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 R43(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 R66(40) ring motifs, forming molecular sheets running parallel to (101) and these are further connected by π–π interactions.

Keywords

• crystal structure
• cation
• anion
• disorder
• pyridine derivatives
• hydrogen bonding
• halogen bonding
• molecular sheets