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Title: Synthesis and reactivity of cobalt complexes derived from tris(2-pyridylthio)methane ligand: Structural characterization of cobalt(III) complexes containing cobalt–carbon bond
Authors: Halder, Partha
Paine, Tapan Kanti
Keywords: Organometallic compounds;Organocobalt complexes;Metal–carbon bond;Solid state structure;Cobalt;Oxidation
Issue Date: Sep-2011
Publisher: NISCAIR-CSIR, India
Abstract: The synthesis, characterization and reactivity of a cobalt(II) complex, [(HL1)CoII(PyS)](ClO4) (1) (where HL1 = tris(2-pyridylthio)methane and PyS = monoanionic pyridine-2-thiolate) are discussed. Complex (1) reacts with molecular oxygen to yield a mononuclear low-spin cobalt(III) complex, [(L1)CoIII(PyS)](ClO4) (2). On the other hand, treatment of (1) with a protic acid (pyridinium perchlorate) followed by a base (triethylamine) and dioxygen forms an isomeric cobalt(III) complex, [(L2)CoIII(PyS)](ClO4) (3) (L2 = 1-[bis(2-pyridylthio)methyl]pyridine-2-thione). Ligand HL1 (in 1) rearranges to L2 (in 3) during the reaction as a result of C–S bond cleavage and subsequent C–N bond formation. X-ray crystal structures of both (2) and (3) reveal a distorted octahedral coordination geometry at cobalt(III) center with a strong cobalt–carbon bonding interaction. A four-coordinate distorted tetrahedral cobalt(II) complex, [CoII(PySH)4](ClO4)2 (4) is formed via C–S bond cleavage of HL1 in the reaction of (1) with an excess amount of pyridinium perchlorate. The electronic structure of (2) as established by DFT calculation suggests a delocalized LUMO with significant contribution from the metal ion. The organocobalt(III) complex converts to an air-stable organocobalt(II) complex (2red) upon one-electron reduction.
Page(s): 1394-1402
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.50A(09-10) [September-October 2011]

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