Crystallographic investigation of n-Aminopyridinium perhalometallates

Abstract

This dissertation presents the results of a crystallographic investigation into nineteen novel n-aminopyridinium perhalometallates of the general formula (C5H7N2 +)2MX4 2- where n = 2, 3 or 4, M = Zn, Cd or Hg and X = Cl, Br or I. The aim was to identify positional effects of the cation hydrogen bonding donor groups on the structures and to possibly identify robust synthons. Overall structural trends were also studied. The hybrid crystals were synthesized using temperature controlled crystallization methods and were characterized using X- ray diffraction techniques. Eighteen of the nineteen hybrid crystals displayed isolated tetrahedral perhalometallate anions. The results were classified into six different classes of isostructural compounds. Eight of the nineteen hybrid structures (42%) contained water. The 42% include two 3-ammoniopyridinium structures and all cadmium and mercury containing 4-aminopyridinium structures. The effect of a change in metal and/ or halide on the structure was investigated, and the overall structural trends in each n-aminopyridinium family were identified. Four different synthons were observed in the 2-aminopyridinium series while one synthon was observed throughout the 4-aminopyridinium series. A common synthon was observed in both the 3-aminopyridinium and 3-ammoniopyridinium series.