A Cu(II)-mediated C-H oxygenation of sterically hindered tripyridine ligands to form triangular Cu(II)3 complexes

Masahito Kodera, Yoshimitsu Tachi, Toshio Kita, Hiromu Kobushi, Yoshinori Sumi, Koji Kano, Motoo Shiro, Masayuki Koikawa, Tadashi Tokii, Masaaki Ohba, Hisashi Okawa

研究成果: Contribution to journalArticle査読

48 被引用数 (Scopus)

抄録

Two sterically hindered tris-pyridyl methane ligands, tris(6-methyl-2-pyridyl)methane (L1) and bis(6-methyl-2-pyridyl)pyridylmethane (L2), are newly synthesized. Under aerobic conditions, Ln (n = 1 or 2) reacts with CuX2 (X = Cl or Br), oxygenated at the methine position to LnOH or LnOMe. The former alcoholate ligand creates trinuclear Cu(II) complexes [Cu3(X)(LnO)3](PF6)2 {(X, n) = (Br, 1) 1, (Cl, 1) 2, (Br, 2) 3, or (Cl, 2) 4} in which the alkoxide oxygen atoms bridge copper centers. The crystal structures of 1-4 are presented along with their magnetic susceptibility data. The weak antiferromagnetic coupling between the Cu(II) centers in this trinuclear arrangement is due to weak interaction of the magnetic orbitals (dz2) which are oriented along three alternate sides in a hexagon of the Cu3O3 core in 1-4. Under anaerobic conditions, L1 reacts with CuBr2 to form a square pyramidal complex [CuL1Br2] (9) with the ligand facially capping. [Cu(Br)2(L1OMe)] (10) was obtained after the suspension of 9 in MeOH was stirred under air for 48 h. In the presence of cyclohexene, 9 is converted to [Cu(Br)(L1)]m (m = 1 or 2) 5 quantitatively to give trans-1,2-dibromocyclohexane, indicating that Br2 is generated during the reaction. The FAB MS spectrum of [18O]-1 prepared by the reaction of L1 with CuBr2 under 18O2 shows that the ligand of [18O]-1 is L118O-. L1 18OH, L1OCD3, and bis(6-methyl-2-pyridyl) ketone were obtained from reaction of L1 with CuBr2 in CD3OD under 18O2. These results indicate that the origins of the O atom in L1OH and L1OMe are O2 and MeOH, respectively. On the basis of these results, a mechanism of the oxygenation of L1 in the present system will be proposed.

本文言語英語
ページ(範囲)226-234
ページ数9
ジャーナルInorganic chemistry
39
2
DOI
出版ステータス出版済み - 1 24 2000

All Science Journal Classification (ASJC) codes

  • 物理化学および理論化学
  • 無機化学

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