1-(2-Methyl-phen-yl)-4,4'-bipyridin-1-ium tetra-fluorido-borate.

Crystals of the title compound, C 17 H 15 N 2 + ·BF 4 - , were unexpectedly grown from crystallization attempts of [Pt(4,4'-bpy) 4 ](BF 4 ) 2 [Smith et al. (2019 ▸). Comments Inorg. Chem. 39 , 188-215] using toluene and aceto-nitrile. The tetra-fluoro-borate anion and the central pyridinium ring of the cation are disordered, with atomic site occupancies close to ½. The tolyl group of the cation has a 75.31 (11)° twist relative to the unsubstituted pyridyl group. This rotation allows for a centrosymmetric dimer of cations with weak hydrogen bonding between the pyridyl nitro-gen atom and a methyl H atom on the neighbouring cation.