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951.
952.
Marchewka MK Baran J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(1-2):201-210
Vibrational spectra of M4LiH3(XO4)4 family, where M=K, Rb, X=S, Se together with Na5H3(SeO4)4.2H2O and Na2SeO4.H2SeO3.H2O crystals were compared. Similarities and differences are described. The spectroscopic manifestation of the presence of hydrogen bonds is discussed. Position of the bands corresponding to bending type of vibrations (in-plane and out-of plane) of hydrogen bonds is analyzed in the function of temperature. Small dynamic splitting of the bands due to weak interactions between ions is noticed. 相似文献
953.
Carmen I. Cabello Enrique J. Baran 《Monatshefte für Chemie / Chemical Monthly》1987,118(11):1257-1262
The infrared andRaman spectra of polycrystalline samples of K2HAsCr2O10 were recorded and an assignment for the complete vibrational spectrum is proposed. The thermal behaviour of the compound has also been investigated by means of TG- and DTA-methods. The spectral and thermal characteristics of the substance resemble that of K2HPCr2O10, although some differences have been found and explained. 相似文献
954.
Preparation and Properties of Vanadyl(IV) Pentacyanonitrosylferrate(II), VO[Fe(CN)5NO] · 2 H2O The preparation of VO[Fe(CN)5NO] · 2 H2O is described for the first time. Its electronic, infrared, and 57Fe-Mössbauer spectra were recorded and discussed. The thermal degradation was investigated by means of TG and DTA measurements and shows a very complex behaviour. A new preparative method for (VO)2[Fe(CN)6] · 10 H2O is also described and some of its spectroscopic properties were investigated and compared with those of VO[Fe(CN)5NO] · 2 H2O. 相似文献
955.
Coordination of Vanadium in the Phases 4 PbO · V2O5 and 8 PbO · V2O5 It is demonstrated, using infrared spectroscopy, that the coordination of vanadium in the two binary phases 4 PbO · V2O5 and 8 PbO · V2O5 is tetrahedral. The spectra in the V? O stretching region closely resembles that of the lead(II) orthovanadate, Pb3(VO4)2. 相似文献
956.
The first synthesis of (+)-austamide (1), (+)-deoxyisoaustamide (2), and (+)-hydratoaustamide (10) by a very direct route is described (Scheme 1). Starting from tryptophan methyl ester (3) intermediate 5 is generated in two steps in >98% overall yield. The key step in the synthesis is a novel cyclization of 5 involving organopalladium intermediates which gives the dihydroazocine 6. From this key intermediate the target structures are accessible in just a few steps as shown in Scheme 1. The remarkable conversion of 5 --> 6 can be rationalized by the mechanistic pathway shown in Scheme 2 that involves a multistep sequence which includes palladation, cyclization, and rearrangement. 相似文献
957.
Janusz Baran Irena Bogdanska Dominique Jan Lionel Delaude Albert Demonceau Alfred F. Noels 《Journal of molecular catalysis. A, Chemical》2002,190(1-2):109-116
Novel eight-membered ring unsaturated lactams were synthesized and tested as monomers for the ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The reaction of a N-protected cyclic alkeneamine was also investigated. The Grubbs’ benzylidene complexes RuCl2(=CHPh)(PCy3)2 or RuCl2(=CHPh)(PCy3)(IMesH2) and selected ruthenium–arene species bearing either phosphine or stable Arduengo-type N-heterocyclic carbene ligands served as catalyst precursors. In most cases, isomerization of the starting materials took place and only 1-benzyl-1-aza-2-ketocyclooct-5-ene afforded a polymeric product. This polyamide was characterized by numerous analytical techniques. 相似文献
958.
Chen YL Lee SW Chi Y Hwang KC Kumar SB Hu YH Cheng YM Chou PT Peng SM Lee GH Yeh SJ Chen CT 《Inorganic chemistry》2005,44(12):4287-4294
A new series of Os(II) diimine complexes with the general formula [Os(N(wedge)N)(CO)(2)I(2)], N(wedge)N = 2,2'-bipyridine (bpy) (1), 4,4'-di-tert-butyl-2,2'-bipyridine (dbubpy) (2), 4,7-diphenyl-1,10-phenanthroline (dpphen) (3), 2-(2'-pyridyl)benzoxazole (pboz) (4), and 5-tert-butyl-2-(2'-pyridyl)benzoxazole (bupboz) (5), were synthesized and characterized by spectroscopic methods and by a single-crystal X-ray diffraction study on the dpphen complex 3. The corresponding photophysical properties were studied using UV-vis and emission spectrometry. The resulting phosphorescence features both in solution and as a solid film, in combination with the MO calculation, lead us to conclude that the emissions originate from mixed halide-to-ligand (XLCT approximately 70%) and metal-to-ligand (MLCT approximately 30%) transitions instead of the typical MLCT transition. Using complexes 4 and 5 as the dopant emitters, we evaluated their potential to serve as a phosphor for organic light emitting diodes by examining their electroluminescent performances. Reddish orange electroluminescence centered around 600 nm was observed for organic light emitting diodes (OLEDs) fabricated using complex 5 as the emitter; the device efficiency was shown to be as high as 2.8% (and 5.0 cd/A or 2.7 lm/W), and the peak luminance was shown to be 5600 cd/m(2) at a driving voltage of approximately 15 V. 相似文献
959.
960.
Drozd M Baran J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(13-14):2953-2965
The polarized IR-microscope spectra of C(NH2)3.HSeO4 small single crystal samples were measured at room temperature. The spectra are discussed with the framework of oriented gas model approximation and group theory. The stretching nuOH vibration of the hydrogen bond with the O...O distance of 2.616 A gives characteristic broad AB-type absorption in the IR spectra. The changes of intensity of the AB bands in function of polarizer angle are described. Detailed assignment for bands derived from stretching and bending modes of selenate anions and guanidinium cations were performed. The observed intensities of these bands in polarized infrared spectra were correlated with theoretical calculation of directional cosines of selected transition dipole moments for investigated crystal. The vibrational studies seem to be helpful in understanding of physical and chemical properties of described compound and also in design of new complexes with exactly defined behaviors. 相似文献