Analyses structurales et spectrales du 5,6‐diméthyluracile

Abstract

The molecular structure of 5,6-dimethyluracil monohydrate C 6 H 8 N 2 O 2 H 2 O has been determined by X-ray diffraction method. The crystals are monoclinic space group P2 1 /n with a = 6.667 (2), b = 6.784 (4), c = 16.759 (2)Å, b = 99.08 (2)°, V = 748.6 (5)Å 3 and z = 4. The structure was refined to R = 0.064. The Raman and infrared spectra of the crystalline powders of the 5,6-dimethyluracil monohydrate, anhydrous and deuterated forms were investigated from 4000-200 cm −1 . An assignment of the normal modes is proposed. RÉSUMÉLa structure moléculaire du 5,6-diméthyluracile monohydrate C 6 H 8 N 2 O 2 H 2 O aété déterminée par diffraction des rayons X. Les cristaux appartiennent au groupe d'espace monoclinique P2 1 /n avec a = 6,667 (2), b = 6,784 (4), c = 16,759 (2)Å, b = 99, 08 (2), V = 748,6 (5)Å 3 et z = 4. La structure aété affinée jusqu'à un facteur R = 0,064. Les spectres Raman et infrarouge des poudres cristallines du 5,6-diméthyluracile monohydrate, anhydre et deutérié ontété analysés de 4000à 200 cm −1 . Une attribution de l'ensemble des vibrations fondamentales aété proposée.

Recent advances in linear and non‐linear Raman spectroscopy. Part III

“…Quite often, SERS was also employed to determine the orientation of the molecules on a metal surface. Such studies are compiled here for the following molecules: 1H-and 3H-imidazo [4,5-b]pyridine and their methyl derivatives, [113] copper(II) chloride and bromide compounds of KCuBr 3 , [114] 5,6-diméthyluracile, [115] [C(NH 2 ) 3 ] 2 M II (H 2 O) 4 (SO 4 ) 2 , M II = Mn, Cd and VO, [116] potassium trimethylsilanolate, [117] 2-aminopyridinium-4-hydroxybenzenosulfonate, [118] the H 4 I 2 O 10 2− ion in CuH 4 I 2 O 10 · 6H 2 O, [119] 2-amino-4,6-dihydroxypyrimidine, [120] 3 (or 4 or 6)-methyl-5-nitro-2-pyridinethiones, [121] 2-methyl-4-nitroaniline (MNA) crystal, [122] 2-amino-5-chloropyridinium hydrogen selenate, [123] the food dye amaranth, [124] transstilbene in the excited singlet state, [125] chloramphenicol, [126] oroxylin, [127] 4-fluoro-N-(2-hydroxy-4-nitrophenyl)benzamide, [128] phenanthridine, [129] 3,5 dichloro hydroxy benzaldehyde and 2,4 dichloro benzaldehyde. [130] Solid State (Minerals, Crystals, Linear Chains, Glasses, Ceramics and Disordered Materials) Minerals A great number of minerals have been studied during 2008 by the Frost group [131 -146] using both Raman and infrared spectroscopies: smithsonite, [131] the uranyl carbonate mineral voglite, [132] hydrotalcite with CO 3 2− and (MoO 4 ) 2− anions in the interlayer, [133] the uranyl phosphate minerals phosphuranylite and yingjiangite, [134] the uranyl carbonate mineral zellerite, [135] the molybdate-containing uranyl mineral calcurmolite, [136] the oxalate mineral wheatleyite Na 2 Cu 2+ (C 2 O 4 ) 2 ·2H 2 O, [137] the nickel silicate mineral pecoraite, [138] synthetic nesquehonite, [139] the uranyl mineral, compreignacite, K 2 [(UO 2 ) 3 O 2 (OH) 3 ] 2 ·7H 2 O, [140] the hydroxy nickel carbonate minerals nullaginite and zaratite, …”