{"doi":"10.1021/ic100714m","title":"Superbasic Amidine Monodentate Ligands in<i>fac</i>-[Re(CO)<sub>3</sub>(5,5′-Me<sub>2</sub>bipy)(Amidine)]BF<sub>4</sub>Complexes: Dependence of Amidine Configuration on the Remote Nitrogen Substituents","abstract":null,"journal":"Inorganic Chemistry","year":2010,"id":679625,"datarank":0.4493598410330987,"base_score":2.995732273553991,"endowment":2.995732273553991,"self_citation_contribution":0.4493598410330987,"citation_network_contribution":0.0,"self_endowment_contribution":0.4493598410330987,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":19,"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":537827,"name":"Frank R. Fronczek","orcid":"0000-0001-5544-2779","position":1,"is_corresponding":false},{"id":1775724,"name":"Patricia A. Marzilli","orcid":null,"position":2,"is_corresponding":false},{"id":217731,"name":"Luigi G. Marzilli","orcid":null,"position":3,"is_corresponding":false},{"id":1775722,"name":"Theshini Perera","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Superbasic Amidine Monodentate Ligands in<i>fac</i>-[Re(CO)<sub>3</sub>(5,5′-Me<sub>2</sub>bipy)(Amidine)]BF<sub>4</sub>Complexes: Dependence of Amidine Configuration on the Remote Nitrogen Substituents","abstract":"Addition of various RNH(2) to fac-[Re(CO)(3)(5,5'-Me(2)bipy)(CH(3)CN)]BF(4) (1) converts the acetonitrile ligand to the amidine ligand (a superbase) in fac-[Re(CO)(3)(5,5'-Me(2)bipy)(HNC(CH(3))NHR)]BF(4) products. Each complex has four conceivable isomers (E, E', Z, and Z') because the amidine CN bonds have double-bond character, and the two remote NHR group substituents are different. The reaction of 1 in acetonitrile is complete in 6 to 96 h (25 degrees C) and forms fac-[Re(CO)(3)(5,5'-Me(2)bipy)(HNC(CH(3))NHR)]BF(4) E' and Z isomers. Only the E' isomer formed crystals (R = methyl, isopropyl, isobutyl, tert-butyl, and benzyl). Upon dissolution of such crystals in acetonitrile-d(3), NMR spectra with highly dominant E' signals gradually changed (approximately 15 min at room temperature) to spectra with signals for an equilibrium mixture of E' and Z isomers. Such slow E'-to-Z isomer interchange is also indicated by 2D ROESY NMR data used primarily to assign solution structure. Equilibrium ratios (E':Z) of approximately 65:35 for R = methyl, isopropyl, and isobutyl and 83:17 for R = tert-butyl demonstrate that increasing the remote NHR group steric bulk above a threshold size favors the E' isomer. Consistent with this trend, fac-[Re(CO)(3)(5,5'-Me(2)bipy)(HNC(CH(3))NH(2))]BF(4), with a remote NH(2) (low bulk) group, favors the Z isomer. In contrast, although the remote NH(benzyl) group in fac-[Re(CO)(3)(5,5'-Me(2)bipy)(HNC(CH(3))NH(CH(2)C(6)H(5))]BF(4) has only moderate bulk, the E' isomer has high abundance as a result of favorable 5,5'-Me(2)bipy/benzyl stacking, evidence for which is present in both solid and solution states. The fac-[Re(CO)(3)(5,5'-Me(2)bipy)(HNC(CH(3))NHR)]BF(4) E isomer can be detected in solvents of low polarity. However, the Z' isomer was not observed, undoubtedly because unfavorable remote-group clashes with the equatorial ligands destabilize this isomer. Challenge studies with a 5-fold excess of 4-dimethylaminopyridine in acetonitrile-d(3) establish that fac-[Re(CO)(3)(5,5'-Me(2)bipy)(HNC(CH(3))NHCH(CH(3))(2))]BF(4) is robust because the isopropylamidine ligand was not displaced, consistent with the superbase character of amidine ligands.","is_dataset_classified":null,"base_score":2.995732273553991,"endowment":2.995732273553991,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"20593850","pmcid":null,"openalex_id":"https://openalex.org/W1979842844","authors":[],"funders":[{"funder_name":"NIDDK NIH HHS","grant_id":"R37 DK038842","title":null}],"total_grants":1,"fwci":1.428,"citation_percentile":0.79074103,"influential_citations":0,"citation_trend":[{"year":2012,"count":3},{"year":2013,"count":3},{"year":2014,"count":2},{"year":2016,"count":1},{"year":2017,"count":1},{"year":2019,"count":1},{"year":2021,"count":1},{"year":2022,"count":1},{"year":2023,"count":1},{"year":2024,"count":1},{"year":2025,"count":1}],"oa_status":"closed","license":null,"oa_locations":[{"url":"https://pubs.acs.org/doi/pdf/10.1021/ic100714m","host_type":"publisher"},{"url":"https://doi.org/10.1021/ic100714m","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/20593850","host_type":"repository"},{"url":"https://repository.lsu.edu/chemistry_pubs/3756","host_type":"journal"}],"fields_of_study":["Organometallic Complex Synthesis and Catalysis","Metal complexes synthesis and properties","Lanthanide and Transition Metal Complexes","Amidines","Crystallography, X-Ray","Ligands","Magnetic Resonance Spectroscopy","Nitrogen","Organometallic Compounds","Solvents","Stereoisomerism"],"mesh_terms":["Amidines","Ligands","Nitrogen","Magnetic Resonance Spectroscopy","Organometallic Compounds","Solvents","Stereoisomerism","Crystallography, X-Ray"],"keywords":["Amidine","Chemistry","Denticity","Medicinal chemistry","Stereochemistry","Crystallography","Crystal structure"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Clean water and sanitation"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-17T13:31:18.571147Z","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":[]}