An UV-Visible study of the stability of the ruthenium hexaammine cation in BEA zeolites—comparison with NaY

Preparation and characterization of molybdenum sulfide supported on β-zeolites obtained from [Mo3S4(H2O)9]4+ precursor

“…It is therefore proposed that during this preparation in the presence of ammonia, there is oligomerization into rather small entities or even polymerization of [Mo 3 S 4 ] 4+ accompanied by precipitation on the external surface of the zeolite grain. This would be consistent with the deposition of the rather high Mo loading ($4 wt.%, Table 5), which on the other hand cannot be explained by a mechanism of cation exchange on the external surface since its area is negligible compared to the internal surface [27]. It may be added that such a phenomenon of oligomerization/polymerization may not be detected by UV-visible and XANES which show large similarities between the catalyst after ''exchange'' and drying and [Mo 3 S 4 (H 2 O) 9 ]Cl 4 ÁNH 4 Cl, because these techniques are essentially sensitive to the environment of the first and second coordination sphere of the cations.…”

Theoretical investigation on the ground state properties of the hexaamminecobalt(iii) and nitro–nitrito linkage isomerism in pentaamminecobalt(iii) in vacuo

“…A similar transition was observed in [Ru(NH 3 ) 6 ] 3+ UV-vis spectrum also arising from t 1u and e g . 73,74 Daul et al 74 investigated the electronic structure of [Ru(NH 3 ) 6 ] 3+ using extended Huckel molecular orbitals method and reported that ammonia are rotating freely to keep an octahedral site symmetry. The d–d transitions in octahedral [Co(NH 3 ) 6 ] 3+ and [Ru(NH 3 ) 6 ] 3+ complexes are forbidden due to the presence of a center of inversion following Laporte rule 75 which states that allowed transitions in centro-symmetric molecules should involve change in parity between gerade and ungerade orbitals.…”

“…3,58,[65][66][67][68][69][70][71][72][73][74] [Ru(NH 3 ) 6 ] 3+ , [Cr(NH 3 ) 6 ] 3+ and [Fe(NH 3 ) 6 ] 2+ ions can be considered as octahedral in which the d orbital of the transition metal splits in t 2g and e g . For comparison, the most popular functional for transition metal B3LYP was employed with LanL2DZ basis set for all atoms on the D 3d symmetry of the low-spin states [ 1 A 1g : (t 2g )6 (e g ) 0 ] and [ 2 T 2g : (t 2g )5 (e g ) 0 ] of [Co(NH 3 ) 6 ] 3+ and [Ru(NH 3 ) 6 ] 3+, and high spin states [ 4 T 2g : (t 2g ) 3 (e g ) 0 ] and [ 5 T 2g : (t 2g ) 4 (e g ) 2 ] of [Cr(NH 3 ) 6 ] 3+ and [Fe(NH 3 ) 6 ] 2+ .…”

Interactions between DNA Purines and Ruthenium Ammine Complexes within Nanostructured Sol−Gel Silica Matrixes

“…In basic solution, the deprotonation of the Ru complex (eq ) is evidenced by the broadband with a maximum at ∼400 nm, assigned to the LMCT from NH 2 − in the species ([Ru(NH 3 ) 5 NH 2 ] 2+ ), which confers the solution a deep yellow color. , Encapsulation of the Ru complex at 60 °C (method I) results in a clear reduction of the LMCT band to a shoulder of a new very strong band centered at 339 nm, and in the appearance of a weak Ru-brown related band at lower energy (∼463 nm). The band at 339 nm may be interpreted as (i) a Ru-brown related band; (ii) a Cl → Ru 3+ CT typical of [Ru(NH 3 ) 5 Cl] 2+ , an intermediate that can be formed by ligand exchange in the sol−gel medium; , (iii) an increased d−d band of the Ru complex, as a consequence of a higher distortion of its octahedral geometry due to confinement effects and/or electrostatic interactions with siloxy (SiO − ) groups of the silica matrix. ,, Either way, it becomes clear that encapsulation of the Ru complex by method I results in an extended decomposition compared to method II.…”

“…These reactions have been the object of extensive studies in solution, ,– in zeolites, – and in other micro- and mesoporous supports. – It was shown that the stability of the [Ru(NH 3 ) 6 ] 3+ complex can be drastically affected by the pore structure (dimensions and geometry), framework basicity, and atmosphere nature, as well as by the level of hydration . Such structural and textural characteristics of the support are particularly relevant, since the reactions involved in the decomposition of [Ru(NH 3 ) 6 ] 3+ , namely, toward the formation of ruthenium trimers, are dependent on the available space and mobility of the molecules inside the porous network, and on the presence of a favorable chemical environment.…”