Construction and structure of coordination polymers based on tetrahedral Cu4OBr6 centres linked by pyrazine

A model of 1D-, 2D-, and 3D-frameworks constructed of tetrahedral centres l inked by rod-like ligands according to the regularities given by diamond an d lonsdaleite lattices has been developed. The composition of the SD-framew ork polymer is expressed by the formula O-chs (b)([2chs-0.5(ch+cs)-hs]) (t) ([c(h+s)+2hs]), where c, h, and s represent the numbers of the tetrahedral centres O in three different dimensions of the SD-framework, b and t denote the relative amounts of bridging and terminal rod-like ligands, respective ly. For related sheet and chain polymers the formulas O-ch (b)([1.5ch-0.5c- h]) (t)([ch+c+2h]) and O-c (b)([c-1]) (t)([2c+2]) have been derived, respec tively. The formulas have been applied to a series of synthesized Cu4OBr6(p yz)(p) (p = 2.25-3.95) complexes in order to describe their structure. The complex with the value of p = 3.17 consists of chains comprising about 6 li nked tetrahedral Cu4OBr6 centres. The values of p = 3.04 and 2.90 correspon d to sheet structures with 9 and 16 linked centres, respectively. The struc tures of the complexes with p = 2.41 and 2.25 consist of 3D-frameworks. For the former complex 124 and for the latter one 503 linked tetrahedral Cu4OB r6 centres have been estimated.