{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T14:48:35Z","timestamp":1789138115169,"version":"build-2803163510"},"reference-count":88,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2024,6,26]],"date-time":"2024-06-26T00:00:00Z","timestamp":1719360000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The amount of free ions, ion pairs, and higher aggregate of the possible species present in a solution during the gold(I)-catalyzed alkoxylation of unsaturated hydrocarbon, i.e., ISIP (inner sphere ion pair) [(NHC)AuX] and OSIP (outer sphere ion pairs) [(NHC)Au(TME)X] [NHC 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene; TME = tetramethylethylene (2,3-bis methyl-butene); X\u2212 = Cl\u2212, BF4\u2212, OTf\u2212; and OTs\u2212 BArF4\u2212 (ArF = 3,5-(CF3)2C6H3)], has been determined. The 1H and 19F DOSY NMR measurements conducted in catalytic conditions indicate that the dissociation degree (\u03b1) of the equilibrium ion pair\/free ions {[(NHC)Au(TME)X] [(NHC)Au(TME)]+ + X\u2212} depends on the nature of the counterion (X\u2212) when chloroform is the catalytic solvent: while the compounds containing OTs\u2212 and OTf\u2212 as the counterion gave a low \u03b1 (which means a high number of ion pairs) of 0.13 and 0.24, respectively, the compounds containing BF4\u2212 and BArF4\u2212 showed higher \u03b1 values of 0.36 and 0.32, respectively. These results experimentally confirm previous deductions based on catalytic and theoretical data: the lower the \u03b1 value, the greater the catalytic activity because the anion that can activate methanol during a nucleophilic attack, although the lower propensity to activate methanol of BF4\u2212 and BArF4\u2212, as suggested by the DFT calculations, cannot be completely overlooked. As for the effect of the solvent, \u03b1 increases as the dielectric constant increases, as expected, and in particular, green solvents with high dielectric constants show a very high \u03b1 (0.90, 0.84, 0.80, and 0.70 for propylene carbonate, \u03b3-valerolactone, acetone, and methanol, respectively), thus confirming that the moderately high activity of NHC-Au-OTf in these solvents is due to the specific effect of polar functionalities (O-H, C=O, O-R) in activating methanol. Finally, the DOSY measurements conducted in p-Cymene show the formation of quadrupole species: under these conditions, the anion can better exercise its \u2018template\u2019 and \u2018activating\u2019 roles, giving the highest TOF.<\/jats:p>","DOI":"10.3390\/molecules29133018","type":"journal-article","created":{"date-parts":[[2024,6,26]],"date-time":"2024-06-26T07:20:06Z","timestamp":1719386406000},"page":"3018","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Diffusion Nuclear Magnetic Resonance Measurements on Cationic Gold (I) Complexes in Catalytic Conditions: Counterion and Solvent Effects"],"prefix":"10.3390","volume":"29","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5615-8881","authenticated-orcid":false,"given":"Filippo","family":"Campagnolo","sequence":"first","affiliation":[{"name":"Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Universit\u00e0 di Udine, Via Cotonificio 108, I-33100 Udine, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0382-0525","authenticated-orcid":false,"given":"Eleonora","family":"Aneggi","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Universit\u00e0 di Udine, Via Cotonificio 108, I-33100 Udine, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2648-1848","authenticated-orcid":false,"given":"Walter","family":"Baratta","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Universit\u00e0 di Udine, Via Cotonificio 108, I-33100 Udine, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Talha","family":"Munir","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Universit\u00e0 di Udine, Via Cotonificio 108, I-33100 Udine, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7765-1715","authenticated-orcid":false,"given":"Daniele","family":"Zuccaccia","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Universit\u00e0 di Udine, Via Cotonificio 108, I-33100 Udine, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,6,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1039\/C3CC45518A","article-title":"Intriguing mechanistic labyrinths in gold(I) catalysis","volume":"50","author":"Obradors","year":"2014","journal-title":"Chem. 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