Synthesis of N-(2,4-dinitrophenyl) derivatives of D-ribosylamines; unexpected reaction and hydrolysis products.

Reaction of 2,3-O-isopropylidene-d-ribofuranosylamine with 2,4-dinitrofluorobenzene afforded the crystalline 2,3-O-isopropylidene-N-(2,4-dinitrophenyl)-ß-d-ribofuranosylamine (3) and a 1:1 crystalline complex of 2,3-O-isopropylidene-N-(2,4-dinitrophenyl-α-d-ribofuranosylamine and 2,3-O-isopropylidene-ß-d-ribofuranose; controlled acidic hydrolysis of 3 afforded N-(2,4-dinitrophenyl-α-d-ribopyranosylamine and not the expected ß-d-furanosylamine derivative. The structures of the new compounds were confirmed by NMR spectroscopy and X-ray crystallography.

Structure of sodium bis(N-methyl-iminodiacetato)iron(III): trans-meridional N-coordination in the solid state and in solution.

The results of a detailed solid state and solution structural study of the Fe(III) bis-mida complex [Fe(III)(mida)(2)]- (mida = N-methyl-iminodiacetate) are reported. The structure of the sodium salt Na[Fe(mida)2][NaClO4]2.3H2O (1) was determined by single-crystal X-ray analysis. The complex anion in 1 contains a six-coordinate Fe(III) centre bound to two tridentate mida ligands arranged in the meridional configuration, and the mer Fe(III)N2O4 chromophore shows a high degree of distortion from regular octahedral symmetry. Raman- and UV/VIS/NIR spectroscopic measurements showed that no gross changes take place in the Fe(III) coordination sphere upon redissolution in water. Quantum chemical calculations of all three possible configurations of the [Fe(mida)2]- complex ion in the gas phase support the finding that the mer isomer is more stable than the u-fac (cis) and s-fac (trans) isomers. Redox potential measurements of the Fe(III/II)(mida) couple in dependence of pH led to the following values for the equilibrium contants: log beta(III)(101) = 11.98 +/- 0.05, log beta(III)(102) = 20.49 +/- 0.01, pK(III)(a1 OH) = 7.81; log beta(II)(101) = 6.17 +/- 0.01, log beta(II)(102) = 11.39 +/- 0.01.