Organotin (IV) carboxylates with the general formulae R2Sn(Cl)L [R = Me (1), n-Bu (2), Ph (3)] and R3SnL [R = Me (4), Ph (5)] have been synthesized by the reaction of 4-piperidinecarboxylic acid (HL) with KOH and R2SnCl2 (R = Me, n-Bu, Ph)/R3SnCl (R = Me, Ph) in methanol under stirring conditions. The metal ligand binding site, structure, and stability of complexes have been verified by FT-IR, ...

We present a comparative assessment of the accuracy of two different approaches for evaluating dispersion interactions: interatomic pairwise corrections and semiempirical meta-generalized-gradient-approximation (meta-GGA)-based functionals. This is achieved by employing conventional (semi)local and (screened-)hybrid functionals, as well as semiempirical hybrid and nonhybrid meta-GGA functionals...

A new force field has been customized for the variation of polynorbornene that contains a bicycloheptane group in the backbone structure. The force field was developed from ab initio density functional theory (DFT), and semiempirical electronic structure calculations for both stereochemical dimers of the 2,3 exoexo isomer of polynorbornene. The bond length and bond angle parameters were determi...

New dimeric quaternary alkylammonium conjugates of sterols were obtained by two step reactions of ergosterol, cholesterol and cholestanol with bromoacetic acid bromide, followed by bimolecular nucleophilic substitution with N,N,N',N'-tetramethyl-1,3-propanediamine, N,N,N',N'',N''-pentamethyldiethylenetriamine and 3,3'-iminobis- (N,N-dimethylpropylamine). The product structures were confirmed by ...

Lately, there has been great interest in performing free-energy perturbation (FEP) at the combined quantum mechanics and molecular mechanics (QM/MM) level, e.g. for enzyme reactions. Such calculations require extensive sampling of phase space, which typically is prohibitive with density-functional theory or ab initio methods. Therefore, such calculations have mostly been performed with semiempi...