NEW DINUCLEAR PENTACOORDINATED AND HEXACOORDINATED NICKEL(II) COMPLEXES WITH MU-AZIDO BRIDGES - CRYSTAL-STRUCTURES OF FERROMAGNETICALLY COUPLED (MU-N3)2[NI(ME3[12]N3)]2(CLO4)2.2H2O AND (MU-N3)2[NI(232-N4)]2(CLO4)2

The synthesis, characterization, and properties of the dinuclear Ni(II) complexes (mu-N3)2[Ni(Me3[12]N3)]2-(ClO4)2.2H2O (1), (mu-N3)2[Ni(Me4[12]N3)]2(ClO4)2.H2O (2), and (mu-N3)2[Ni(232-N4)]2(ClO4)2 (3) are reported. Me3[12]N3 is 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene, Me4[12]N3 is its 9-methyl derivative, and 232-N4 is N,N'-bis(2-aminoethyl)-1,3-propanediamine. The crystal structure of 1 was solved by Patterson synthesis and refined to a discrepancy factor of 0.043. The crystals are monoclinic, space group P2(1)/n, with lattice constants a = 10.151(2) angstrom, b = 15.478(3) angstrom, c = 12.317(2) angstrom, beta = 106.60(2)-degrees, and Z = 2. The dimer consists of two pentacoordinated nickel atoms coordinated to two 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene and two end-on azido bridging ligands. Each nickel(II) has a distorted trigonal bipyramidal environment. The crystal structure of 3 was solved by Patterson synthesis and refined to a discrepancy factor of 0.045. The crystals are monoclinic, space group P2(1)/n, with lattice constants a = 11.892(2) angstrom, b = 13.611(3) angstrom, c = 9.340(i) angstrom, beta = 106.03(l)-degrees, and Z = 2. The dimer consists of two nickel atoms coordinated to two N,N'-bis(2-aminoethyl)-1,3-propanediamine and two end-on azido bridging ligands. Each nickel (II) has a distorted octahedral environment. Magnetic susceptibility data for the three compounds were recorded between 290 and 4 K, showing strong ferromagnetic coupling for 1 and 3 and strong antiferromagnetic coupling for 2. These data were fitted giving the parameters J = 43.9 cm-1, D = -13.4 cm-1, and z'J'= -1.0 cm-1 for 1, J = -84.4 cm-1, D = -15.7 cm-1, and z'J'= 0.9 cm-1 for 2, and J = 33.8 cm-1, D = -21.5 cm-1, and z'J'= -0.08 cm-1 for 3. Magnetic interactions in these compounds are discussed in terms of bonding differences, and magneto-structural trends are given.