X-Ray studies on potent new curariform agents. Part 2. The crystal and molecular structure of 3,3′-thiobis-(2-methyl-1-phenylimidazo[1,5-a]pyridinium) bistetrafluoroborate(III)

Abstract

The structure of the title compound, representative of a new series of powerful and selective neuromuscular blocking agents has been determined by a three-dimensional X-ray analysis. Monoclinic crystals in space group P2₁/c have lattice parameters a= 15.517(2), b= 14.054(3), c= 13.862(2)Å, β= 108.88(1)°, and Z= 4. The structure was solved by centro-symmetric symbolic addition and refined by full-matrix least-squares calculations to R= 0.080 for 1 133 reflections. The molecule consists of two identical halves inclined at an angle of 72.8° joined by a sulphide link. Quaternary nitrogen atom separations are all < 4.8 Å, and the non-planarity of the molecule is in striking contrast with related compounds which show comparable activity.