A novel samarium(ii) complex bearing a dianionic bis(phenolate) cyclam ligand: synthesis, structure and
Leonor Maria1, Marina Soares2, Isabel C Santos1
1Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066 Bobadela LRS, Portugal. leonorm@ctn.ist.utl.pt.
Abstract:
The reaction of the hexadentate dianionic 1,4,8,11-tetraazacyclotetradecane-based bis(phenolate) ligand, (tBu2ArO)2Me2-cyclam(2-), with [SmI2(thf )2] in thf resulted in the formation of the divalent samarium complex [Sm(κ(6)-{(tBu2ArO)2Me2-cyclam})] (1). X-ray diffraction studies revealed that after recrystallization from n-hexane/thf complex 1 has a monomeric structure and does not contain thf molecules coordinated to the Sm(II) center. However, UV-vis and (1)H NMR spectroscopy of 1 evidenced the formation of thf-solvated complexes in neat thf. Reductive studies show that complex 1 can act as a single electrontransfer reagent and form well-defined Sm(III) species. The reaction of 1 with several substrates, namely, TlBPh4, pyridine N-oxide, OPPh3, SPPh3 and bipyridines, are reported. Spectroscopy studies, including NMR, and single crystal X-ray diffraction data are in agreement with the formation of cationic Sm(III) species, monochalcogenide bridged Sm(III) complexes and Sm(III) complexes with bipyridine radical ligand, respectively.
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