CRYSTAL-STRUCTURE OF A CARBOXYLATE-BRIDGED CHAIN AND A MONONUCLEAR COMPLEX OF NICKEL AND THE MAGNETIC-BEHAVIOR OF [NI(DTMA)(HIM)]N[CLO4]N (HDTMA = DIETHYLENETRIAMINE-N'-ACETIC ACID, HIM = IMIDAZOLE)

The molecular structures of a carboxylate-bridged chain and a mononucl ear complex of nickel(II) with dtma (Hdtma = diethylenetriamine-N'-ace tic acid) and Him (Him = imidazole) ligands were determined by single- crystal X-ray analysis. The complex [Ni(dtma)(Him)]n[ClO4]n 1 crystall izes in the monoclinic system, space group P2(1)/c, with a = 8.255(1), b = 16.918(3), c = 11.114(1) angstrom and beta = 104.77(1)degrees and the complex [Ni(dtma)(Him)2]ClO4.H2O 2 in the orthorhombic system, sp ace group P2(1)2(1)2(1), with a = 9.940(3), b = 12.917(3) and c = 14.6 02(3) angstrom. The crystal structure of complex 1 contains chains of carboxylate-bridged nickeL(II) metal ions. Its variable-temperature (1 .8-300 K) magnetic susceptibility was determined. The carboxylate brid ge in complex 1 could only mediate a very weak ferromagnetic exchange interaction and the magnetic behaviour is better explained by single-i on anisotropy.