DFT Approach for Predicting C NMR Shifts of Atoms Directly Coordinated to Pt: Scopes and Limitations.

In this study, comparative analysis of calculated and experimental C NMR shifts for a wide range of model platinum complexes showed that, on the whole, the theory reproduces the experimental data well. The chemical shifts of carbon atoms directly bonded to Pt can be calculated well only within the framework of the fully relativistic matrix Dirac-Kohn-Sham (mDKS) level ( = 0.9973, = 3.

NMR "Finger Prints" of N-Heterocyclic Carbenes, DFT Analysis: Scopes and Limitations.

The scopes and limitations of theoretical methods for estimating various NMR metrics of NHCs are considered on a wide range of model NHCs and their derivatives, using a number of computational approximations. On the whole, the most reliable, from the point of view of predictability and insusceptibility to additional effects, are P/C NMR shifts of NHC-phosphinidene adducts and C CSs of carbenes themselves. The method based on the analysis of Se CS NHC-selenoureas has some limitations since the observed NMR parameters can also be modulated by exchange effects due to their formation with non-classical hydrogen bonds.

DFT Calculations of P NMR Chemical Shifts in Palladium Complexes.

In this study, comparative analysis of calculated (GIAO method, DFT level) and experimental P NMR shifts for a wide range of model palladium complexes showed that, on the whole, the theory reproduces the experimental data well. The exceptions are the complexes with the P=O phosphorus, for which there is a systematic underestimation of shielding, the value of which depends on the flexibility of the basis sets, especially at the geometry optimization stage. The use of triple-ζ quality basis sets and additional polarization functions at this stage reduces the underestimation of shielding for such phosphorus atoms.

Tautomeric preference in lumazines, deazalumazines, isoalloxazines and pyrimidines and its effect on the reactivity of alkyl groups.

In lumazines, deazalumazines and pyrimidines, there are extremely low-energy "rare" tautomers (<2.3 kcal/mol), this fact perfectly explains the observed mobility of usually "non-labile" protons of methyl groups in such systems. In general, the dependence of tautomeric preference on structure correlates well with experimental findings.

Asymmetric 1,3-dipolar cycloaddition reaction of chiral 1-alkyl-1,2-diphospholes with diphenyldiazomethane.

The 1,3-dipolar cycloaddition of chiral 1-alkyl-1,2-diphosphacyclopenta-2,4-dienes ((1-(-)-menthyl)oxymethyl-1,2-diphosphole and 1-(+)-neomenthyl-1,2-diphosphole) with diphenyldiazomethane leads to novel -chiral bicyclic phosphiranes having six chiral centers. The degree of diastereoselectivity depends on the substituent at phosphorus, and dramatically increases in the case of (+)-neomenthyl group (de up to 71%). DFT calculations indicate that the cycloaddition is thermodynamically controlled.

6-Methyluracil derivatives as peripheral site ligand-hydroxamic acid conjugates: Reactivation for paraoxon-inhibited acetylcholinesterase.

New uncharged conjugates of 6-methyluracil derivatives with imidazole-2-aldoxime and 1,2,4-triazole-3-hydroxamic acid units were synthesized and studied as reactivators of organophosphate-inhibited cholinesterase. Using paraoxon (POX) as a model organophosphate, it was shown that 6-methyluracil derivatives linked with hydroxamic acid are able to reactivate POX-inhibited human acetylcholinesterase (AChE) in vitro. The reactivating efficacy of one compound (5b) is lower than that of pyridinium-2-aldoxime (2-PAM).