Polynuclear Complexes Containing the Redox Noninnocent Schiff Base Ligand 2-[(E)-2-Mercaptophenylimino]methyl-4,6-di-tert-butylphenolate(2-)

The N,O,S-donor Schiff base ligand 2-[(E)-(2-mercaptophenylimino)methyl]-4,6-di-tert-butylphenolate(2-) (H2L) was deprotonated with triethylamine (2equiv.) and treated with equimolar amounts of Cu(OAc)(2)center dot H2O, PtCl2, Pd(OAc)(2), and CoCl2, respectively. The versatility of L2- is realized in the self-assembly of four polynuclear complexes: dimeric [Cu-2(II)(L)(2)] (1), trimeric [Pt-3(II)(L)(3)] (2), and the two tetrameric complexes [Pd-4(II)(L)(4)] (3) and [Co-4(III)(L)(6)] (4), all characterized by X-ray crystallography. Electronic structure calculations (DFT) on dimeric 1 show that the two singly occupied Cu d(x2-y2) orbitals are antiferromagnetically coupled, and the calculated J = -724 cm(-1) agrees well with the experimental data. Complexes 3 and 4 possess several reversible one-electron, ligand-centered oxidations with electronic absorption and EPR spectroscopy displaying all the hallmarks of coordinated phenoxyl radicals. This feature further endorses our assignment of the generation of phenoxyl radicals upon oxidation and underscores the redox noninnocence of this Schiff base ligand. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)