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** Deuterium kinetic isotope effects theoretical calculations **

Wolfsberg, M. and Stem, M. J. Validity of some approximation procedures used in the theoretical calculation of isotope effects. Pure Appl. Chem. 8, 225 (1964) Secondary isotope effects as probes for force constant changes. Ibid. 8, 325 (1964). [Pg.342]

It should be noted in passing that Mulliken also examined the isotope effect on the quadratic terms in the equations for the band heads. These ratios should theoretically show an isotope effect proportional to the reduced masses of the diatomic molecules (rather than the square root of the reduced masses). While Mulliken concludes that these ratios also confirm that the molecule is BO rather than BN, the four experimental ratios show a fairly large scatter so that the case for identifying the molecule is not as strong as that from the experimental a and b ratios. He also measured some of the rotational lines in the spectra of BO and considered the measured and theoretical isotope effects. Here one experimental isotope ratio checks the theoretically calculated ratio quite well, but for the other two the result was unsatisfactory. However, Mulliken judged the error to be within the experimental uncertainty. [Pg.28]

Fig. 5.5 PlotofT2 ln(fc/fg) = T2 I n (fc / fv) for some isotopically substituted cthylcncs. The solid lines are theoretically calculated from the isotope independent force field in Table 5.7 (Reused with permission from Bigeleisen, J., Fuks, S., Ribnikar, S. V., and Yato, Y., J. Chem. Phys. 66, 1689 (1977). Copyright 1977, American Institute of Physics) |

The molecular ion of Ci2H27SnCl is expected to produce a very complex pattern, because of the combination of the characteristic natural abundances of the isotopes of Sn, Cl and C. The theoretical calculation of the intensity pattern has taken into account all the ten isotopes of Sn, the two isotopes of Cl, three distinct contributions due to the 12 carbons (144, 145, 146), and the two significant contributions due to the 27 hydrogens (27 and 28). Of the 120 combinations, many overlap. [Pg.171]

Recently, this view of secondary a-deuterium KIEs has had to be modified in the light of results obtained from several different theoretical calculations which showed that the Ca—H(D) stretching vibration contribution to the isotope effect was much more important than previously thought. The first indication that the original description of secondary a-deuterium KIEs was incorrect was published by Williams (1984), who used the degenerate displacement of methylammonium ion by ammonia (equation (4)) to model the compression effects in enzymatic methyl transfer (SN2) reactions. [Pg.147]

** Deuterium kinetic isotope effects theoretical calculations **

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