Partial molar volumes and viscosity B-coefficients for N,N/-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride in methanolic solutions of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate at T = (298.15, 308.15, and 318.15) K

• Methanolic solutions of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate used as solvent.
• N,N/-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride, used as solute.
• Parameters discussed on the basis of ion–ion and ion–solvent interactions.
• Presence of strong solute–solvent interactions.
• Thermodynamics of viscous flow were discussed.

Ion–ion and ion–solvent interactions for N,N/-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride, [Cr(salen)(H2O)2]Cl, dissolved in solutions of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, [bdmim]BF4 (0.005 to 0.020 mol · dm−3) in methanol (MeOH) were investigated by a combination of physicochemical properties at 298.15, 308.15 and 318.15 K under ambient pressure. From measured solution densities and viscosities apparent molar volume (φV  ), the slope (SV∗), standard partial molar volume (φV0), transfer volume (ΔtφV0), the viscosity B-coefficient, its temperature derivative (∂B/∂T), solvation number (Sn), etc.   were calculated and discussed on the basis of ion–ion and ion–solvent interactions. In the investigated temperature range, the relation: φV0=a0+a1T, was used to determine the temperature dependence of the partial molar volumes φV0, i.e.  , partial molar expansibilities (φE0). Temperature dependence of the viscosity B-coefficient (∂B/∂T) values revealed the complex to be a long-range structure breaker. Thermodynamics of viscous flow were discussed on the basis of the transition state theory.

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