title: Crystal structure of a second polymorph of tetra-kis-(pyridin-2-yl)methane.
abstract: A second polymorph of the title compound, C21H16N4, is reported. The original polymorph was solved by our group [Matsumoto et al. (2003 ▶). Tetra-hedron Lett. 44, 2861-2864] in the monoclinic space group C2/c and refined to R = 0.050. Now the crystal structure of a tetra-gonal polymorph (space group P-421 c) has been solved and refined to R = 0.036. In the crystal, there are no strong inter-molecular inter-actions. Reflecting the high symmetry of the mol-ecular structure, the asymmetric unit is a quarter of the mol-ecule, and the mol-ecule exhibits S4 symmetry along the c axis in the crystal.
authors.affiliation: Institute of Natural Sciences, Senshu University, Higashimita 2-1-1, Kawasaki, Kanagawa 214-8580, Japan.
authors.forename: Kouzou
authors.initials: K
authors.lastname: Matsumoto
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kannami
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Fuyuhiro
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Masaji
authors.initials: M
authors.lastname: Oda
keywords: S4 symmetry; bridging ligands; crystal structure; polymorph; pyridine