Infrared absorption spectra of the systems of silica gel - H216O,D216O,H218O, and some organic vapors were measured in order to assign the bands senstive to adsorption at 870 and around 950 cm−1. Deuteration of silica gel caused the absorption decrease at 870 cm−1 and the appearance of a band at 620 cm−1. The band around 950 cm−1 appearing by adsorption not only of water but also of organic vapors showed no shift on deuteration, but shifted toward low frequency side by 25 cm−1 on the substitution of 16O of surface silanol groups with 18O. From these facts the bands at 870, 620 and 950 cm−1 were assgned to Si–OH bending, Si–OD bending and Si–O stretching vibrations of surface silanol groups, respectively. The oxygen atom of silanol groups of silca gel was found to exchange with that of adsorbed water molecules even at room temperature for a sample treated at temperature below 300°C. On the other hand, higher reaction temperature of ca. 200°C was necessary for a sample calcined at 800°C. mechanism of the oxygen atom exchange recation was discussed.
A nucleoside catalyzing the oxidoreduction of NADH and K3Fe(CN)6 was isolated from Torula yeast RNA and also obtained in 0.05% yield by a series of steps: SDS-phenol extraction, nuclease P1 digestion, alkaline phosphatase digestion, anion exchange chromatography, and HPLC on an ODS column. Its chemical structure was clearly determined at 5-hydroxycytidine, from the results of FAB-MS and 1H and 13C NMR spectroscopies. The mass spectra, chromatographic behavior, UV spectra, and NMR spectra of this nucleoside from natural and synthetic sources were identical. This is the first report of an RNA catalyst having catalytic activity except for the cleavage and ligation of phosphodiester bonds of RNA. That an RNA has oxidoreduction activity indicates new possibilities for RNAs as "living molecules". 5-Hydroxycytidine may be a vestige of RNAs that formerly possessed metabolizing ability.
Reaction of [{Ru(CH3CN)3[P(OMe)3]2}2(μ-S2)](PF6)3 with a mixture of acetylene and O2 gave a novel ruthenium(IV) dimer complex [{Ru(IV)(PFO3)[P(OMe)3]2}2(μ-S)(μ-PF2O2)2]. The newly formed bridging and terminal ligands PF2O2− and PFO32− are produced from the reaction of PF6− with trace amounts of H2O in the solvent. Although acetylene is not incorporated in the final product, it is necessary to accelerate the reaction. Ruthenium(IV) complexes with S2− ligand are rare and only two examples are previously known. The crystal of [{Ru(PFO3)[P(OMe)3]2}2(μ-S)(μ-PF2O2)2] is monoclinic, space group P21/n, a = 11.061(5), b = 20.764(4), c = 17.074(3) Å, β = 95.74(2)°, V = 3901(1) Å3, and Z = 4. The bridging PF2O2− ligand coordinates to Ru atoms with the two oxygen atoms, while the terminal PFO32− ligand coordinates to a Ru atom with one of the oxygen atoms. The molecular structure is confirmed by 31P and 19F NMR spectroscopy.
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