Coordination behaviour of sulfanilamide derivatives. Crystal structures of[Hg( sulfamethoxypyridazinato)(2)], [Cd(sulfadimidinato)(2)(H2O)] center dot 2H(2)O and [Zn(sulfamethoxazolato)(2)-(pyridine)(2)(H2O)(2)]

Hg(II), Cd(II) and Zn(II) complexes with the ligands sulfadimethoxine, sulf amethoxypyridazine, sulfadiazine, sulfamerazine, sulfadimidine and sulfamet hoxazole have been prepared and characterised by spectral data. H-1 and C-1 3 NMR have been used to interpret the structural characteristics of the com plexes in solution. The X-ray crystal structures of [Hg(sulfamethoxypyridaz inato)(2)] (2a), [Cd(sulfadimidinato)(2)(H2O)] center dot 2H(2)O (4b) and [ Zn(sulfamethoxazolato)(2)(py)(2)(H2O)(2)] (6d) have been determined. In com plex 2a the Hg(II) ion lies on an inversion centre and exhibits linear coor dination by two sulfonamidic nitrogen atoms [Hg-N(1) = 2.071(4) Angstrom] o f the two deprotonated sulfamethoxypyridazinato ligands. The polymeric Cd(I I) complex (4b) exhibits a high distorted-octahedral geometry, involving th e sulfonamidic nitrogen [Cd-N(1) = 2.328(6); Cd-N(1') = 2.326(6) Angstrom] and the heterocyclic N(3)/N(2') [Cd-N(3) = 2.307(6) Angstrom; Cd-N(2') = 2. 426(6) Angstrom] of two bidentate sulfadimidine ligands, the terminal amino N(4'b) [Cd-N(4'b) = 2.379(7) Angstrom] of a third sulfadimidine which is b onded to an adjacent Cd(II), and the O(3) atom of a coordinated water molec ule [Cd-O(3) = 2.334(6) Angstrom]. In complex 6d the geometry around the Zn (II) ion can be described as a slightly distorted compressed octahedron. Tw o pyridine [Zn-N(16) = 2.1841(17) Angstrom] and two isoxazole N atoms [Zn-N (2) = 2.1736(15) Angstrom] are located in the equatorial plane and two oxyg en atoms of two water molecules [Zn-O(4) = 2.0984(14) Angstrom] are placed in the apical positions. IR and NMR spectral studies suggest a similar beha viour of the Cd(II) and Zn(II) complexes, both in solid state and solution, and different to the corresponding Hg(II) complexes. Thus H-1 and C-13 NMR spectra, in DMSO-d(6), of Cd(II) and Zn(II) compounds show coordination ma inly through the heterocyclic nitrogen while the corresponding Bg(II) deriv atives seem to be coordinated through the sulfonamidic nitrogen. (C) 2000 E lsevier Science Ltd All rights reserved.