One- and two-dimensional coordinationpolymers of zinc(II) with pyrazine. Solid state reactions and decomposition kinetics of the interconvresion reactions

摘要

The reaction of zinc(II) bromide with pyrazine yielded the two coordination polymers [ZnBr_2(pyz)] 1 and [ZnBr_2(pyz)_2] 2. Crystal structures of these two compounds show that 1 is a 1-D zigzag chain polymer while 2 forms a regular square-grid (4,4) network. Adjacent grids in 2 are slipped in one direction so that the axial bromide ions on one layer project into the caities of the grids in adjecent layers. The solid-state reaction of 1 with pyrazine yield 2, and 2 in its turn is readily converted into 1 by heating. The activation energy of the latter process has been determined as 99.8 kJ mol~(-1).