Crystal structure of a second polymorph of tetrakis(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 ▶). Tetra­hedron Lett. 44, 2861–2864] in the monoclinic space group C2/c and refined to R = 0.050. Now the crystal structure of a tetra­gonal polymorph (space group P-421 c) has been solved and refined to R = 0.036. In the crystal, there are no strong inter­molecular inter­actions. Reflecting the high symmetry of the mol­ecular structure, the asymmetric unit is a quarter of the mol­ecule, and the mol­ecule exhibits S4 symmetry along the c axis in the crystal.

Crystal structure of tetrakis(1-oxidopyridin-2-yl)methane methanol tetrasolvate

“…The bond lengths and angles of pyridine rings are similar to those of 2methylpyridine N-oxide (Betz et al, 2011). The C1-C2 bond length [1.5472 ( 11) Å] is similar to that of tetrakis- (Matsumoto et al, 2014) and the prominent C1-C2 bond elongation by N-oxidation is not observed. The N-O bond length [1.3174 ( 14) Å] is also normal value in considering the formation of hydrogen bond with methanol molecule (Eichhorn, 1987…”

“…For coordination polymers of pyridine N-oxides, see: Henkelis et al (2012). For structures of related molecules, see: Betz et al (2011); Matsumoto et al (2014). For the effect of the formation of hydrogen bonds on the N-O bond length of pyridine N-oxides, see: Eichhorn (1987…”