Crystallographic and theoretical studies of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)-chloranilic acid (1/1) with intermolecular O-H•••N hydrogen bonds and S•••O heteroatom interactions

The molecular and crystal structure of a 1:1 co-crystal of 4,4'- dimethyl-7,7'-bi([1,2,5]thiadiazolo[3,4-b] pyridylidene)-chloranilic acid, (1), has been determined by X-ray diffraction at the monoclinic space group P2(1)/c with cell parameters of a = 8.422(6), b = 7.343(4), c = 16.112(7) angstrom, beta = 104.988(8)degrees, V = 962.5(10) angstrom(3) and Z = 2. In the crystal structure, two components connect via the intermolecular O-H center dot center dot center dot N hydrogen bonds [2.804(4) angstrom] and S center dot center dot center dot O heteroatom interaction [2.945(3) angstrom] with R-2(2)( 7) couplings to form a unique and infinite one-dimensional supramolecular tape structure. The calculations of (1) at the HF/6-31G(d), MP2/6-31G(d), and B3LYP/6-31G(d) levels can almost reproduce X-ray geometry. In addition, the distances of the intermolecular O-H center dot center dot center dot N and S center dot center dot center dot O interactions by MP2/6-31G(d) and B3LYP/6-31G(d) levels agree well with those in the crystal. The calculated binding energies corrected BSSE and ZPE are -4.487 (HF), -7.473 (MP2), and -5.640 (B3LYP) kcal/mol. The results suggest that the complex (1) is very stable and the dispersion interaction is significantly important for the attractive intermolecular interaction in (1). The NBO analysis has revealed that the n(N) -> sigma*(O-H) interaction gives the strongest stabilization to the system and the major interaction for the intermolecular S center dot center dot center dot O contact is n(O) -> sigma*(S-N).