{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T03:44:45Z","timestamp":1790307885026,"version":"4.1.0"},"reference-count":35,"publisher":"American Association for the Advancement of Science (AAAS)","issue":"6807","license":[{"start":{"date-parts":[[2027,7,9]],"date-time":"2027-07-09T00:00:00Z","timestamp":1815091200000},"content-version":"vor","delay-in-days":365,"URL":"https:\/\/www.science.org\/content\/page\/science-licenses-journal-article-reuse"}],"funder":[{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["CHE-2403841"],"award-info":[{"award-number":["CHE-2403841"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000015","name":"U.S. Department of Energy","doi-asserted-by":"publisher","award":["DE-SC0008501"],"award-info":[{"award-number":["DE-SC0008501"]}],"id":[{"id":"10.13039\/100000015","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.science.org"],"crossmark-restriction":true},"short-container-title":["Science"],"published-print":{"date-parts":[[2026,7,9]]},"abstract":"<jats:p>\n                    The conventional framework for chemical bonding between main-group elements involves separate \u03c3 and \u03c0 orbitals to describe multiple bonds. However, relativistic effects mix these orbitals in molecules containing heavy elements through spin\u2013orbit coupling, leaving the total angular-momentum projection (\u03c9) as the only good quantum number. Direct experimental evidence that relativistic effects change the \u03c3-\u03c0 bonding framework has remained elusive. Here, we probe the carbon-bismuth triple bond in the CBi\n                    <jats:sup>\u2212<\/jats:sup>\n                    anion using high-resolution cryogenic photoelectron spectroscopy, coupled with relativistic four-component Dirac-Coulomb coupled-cluster calculations. Even though the CBi\n                    <jats:sup>\u2212<\/jats:sup>\n                    anion is isovalent to the well-known CN\n                    <jats:sup>\u2212<\/jats:sup>\n                    species, we demonstrate that the traditional \u03c3 + 2\u03c0 triple-bond picture collapses into a pure \u03c0-like |\u03c9| = 3\/2 and two |\u03c9| = 1\/2 Kramers pairs containing substantial \u03c3\/\u03c0 mixing.\n                  <\/jats:p>","DOI":"10.1126\/science.aei1285","type":"journal-article","created":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T18:02:13Z","timestamp":1783620133000},"page":"184-187","update-policy":"https:\/\/doi.org\/10.34133\/aaas_crossmark","source":"Crossref","is-referenced-by-count":1,"title":["Relativistic collapse of the classical triple bond in the CBi\n                    <sup>\u2212<\/sup>\n                    molecular ion"],"prefix":"10.1126","volume":"393","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9257-0347","authenticated-orcid":true,"given":"Deniz","family":"Kahraman","sequence":"first","affiliation":[{"name":"Department of Chemistry, Brown University, Providence, RI, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-1436-7772","authenticated-orcid":true,"given":"Jie","family":"Hui","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Brown University, Providence, RI, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-7936-4432","authenticated-orcid":true,"given":"Xin-Yu","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Brown University, Providence, RI, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-2411-7267","authenticated-orcid":true,"given":"Neil A.","family":"Ellis","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Brown University, Providence, RI, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0023-1872","authenticated-orcid":true,"given":"Hyun Wook","family":"Choi","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Brown University, Providence, RI, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4901-3235","authenticated-orcid":true,"given":"Kirk A.","family":"Peterson","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Washington State University, Pullman, WA, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1816-5738","authenticated-orcid":true,"given":"Lai-Sheng","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Brown University, Providence, RI, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"221","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja02261a002"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja01355a027"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr00085a006"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-physchem-032511-143755"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.457082"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.3702628"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1021\/ar50140a001"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1021\/ar50140a002"},{"key":"e_1_3_2_10_2","doi-asserted-by":"publisher","DOI":"10.1002\/cphc.201100682"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1098\/rspa.1928.0023"},{"key":"e_1_3_2_12_2","doi-asserted-by":"publisher","DOI":"10.1098\/rspa.1929.0094"},{"key":"e_1_3_2_13_2","doi-asserted-by":"publisher","DOI":"10.1093\/oso\/9780195140866.001.0001"},{"key":"e_1_3_2_14_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.441223"},{"key":"e_1_3_2_15_2","doi-asserted-by":"publisher","DOI":"10.1021\/j100355a005"},{"key":"e_1_3_2_16_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0040-4020(02)01000-1"},{"key":"e_1_3_2_17_2","doi-asserted-by":"publisher","DOI":"10.1039\/c3ob26537d"},{"key":"e_1_3_2_18_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.aaz2258"},{"key":"e_1_3_2_19_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.0c10092"},{"key":"e_1_3_2_20_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.464244"},{"key":"e_1_3_2_21_2","unstructured":"J. E. Pollard Photoelectron Photoion Molecular Beam Spectroscopy (Ph.D. thesis Department of Chemistry University of California Berkeley Berkeley CA 1982) p. 55."},{"key":"e_1_3_2_22_2","unstructured":"D. Kahraman J. Hui X. Y. Zhang N. A. Ellis H. W. Choi K. A. Peterson L. S. Wang Tabular Data and Computational Details for the CBi Spectroscopic Analysis [Data set] Zenodo (2026); https:\/\/doi.org\/10.5281\/zenodo.20249312."},{"key":"e_1_3_2_23_2","doi-asserted-by":"publisher","DOI":"10.1080\/0144235X.2016.1147816"},{"key":"e_1_3_2_24_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.4891701"},{"key":"e_1_3_2_25_2","doi-asserted-by":"publisher","DOI":"10.1063\/5.0170325"},{"key":"e_1_3_2_26_2","doi-asserted-by":"publisher","DOI":"10.1039\/D5SC07306E"},{"key":"e_1_3_2_27_2","doi-asserted-by":"publisher","DOI":"10.1039\/C9CP03353J"},{"key":"e_1_3_2_28_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.472655"},{"key":"e_1_3_2_29_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.5053846"},{"key":"e_1_3_2_30_2","doi-asserted-by":"publisher","DOI":"10.1007\/s00214-006-0126-0"},{"key":"e_1_3_2_31_2","doi-asserted-by":"publisher","DOI":"10.1007\/s00214-012-1217-8"},{"key":"e_1_3_2_32_2","doi-asserted-by":"publisher","DOI":"10.1007\/s00214-016-1884-y"},{"key":"e_1_3_2_33_2","doi-asserted-by":"publisher","DOI":"10.1007\/s00214-005-0028-6"},{"key":"e_1_3_2_34_2","doi-asserted-by":"publisher","DOI":"10.1016\/0009-2614(96)00898-6"},{"key":"e_1_3_2_35_2","doi-asserted-by":"publisher","DOI":"10.1063\/5.0004844"},{"key":"e_1_3_2_36_2","unstructured":"L. Visscher H. J. Aa. Jensen R. Bast A. S. P. Gomes and T. Saue with contributions from I. A. Aucar V. Bakken J. Brandejs C. Chibueze J. Creutzberg K. G. Dyall S. Dubillard U. Ekstr\u00f6m E. Eliav T. Enevoldsen E. Fa\u00dfhauer T. Fleig O. Fossgaard L. Halbert E. D. Hedeg\u00e5rd T. Helgaker B. Helmich-Paris J. Henriksson M. van Horn M. Ilia\u0161 Ch. R. Jacob S. Knecht S. Komorovsk\u00fd O. Kullie J. K. L\u00e6rdahl C. V. Larsen Y. S. Lee N. H. List H. S. Nataraj M. K. Nayak P. Norman A. Nyvang M. Olejniczak J. Olsen J. M. H. Olsen A. Papadopoulos Y. C. Park J. K. Pedersen M. Pernpointner J. V. Pototschnig R. Di Remigio M. Repisky K. Ruud P. Sa\u0142ek B. Schimmelpfennig B. Senjean A. Shee J. Sikkema A. Sunaga A. J. Thorvaldsen J. Thyssen J. van Stralen M. L. Vidal S. Villaume O. Visser T. Winther S. Yamamoto X. Yuan DIRAC a relativistic ab initio electronic structure program Release DIRAC24 (2024) Zenodo; https:\/\/doi.org\/10.5281\/zenodo.10680560."}],"container-title":["Science"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.science.org\/doi\/pdf\/10.1126\/science.aei1285","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/www.science.org\/doi\/pdf\/10.1126\/science.aei1285","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T18:02:40Z","timestamp":1783620160000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.science.org\/doi\/10.1126\/science.aei1285"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,9]]},"references-count":35,"journal-issue":{"issue":"6807","published-print":{"date-parts":[[2026,7,9]]}},"alternative-id":["10.1126\/science.aei1285"],"URL":"https:\/\/doi.org\/10.1126\/science.aei1285","relation":{},"ISSN":["0036-8075","1095-9203"],"issn-type":[{"value":"0036-8075","type":"print"},{"value":"1095-9203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,9]]},"assertion":[{"value":"2026-04-17","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-05-19","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-07-09","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}