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The alkali metal (Na+, K+, Rb+, Cs+) bis-dithiocarbamate (bis-dtc) salts of N,N′-dibenzyl-1,2-ethylenediamine have been prepared from the reaction of N,N′-dibenzyl-1,2-ethylenediamine with carbon disulfide in the presence of two equivalents of the corresponding alkali metal hydroxide. Additionally, the analogous triethylammonium derivative has been obtained. The resulting compounds have been analyzed as far as possible by elemental analysis, FAB+mass spectrometry, IR, UV-Vis and NMR (1H, 13C) spectroscopy, and single-crystal X-ray diffraction, showing that the composition of the metal salts can be described by the general formula [{[(H2O)xM-µ-(H2O)yM(H2O)x][bis-dtc]}n] (1, M = Na+, x= 3, y= 2; 2, M = K+, x= 1, y= 2; 3, M = Rb+, x= 0, y= 1; 4, M = Cs+, x= 0, y= 1; 5, M = Et3HN+, x= 0, y= 0). The solid-state and solution studies showed that all alkali metal ions participate in the formation of M–O and cation-π(arene) interactions, while M–S interactions are only observed for the larger alkali metals K+, Rb+and Cs+. As expected, within the alkali metal group there is a clear tendency for a decreasing number of M–O bonds in favor of M–S and cation–π(arene) interactions, however, only K+forms a semi-sandwich type complex with η6-coordination. [ABSTRACT FROM AUTHOR]

Kinetics of the cleavage of two phosphate diesters, bis(4-nitrophenyl) phosphate and 2-hydroxypropyl 4-nitrophenyl phosphate and a triester, 4-nitrophenyl diphenyl phosphate, in the presence of Mg(ii), Ca(ii) and Sr(ii) were studied in 90% vol. DMSO at 37 °C. The alkaline hydrolysis of the triester was inhibited by all cations, but with both phosphodiesters strong catalytic effects were observed. Potentiometric titrations of metal perchlorates by Bu4N(OH) revealed formation of M2(OH)3+, M(OH)+, M(OH)2and M2(OH)5−species. Rate constants for phosphodiester cleavage by individual species were obtained from analysis of rate–concentration profiles. Observed first-order rate constants in the presence of 1–2 mM Mg(ii) or Ca(ii) in neutral and weakly basic solutions were 108–1011times higher than those for background hydrolysis at the same pH while in water additions of up to 50 mM metal produced <100-fold accelerations. Possible structures of DMSO solvated catalyst–substrate complexes were modeled by DFT calculations with Mg(ii). The increased catalytic activity in 90% DMSO is attributed to stronger association of hydroxide ions and anionic phosphodiesters with metal ions and to preferable solvation of cations by DMSO, which creates favorable for reaction anhydrous microenvironment in the coordination sphere of the catalyst. [ABSTRACT FROM AUTHOR]