Cobalt(III) Complexes with Quadridentate Ligands. III. The Preparation and Properties of the Salicylato or Dichloro(quadridentate amine)cobalt(III) Complexes

Abstract

Abstract In the 1H and 13C NMR spectra of trans- or cis-dichloro(quadridentate amine)cobalt(III) chloride hydrates, [CoCl2L]Cl·nH2O (L: 2,2,2-tet(trien) (1a), 2,3,2-tet (1b), 3,2,3-tet (1c), and 3,3,3-tet (1d)), the signals of their methylene protons and methylene carbons have been assigned to the individual methylene protons and methylene carbon of the coordinated quadridentate amine ligands. The order of 1H and 13C chemical shift of their methylene protons and methylene carbon is as follows: (Remark: Graphics omitted.) Thus, the signal of the center methylene protons (or carbon) of the coordinated quadridentate amine ligands appears at higher field than that of the NH-side methylene protons (or carbon). cis-β1-Salicylato(3,7-diazanonane-1,9-diamine)cobalt(III) chloride hydrate, cis-β1-[Co(sal)(2,3,2-tet)]Cl·H2O (3b), and cis-β2-salicylato(quadridentate amine)cobalt(III) chloride hydrates, cis-β2-[Co(sal)L]Cl·nH2O (L: 2,3,2-tet (4b), 3,2,3-tet (4c) and 3,3,3-tet (4d)) have been isolated from a reaction mixture of sodium salicylate or salicylic acid and 1b–d. The properties of 3b and 4b are similar to those of the previously reported complexes 3a (L: 2,2,2-tet, β1-form) and 4a (L: 2,2,2-tet, β2-form), respectively. Those of 4c are similar to those of 4d. Complex 4d is the most unstable complex among 4a–d. This property is attributable to the center methylenes of the coordinated quadridentate amine ligands.