Structural, electronic and magnetic properties of Cu(II) complexes of 2-substituted tropones bearing a ferrocenyl group at 5-position.
Structural, electronic and magnetic properties of Cu(II) complexes of 2-substituted tropones bearing a ferrocenyl group at 5-position.
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铁(II)-铜(II)-铁(II)异三核配合物[Cu(FcTropOMe)(2)(H(2)O)(2)](OTf)(2)(FcTropOMe=5-二茂铁基-2-甲氧基托酮)(1)，[Cu(FcTropNEt(2))(2)](OTf)(2)(FcTropNEt(2)=2-(N，合成了N-二乙氨基-5-二茂铁基托酮(2)和[Cu(FcTropNEt)(2)](FcTropNEt=2-(N-乙氨基)-5-二茂铁基肌酸)(3)。此外，通过3的电化学氧化，成功地合成了Fe(III)-Cu(II)-Fe(III)异三核配合物[Cu(FcTropNEt)(2)](2+)(3(2+))的六氟磷酸盐。通过比较阳离子配合物1和2的X-射线结构和吸收光谱，发现2-二乙氨基托酮配体比2-甲氧基托酮配体更能诱导二茂铁基到托洛酮-铜(II)部分的分子内电荷转移。另一方面，3(2+)在近红外(NIR)区域有一个与2相似的宽CT谱带，可归属为从肌钙基铜(II)到二茂铁的转变。至于3(2+)(Pf(6)(-))(2)的磁性质，磁化率的温度依赖关系和固态和溶液中的ESR测量表明，尽管通过氨基肌钙和环戊二烯基团有很长的路径，但S=1/2的低自旋Fe(III)离子和S=1/2的Cu(II)离子之间存在很强的铁磁相互作用(J(Fe-Cu)=+12.0 cm(-1))。密度泛函理论计算支持这种分子内铁磁性，这种铁磁性是通过pi-间隔基团的自旋极化机制引起的。
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.