Spectroscopic studies salts

Historically, the first spectroscopic studies involved characterizing the emission of visible light from the sun, from flames, and from salts added to flames. Our survey of spectroscopy, however, begins with absorption because it is the more important technique in modern analytical spectroscopy. 

Zincke salts have played an important role in the synthesis of NAD /NADH coenzyme analogs since a 1937 report on the Zincke synthesis of dihydropyridine 7 for use in a redox titration study.The widely utilized nicotinamide-derived Zincke salt 8, first synthesized by Lettre was also used by Shifrin in 1965 for the preparation and study of NAD /NADH analogs. In 1972, Secrist reported using 8 for synthesis of simplified NAD analogs such as 10 for use in spectroscopic studies (Scheme 8.4.4). Subsequent utilization of 8 is discussed later in this article. 

Formylthiophene thiosemicarbazone, 26, forms [Co(26)2A2]A and [Co(26)A3(H20)] (A = Cl, Br, I, NO3, and OAc), by varying the preparative hgand to cobalt(II) salt mole ratio in hot ethanol [201]. Addition of sodium hydroxide allows isolation of [Co(29-H)3]. All complexes are weakly paramagnetic indicating spin paired complexes. Spectroscopic studies showed bonding via the azomethine nitrogen and thiol sulfur, but not the thiophene sulfur. 

These two salts were studied by the Oxford physics group in the early days of ESR spectroscopy.8 The Cr(m) and V(n) salts were doped into diamagnetic single crystals of K3Co(CN)6 and K4Fe(CN)6, respectively. The spin-orbit coupling parameters found from the spectroscopic study are listed, together with the g-components, in Table 6.2. 

The phosphorescence of Pt2 (I OsKHq in aqueous solution is quenched by l,l-bis(2-sulfoethyl)-4,4f-bipyridinium inner salt (BSEP). Transient absorption attributable to BSEP ( nax 610 nn) is observed in flash kinetic spectroscopic studies of aqueous solutions containing Pt2( Os Hq and BSEP, thereby establishing an electron transfer quenching mechanism ... 

VO(acac)2 < VO(Et-acac)2 VO(Me-acac)2 BMOV. Conversion rates for all hydrolysis products were faster than for the original species. Both EPR and visible spectroscopic studies of solutions prepared for administration to diabetic rats ocumented both a salt effect on the species formed and formation of a new halogen-containing complex. The authors concluded that vanadium compound efficacy with respect to long-term lowering of plasma glucose levels in diabetic rats traced the concentration of the hydrolysis product in the administration solution. 

CopperdI) dimethyl sulfoxide complexes [Cu(Me2SO)n]2+ n = 4 (309, 391) n = 5 (496) n = 9 (221)] have been synthesized and assigned as O-bonded by spectroscopic study. The Ph2SO complex [Cu(Ph2SO)4]2+ (228) has been prepared and isolated as its perchlorate salt. Preliminary crystallographic data (320) and ESR data (483) are available which suggest D4h symmetry for the metal-ion site. 

When a cupric salt is added to a polymer-ligand solution, a greenSpectroscopic study indicated that complex formation between Cu and a polymer-ligand was not a step-by-step mechanism and that the composition of the complex, Cu(ligandK, in a polymer ligand remained constant throughout the course of the reaction ( ). 

Another example of kinetic vs thermodynamic control is observed in an NMR-spectroscopic study of the ring opening of several 1-methoxy-3-carbamoylpyridinium salts by liquid ammonia. The study shows that... 

The results of a vibrational spectroscopic study of the SO2 complexes [RuX(S02)(NH3)4]" (X = Cl, Br) and [Ru(H20)(S02)NH3)4] + have been reported the j/(sym) and j/(asym) modes of the 5 -bound SO2 ligand come at lower frequencies than those of the free molecule. The ammonium salt of the sulfito complex tra 5-[Ru(S03-5)2(NH3)4] 4H20 has been structurally characterized. Although the crystals are stable when retained in the mother liquor, the isolated compound is only stable at 298 K for several days. Relationships between the structural and vibrational spectroscopic data are discussed. ... 

The undefined mechanism of the aldol-type Mukaiyama and Sakurai allylation reactions arose the discussion and interest in mechanistic studies [143-145]. The proposed mechanism was proved to proceed through the catalytic activation of the aldehyde and its interaction with the silyl ketene acetal or allylsilane producing the intermediate. From that point the investigation is complicated with two possible pathways that lead either to the release of TMS triflate salt and its electrophihc attack on the trityl group in the intermediate or to the intramolecular transfer of the TMS group to the aldolate position resulting in the evolution of the trityl catalyst and the formation of the product (Scheme 51). On this divergence, series of experimental and spectroscopic studies were conducted. 

The self-assembly of this fundamental building block of chromatin is a topic of enduring interest. DNase I digestion experiments as well as spectroscopic studies indicate that nucleosome core particles can be reconstituted by salt-jump (i.e., diluting NaCl concentration from 2.0 to 0.2 M) or by direct mixing of histones and DNA at the lower salt concentration. Daban and Cantor used the increase in eximer fluorescence to investigate the reassembly process in terms of a two-state model ... 

Music, S. Vertes, A. Simmons, G.W Czako-Nagy, I. Leidheiser, H.Jr. (1982) Mossbauer spectroscopic study of the formation of Fe(III) oxyhydroxides and oxides by hydrolysis of aqueous Fe(III) salt solutions. J. Colloid Interface Sd. 85 256—266... 

Umebayashi, Y, Fujimori, T., Sukizaki, T., Asada, M., Fujii, K., Kanzaki, R., and Ishiguro, S.-L, Evidence of conformational equilibrium of l-ethyl-3-methylimi-dazolium in its ionic liquid salts Raman spectroscopic study and quantum chemical calculations, J. Phys. Chem. A, 109,8976-8982,2005. 

Lin, S.-T., Ding, M.-R, Ghang, C.-W. et al.. Nuclear magnetic resonance spectroscopic study on ionic liquids of l-alkyl-3-methylimidazolium salts. Tetrahedron, 60, 9441,2004. 

Ions like S2, SeJ and SSe are found to align along the <110> directions in most alkali halides, while in Nal, KBr and KI, the S—bond of S2 is oriented along the <100> direction. In the case of Oj, the p orbitals are parallel to the <100> direction in sodium salts but are parallel to the direction in rubidium and potassium salts. Extensive spectroscopic studies have been reported on molecular ions such as NO, NO3, Cr04 and MnO . Several reviews(Corish et al, 1977 Bridges, 1975 Grimes, 1976) are available on such impurity-doped solids. 

H and NMR spectroscopic studies of 64 showed that the structure present in the solid state is retained in solution. That the reactivity of 64 is different compared to that of normal organozinc compounds became evident from a hydrolysis reaction of 64 with a carboxylic acid affording the corresponding zinc salt of the carboxylic acid and metallic zinc in a 1 1 ratio and pentamethylcyclopentadiene. This product formation suggests the... 

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