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

Abstract

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.