752994-89-1Relevant academic research and scientific papers
Dimetallic complexes of acyclic pyridine-armed ligands derived from 3,6-diformylpyridazine
Plieger, Paul G.,Downard, Alison J.,Moubaraki, Boujemaa,Murray, Keith S.,Brooker, Sally
, p. 2157 - 2165 (2004)
Abis(pyridine-armed) acyclic Schiff base ligand L1 has been synthesised from 3,6-diformylpyridazine and two equivalents of 2-(2-aminoethyl)pyridine. Reduction of this ligand using NaBH4 resulted in the formation of the amine analogue L2. Complexes of the form [M2L1(μ-X)]Y 2ClO4 [where: M = Cu(II), X = OH- and Y = ClO4- 1, Cl- 2, Br- 3 or I - 4; M = Co(II), X = OH- and Y = ClO4 - 5; M = Ni(II), X = SCN- 6 or X = N3 - 7 and Y = ClO4-], and [Cu2L2(μ- OH)](ClO4)3 8 were prepared and characterised. The complexes 1 and 5-7 have been characterised by single-crystal X-ray diffraction. The acyclic ligand LI provides three nitrogen donor atoms per metal centre, including a pyridazine bridge between the metal centres, and the anion X also bridges the two metal centres. As required, coordinating solvent molecules or additional anions make up the remainder of the coordination sphere. The two copper centres of 1 are very strongly antiferromagnetically coupled (2J= -1146 cm-1) via the pyridazine and hydroxide ion bridges, whereas the competing antiferromagnetic pyridazine bridging pathway and ferromagnetic 1,1-bridging azide pathway resulted in the observation of weak antiferromagnetic exchange in the dinickel(II) complex 7 (2J= -14 cm-1). Electrochemical examination of L1, L2 and complexes 1 and 5-8 revealed multiple redox processes. These have been tentatively assigned to a mixture of metal centred and ligand centred redox processes on the basis of cyclic voltammetry and coulometry results and comparisons with literature examples.
