Deuterated isotopomers

In most cases the photofragmentations were also carried out with the corresponding deuterated isotopomers (see indications in the formula). By this means the structural identification of the new species by comparison between the experimental and calculated spectra became much more reliable. Furthermore it was again possible to register the bands of "complexed" deuterium molecules [16] [23-D2 v = 2994 cm"1 24-D2 v = 3010 / 3005 cm"1]. 

Calculation of Highly Excited Vibrational Energy Levels of Hydrogen Peroxide and Its Deuterated Isotopomers. 

Fig. 6.30. El mass spectra of dipentyl terephthalate (a) and a deuterated isotopomer (b). Adapted fromRef. [86] with permission. John Wiley Sons, 1985.

The role of CYP2E1 in a-oxidation of A-nitrosodiethanolamine was probed by using the deuterated isotopomers A-nitroso[a-D4]diethanolamine and 7V-nitroso-[P-D4]diethanolamine. 7V-Nitrosodiethanolamine and 7V-nitroso[P-D4]diethanolamine were equally cytotoxic to human CYP2E1-transfected V79 cells, while 7V-nitroso-[a-D4]diethanolamine was not. Significant DNA single-strand break levels were... 

The structures and isomerization of C4Hg+ ions in connection with the problem of ethylene clusters has been the subject of many studies. Doepker and Ausloos192 studied the photolysis of cyclobutane, its deuterated isotopomer and mixtures thereof, and in their detailed product analysis they found cA-2-butene, trans-2-butene and 1-butene as major ionic products in the approximate ratio of 1 1 2. Lias and Ausloos193 determined... 

Metastable loss of H2 is only observed for the chloro and bromo compounds. For X = F, the exothermicity of the protonation-dissociation sequence (7 kcalmol-1) is probably not sufficient to exceed the energy barrier for H2 loss, which for the 1,2-H2 elimination is predicted by theoretical calculations to be 18 kcalmol1 (thermochemical data for a 1,1 -H2 elimination are not available)106. For X = I, the protonation-dissociation reaction is exothermic by 41 kcal mol-1 and the absence of a metastable peak for this process is probably due to a very high activation barrier. The existence of an energy barrier for the H2 (HD) elimination from protonated chloro- and bromohalomethane, and their deuterated isotopomers was indeed revealed by the large KER values (140 eV) associated with their metastable decomposition. An intensity ratio of about 50 was measured for metastable peaks due to H2 and HX losses in accordance with the known thermochemical data which establish that H2 loss is less endothermic than HX loss by 10 kcalmol-1 and 28 kcalmol-1 for X = Cl and Br, respectively109. 

The appropriate C6D5 deuterated isotopomers of 28, 29 and 32 were also studied. C—D carbons in the deuterated isopotomers behave in dipolar dephased spectra as quaternary carbons and the changes in spectral patterns of nondeuterated and pentadeuterated compounds were used for 13C chemical shift assignment. The spectra of 28, 30, 31 and 32 were also recorded at elevated temperature. It was found, contrary to Maciejewska s results,87 that in 28, 30 and 32 rotation of the aromatic rings is induced at elevated temperatures. 

Polyglycine, H(-CO-CH2-NH)n-H, is the simplest polypeptide. It has two solid state structures. Form I consists of chains of polymer that are hydrogen-bonded into two-dimensional sheets. This form (including selectively deuterated isotopomers) has been studied by INS [53-55]. The spectra were interpreted similarly to those of N-methylacetamide. Reexamination of the spectra with periodic-DFT calculations is necessary. Acetanilide, C6H5-NH-C(=0)-CH3, forms hydrogen-bonded chains similar to N-methylacetamide and as such is a potential model for phenyl substituted peptides. However, the interest in acetanilide is that the... 

The hydride and H2 ligands in [IrH(H2)(bq)(PPh3)2]+ and other H(H2) complexes have equal Brpnsted acidity as discussed above, yet reactions with partially deuterated isotopomers show that r 2-H2 is selectively deprotonated [Eq. 

The treatment of the diiridium(lll) complex 12 (Scheme 11) with has been shown to afford deuterated isotopomers of 12, indicating that this dM species also activates dihydrogen. [40] In this case, instead of oxidative addition prod-... 

In a way similar to that previously shown for ethylene, the reaction of 12 with the alkyne leads to a compound in which the vinyl moiety and the labile acetonitrile ligand are situated on different metal centers. Dissociation of the acetonitrile from this intermediate would provide a reaction site for hydrogen, leading to the formation of cfr-stilbene. Since the olefin is formed at a labile coordination position of the complex, it can be easily released to restart the catalytic cycle. In favor of this mechanism, when the vinyl intermediate species was reacted with Dj, non-deuterated cw-stilbene together with deuterated isotopomers of 12 were formed. 

Anet FAL, Rawdah TN (1978) Cyclododecane. Force-field calculations and H NMR spectra of deuterated isotopomers. J. Am. Chem. Soc. 100 7166... 

Table 18. Calculated vibrational corrections to 7(C,H) and J (C,H), for the five deuterated isotopomers of methane at 300 K. All values in Hz"...

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