Spectroscopic data exchange reactions

This uncatalyzed reaction occurs at an acceptable rate at room temperature (298 K), a = (15/14)aq/(15/14)gas = 1.055. The value calculated from spectroscopic data is 1.096 (Chapter 4), so parasitic bleed to species other than NO(g) and HN03(aq) is indicated (the chemistry shown in Equation8.13 is oversimplified). In the exchange aqueous acid trickles down through a packed column countercurrent to a rising NO stream. A two column cascade was employed in which 4% of the acid flow is... 

LMCT) transition indicates that PtCll is sorbed within Gn-OH dendrimers. The spectroscopic data also indicate that the nature of the interaction between the dendrimer and Cu or Pt ions is quite different. As discussed earlier, Cu + interacts with particular tertiary amine groups by complexation, but PtCl undergoes a slow ligand-exchange reaction, which is consistent with previous observations for other Pt + complexes [119]. The absorbance at 250 nm is proportional to the number of PtCl ions in the dendrimer over the range 0-60 (G4-OH(Pb+)n, n = 0 - 60), which indicates that it is possible to control the G4-OH/Pb+ ratio. 

Richard followed the course of the reactions of Cr(CO)6 and Mo(CO)6 with hexamethylborazine by UV-vis spectroscopy but although he observed that the intensity of the absorption maximum of the hexacarbonyls at around 290 nm decreased and a new band at around 350 nm appeared, he was unable to identify the new product. Experiments with other starting materials such as norborna-diene chromium and molybdenum tetracarbonyl or tris(aniline) molybdenum tricarbonyl which readily react with arenes by ligand exchange, also failed. The key to success was to use tris(acetonitrile) chromium tricarbonyl as the precursor, which in dioxan under reduced pressure afforded the desired hexamethylborazine chromium tricarbonyl as a stable crystalline solid in 90% yield. This was the breakthrough and, after we had communicated the synthesis and spectroscopic data of the complex in the January issue 1967 of Angewandte Chemie, Richard finished his work and defended his Ph.D. thesis in June 1967. Six months before, in December 1966,1 defended my Habilitation thesis in front of the faculty and became Privatdozent (lecturer) on the 1st of January 1967. 

It was, however, impossible to establish a correlation between the effect of any HF impurity and bimolecular exchange by NMR spectroscopic data. The activation energy of the exchange reaction between SiFg and HF as calculated from the shape of the F resonance line is 8.5 1.0 kcal mol One should bear in mind that HF and other compounds which interact with RSiF to form HF, that is H O, CH3OH, etc., favor fluorine exchange. The acceptors Pr NH, (McjS NH, etc. bond HF in the solution and inhibit this process . 

Several studies of bimetallic complexes in which the donor and acceptor are linked across aliphatic chains have demonstrated that these are generally weakly coupled systems. " Studies of complexes linked by l,2-bis(2,2 bipyridyl-4-yl)ethane (bb see Figure 5), indicate that these are good models of the precursor complexes for outer-sphere electron-transfer reactions of tris-bipyridyl complexes. A careful comparison of kinetic and spectroscopic data with computational studies has led to an estimate of //rp = 20cm for the [Fe(bb)3pe] + self-exchange electron transfer. In a related cross-reaction, the Ru/bpy MLCT excited state of [(bpy)2Ru(bb)Co(bpy)2] + is efficiently quenched by electron transfer to the cobalt center in several resolved steps, equations (57) and (58). ... 

The significance of the changes in concentration of the species in the two phases is illustrated by calculations of the theoretical values for caic. (Table IV). Mouse et al. (29) have used spectroscopic data to calculate the enrichment factors for the three exchange Reactions 6, 7,... 

Whereas at 253 K only the monomeric molecule is detectable, at 283 K a small signal arises from the dimeric species (Fig. 2). At 313 K coalescence is observed between these two species, llirthermore, an intramolecular exchange reaction of the terminal and the bridging phosphanide ligands of the dimer broadens the singlets. The latter process is fast on the NMR time scale. The spectroscopic data are compared in Table 1. For the barium derivative shown in Fig. 3 the bicyclic structure has been proven by the small Vp p coupling of 6.7 Hz at 213 K which leads to a quartet for... 

The interaction between COCIF and SbF has been investigated in SOjClF by sp n.m.r. spectroscopy [99]. In dilute solution, the sp n.m.r. spectroscopic data were interpreted in terms of the formation of SbFj.COClF at -95 C at higher temperatures, or in more concentrated solutions, halide exchange occurs, and COFj and SbF. COFj were detected [99]. The same adduct is also formed, as a by-product, in the reaction between phosgene and SbFj in SOjClF (see Section 9.1.4.4) [1653c] the COCIF ligand is O-bonded. 

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