ber Chalkogenolate. LIV. Untersuchungen �ber Thioameisens�uren 2. Darstellung und Eigenschaften von Dithioformiaten

Insertion of CS2into the Mg–H bond: synthesis and structural characterization of the magnesium dithioformate complex, [TismPriBenz]Mg(κ2-S2CH)

Insertion of CS₂into the Mg–H bond of [Tism^PriBenz]MgH affords [Tism^PriBenz]Mg(κ²-S₂CH), the first structurally characterized magnesium dithioformate compound.

Spectral and theoretical studies of N-p-(ethylbenzene)thiobenzohydroxamic acid metal chelates

The preparation of N-p-(ethylbenzene)thiobenzohydroxamic acid chelates with several metal ions and their spectral properties are described in this paper. This is followed by a theoretical study of metal complexes of some thiohydroxamic acids, as well as the prepared chelates. The electronic properties of the metal complexes are discussed. The experimental and theoretical electronic spectra are also compared. A possible reason for the smaller pKa values of thiohydroxamic acid complexes than those of the corresponding hydroxamic acids is given.

Amide isosteres of lexitropsins: synthesis, DNA binding characteristics and sequence selectivity of thioformyldistamycin

The synthesis and properties of an amide isostere of the antibiotic distamycin, thioformyldistamycin 3 is described. Compound 3 exists predominantly in the E conformation of the thioamide group in freshly prepared DMSO solution but is converted into the Z form, predicted by molecular mechanics to be more stable, on standing for 24 h. The coalescence temperature in DMSO is 110 degrees C by 1H-NMR. The thioformyl moiety of 3 is resistant to both peptidase action and acid treatment. Complementary strand MPE footprinting on a EcoRI/Hind III restriction fragment of pBR322 DNA demonstrated that either E or Z forms of 3 give a single set of footprints very similar to that of the parent antibiotic with strongest protection at TAAG and TATTAT with moderately strong protection at ATTT and AAAA. The strength of binding of 3 and distamycin from delta Tm measurements to either poly.d(AT) or calf thymus DNA is comparable. Molecular modeling predicted a preferred conformation for 3 wherein the C = S bond has a torsional angle of 110 degrees with the pyrrole ring. The energy difference between this conformation and the E form is less than 1 kcal/mole. In contrast the E-form has an energy 17.3 kcal/mole greater than the Z and a value of 26.3 kcal/mole was calculated for the energy barrier between the two isomers.