New isomeric phenylmercury(II)-dithiocarbamates: Influence of positional isomeric phenolic group on supramolecular framework and Hg···S Spodium bonding interactions

Three new positional isomeric phenolic -OH functionalized phenylmercury(II) dithiocarbamates with general compositions [(C₆H₅)HgS₂CN(CH₂C₆H₅)(CH₂C₆H₄-o-OH)] (Hg-1); [(C₆H₅)HgS₂CN(CH₂C₆H₅)(CH₂C₆H₄-m-OH)] (Hg-2) and [(C₆H₅)HgS₂CN(CH₂C₆H₅)(CH₂C₆H₄-p-OH)] (Hg-3) have been synthesized and characterized. The single crystal X-ray diffraction analyses reveal that Hg(II) core adopts distorted linear geometry fulfilled by one sulfur of the dithiocarbamate ligand and phenyl carbon. Another doubly bonded sulfur of dtc ligand exhibits intramolecular Hg···S Spodium bonding (SpB) interaction thereby leading to distortion in the linear geometry around Hg(II). The supramolecular framework of all three complexes is stabilized by weak intermolecular Hg···S SpB interactions along with S···H, C···H and O···H intermolecular interactions. The isomeric positions of the –OH group affects the supramolecular frameworks engendering single helical motifs held by O[sbnd]H···C(Ar) and pair of O[sbnd]H···S and C[sbnd]H···S interactions in Hg-1 and Hg-3 respectively while Hg-2 displays a two-dimensional sheet like motif sustained by O···H -C(Ar) interactions. These interactions further have been investigated and correlated using Hirshfeld surface analyses and computational studies. The QTAIM and NBO analyses indicate that for Hg-2, the computed intermolecular Hg···S SpB interaction energies are 3.64 and 3.86 kcal·mol^-1, respectively thereby suggesting the best stability of intermolecular Hg···S SpB interaction in the meta-isomer, Hg-2. This investigation provides newer insight into the factor affecting the supramolecular frameworks and Spodium bonding interactions in phenylmercury(II) dithiocarbamates.