Copper(II) complexes of isomeric aminophenylhydroxamic acids. A novel 'clam-like' dimeric metallacrown and polymeric helical structure containing interlinked unique copper(II) sites

The reaction of 3-aminophenylhydroxamic acid with CuSO4. 5H(2)O in aqueous solution gives the novel helical polymer [Cu-3(3-Apha)(4)(H2O)SO4](n). 8H(2 )O 1 the structure of which contains interlinked repeating units having thr ee unique neutral, anionic and cationic copper(II) sites. In this complex t he copper(II) sites are magnetically non-interacting. A similar reaction wi th 2-aminophenylhydroxamic acid gives the novel dimeric 'metallacrown' [Cu- 5(2-AphaH(-1))(4)(mu -SO4)(H2O)(2)](2). 10H(2)O 2 which has a 'clam-like' s tructure showing strong antiferromagnetic behaviour. In contrast to the abo ve ligands, 4-aminophenylhydroxamic acid gives the monomeric square planar complex Cu(4-Apha)(2).H2O 3 which exhibits paramagnetic behaviour. Crystal structures of all three complexes are reported.