Syntheses, crystal structures, weak interaction, magnetic and photoluminescent properties of two new organic–inorganic molecular solids with disubstituted benzyl triphenylphosphinium and tetra(isothiocyanate)cobalt(II) anion

• Two molecular solids containing [Co(NCS)4]2− dianion were synthesized and characterized.
• The cations form a column through the C–H⋯π, π⋯π or Cl⋯π interactions.
• The anion and the cation are linked by C–H⋯S hydrogen bonds and Cl⋯S interactions.
• Both two molecular solids show an ultraviolet fluorescence emission at room temperature.
• Two molecular solids show a weak antiferromagnetic coupling behavior up the temperature is lowered.

Two new organic–inorganic molecular solids of tetra(isothiocyanate)cobalt(II) dianion and disubstituted benzyl triphenylphosphinium, [2Cl4FBzTPP]2[Co(NCS)4] (1) and [2Cl4ClBzTPP]2[Co(NCS)4] (2) ([2Cl4FBzTPP]+ = 1-(2′-chloro-4′-fluorobenzyltriphenylphosphonium) and [2Cl4ClBzTPP]+ = 1-(2′,4′-dichlorobenzyltriphenylphosphonium), were synthesized and characterized by elemental analysis, FT-IR, UV–Vis spectra, ESI-MS and single crystal X-ray diffraction method. Compounds 1 and 2 crystallize in the monoclinic Pc and triclinic P-1, respectively. The Co(II) ion of the [Co(NCS)4]2− anion shows a distorted tetrahedral coordination geometry. The [2Cl4FBzTPP]+ cations containing P(2) atoms in 1 form a column by the Cl⋯π interactions, while the [2Cl4ClBzTPP]+ cations in 2 form two columns by the C–H⋯π and π⋯π interactions. The anion and the cation are linked by C–H⋯S hydrogen bonds and Cl⋯S interactions. Magnetic susceptibility measurement in the temperature range 2–300 K shows that both 1 and 2 exhibit a weak antiferromagnetic exchange interaction as the temperature falls, and ultraviolet fluorescence emission in the solid state at room temperature.

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