Research Article: 2,5-Bis[4-(dimethyl­amino)­phen­yl]-3,6-dimethyl­pyrazine

Date Published: June 01, 2011

Publisher: International Union of Crystallography

Author(s): Sebastian Moschel, Dieter Schollmeyer, Heiner Detert.

http://doi.org/10.1107/S160053681101748X

Abstract

The title compound, C22H26N4, was prepared from p-dimethyl­amino­propiophenone in six steps. The mol­ecule has no crystallographic symmetry. The dihedral angles between the pyrazine ring and the phenyl rings are 35.81 (6) and 37.11 (8)°. The dimethyl­amino groups are essentially planar (sum of the bond angles at N = 359.3 and 359.9°) and nearly coplanar with the adjacent aromatic ring [dihedral angles = 5.54 (11) and 7.40 (3)°]. This effect and the short aniline C—N bonds can be rationalised in terms of charge transfer from the amino groups to the central pyrazine ring.

Partial Text

The title compound was prepared as a fundamental chromophore and as an inter­mediate for the preparation of acidochromic dyes, see: Detert & Sugiono (2005 ▶); Schmitt et al. (2008 ▶); Nemkovich et al. (2010 ▶). Conjugated oligomers with a pyrazine center and lateral donors are solvatochromic probes, see: Collette & Harper (2003 ▶) and Schmitt et al. (2011 ▶). 2,5-Diphenyl­pyrazine shows inter­planar angles of about 21° (Pieterse et al., 2000 ▶); due to steric hindrance these angles are opened up to 37–49° in the tetra­phenyl­pyrazine (Bartnik et al., 1999 ▶). The planarization of terminal amino groups and short aniline C—N bonds due to strong electronic coupling has also been observed in 2,5-bis­(p-dimethyl­amino­styr­yl)pyrazine, see: Fischer et al. (2011 ▶).

 

Source:

http://doi.org/10.1107/S160053681101748X

 

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