Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding
Autor(a) principal: | |
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Data de Publicação: | 2010 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10400.1/4264 |
Resumo: | The nitro group is active in metabolic systems and can be found as an integral part of a number of useful curative drugs and many toxic substances. The basis for much of this activity is not fully understood. It is not necessarily caused directly by through-bond electronic effects but may also be due to direct H-bonding to nitro or to indirect interference by the nitro group with existing H-bonding. An unusual effect of a nitro substituent on kinetic results from urethane addition/elimination reactions (Scheme 1) has been ascribed to some form of self-association, which was neither specified nor quantified. To investigate self-association phenomena caused by a nitro group, a bond energy/bond order formula for N–O bonds has been developed and then used to interpret relative amounts of covalent and ionic contributions to total N–O bond energy. Calculated bond energies were then used to obtain enthalpies of formation for H-bonds to nitro groups in crystals and in solution. Similar results from solution data reveal that direct H-bonding to nitro is much weaker than in crystals, unless intramolecular H-bonding can occur. The results revealed that the 'self-association' effects observed for nitro substituents in urethanes (Scheme 1) were not caused by nitro participating directly in intermolecular bonding to NH of another urethane but by an indirect intramolecular action of the nitro group on pre-existing normal NH–O amide/amide type H-bonding. |
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Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bondingBond Energy/Bond Order relationshipsAddition/elimination of arylurethanesNitro groups and hydrogen-bondingN-O linkagesIonicityThe nitro group is active in metabolic systems and can be found as an integral part of a number of useful curative drugs and many toxic substances. The basis for much of this activity is not fully understood. It is not necessarily caused directly by through-bond electronic effects but may also be due to direct H-bonding to nitro or to indirect interference by the nitro group with existing H-bonding. An unusual effect of a nitro substituent on kinetic results from urethane addition/elimination reactions (Scheme 1) has been ascribed to some form of self-association, which was neither specified nor quantified. To investigate self-association phenomena caused by a nitro group, a bond energy/bond order formula for N–O bonds has been developed and then used to interpret relative amounts of covalent and ionic contributions to total N–O bond energy. Calculated bond energies were then used to obtain enthalpies of formation for H-bonds to nitro groups in crystals and in solution. Similar results from solution data reveal that direct H-bonding to nitro is much weaker than in crystals, unless intramolecular H-bonding can occur. The results revealed that the 'self-association' effects observed for nitro substituents in urethanes (Scheme 1) were not caused by nitro participating directly in intermolecular bonding to NH of another urethane but by an indirect intramolecular action of the nitro group on pre-existing normal NH–O amide/amide type H-bonding.Michigan PublishingSapientiaJohnstone, Robert A. W.Loureiro, Rui M. S.Labat, G.Cristiano, Maria Lurdes Santos2014-06-11T12:37:23Z20102014-06-05T10:57:40Z2010-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10400.1/4264engJohnstone, Robert A. W.; Loureiro, Rui. M.S.; Labat, G.; Cristiano, M.L.S. Bond Energy/Bond Order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding, Arkivoc, 3, 142-169, 2010.1551-7012AUT: MCR00716;info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-07-24T10:15:33Zoai:sapientia.ualg.pt:10400.1/4264Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T19:57:43.273530Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding |
title |
Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding |
spellingShingle |
Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding Johnstone, Robert A. W. Bond Energy/Bond Order relationships Addition/elimination of arylurethanes Nitro groups and hydrogen-bonding N-O linkages Ionicity |
title_short |
Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding |
title_full |
Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding |
title_fullStr |
Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding |
title_full_unstemmed |
Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding |
title_sort |
Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding |
author |
Johnstone, Robert A. W. |
author_facet |
Johnstone, Robert A. W. Loureiro, Rui M. S. Labat, G. Cristiano, Maria Lurdes Santos |
author_role |
author |
author2 |
Loureiro, Rui M. S. Labat, G. Cristiano, Maria Lurdes Santos |
author2_role |
author author author |
dc.contributor.none.fl_str_mv |
Sapientia |
dc.contributor.author.fl_str_mv |
Johnstone, Robert A. W. Loureiro, Rui M. S. Labat, G. Cristiano, Maria Lurdes Santos |
dc.subject.por.fl_str_mv |
Bond Energy/Bond Order relationships Addition/elimination of arylurethanes Nitro groups and hydrogen-bonding N-O linkages Ionicity |
topic |
Bond Energy/Bond Order relationships Addition/elimination of arylurethanes Nitro groups and hydrogen-bonding N-O linkages Ionicity |
description |
The nitro group is active in metabolic systems and can be found as an integral part of a number of useful curative drugs and many toxic substances. The basis for much of this activity is not fully understood. It is not necessarily caused directly by through-bond electronic effects but may also be due to direct H-bonding to nitro or to indirect interference by the nitro group with existing H-bonding. An unusual effect of a nitro substituent on kinetic results from urethane addition/elimination reactions (Scheme 1) has been ascribed to some form of self-association, which was neither specified nor quantified. To investigate self-association phenomena caused by a nitro group, a bond energy/bond order formula for N–O bonds has been developed and then used to interpret relative amounts of covalent and ionic contributions to total N–O bond energy. Calculated bond energies were then used to obtain enthalpies of formation for H-bonds to nitro groups in crystals and in solution. Similar results from solution data reveal that direct H-bonding to nitro is much weaker than in crystals, unless intramolecular H-bonding can occur. The results revealed that the 'self-association' effects observed for nitro substituents in urethanes (Scheme 1) were not caused by nitro participating directly in intermolecular bonding to NH of another urethane but by an indirect intramolecular action of the nitro group on pre-existing normal NH–O amide/amide type H-bonding. |
publishDate |
2010 |
dc.date.none.fl_str_mv |
2010 2010-01-01T00:00:00Z 2014-06-11T12:37:23Z 2014-06-05T10:57:40Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10400.1/4264 |
url |
http://hdl.handle.net/10400.1/4264 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
Johnstone, Robert A. W.; Loureiro, Rui. M.S.; Labat, G.; Cristiano, M.L.S. Bond Energy/Bond Order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding, Arkivoc, 3, 142-169, 2010. 1551-7012 AUT: MCR00716; |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Michigan Publishing |
publisher.none.fl_str_mv |
Michigan Publishing |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
instname_str |
Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
instacron_str |
RCAAP |
institution |
RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
collection |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository.name.fl_str_mv |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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1799133189472518144 |