Proton shift data, room-temperature

Table III exemplifies by some room temperature Cp-proton shift data of Yb3+-complexes the high diagnostic value even of one singular NMR shift value per system. More sophisticated studies are concerned with the complete temperature dependence of particular resonances over a range of usually 100 degrees (-70 to + 30 °C).

We pass next to the Ln(III) bis-dipicolinate complexes, shown in Fig. 6. There is no crystal structure for the complexes. Flowever detailed examination of the proton NMR spectra at room temperature shows that the shift ratios are again constant throughout the series and that absolute shifts follow Bleaney s predicted values, Table 3. The complexes must be isostructural and must have axial symmetry. Again the use of relaxation data gives an independent assessment of the relative distances of meta and para protons. We can put all the data together and give a structure for the complex ion as in Fig. 6 leaving three water molecules in the inner sphere. To prove that this is so we must analyse the proportions of the water, both bound and outer sphere. 

Because of the ambiguity of the and 3 Ip NMR data for 2a, a variable temperature study was performed on samples of 2a, 4, and 5 in DCCI3. Except for a few very minor changes in chemical shifts, the proton and phosphorus NMR spectra of 2a were unaffected from +55 Cto -55 C. Room temperature NMR... 

In poly(3-hexyl thiophene), a shift in absorption intensity maximum of ca. 0.5 eV occurs between room temperature and 180 C [326]. In the case of poly(3-octyl thiophene, a marked change in the signature of the proton at the 3-position is observed, as seen in the H NMR spectra of Fig. 9-12 [261]. As can be seen in the comparative thermochromic and solvatochromic data for poly(3-hexyl thiophene) in Fig. 9-13a.b. the actual magnitude of the effects is quite small. 

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