the binuclear benzimidazole complex has the highest cancer cell selectivity. The silver uptake was measured by ICP-MS and highlights a strong link between cytotoxicity and cellular uptake. DNA interaction studies, molecular docking, and evaluation of reactive oxygen species (ROS) have been conducted for the most promising complexes to identify modes of action. Overall, the binuclear benzimidazole complex is the most selective and promising candidate against the MDA-MD-231 (breast cancer) cell line and has potential to be developed for treatment of late-stage breast cancers.
本研究合成了五种新的功能化（苯）咪唑鎓 N-杂环（NHC）配体（L）和四种新的（苯）咪唑银（I）NHC（Ag(I)-NHC）单核[Ag(L)2](PF6)或双核[Ag2(L)2](PF6)2 型配合物。这些配合物已得到全面表征，包括三种新结构的单晶 X 射线衍射。这些配合物及其相应的游离 NHC 配体针对乳腺癌和非癌细胞系进行了筛选，结果表明单核苯并咪唑配合物的活性最高，而双核苯并咪唑配合物对癌细胞的选择性最高。银的吸收是通过 ICP-MS 测量的，凸显了细胞毒性与细胞吸收之间的密切联系。对最有前景的复合物进行了 DNA 相互作用研究、分子对接和活性氧（ROS）评估，以确定其作用模式。总之，双核苯并咪唑复合物是对 MDA-MD-231（乳腺癌）细胞系最具选择性和前景的候选化合物，有望开发用于治疗晚期乳腺癌。
{"title":"Fluorinated N-Heterocyclic Carbene Silver(I) Complexes with High Cancer Cell Selectivity","authors":"Oliver S. King, Benjamin J. Hofmann, Aran E. Boakye-Smith, Amy J. Managh, Tameryn Stringer, Rianne M. Lord","doi":"10.1021/acs.organomet.4c00292","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00292","url":null,"abstract":"This work presents the synthesis of five new functionalized (benz)imidazolium <i>N</i>-heterocyclic (NHC) ligands (<b>L</b>) and four new (benz)imidazole silver(I) NHC (Ag(I)-NHC) complexes of mononuclear <b>[Ag(L)<sub>2</sub>](PF<sub>6</sub>)</b> or binuclear <b>[Ag<sub>2</sub>(L)<sub>2</sub>](PF<sub>6</sub>)<sub>2</sub></b> type. The complexes have been fully characterized, including single crystal X-ray diffraction of three new structures. The complexes and their corresponding free NHC ligands have been screened against breast cancer and noncancerous cell lines, showing the mononuclear benzimidazole complex has the highest activity, while the binuclear benzimidazole complex has the highest cancer cell selectivity. The silver uptake was measured by ICP-MS and highlights a strong link between cytotoxicity and cellular uptake. DNA interaction studies, molecular docking, and evaluation of reactive oxygen species (ROS) have been conducted for the most promising complexes to identify modes of action. Overall, the binuclear benzimidazole complex is the most selective and promising candidate against the MDA-MD-231 (breast cancer) cell line and has potential to be developed for treatment of late-stage breast cancers.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1021/acs.organomet.4c00244
Jiaying Su, Yexinzi Jiang, Jun Zhu
Hyperconjugative aromaticity, an integration of two chemical concepts, aromaticity and hyperconjugation, was first proposed in 1939. Recently, breaking through the main group elements, the hyperconjugative aromaticity has been successfully extended to the transition metal system, including groups 7, 9, 10, and 11 organometallic substituents. Here, we demonstrate that the missing group 8 transition metal substituents also possess a powerful ability to induce hyperconjugative aromaticity in cyclopentadiene via density functional theory calculations. It is found that metal–metal bonding will distinctly reduce the hyperconjugative aromaticity. Unexpectedly, the combination of a metal–metal double bond with a bridged carbonyl can significantly restore the aromaticity. Our findings expand the scope of both hyperconjugative aromaticity and metallaaromatic chemistry.
{"title":"Predicting the Hyperconjugative Aromaticity in Cyclopentadiene Containing Group 8 Transition Metal Substituents","authors":"Jiaying Su, Yexinzi Jiang, Jun Zhu","doi":"10.1021/acs.organomet.4c00244","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00244","url":null,"abstract":"Hyperconjugative aromaticity, an integration of two chemical concepts, aromaticity and hyperconjugation, was first proposed in 1939. Recently, breaking through the main group elements, the hyperconjugative aromaticity has been successfully extended to the transition metal system, including groups 7, 9, 10, and 11 organometallic substituents. Here, we demonstrate that the missing group 8 transition metal substituents also possess a powerful ability to induce hyperconjugative aromaticity in cyclopentadiene via density functional theory calculations. It is found that metal–metal bonding will distinctly reduce the hyperconjugative aromaticity. Unexpectedly, the combination of a metal–metal double bond with a bridged carbonyl can significantly restore the aromaticity. Our findings expand the scope of both hyperconjugative aromaticity and metallaaromatic chemistry.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1021/acs.organomet.4c00260
Lorenzo C. Ruiz De Castilla, Tuhin Ganguly, Babak Tahmouresilerd, Croix J. Laconsay, Judy I. Wu, Loi H. Do
Cation tuning is a simple yet powerful strategy to modulate the reactivity of polymerization catalysts, but the design rules to achieve maximum cation effects are not well understood. In the present work, it was demonstrated that inserting a methylene spacer between a nickel phenoxyimine complex and an M-polyethylene glycol (PEG) (where M = Li+, Na+, K+, or Cs+) unit led up to >70-fold increase in ethylene polymerization activity and 6-fold higher polymer molecular weight relative to that of the first-generation catalysts. It is hypothesized that these effects are due to the exclusive formation of 1:1 over 2:1 nickel:alkali species and closer proximity of the M-PEG moiety to the nickel center. These results suggest that the successful creation of cation-responsive catalysts requires an understanding of the cation binding stoichiometry as well as the structural and electronic changes associated with its host–guest interactions.
{"title":"Optimizing the Cation Binding Pocket in Nickel Phenoxyimine Catalysts Improves Ethylene Polymerization Efficiency","authors":"Lorenzo C. Ruiz De Castilla, Tuhin Ganguly, Babak Tahmouresilerd, Croix J. Laconsay, Judy I. Wu, Loi H. Do","doi":"10.1021/acs.organomet.4c00260","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00260","url":null,"abstract":"Cation tuning is a simple yet powerful strategy to modulate the reactivity of polymerization catalysts, but the design rules to achieve maximum cation effects are not well understood. In the present work, it was demonstrated that inserting a methylene spacer between a nickel phenoxyimine complex and an M-polyethylene glycol (PEG) (where M = Li<sup>+</sup>, Na<sup>+</sup>, K<sup>+</sup>, or Cs<sup>+</sup>) unit led up to >70-fold increase in ethylene polymerization activity and 6-fold higher polymer molecular weight relative to that of the first-generation catalysts. It is hypothesized that these effects are due to the exclusive formation of 1:1 over 2:1 nickel:alkali species and closer proximity of the M-PEG moiety to the nickel center. These results suggest that the successful creation of cation-responsive catalysts requires an understanding of the cation binding stoichiometry as well as the structural and electronic changes associated with its host–guest interactions.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1021/acs.organomet.4c00246
Arseniy A. Otlyotov, Timofey P. Rozov, Andrey D. Moshchenkov, Yury Minenkov
A database of conformational energies (CEs) of 16 transition metal (TM) complexes relevant to catalysis is automatically created by employing the new conformer generator program Uniconf. The generation procedure starts from an arbitrary high-energy structure and consistently produces conformer(s) similar to or even more energetically favorable than the optimized reference conformer retrieved from the Cambridge Structural Database. The reference CEs obtained with common dispersion-corrected functionals are employed to test the low-cost semiempirical methods. The superiority of the GFNn-xTB schemes over PM6*/7 methods is confirmed by the basic statistical analysis of the CEs. In addition, the influence of the vibrational thermostatistical (ΔGtherm) and continuum solvation (ΔGsolv) corrections on the CEs is examined in the framework of the (modified) scaled rigid-rotor-harmonic oscillator, (m)sRRHO, approximation, and solvation model based on density (SMD). In general, conformational Gibbs free energies exhibit excellent correlation with the respective electronic energies, especially if a more robust msRRHO scheme is employed for the calculation of ΔGtherm and in the case of a nonpolar solvent. The deviations from the perfect correlation occur if reduced CE windows of <5 kcal mol–1 are considered, implying a greater influence of these effects on the sorting of the low-energy structures.
{"title":"16TMCONF543: An Automatically Generated Data Set of Conformational Energies of Transition Metal Complexes Relevant to Catalysis","authors":"Arseniy A. Otlyotov, Timofey P. Rozov, Andrey D. Moshchenkov, Yury Minenkov","doi":"10.1021/acs.organomet.4c00246","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00246","url":null,"abstract":"A database of conformational energies (CEs) of 16 transition metal (TM) complexes relevant to catalysis is automatically created by employing the new conformer generator program Uniconf. The generation procedure starts from an arbitrary high-energy structure and consistently produces conformer(s) similar to or even more energetically favorable than the optimized reference conformer retrieved from the Cambridge Structural Database. The reference CEs obtained with common dispersion-corrected functionals are employed to test the low-cost semiempirical methods. The superiority of the GFN<i>n</i>-xTB schemes over PM6*/7 methods is confirmed by the basic statistical analysis of the CEs. In addition, the influence of the vibrational thermostatistical (Δ<i>G</i><sub>therm</sub>) and continuum solvation (Δ<i>G</i><sub>solv</sub>) corrections on the CEs is examined in the framework of the (modified) scaled rigid-rotor-harmonic oscillator, (m)sRRHO, approximation, and solvation model based on density (SMD). In general, conformational Gibbs free energies exhibit excellent correlation with the respective electronic energies, especially if a more robust msRRHO scheme is employed for the calculation of Δ<i>G</i><sub>therm</sub> and in the case of a nonpolar solvent. The deviations from the perfect correlation occur if reduced CE windows of <5 kcal mol<sup>–1</sup> are considered, implying a greater influence of these effects on the sorting of the low-energy structures.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1021/acs.organomet.4c00335
Bing Jing, Cheng Zhu, Fen Wang, Jianfeng Li, Chunming Cui
Rare-earth metal dialkyls have attracted considerable attention in a variety of chemical transformations, such as hydroelementation of unsaturated substrates and olefin polymerization. However, stable rare-earth dialkyls are still very limited in number because of their poor thermal stability. In this paper, silaimine-functionalized cyclopentadienyl ligands C5Me4H–Si(L)═NR (L = PhC(NtBu)2 and R = 2,6-iPr2C6H3 for 1 and SiMe3 for 2) were applied for the synthesis of yttrium and scandium dialkyls (3–5). σ-Bond metathesis reactions of silaimine-Cp yttrium dialkyl 3 with aniline and 2,6-dimethylpyridine yielded the yttrium diamide complex (6) and the C(sp3)–H bond-activated yttrium dibenzyl complex (7), respectively. The yttrium diamidinate complex (8) was generated from the reaction of 3 with N,N′-diisopropylcarbodiimide. The yttrium and scandium dialkyls 3 and 5 and the reaction products 6-thf, 7, and 8 have been structurally characterized by X-ray diffraction analysis. Notably, silaimine-Cp yttrium dialkyl 4 displayed high activity and excellent functional group tolerance in the catalytic addition of terminal alkynes and amines to carbodiimides.
{"title":"Rare-Earth Dialkyls Supported by Silaimine-Cp Ligand: Synthesis, Reactivity, and Catalytic Addition of Alkynes and Amines to Carbodiimides","authors":"Bing Jing, Cheng Zhu, Fen Wang, Jianfeng Li, Chunming Cui","doi":"10.1021/acs.organomet.4c00335","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00335","url":null,"abstract":"Rare-earth metal dialkyls have attracted considerable attention in a variety of chemical transformations, such as hydroelementation of unsaturated substrates and olefin polymerization. However, stable rare-earth dialkyls are still very limited in number because of their poor thermal stability. In this paper, silaimine-functionalized cyclopentadienyl ligands C<sub>5</sub>Me<sub>4</sub>H–Si(L)═NR (L = PhC(N<i>t</i>Bu)<sub>2</sub> and R = 2,6-<i>i</i>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub> for <b>1</b> and SiMe<sub>3</sub> for <b>2</b>) were applied for the synthesis of yttrium and scandium dialkyls (<b>3–5</b>). σ-Bond metathesis reactions of silaimine-Cp yttrium dialkyl <b>3</b> with aniline and 2,6-dimethylpyridine yielded the yttrium diamide complex (<b>6</b>) and the C(sp<sup>3</sup>)–H bond-activated yttrium dibenzyl complex (<b>7</b>), respectively. The yttrium diamidinate complex (<b>8</b>) was generated from the reaction of <b>3</b> with <i>N</i>,<i>N</i>′-diisopropylcarbodiimide. The yttrium and scandium dialkyls <b>3</b> and <b>5</b> and the reaction products <b>6-thf</b>, <b>7</b>, and <b>8</b> have been structurally characterized by X-ray diffraction analysis. Notably, silaimine-Cp yttrium dialkyl <b>4</b> displayed high activity and excellent functional group tolerance in the catalytic addition of terminal alkynes and amines to carbodiimides.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1021/acs.organomet.4c00313
Emily L. Nolan, Fengrui Qu, Melanie S. Sanford
This communication describes structure and reactivity studies of cyclometalated cobalt complexes formed during the dehydrogenative dimerization of 2,3,4,5-tetrafluoro-N-(quinolin-8-yl)benzamide. This substrate undergoes cyclometalation at Co(OAc)2 to form an NNC cobalt(II) pincer complex. Single-electron oxidation with AgOAc results in a cobalt(III) intermediate that undergoes a second directed C(sp2)–H activation to yield a bis-cyclometalated octahedral cobalt(III) product. This cobalt(III) species is inert to thermal carbon–carbon bond-forming reductive elimination upon heating at 160 °C for 48 h. However, treatment with ferrocenium oxidants at room temperature results in oxidatively induced carbon–carbon coupling via a putative cobalt(IV) intermediate.
{"title":"Exploration of Organometallic Cobalt Intermediates in an Aminoquinoline-Directed Dehydrogenative Dimerization Reaction","authors":"Emily L. Nolan, Fengrui Qu, Melanie S. Sanford","doi":"10.1021/acs.organomet.4c00313","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00313","url":null,"abstract":"This communication describes structure and reactivity studies of cyclometalated cobalt complexes formed during the dehydrogenative dimerization of 2,3,4,5-tetrafluoro-<i>N</i>-(quinolin-8-yl)benzamide. This substrate undergoes cyclometalation at Co(OAc)<sub>2</sub> to form an NNC cobalt(II) pincer complex. Single-electron oxidation with AgOAc results in a cobalt(III) intermediate that undergoes a second directed C(sp<sup>2</sup>)–H activation to yield a bis-cyclometalated octahedral cobalt(III) product. This cobalt(III) species is inert to thermal carbon–carbon bond-forming reductive elimination upon heating at 160 °C for 48 h. However, treatment with ferrocenium oxidants at room temperature results in oxidatively induced carbon–carbon coupling via a putative cobalt(IV) intermediate.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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