The crystal and molecular structure of lead hexa-antipyrine perchlorate

Abstract

Lead hexa-antipyrine perchlorate is isomorphous with a series of metal hexa-antipyrine perchlorates, M(C 11 H 12 ON 2 ) 6 (CIO 4 ) 2 , where M = Mg 2+ , Ca 2+ or Zn 2+ and crystallizes in a hexagonal unit having dimensions a = 14.33 (±0.03), c = 9.75 (±0.03) A and space group P3 (C⅔t). The solution of the structure in the c-axis projection was facilitated by the heavy-atom method using (hki0) reflexions. A knowledge of the z coordinates obtained previously from a study of the magnesium compound was utilized to work out the complete structure and the refinement was done three-dimentional least-squares method to an agreement index of 0.079 for 736 observed reflexions. In structure, each Pb 2+ ion is surrounded by six antipyrine oxygen atoms in a slightly distorted octahedral form with Pb-O(6) = 2.446 (±0.016) A. The five-membered pyrazolone ring is planar and is inclined at an angle of 68° to the phenyl ring. The tetrahedral ClO 4 ions occupy viods provided by the adjacent antipyrine groups. The two non-equivalent Cl-O bonds, Corrected for effects of thrmal oscillation, have lengths 1.453 (I) and 1.457 A(3) respectively.