0000000000861696
AUTHOR
Juha Hurmalainen
Mono‐ and Bis(imidazolidinium ethynyl) Cations and Reduction of the Latter To Give an Extended Bis‐1,4‐([3]Cumulene)‐p-carboquinoid System
An extended π-system containing two [3]cumulene fragments separated by a p-carboquinoid and stabilized by two capping N-heterocyclic carbenes (NHCs) has been prepared. Mono- and bis(imidazolidinium ethynyl) cations have also been synthesized from the reaction of an NHC with phenylethynyl bromide or 1,4-bis(bromoethynyl)benzene. Cyclic voltammetry coupled with synthetic and structural studies showed that the dication is readily reduced to a neutral, singlet bis-1,4-([3]cumulene)-p-carboquinoid as a result of the π-accepting properties of the capping NHCs. peerReviewed
Direct observation of a borane-silane complex involved in frustrated Lewis-pair-mediated hydrosilylations.
Perfluorarylborane Lewis acids catalyse the addition of silicon-hydrogen bonds across C=C, C=N and C=O double bonds. This 'metal-free' hydrosilylation has been proposed to occur via borane activation of the silane Si-H bond, rather than through classical Lewis acid/base adducts with the substrate. However, the key borane/silane adduct had not been observed experimentally. Here it is shown that the strongly Lewis acidic, antiaromatic 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene forms an observable, isolable adduct with triethylsilane. The equilibrium for adduct formation was studied quantitatively through variable-temperature NMR spectroscopic investigations. The interactio…
Intermolecular oxidative dehydrogenative 3,3′-coupling of benzo[b]furans and benzo[b]thiophenes promoted by DDQ/H+: total synthesis of shandougenine B
With an excess of a strong acid, 2,3-dichloro-5,6-dicyano-1,4-quinone (DDQ) is shown to promote metal-free intermolecular oxidative dehydrogenative (ODH) 3,3'-coupling of 2-aryl-benzo[b]furans and 2-aryl-benzo[b]thiophenes up to 92% yield as demonstrated with 9 substrates. Based on the analysis of oxidation potentials and molecular orbitals combined with EPR, NMR and UV-Vis observations, the studied reaction is initiated by a DDQ-substrate charge transfer complex and presumably proceeds via oxidation of the substrate into an electrophilic radical cation that further reacts with another molecule of a neutral substrate. The coupling reactivity can easily be predicted from the oxidation potent…
Synthesis and characterisation of p-block complexes of biquinoline at different ligand charge states
The first examples of p-block coordination complexes of biquinoline, namely [(biq)BCl2]Cl and [(biq)BCl2]˙, were synthesized and structurally characterized. The acquired data allowed the estimation of the ligand charge state based on its metrical parameters. The subsequent use of this protocol, augmented with theoretical calculations, revealed ambiguities in the published data for transition metal complexes of biquinoline. peerReviewed
Synthesis of new hybrid 1,4-thiazinyl-1,2,3-dithiazolyl radicals via Smiles rearrangement
The condensation reaction of 2-aminobenzenethiols and 3-aminopyrazinethiols with 2-amino-6-fluoro-N-methylpyridinium triflate afforded thioether derivatives that were found to undergo Smiles rearrangement and cyclocondensation with sulphur monochloride to yield new hybrid 1,4-thiazine-1,2,3-dithiazolylium cations. The synthesized cations were readily reduced to the corresponding stable neutral radicals with spin densities delocalized over both 1,4-thiazinyl and 1,2,3-dithiazolyl moieties. peerReviewed
Direct observation of a borane–silane complex involved in frustrated Lewis-pair-mediated hydrosilylations
Perfluorarylborane Lewis acids catalyse the addition of silicon–hydrogen bonds across C=C, C=N and C=O double bonds. This ‘metal-free’ hydrosilylation has been proposed to occur via borane activation of the silane Si–H bond, rather than through classical Lewis acid/base adducts with the substrate. However, the key borane/silane adduct had not been observed experimentally. Here it is shown that the strongly Lewis acidic, antiaromatic 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene forms an observable, isolable adduct with triethylsilane. The equilibrium for adduct formation was studied quantitatively through variable-temperature NMR spectroscopic investigations. The interacti…
Mono‐ and Bis(imidazolidinium ethynyl) Cations and Reduction of the Latter To Give an Extended Bis‐1,4‐([3]Cumulene)‐ p ‐carboquinoid System
An extended π-system containing two [3]cumulene fragments separated by a p-carboquinoid and stabilized by two capping N-heterocyclic carbenes (NHCs) has been prepared. Mono- and bis(imidazolidinium ethynyl) cations have also been synthesized from the reaction of an NHC with phenylethynyl bromide or 1,4-bis(bromoethynyl)benzene. Cyclic voltammetry coupled with synthetic and structural studies showed that the dication is readily reduced to a neutral, singlet bis-1,4-([3]cumulene)-p-carboquinoid as a result of the π-accepting properties of the capping NHCs.
Experimental and computational studies of unconventional main group compounds : stable radicals and reactive intermediates
Ever since their discovery, radicals have intrigued the minds of experimental and theoretical chemists alike. While the vast majority of radicals are transient species, a large number of stable and persistent radicals are also known. This has enabled the use of radicals in different applications. For example, radicals are highly useful in chemical synthesis due to their selectivity and functional group tolerance. Detailed knowledge of the electronic structure of synthetic intermediates, both radical and non-radical, enables chemists to improve existing synthesis routes and to design completely new ones. This thesis is divided into two parts. The first part begins with an introduction to the…
Comment on "Crystallographic Snapshot of an Arrested Intermediate in the Biomimetic Activation of CO2"
Out of focus: A recent Communication published in this journal describes the synthesis of [nBu4N]HCO3. The authors performed a single-crystal X-ray study that revealed a putative species described as an incipient hydroxide ion engaging in a long, and presumably weak, interaction with CO2. Our recent exploration of the coordination chemistry of CO2 with small ions leads us to believe that such an exceptional bonding situation is unlikely. Instead, we argue that the crystal structure is that of [nBu4N]O2CCH3 and therefore not representative of the bulk powder from the synthesis. peerReviewed
Comment on “Crystallographic Snapshot of an Arrested Intermediate in the Biomimetic Activation of CO2”
Out of focus: A recent Communication published in this journal describes the synthesis of [nBu4 N]HCO3 . The authors performed a single-crystal X-ray study that revealed a putative species described as an incipient hydroxide ion engaging in a long, and presumably weak, interaction with CO2 . Our recent exploration of the coordination chemistry of CO2 with small ions leads us to believe that such an exceptional bonding situation is unlikely. Instead, we argue that the crystal structure is that of [nBu4 N]O2 CCH3 and therefore not representative of the bulk powder from the synthesis.
CCDC 1549500: Experimental Crystal Structure Determination
Related Article: Brian M. Barry, R. Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N. Robertson, William L. McClennan, Alex J. Veinot, Tracey L. Roemmele, Ulrike Werner-Zwanziger, René T. Boeré, Heikki M. Tuononen, Jason A. C. Clyburne, Jason D. Masuda|2018|Angew.Chem.,Int.Ed.|57|749|doi:10.1002/anie.201711031
CCDC 1549501: Experimental Crystal Structure Determination
Related Article: Brian M. Barry, R. Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N. Robertson, William L. McClennan, Alex J. Veinot, Tracey L. Roemmele, Ulrike Werner-Zwanziger, René T. Boeré, Heikki M. Tuononen, Jason A. C. Clyburne, Jason D. Masuda|2018|Angew.Chem.,Int.Ed.|57|749|doi:10.1002/anie.201711031
CCDC 1519804: Experimental Crystal Structure Determination
Related Article: Petra Vasko, Juha Hurmalainen, Akseli Mansikkamäki, Anssi Peuronen, Aaron Mailman, Heikki M. Tuononen|2017|Dalton Trans.|46|16004|doi:10.1039/C7DT03243A
CCDC 1518784: Experimental Crystal Structure Determination
Related Article: Juha Hurmalainen, Akseli Mansikkamäki, Ian S. Morgan, Anssi Peuronen, Heikki M. Tuononen|2017|Dalton Trans.|46|1377|doi:10.1039/C6DT04504A
CCDC 1519805: Experimental Crystal Structure Determination
Related Article: Petra Vasko, Juha Hurmalainen, Akseli Mansikkamäki, Anssi Peuronen, Aaron Mailman, Heikki M. Tuononen|2017|Dalton Trans.|46|16004|doi:10.1039/C7DT03243A
CCDC 1549502: Experimental Crystal Structure Determination
Related Article: Brian M. Barry, R. Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N. Robertson, William L. McClennan, Alex J. Veinot, Tracey L. Roemmele, Ulrike Werner-Zwanziger, René T. Boeré, Heikki M. Tuononen, Jason A. C. Clyburne, Jason D. Masuda|2018|Angew.Chem.,Int.Ed.|57|749|doi:10.1002/anie.201711031
CCDC 1536800: Experimental Crystal Structure Determination
Related Article: Petra Vasko, Juha Hurmalainen, Akseli Mansikkamäki, Anssi Peuronen, Aaron Mailman, Heikki M. Tuononen|2017|Dalton Trans.|46|16004|doi:10.1039/C7DT03243A
CCDC 1010911: Experimental Crystal Structure Determination
Related Article: Adrian Y. Houghton, Juha Hurmalainen, Akseli Mansikkamäki, Warren E. Piers, Heikki M. Tuononen|2014|Nature Chemistry|6|983|doi:10.1038/nchem.2063
CCDC 1549499: Experimental Crystal Structure Determination
Related Article: Brian M. Barry, R. Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N. Robertson, William L. McClennan, Alex J. Veinot, Tracey L. Roemmele, Ulrike Werner-Zwanziger, René T. Boeré, Heikki M. Tuononen, Jason A. C. Clyburne, Jason D. Masuda|2018|Angew.Chem.,Int.Ed.|57|749|doi:10.1002/anie.201711031
CCDC 1519808: Experimental Crystal Structure Determination
Related Article: Petra Vasko, Juha Hurmalainen, Akseli Mansikkamäki, Anssi Peuronen, Aaron Mailman, Heikki M. Tuononen|2017|Dalton Trans.|46|16004|doi:10.1039/C7DT03243A
CCDC 1549503: Experimental Crystal Structure Determination
Related Article: Brian M. Barry, R. Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N. Robertson, William L. McClennan, Alex J. Veinot, Tracey L. Roemmele, Ulrike Werner-Zwanziger, René T. Boeré, Heikki M. Tuononen, Jason A. C. Clyburne, Jason D. Masuda|2018|Angew.Chem.,Int.Ed.|57|749|doi:10.1002/anie.201711031
CCDC 1519806: Experimental Crystal Structure Determination
Related Article: Petra Vasko, Juha Hurmalainen, Akseli Mansikkamäki, Anssi Peuronen, Aaron Mailman, Heikki M. Tuononen|2017|Dalton Trans.|46|16004|doi:10.1039/C7DT03243A
CCDC 1036823: Experimental Crystal Structure Determination
Related Article: Juha Hurmalainen, Michael A. Land, Katherine N. Robertson, Christopher J. Roberts, Ian S. Morgan, Heikki M. Tuononen and Jason A. C. Clyburne|2015|Angew.Chem.,Int.Ed.|54|7484|doi:10.1002/anie.201411654
CCDC 1536801: Experimental Crystal Structure Determination
Related Article: Petra Vasko, Juha Hurmalainen, Akseli Mansikkamäki, Anssi Peuronen, Aaron Mailman, Heikki M. Tuononen|2017|Dalton Trans.|46|16004|doi:10.1039/C7DT03243A
CCDC 1519807: Experimental Crystal Structure Determination
Related Article: Petra Vasko, Juha Hurmalainen, Akseli Mansikkamäki, Anssi Peuronen, Aaron Mailman, Heikki M. Tuononen|2017|Dalton Trans.|46|16004|doi:10.1039/C7DT03243A
CCDC 1549498: Experimental Crystal Structure Determination
Related Article: Brian M. Barry, R. Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N. Robertson, William L. McClennan, Alex J. Veinot, Tracey L. Roemmele, Ulrike Werner-Zwanziger, René T. Boeré, Heikki M. Tuononen, Jason A. C. Clyburne, Jason D. Masuda|2018|Angew.Chem.,Int.Ed.|57|749|doi:10.1002/anie.201711031
CCDC 1549504: Experimental Crystal Structure Determination
Related Article: Brian M. Barry, R. Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N. Robertson, William L. McClennan, Alex J. Veinot, Tracey L. Roemmele, Ulrike Werner-Zwanziger, René T. Boeré, Heikki M. Tuononen, Jason A. C. Clyburne, Jason D. Masuda|2018|Angew.Chem.,Int.Ed.|57|749|doi:10.1002/anie.201711031
CCDC 1518783: Experimental Crystal Structure Determination
Related Article: Juha Hurmalainen, Akseli Mansikkamäki, Ian S. Morgan, Anssi Peuronen, Heikki M. Tuononen|2017|Dalton Trans.|46|1377|doi:10.1039/C6DT04504A