Mikhail Y. Redko

Alkali metals in silica gel (M-SG): A new reagent for desulfonation of amines

A novel method for the desulfonation of secondary amines is described. Alkali metals absorbed into nanostructured silica (M-SG) were found to be useful solid-state reagents for the desulfonation of a range of N,N-disubstituted sulfonamides. M-SG reagents are room-temperature-stable free-flowing powders that retain the chemical reactivity of the parent metal, decreasing the danger and associated cost of using reactive metals.

Role of Cation Complexants in the Synthesis of Alkalides and Electrides

Publisher Summary This chapter reviews the requirements, design, and methodology involved in the synthesis of alkalides and electrides, culminating with the recent designed synthesis of a thermally stable electride. Solid alkalides and electrides are formed by precipitation, crystallization, or solvent evaporation from solutions that contain complexed cations and either alkali metal anions or solvated electrons. No quantitative equilibrium data are available for complexant-free alkali metal solutions in the solvents used to synthesize alkalides and electrides (MeNH 2 , EtNH 2 , Me 2 O). It is the irreversible decomposition of oxa–complexants rather than decomplexation that limits the temperature stability of alkalides and electrides that contain crown ethers and cryptands. Research with alkalides and electrides would certainly have been simpler if crown ethers and cryptands were able to withstand the strong reducing power of alkali metal anions and trapped electrons. In the study of the decomposition products of some thirty solid alkalides and electrides that contained CH 2 -O-CH 2 -CH 2 -O-CH 2 groups, it was found that the initial products were ethylene and a glycolate.

Comparison of structural effects on Eu(III) complexes with cyclohexyl and benzene polycarboxylic acids

Abstract The thermodynamics ( β , Δ H , Δ S ) of complexation, the residual hydration of the complexed metal ion and the metal-ligand coordination number of the complexes formed by interaction of Eu(III) with 1, 3, 5-cyclohexyltricarboxylic acid, 1, 2, 3- and 1, 2, 4-benzenetricarboxylic acids, cyclohexylhexacarboxylic (CHHS) acid and benzenehexacarboxylic (mellitic) acid have been studied. The 1, 3, 5-cyclohexyltricarboxylate ligand binds by only a single carboxylate while the 1, 2, 3-, and 1, 2, 4-benzene tricarboxylate ligands bind via two carboxylates. The mellitate complexes were found to have bidentate chelation and a residual hydration number, N H 2 O , complexed Eu(III) of ca. 7 in acid-to-neutral solutions. By contrast, in the Eu-CHHS complexation, the coordination number for the ligand binding, CN L , was 2 in acidic to neutral in basic solutions while the residual hydration number of the Eu(III) changed from 6 to 7 in acidic solutions to 2.5 in alkaline solutions. This is interpreted to indicate the formation of [Eu(CHHS)(OH)(H 2 O) 2 ] 4− . The data are discussed in terms of ligand steric effects upon complexation.