Thallium(i)phosphorodithioates containing intra- and intermolecular p-hole triel bonds

Thallium compounds, i.e. Tl+[S2P{OC6H3(2,5-(CH3)(2))}(2)](-) (1) and Tl+[S2P{OC6H3(3,5-(CH3)(2))}(2)](-) (2), stabilized by intra- and intermolecular triel bonds were isolated and characterized by FT-IR, NMR (P-31, H-1 and C-13) spectroscopy, and SC-XRD analysis. The crystal structures of 1 and 2 belong to monoclinic crystal systems with the space group C2/c and P2(1)/n, respectively. Interestingly, the positively charged Tl atom is bonded attractively with the p-holes of the 1,1-dithioate moiety. These compounds exist in ionic form and exhibit Tl center dot center dot center dot S and Tl center dot center dot center dot pi p contacts (TrBs), which assist the formation of unique supramolecular polymeric architectures owing to the stereochemically active lone pair of electrons and hemi-directed coordination sphere around thallium. A differentiating feature in compound 2 is the formation of a unique Tl center dot center dot center dot pi/pi center dot center dot center dot pi/ Tl center dot center dot center dot pi self-assembly. The attractive nature of TrB was further confirmed by DFT calculations using the quantum theory of atoms-in-molecules (QTAIM) and non-covalent interaction plot (NCIPlot) index methods. A systematic Hirshfeld surfaces analysis was also carried out to compare the intermolecular interactions.