Pseudopolymorphism of [2,5-bis(2-pyridyl)­pyrazine]­ferrocenyl(methyl)­boron hexa­fluoro­phosphate

Two pseudopolymorphs of [2,5-bis(2-pyridyl)­pyrazine]­ferrocenyl­(methyl)­boron hexa­fluoro­phosphate have been determined at 173 K, namely the diethyl ether hemisolvate, [Fe(C₅H₅)(C₂₀H₁₇BN₄)]PF₆·0.5C₄H₁₀O, (I), which forms red crystals with Z′ = 1, and the aceto­nitrile hemisolvate, [Fe(C₅H₅)(C₂₀H₁₇BN₄)]PF₆·0.5CH₃CN, (II), which yields green–brown crystals with Z′ = 2. Despite the different crystal packing, the cations in (I) and (II) are similar. The 2,5-bis(2-pyridyl)­pyrazine moiety is almost planar and displays bending along its long axis compared with free 2,5-bis(2-pyridyl)­pyrazine. It is remarkable that both crystals were obtained from the same aceto­nitrile/diethyl ether solution.