Structural, electronic and magnetic properties of Cu(II) complexes of 2-substituted tropones bearing a ferrocenyl group at 5-position.
Heterotrinuclear Fe(II)-Cu(II)-Fe(II) complexes [Cu(FcTropOMe)(2)(H(2)O)(2)](OTf)(2) (FcTropOMe = 5-ferrocenyl-2-methoxytropone) (1), [Cu(FcTropNEt(2))(2)](OTf)(2) (FcTropNEt(2) = 2-(N,N-diethylamino)-5-ferrocenyltropone) (2) and [Cu(FcTropNEt)(2)] (FcTropNEt = 2-(N-ethylamino)-5-ferrocenyltroponate) (3) were synthesized. In addition, a hexafluorophosphate salt of heterotrinuclear Fe(III)-Cu(II)-Fe(III) complex [Cu(FcTropNEt)(2)](2+) (3(2+)) was successfully obtained as single crystals by electrochemical oxidation of 3. By comparing the X-ray structures and absorption spectra of dicationic complexes 1 and 2, the 2-(diethylamino)tropone ligand was found to induce a greater intramolecular charge transfer (CT) from ferrocenyl to tropone-Cu(II) moieties than the 2-methoxytropone ligand. On the other hand, 3(2+) showed a broad CT band in the near-infrared (NIR) region similar to 2, which can be assigned to a transition from troponato-Cu(II) to ferrocenium moieties. As for the magnetic properties of 3(2+)(PF(6)(-))(2), measurements of temperature dependence of magnetic susceptibility and ESR on the solid state and in solution revealed the presence of a strong ferromagnetic interaction (J(Fe-Cu) = +12.0 cm(-1)) between the low spin Fe(III) ion with S = 1/2 and Cu(II) ion with S = 1/2 despite a long distance pathway via the aminotroponato and cyclopentadienyl moieties. DFT calculations supported this intramolecular ferromagnetism, which is induced by a spin polarization mechanism through the pi-spacers.
Nishinaga
Tohru
T
Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan. nishinaga-tohru@tmu.ac.jp
Aono
Tomoshi
T
Isomura
Eigo
E
Watanabe
Sayaka
S
Miyake
Yoshihiro
Y
Miyazaki
Akira
A
Enoki
Toshiaki
T
Miyasaka
Hitoshi
H
Otani
Hiroyuki
H
Iyoda
Masahiko
M
D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004583:Electrons; D005296:Ferrous Compounds / Q000737:chemistry*; D008280:Magnetics; D000075163:Metallocenes; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism; D014334:Tropolone / Q000031:analogs & derivatives* / Q000737:chemistry
D005296:Ferrous Compounds; D000075163:Metallocenes; D009942:Organometallic Compounds; D003300:Copper; D014334:Tropolone; C003730:tropone; C004998:ferrocene