284021-47-2Relevant academic research and scientific papers
Molecular and electronic structures of bis(pyridine-2,6-diimine)metal complexes [ML2](PF6)(n) (n = 0, 1, 2, 3; M = Mn, Fe, Co, Ni, Cu, Zn)
De Bruin, Bas,Bill, Eckhard,Bothe, Eberhard,Weyhermueller, Thomas,Wieghardt, Karl
, p. 2936 - 2947 (2000)
A series of mononuclear, octahedral first-row transition metal ion complexes mer-[M(II)L02](PF6)2 containing the tridentate neutral ligand 2,6-bis[1-(4-methoxyphenylimino)ethyl]pyridine (L0) and a Mn(II), Fe(II), Co(II), Ni(II), Cu(II), or Zn(II) ion have been synthesized and characterized by X-ray crystallography. Cyclic voltammetry and controlled potential coulometry show that each dication (except those of Cu(II) and Zn(II)) can be reversibly one-electron-oxidized, yielding the respective trications [M(III)L02]3+, and in addition, they can be reversibly reduced to the corresponding monocations [ML2]+ and the neutral species [ML2]0 by two successive one-electron processes. [MnL2]PF6 and [CoL2]PF6 have been isolated and characterized by X-ray crystallography; their electronic structures are described as [Mn(III)L12]PF6 and [Co(I)L02]PF6 where (L1)1- represents the one-electron-reduced radical form of L0. The electronic structures of the tri-, di-, and monocations and of the neutral species have been elucidated in detail by a combination of spectroscopies: UV-vis, NMR, X-band EPR, Mossbauer, temperature-dependent magnetochemistry. It is shown that pyridine-2,6-diimine ligands are noninnocent ligands that can be coordinated to transition metal ions as neutral L0 or, alternatively, as monoanionic radical (L1)1-. All trications are of the type [M(III)L02]3+, and the dications are [M(II)L02]2+. The monocations are described as [Mn(III)L12]+ (S = 0), [Fe(II)L0L1]+ (S = 1/2 ), [Co(I)L02]+ (S = 1), [Ni(I)L02]+ (S = 1/2 ), [Cu(I)L02]+ (S = 0), [Zn(II)L1L0]+ (S = 1/2 ) where the Mn(III) and Fe(II) ions are low-spin-configurated. The neutral species are described as [Mn(II)L12]0, [Fe(II)L12]0, [Co(I)L0L1]0, [Ni(I)L0L1]0, and [Zn(II)L12]0; their electronic ground states have not been determined.
