Crystal structure determination of two pyridine derivatives: 4-[(E)-2-(4-methoxyphenyl)ethenyl]-1-methylpyridin-1-ium hexafluoro-λ6-phosphane and 4-[(E)-2-[4-(dimethylamino)phenyl]ethenyl]-1-phenyl-1λ5-pyridin-1-ylium hexafluoro-λ6-phosphane

Abstract

The title molecular salts, C16H16NO+·PF6 −, (I), and C21H21N2 +·PF6 −, (II), are pyridine derivatives. In compound (I), the cation comprises a methyl N-substituted pyridine ring and a methoxy-substituted benzene ring connected by a C=C double bond. The F atoms of the PF6 − anion are disordered over two sets of sites with refined occupancy factors of 0.614 (7):0.386 (7). In compound (II), the cation comprises a pyridine ring attached to unsubstituted phenyl ring and a dimethylaniline ring, which are connected by a C=C double bond. The anion is PF6 −. In both salts, the cation adopts an E configuration with respect to the C=C bond. The pyridine ring makes a dihedral angle of 9.86 (12)° with the methoxy-substituted benzene ring in compound (I) and 11.2 (3)° with the dimethylamine-substituted benzene ring in compound (II). In compound (I), the crystal packing is stabilized by weak C—H...F intermolecular interactions which result in R 4 3(14) ring motifs, forming molecular sheets running parallel to (\overline{1}03). These are further stabilized by weak P—F...π interactions. In compound (II), the crystal packing is stabilized by C—H...F interactions, which result in R 6 6(40) ring motifs, forming molecular sheets running parallel to (101) and these are further connected by π–π interactions.