Preparation, Properties, and Reactivities of Unprecedented Oxo-Sulfido Nb(IV) Aqua Ions and Crystal Structure of (Me2NH2)6[Nb5(µ3-S)2(µ3-O)2(µ2-O)2(NCS)14]·3.5H2O Научная публикация
Журнал |
Inorganic Chemistry
ISSN: 0020-1669 , E-ISSN: 1520-510X |
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Вых. Данные | Год: 2006, Том: 45, Номер: 13, Страницы: 5008-5017 Страниц : 10 DOI: 10.1021/ic052145i | ||||||
Ключевые слова | CUBANE-TYPE MOLYBDENUM; CUBOIDAL CLUSTERS; SUBSTITUTION; TRINUCLEAR; CHEMISTRY; KINETICS; APPROXIMATION; THIOCYANATE; MECHANISM; ENERGIES | ||||||
Авторы |
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Организации |
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Информация о финансировании (2)
1 | Technical University of Denmark | |
2 | Институт неорганической химии им. А.В. Николаева СО РАН |
Реферат:
By treatment of Zn-reduced ethanolic solutions of NbCl5 with HCl in the presence of sulfide followed by cation-exchange chromatography, two oxo-sulfido niobium aqua ions, the red [Nb4(μ4-S)(μ2-O)5(H2O)10]4+ and the yellow-brown [Nb5(μ3-S)2(μ3-O)2(μ2-O)2(H2O)14]8+, were isolated. Both readily form their respective thiocyanate complexes, for which the structure for the former has been previously reported. Brown crystals of (Me2NH2)6[Nb5S2O4(NCS)14]·3.5H2O (1) were isolated in the case of the latter, and the structure was determined by X-ray crystallography (space group: a = 15.4018(5) Å, b = 21.1932(8) Å, c = 22.0487(8) Å, α = γ = 90°, β = 103.4590(10)°, and R1 = 0.0659). An unprecedented pentanuclear Nb5S2O48+ core is revealed in which short Nb−Nb distances (2.7995(8)−2.9111(8) Å) are consistent with metal−metal bonding. A stopped-flow kinetic study of the 1:1 equilibration of NCS- with [Nb4(μ4-S)(μ2-O)5(H2O)10]4+ has been carried out. Equilibration rate constants are independent of [H+] in the range investigated (0.5−2.0 M) and at 25 °C; kf = 9.5 M-1 s-1, kaq = 2.6 × 10-2 s-1, and K = 365 M-1. Conditions with first NCS- and then [Nb4(μ4-S)(μ2-O)5(H2O)10]4+ in excess revealed a statistical factor of 4, suggesting the presence of four kinetically equivalent Nb atoms. Attempts to study the 1:1 substitution of NCS- with [Nb5(μ3-S)2(μ3-O)2(μ2-O)2(H2O)14]8+ showed signs of saturation kinetics. Quantum chemical calculations using the density functional theory (DFT) approach were performed on both the Nb4O5S4+ and Nb5O4S28+ naked clusters. The highest occupied and lowest unoccupied molecular orbitals have dominant Nb(4d) character. The HOMO for Nb4O5S4+ is a nondegenerate fully filled MO, whereas for Nb5O4S28+, it is a nondegenerate partially filled MO with one unpaired electron. EPR spectroscopy on [Nb5(μ3-S)2(μ3-O)2(μ2-O)2(H2O)14]8+ shows that the molecule has total anisotropy (C2v), with all three tensors, gx = 2.399, gy = 1.975, and gz = 1.531, resolved. No hyperfine interaction expected from the nuclear moment of I = 9/2 for 93Nb was observed.
Библиографическая ссылка:
Ooi B-L.
, Søtofte I.
, Sokolov M.N.
, Kozlova S.G.
, Rasmussen S.B.
, Nielsen L.C.
, Henriksen J.
Preparation, Properties, and Reactivities of Unprecedented Oxo-Sulfido Nb(IV) Aqua Ions and Crystal Structure of (Me2NH2)6[Nb5(µ3-S)2(µ3-O)2(µ2-O)2(NCS)14]·3.5H2O
Inorganic Chemistry. 2006. V.45. N13. P.5008-5017. DOI: 10.1021/ic052145i WOS Scopus РИНЦ
Preparation, Properties, and Reactivities of Unprecedented Oxo-Sulfido Nb(IV) Aqua Ions and Crystal Structure of (Me2NH2)6[Nb5(µ3-S)2(µ3-O)2(µ2-O)2(NCS)14]·3.5H2O
Inorganic Chemistry. 2006. V.45. N13. P.5008-5017. DOI: 10.1021/ic052145i WOS Scopus РИНЦ
Даты:
Поступила в редакцию: | 16 дек. 2005 г. |
Опубликована online: | 25 мая 2006 г. |
Опубликована в печати: | 1 июн. 2006 г. |
Идентификаторы БД:
Web of science | WOS:000238322700023 |
Scopus | 2-s2.0-33746579354 |
РИНЦ | 13523587 |
Chemical Abstracts | 2006:485359 |
Chemical Abstracts (print) | 145:179600 |
OpenAlex | W2078497311 |