title: Three differently coloured concomitant polymorphs: synthesis, structure and packing analysis of (4-(3',5'-dimethyl-1H-pyrazol-1'-yl)-6-methyl-2-phenylpyrimidine)dichlorocopper(II).
abstract: A novel pyrazolylpyrimidine ligand (L) and its complex CuLCl(2) were prepared and structurally characterized. The simultaneous crystallization of three polymorphs of CuLCl(2), green (G), emerald green (EG) and orange (O), was discovered. The molecular structures vary only slightly between the three forms. The Cu atom forms four coordinate bonds with the two N and two Cl atoms, and a shortened Cu...H contact with an H atom of the phenyl ring in L. The structural difference between polymorphs was analyzed with the boundary surfaces of molecular Voronoi-Dirichlet polyhedra. The difference in colour of the polymorphs is likely to be due to the different pi-pi stackings. There is no stacking in the G modification, but EG and O polymorphs demonstrate face-to-face and slipped stacking, resulting in dimers and infinite chains, respectively. The EG and O polymorphs are packed according to the hexagonal close-packing motif, while in G no special topology is found.
authors.affiliation: A. V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia. peresyp@che.nsk.su
authors.forename: Eugenia V
authors.initials: EV
authors.lastname: Peresypkina
authors.forename: Mark B
authors.initials: MB
authors.lastname: Bushuev
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Virovets
authors.forename: Victor P
authors.initials: VP
authors.lastname: Krivopalov
authors.forename: Ludmila G
authors.initials: LG
authors.lastname: Lavrenova
authors.forename: Stanislav V
authors.initials: SV
authors.lastname: Larionov