{"doi":"10.1002/jcc.20910","title":"Blue shifts of the CH stretching vibrations in hydrogen‐bonded and protonated trimethylamine. Effect of hyperconjugation on bond properties","abstract":"<jats:title>Abstract</jats:title><jats:p>The optimized geometry of isolated trimethylamine (TMA), its hydrogen bond complexes with phenol derivatives and protonated TMA is calculated at the B3LYP/6‐31++G(d,p) level. A natural bond orbital (NBO) analysis on these systems is carried out at the same level of theory. In isolated TMA, one of the CH bond in each of the three CH<jats:sub>3</jats:sub>groups is more elongated than the two other ones. As revealed by the NBO data, this results from a hyperconjugative interaction from the N lone pair to the σ*(CH) orbitals of the CH bonds being in a transoid position with respect to the N lone pair. The formation of an intermolecular OH···N hydrogen bond with phenols results in a decrease of the lone pair effect. A linear correlation is found between the decrease in occupation of the σ*(CH) orbitals and the decrease in the hyperconjugative interaction energy in the complexes and isolated TMA. Complex formation with phenols results in a blue shift of 55–74 cm<jats:sup>−1</jats:sup>of the CH stretching vibrations involved in the lone pair effect. Smaller blue shifts between 14 and 23 cm<jats:sup>−1</jats:sup>are predicted for the other CH bonds. In these complexes, a linear correlation is found between the frequency shifts and the elongation of the CH bonds. Protonation of TMA results in a nearly equalization of all the CH distances and a blue shift of 180 cm<jats:sup>−1</jats:sup>of the CH bonds involved in hyperconjugation with the N lone pair. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008</jats:p>","journal":"Journal of Computational Chemistry","year":2008,"id":666134,"datarank":0.5606504427425053,"base_score":3.7376696182833684,"endowment":3.7376696182833684,"self_citation_contribution":0.5606504427425053,"citation_network_contribution":0.0,"self_endowment_contribution":0.5606504427425053,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":41,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1739578,"name":"Salma Parveen","orcid":null,"position":1,"is_corresponding":false},{"id":1739580,"name":"Subojit Das","orcid":null,"position":2,"is_corresponding":false},{"id":1739581,"name":"Thérèse Zeegers‐Huyskens","orcid":null,"position":3,"is_corresponding":false},{"id":202120,"name":"Asit K. Chandra","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Blue shifts of the CH stretching vibrations in hydrogen‐bonded and protonated trimethylamine. Effect of hyperconjugation on bond properties","abstract":"<jats:title>Abstract</jats:title><jats:p>The optimized geometry of isolated trimethylamine (TMA), its hydrogen bond complexes with phenol derivatives and protonated TMA is calculated at the B3LYP/6‐31++G(d,p) level. A natural bond orbital (NBO) analysis on these systems is carried out at the same level of theory. In isolated TMA, one of the CH bond in each of the three CH<jats:sub>3</jats:sub>groups is more elongated than the two other ones. As revealed by the NBO data, this results from a hyperconjugative interaction from the N lone pair to the σ*(CH) orbitals of the CH bonds being in a transoid position with respect to the N lone pair. The formation of an intermolecular OH···N hydrogen bond with phenols results in a decrease of the lone pair effect. A linear correlation is found between the decrease in occupation of the σ*(CH) orbitals and the decrease in the hyperconjugative interaction energy in the complexes and isolated TMA. Complex formation with phenols results in a blue shift of 55–74 cm<jats:sup>−1</jats:sup>of the CH stretching vibrations involved in the lone pair effect. Smaller blue shifts between 14 and 23 cm<jats:sup>−1</jats:sup>are predicted for the other CH bonds. In these complexes, a linear correlation is found between the frequency shifts and the elongation of the CH bonds. Protonation of TMA results in a nearly equalization of all the CH distances and a blue shift of 180 cm<jats:sup>−1</jats:sup>of the CH bonds involved in hyperconjugation with the N lone pair. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008</jats:p>","is_dataset_classified":null,"base_score":3.7376696182833684,"endowment":3.7376696182833684,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"18270959","pmcid":null,"openalex_id":"https://openalex.org/W2149575470","authors":[],"funders":[],"total_grants":0,"fwci":4.3639,"citation_percentile":0.94427286,"influential_citations":0,"citation_trend":[{"year":2012,"count":4},{"year":2013,"count":3},{"year":2014,"count":1},{"year":2015,"count":2},{"year":2017,"count":3},{"year":2018,"count":1},{"year":2019,"count":1},{"year":2021,"count":1},{"year":2022,"count":2},{"year":2023,"count":1},{"year":2024,"count":1},{"year":2025,"count":1},{"year":2026,"count":5}],"oa_status":"closed","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjcc.20910","host_type":"publisher"},{"url":"https://onlinelibrary.wiley.com/doi/pdf/10.1002/jcc.20910","host_type":"publisher"},{"url":"https://doi.org/10.1002/jcc.20910","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/18270959","host_type":"repository"}],"fields_of_study":["Crystallography and molecular interactions","Molecular Spectroscopy and Structure","Advanced Chemical Physics Studies"],"mesh_terms":["Computer Simulation","Hydrogen Bonding","Methylamines","Models, Chemical","Phenols","Protons","Quantum Theory","Vibration","Reproducibility of Results"],"keywords":["Hyperconjugation","Protonation","Hydrogen bond","Chemistry","Trimethylamine","Computational chemistry","Photochemistry","Molecule","Organic chemistry","Ion"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Affordable and clean energy"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-13T13:26:49.763859Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}