Metal complexes based on tetrathiafulvalene-fused π-extended schiff base ligands - Syntheses, characterization, and properties

摘要

π-Conjugated tetrathiafulvalene (TTF)-based donors with a monoamine moiety, 2-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-1,3-benzodithiol-5-amine (L _a) and 2-(5,6-dihydro[1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene)-1, 3-benzodithiol-5-amine (L _b), have been synthesized. Condensation of the TTF amines with different pyridinecarbaldehydes afforded new TTF-fused π-extended Schiff base ligands, L _a-imine-4-pyridyl (L _1), L _a-imine-3-pyridyl (L _2), and L _b-imine-2-pyridyl (L _3). Four metal complexes based on these Schiff base pyridine ligands, M(hfac) _2(L) _2 (M = Cu ~(II), L = L _1, 4; M = Mn ~(II), L = L _1, 5; M = Cu ~(II), L = L _2, 6; hfac = hexafluoroacetylacetonate) and [Re(CO) _4(L _3)][Re _2(CO) _6Cl _3] (7), have been synthesized and structurally characterized. The ligands in all of the complexes show a near planar structure, and the different coordination modes of the metal ions and relative orientation of the terminal N donors result in a different crystalline organization in the solid state. The absorption spectra and redox behavior of these new compounds have been studied. These paramagnetic complexes are promising building blocks for the construction of multifunctional materials due to their planar structures and inherent redox properties.