An Atropisomeric Chiral 2,2'-bipyridyl-3,3'-dicarboxylic Acid and Corresponding Platinum(II)Complex

摘要

2,2'-Bipyridyl-3,3'-dicarboxylic acid(H_2BDC)spontaneously resolves on crystallization from water,giving monohydrated crystals of the space group P2_12_12_1.In any individual crystal,all the atropisomeric-skewed molecules are of one hand;however,on dissolution in water,optical activity is lost.Strong hydrogen bonding leads to a helical structure,via O-H...N links,and 3 further strong bonds between water and carboxylate groups produce a framework structure.The pK_avalues measured for H_2BDC(3.18(+-)0.04 and 4.59(+-)0.02 at 20(+-)1 degC,in dilute aqueous solution)agree with the zwitterionic form.The reaction of H_2BDC with potassium tetrachloroplatinate(II)in water gives Pt(H_2BDC)Cl_2(centre dot)H_2O.The complex was characterized by elemental analysis and spectroscopic techniques.