Gallium(iii) hydration in aqueous solution of perchlorate, nitrate and sulfate. Raman and 71-Ga NMR spectroscopic studies and ab initio molecular orbital calculations of gallium(iii) water clustersElectronic supplementary information (ESI) available: Unscaled HF/6-31+G* frequencies, intensities and force constants of the hexaaqua-Ga(iii) ion, octadeca-aqua gallium(iii) and octadeca-aqua gallium(iii) cluster. See http://www.rsc.org/suppdata/cp/b2/b202567c/
Notice bibliographique
Résumé
Raman spectra of aqueous Ga(III)- perchlorate, - nitrate and -sulfate solutions were measured. In Ga(III)- perchlorate solutions, a strongly polarized mode of medium intensity at 526 cm−1 and two depolarized modes at 430 cm−1 and 328 cm−1 have been assigned to v1(a1g), v2(eg) and v5(f2g) of the hexaaquagallium(III) ion, [Ga(OH2)63+] (Oh symmetry), respectively. The infrared active mode at 510 cm−1 has been assigned to v3(f1u). The polarized mode v1(a1g) GaO6 has been followed over a temperature range from 25 to 75 °C and band parameters (band maximum, full width of half height and band intensity) have been examined. The position of the v1(a1g) GaO6 mode shifts by only about 2 cm−1 to lower frequencies and broadens by about 10 cm−1 for a 50 °C temperature increase. The Raman spectroscopic data suggest that the hexaaquagallium(III) ion is thermodynamically stable in perchlorate solutions (no inner-sphere complex formation) over the temperature and concentration range measured. In a concentrated Ga(NO3)3 solution, most of the gallium (III) exist in the form of an outer-sphere ion pair, [Ga(OH2)63+ NO3−], except for a few percent of the gallium (III) which occurs as an inner-sphere complex, [Ga(OH2)5ONO2]2+. The nitrato complex is thermodynamically weak and disappears completely upon dilution. Gallium sulfate solutions show a different picture and a thermodynamically stable gallium(III) sulfato complex could be detected using Raman spectroscopy and 71-Ga NMR. The formation of the sulfato complex is favoured with increasing temperature and is thus entropically driven. At higher temperatures a basic gallium(III) sulfate of the alunite type is precipitated and was characterised by wet chemical analysis and X-ray diffraction (XRD). Ab initio geometry optimizations and frequency calculations of [Ga(OH2)n3+] clusters with n = 1 to 6 were carried out at the Hartree–Fock and second order Møller–Plesset levels of theory, using various basis sets up to 6-31+G*. The global minimum structure of the aqua Ga(III) species was reported. The unscaled vibrational frequencies of the [Ga(OH2)63+] cluster were reported and do not correspond well with experimental values because of the missing second hydration sphere. The theoretical binding enthalpy for [Ga(OH2)63+] was calculated and accounts for ca. 62% of the experimental single ion hydration enthalpy for Ga(III). Ab initio geometry optimizations and frequency calculations are also reported for a [Ga(OH2)183+] (Ga[6+12]) cluster with 6 water molecules in the first sphere and 12 water molecules in the second sphere (T symmetry). The calculated v1 GaO6 mode of the gallium [6+12] cluster occurs at 524 cm−1 (HF/6-31G*), in good agreement with the experimental value at 526 cm−1. The other frequencies of the gallium [6+12] cluster also correspond well with the observed frequencies in solution. The theoretical binding enthalpy for [Ga(OH2)183+] was calculated and is slightly underestimated compared to the experimental single ion hydration enthalpy for Ga(III).
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».