Syntheses and Crystal Structures of Three Cadmium（II） Coordination Complexes Based on Flexible 1,2-Bis（imidazol-1~ˊ-yl）ethane

Three Cd（II） coordination complexes,{[Cd（bime）3]（NO3）2·（H2O）3}n（1）,[Cd（bime）Br2]n（2） and [（H2bime）（CdBr4）（H2O）]n（3）（bime = 1,2-bis（imidazol-1-yl）ethane）,have been prepared and characterized.Single-crystal X-ray diffraction analysis reveals that 1~3 crystallize in the trigonal space group P-3,monoclinic space group C2/c and triclinic space group P1,respectively.In 1,bime bridges six-coordinated Cd（II） to generate a two-fold interpenetrating 3D coordination polymer,in which NO3- is not involved in coordination,but serves as a void filler to balance the charge of the 3D framework.The six NO3- and six uncoordinated water molecules form an unprecedented 24-membered macrocycle through hydrogen bonding interaction.In 2,bime in an anti-conformation links the CdBr2 units into a zigzag chain.In 3,bime does not take part in coordination,but is protonated to act as a counter cation of [CdBr4 ]2-.The hydrogen bonds between H2bime and [CdBr4]2- result in the formation of a supramolecular chain.