The 1:1 co-crystal of triphenyl(2,3,5,6-tetrafluorobenzyl)phosphonium bromide and 1,1,2,2-tetrafluoro-1,2-diiodoethane

The title compound, C25H18F4P +·Br-·C2F4I 2, is a 1:1 co-crystal of triphenyl(2,3,5,6-tetrafluorobenzyl) phosphonium (TTPB) bromide and 1,1,2,2-tetrafluoro-1,2-diiodoethane (TFDIE). The crystal structure consists of a framework of TTPB cations held together by C-H⋯Br interactions. In this framework, infinite channels along [100] are filled by TFDIE molecules held together in infinite ribbons by short F⋯F [2.863(2)-2.901(2)Å] interactions. The structure contains halogen bonds (XB) and hydrogen bonds (HB) in the bromide coordination sphere. TFDIE functions as a monodentate XB donor as only one I atom is linked to the Br- anion and forms a short and directional interaction [I⋯Br- 3.1798(7)Å and C-I⋯Br- 177.76(5)°]. The coordination sphere of the bromide anion is completed by two short HBs of about 2.8Å (for H⋯Br) with the acidic methylene H atoms and two longer HBs of about 3.0Å with H atoms of the phenyl rings. Surprisingly neither the second iodine atom of TFDIE nor the H atom on the tetrafluorophenyl group make any short contacts.