Daniele C. Menezes

The influence of cation upon the supramolecular aggregation patterns of dithiocarbamate anions functionalised with hydrogen bonding capacity—the prevalence of charge-assisted O–H⋯S interactions

A range of supramolecular architectures is found in the title dithiocarbamate salts, each with hydrogen bonding functionality in the form of aτ least one hydroxyl group. A common feature in the crystal packing is the prevalence of charge-assisted O–H⋯S hydrogen bonding. In [NH4][S2CN(CH2CH2OH)2] (1), a 3-D network is found mediated by cooperative O–H⋯S, N–H⋯O and N–H⋯S hydrogen bonding. Reducing the hydrogen bonding functionality by replacing the ammonium cation in (1) by the 4-aza-1-azoniabicyclo(2.2.2)octanium cation to give [DABCO-H][S2CN(CH2CH2OH)2] (2), results in a 2-D array. Further reduction of the hydrogen bonding functionality, this time by substituting a CH2CH2OH with an alkyl group to give [DABCO-H][S2CN(CH2CH2OH)CH3] (3) and [DABCO-H][S2CN(CH2CH2OH)CH2CH3] (4) allows for the formation of 1-D supramolecular chains. The introduction of alkali metal cations rather than protic cations removes the possibility of the hydroxyl-O participating in hydrogen bonding interactions as these now coordinate the alkali metal. In the sodium trihydrate, Na[S2CN(CH2CH2OH)2]·3H2O (5), O–H⋯O hydrogen bonds are found along with charge-assisted O–H⋯S contacts so that a 3-D network results. Substituting a CH2CH2OH group with a n-propyl group gives Na[S2CN(CH2CH2OH)CH2CH2CH3]·2H2O (6) and yields a 2-D array. For the anhydrous K[S2CN(CH2CH2OH)2] (7) and Cs[S2CN(CH2CH2OH)2] (8) salts, the crystal packing is dominated by charge-assisted O–H⋯S hydrogen bonding giving 3-D network structures. The systematic analysis of the crystal packing patterns of these salts reveals the importance of charge-assisted O–H⋯S hydrogen bonding in stabilising these crystal structures.

Cyclization of N-alkyldithiocarbamates in alkaline media, a counter example of well-known chemistry – an experimental and theoretical study

In strong alkaline media, the reaction of 2-(tert-butylamino)ethanol (3: R = But) with CS2 at 0°C produced a cyclic dithiocarbamate, 3-tert-butylthiazolidine-2-thione (1: R = But), rather than alkaline metal or ammonium salts of [S2CN(But)CH2CH2OH]−. This is in contrast to isolation of stable alkaline metal or ammonium salts of [S2CN(R)CH2CH2OH]− (R = Me, Et, Pr, or CH2CH2OH) obtained in analogous reactions. The use of Ni(OAc)2, both as a source of Ni(II) and a weaker base, in a one-pot reaction with (3: R = But) and CS2, successfully gave the first reported metal complex of [S2CN(But)CH2CH2OH]−, namely [Ni{S2CN(But)CH2CH2OH}2] (2: R = But). Compounds 1 and 2 have been fully characterized by infrared and NMR spectroscopies, and by X-ray crystallography. DFT calculations on the cyclization and stabilities of [S2CN(R)CH2CH2OH]− (R = Pr and But) have been carried out.