Quantum chemical calculations using density functional theory have been carried out to investigate the basicity of pentaammine(pyrazine)ruthenium(II) and pentacyano(pyrazine)ruthenate(II) ions. Gas phase equilibrium geometries were fully optimized at the local density approximation (LDA) level. Single-point calculations were performed at the optimized gas phase geometries using a generalized gradient approximation (GGA) functional. The basicity of the uncoordinated nitrogen on pyrazine was investigated in gas phase and in aqueous solution, modeling solvent effects using a self-consistent reaction field (SCRF) Onsager model, a discrete electrostatic representation of the water molecules in the first solvation shell, and also a combined SCRF-discrete model within the DFT-GGA methodology. A reasonable level of agreement between theory and experiment is obtained only when using the SCRF-discrete model, suggesting that both specific interactions in the first solvation shell and long-range dielectric effects affect the reactivity of the complexes.