Spectroscopic properties, silver

Croomine is a major alkaloid of the roots and rhizomes of Croomia heterosepala. Its structure (10) has been settled by its chemical reactions and spectroscopic properties, and confirmed by X-ray diffraction analysis of its methiodide. On mild oxidation (dehydrogenation) with silver oxide, the alkaloid affords the corresponding pyrrole.8... 

A) shows an intense and narrow absorption at 340 nm and the excitation spectrum shows a maximum at 340 nm associated with a broad emission centred around 544 nm (Figure 3A, F). At this level of exchange, Uytterhoeven s crystallographic results (3) indicate the probable presence of a charged cluster Ag29+ arising from the simultaneous occupancy (at least to a certain extent, measured by the excess of population in site I ) of one site I and one adjacent site I by a silver ion. Therefore, we associate the species giving rise to these optical spectra with the cluster Ag2spectroscopic properties of which will be described in a later section (where q is shown to be unity). 

On treatment with aqueous silver nitrate it forms a stable crystalline complex (78), from which 75 can be recovered almost quantitatively by addition of ammonia ". Anhydrous nickel(ii) bromide converts cyclooctyne into the trimer (79) with a quantitative yield . However, when the reaction was carried out in the presence of a trace of water, the dimeric cyclobutadiene-nickel bromide complex (80) was obtained in 9-4% yield, together with 79 (85%) . The spectroscopic properties of 80 showed close similarity with those of the tetramethylcyclobutadiene-nickel chloride complex . 

In the following, it will be demonstrated that confocal surface-enhanced Raman microscopy is a powerful tool for exploring optical and spectroscopic properties of molecules adsorbed on silver and gold nanoparticles. It is shown that confocal Raman microscopy coupled with high-resolution electron microscopy has the potential to deliver detailed information about the structure of points of high Raman intensity the so-called hot spots. 

The adenosine diphosphate derivative (98), a recently discovered metabolite produced during tRNA splicing, has been synthesised by reaction of (99) with (100) in the presence of silver acetate. Its spectroscopic properties are also reported. 

In connection with the elucidation of the structures of the products obtained upon reaction of the tropone (496) with perchloric acid, the 6-methoxy-substituted derivatives have been prepared by reaction of (496) with methyl iodide and silver fluoroborate. -Comparison of u.v. spectra indicated that the salts between the tropones (496) and perchloric acid were 6-hydroxy-derivatives of the perchlorate of (497). U.v. and n.m.r. spectra of the systems (496)—(499) are discussed and their properties and reactivities compared with the corresponding JV-phenyl-pyrrole analogue. A preliminary report of the polarographic, i.r., and u.v. spectroscopic properties, as well as the dipole moments, of both the C-annelated systems (496) and (497) without methyl groups in the thiophen ring and also the ion (500) with alkyl, hydroxy, and methoxy-groups in the seven-membered ring has been published. Values of piirR+ between 6 and 7 have been obtained for this system. The spectroscopic properties of metallocene derivatives such as (501)—(503) have also... 

A series of air- and light-stable one-dimensional polymeric silver(i) diisocyanide complexes, 72a-72e (Figure 30), was reported by Harvey, with their structural, spectroscopic, and photophysical properties described in detail.119,120... 

The partial confusion arising after Dewar s and Chatt s reviews were published, was resolved after Chatt and Duncanson reported in 1953 in the Journal of the Chemical Society the results of infrared spectroscopic studies on a range of olefin platinum(II) complexes [38]. In this highly cited paper they proposed, with particular reference to Dewar s model, that in the olefin platinum(II) complexes the cr-type bond would be formed by overlap of the filled re-orbital of the olefin with a vacant 5d6s6p2 hybrid orbital of the platinum atom, and the re-type bond by overlap of a filled 5d6p hybrid orbital of the metal with the empty antibonding re-orbital of the olefin (Fig. 7.8). In addition, Chatt and Duncanson illustrated how the model could be used to interpret not only the physical properties of the olefin platinum compounds, such as the spectroscopic data and dipole moments, but also their reactivity and their greater stability compared to the olefin silver salts. 

Dinuclear complexes were obtained by reacting some binary copper(I) and silver(I) homoleptic pyrazolate complexes with neutral ligands. The trimeric [Cu(dmpz)]3 (23) readily reacted with phen or RNC (R = cyclohexyl) to give the doubly bridged species [(phen)Cu(/i-dmpz)2Cu(phen)], 32, (49) or [(RNC)Cu(/t-dmpz)2Cu(RNC)], 33 (50). The dimeric nature of 32 was argued from its spectroscopic and chemical properties, while 33 was characterized by an X-ray crystal structure analysis (50). 

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