{"doi":"10.1002/jccs.200900174","title":"The π‐Bonding Trend in VIB M(CO)<sub>6</sub> Observed by NMR Spectroscopy — A Natural Bond Orbital View","abstract":"<jats:title>Abstract</jats:title><jats:p>Analysis of carbonyl's 2π orbital populations, [2π], obtained by NMR relaxation time experiments of VIB M(CO)(ẽ<jats:sup>6</jats:sup>‐C<jats:sub>6</jats:sub>H<jats:sub>6</jats:sub>) reveals the 3d &lt; 4d &lt; 5d trend for M r̊ CO back‐donation, as reported values of [2π] for VIB M(CO)<jats:sub>5</jats:sub>(quinuclidine). The same analysis performed on Mn(CO)<jats:sub>3</jats:sub>(ẽ<jats:sup>5</jats:sup>C<jats:sub>5</jats:sub>H<jats:sub>5</jats:sub>) and Re(CO)<jats:sub>3</jats:sub>(ẽ<jats:sup>5</jats:sup>‐C<jats:sub>5</jats:sub>H<jats:sub>5</jats:sub>) also gives 3d &lt; 5d order of back‐donation. The distinctive 3d ∼ 5d &gt; 4d trend reported for VIB M(CO)<jats:sub>6</jats:sub> has been investigated by second‐order perturbation theory analysis within the natural bond orbital (NBO) scheme to search for orbital‐based explanations. Besides the conventional d<jats:sub>π</jats:sub> r̊ 2π donor‐acceptor (DA) interaction in the trend 3d &lt; 4d &lt; 5d, the other DA interaction arising from three‐center‐hyperbond (3CHB) hyperconjugation has been found in the trend 3d &gt;&gt; 5d ∼ 4d. Within the VIB M(CO)<jats:sub>6</jats:sub> family, this 3CHB hyperconjugation is so much higher in Cr(CO)<jats:sub>6</jats:sub> than in W(CO)<jats:sub>6</jats:sub> as to render the overall 2π populations exhibiting the 3d ∼ 5d &gt; 4d trend.</jats:p>","journal":"Journal of the Chinese Chemical Society","year":2009,"id":657648,"datarank":0.24377934355254471,"base_score":1.3862943611198906,"endowment":1.3862943611198906,"self_citation_contribution":0.20794415416798362,"citation_network_contribution":0.0358351893845611,"self_endowment_contribution":0.20794415416798362,"citer_contribution":0.0358351893845611,"corpus_percentile":null,"corpus_rank":null,"citation_count":3,"citer_count":2,"citers_with_citation_signal":1,"citers_with_endowment":1,"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":1716762,"name":"Ker‐Ming Yan","orcid":null,"position":1,"is_corresponding":false},{"id":1716763,"name":"Wen‐Yi Hsu","orcid":null,"position":2,"is_corresponding":false},{"id":1716764,"name":"Min‐Ying Huang","orcid":null,"position":3,"is_corresponding":false},{"id":1716765,"name":"Hui‐Ying Wu","orcid":null,"position":4,"is_corresponding":false},{"id":1716761,"name":"Shao‐Pin Wang","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"The π‐Bonding Trend in VIB M(CO)<sub>6</sub> Observed by NMR Spectroscopy — A Natural Bond Orbital View","abstract":"<jats:title>Abstract</jats:title><jats:p>Analysis of carbonyl's 2π orbital populations, [2π], obtained by NMR relaxation time experiments of VIB M(CO)(ẽ<jats:sup>6</jats:sup>‐C<jats:sub>6</jats:sub>H<jats:sub>6</jats:sub>) reveals the 3d &lt; 4d &lt; 5d trend for M r̊ CO back‐donation, as reported values of [2π] for VIB M(CO)<jats:sub>5</jats:sub>(quinuclidine). The same analysis performed on Mn(CO)<jats:sub>3</jats:sub>(ẽ<jats:sup>5</jats:sup>C<jats:sub>5</jats:sub>H<jats:sub>5</jats:sub>) and Re(CO)<jats:sub>3</jats:sub>(ẽ<jats:sup>5</jats:sup>‐C<jats:sub>5</jats:sub>H<jats:sub>5</jats:sub>) also gives 3d &lt; 5d order of back‐donation. The distinctive 3d ∼ 5d &gt; 4d trend reported for VIB M(CO)<jats:sub>6</jats:sub> has been investigated by second‐order perturbation theory analysis within the natural bond orbital (NBO) scheme to search for orbital‐based explanations. Besides the conventional d<jats:sub>π</jats:sub> r̊ 2π donor‐acceptor (DA) interaction in the trend 3d &lt; 4d &lt; 5d, the other DA interaction arising from three‐center‐hyperbond (3CHB) hyperconjugation has been found in the trend 3d &gt;&gt; 5d ∼ 4d. Within the VIB M(CO)<jats:sub>6</jats:sub> family, this 3CHB hyperconjugation is so much higher in Cr(CO)<jats:sub>6</jats:sub> than in W(CO)<jats:sub>6</jats:sub> as to render the overall 2π populations exhibiting the 3d ∼ 5d &gt; 4d trend.</jats:p>","is_dataset_classified":null,"base_score":1.3862943611198906,"endowment":1.3862943611198906,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"19162232","pmcid":null,"openalex_id":"https://openalex.org/W2140280641","authors":[],"funders":[],"total_grants":0,"fwci":0.5819,"citation_percentile":0.77222998,"influential_citations":0,"citation_trend":[{"year":2021,"count":1}],"oa_status":"closed","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjccs.200900174","host_type":"publisher"},{"url":"https://onlinelibrary.wiley.com/doi/pdf/10.1002/jccs.200900174","host_type":"publisher"},{"url":"https://doi.org/10.1002/jccs.200900174","host_type":"journal"}],"fields_of_study":["Crystallography and molecular interactions","Organometallic Complex Synthesis and Catalysis","Organoboron and organosilicon chemistry"],"mesh_terms":[],"keywords":["Natural bond orbital","Chemistry","Hyperconjugation","Bond order","Crystallography","Computational chemistry","Stereochemistry","Density functional theory","Bond length","Molecule","Organic chemistry"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Life below water"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-12T01:53:13.004853Z","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":[]}