Tale of a twist: magnetic and optical switching in copper(II) semiquinone complexes.
Tale of a twist: magnetic and optical switching in copper(II) semiquinone complexes.
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曲折的故事：铜（II）半醌配合物中的磁和光开关。
DOI：
10.1021/ic200958g
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发表时间：
2011
影响因子：
4.6
通讯作者：
Stack,TDanielP
中科院分区：
文献类型：
--
作者：
Verma,Pratik;Weir,John;Mirica,Liviu;Stack,TDanielP
在苯酚羟基化和儿茶酚氧化中观察到的中间体(C)与侧对过氧化物[Cu2O2(DBED)2]2+（DBED =N1， n2 -二叔丁乙烷-1,2-二胺）通过独立合成和表征确定为铜（II）半醌（[1]+）。具有氧化还原活性的3,5-二叔丁基醌配体与[(DBED)CuI(MeCN)]+反应生成具有单重态基态和强紫色发色团（ε580 ~ 3500 M-1cm-1）的铜（II）半醌[1]+配合物。迄今为止表征的所有其他铜（II）半醌配合物均为顺磁性和弱色（ε800 ~ 500 M-1cm-1）。用顺磁1h NMR和SQUID磁强计表征了[1]+中cui中心与半醌自由基之间的反铁磁耦合。比较x射线晶体结构和密度泛函理论计算将铜（II）半醌配合物的几何结构与其磁性和光学性质联系起来。[1]+独特的可观察性质源于Cu 3d和半醌π轨道的重叠增加，这是由于DBED配体的叔丁基取代基的大各向同性需求导致的结构中的大菱形扭曲（扭曲为51°）。[1]+的独立表征允许中间体ec1的光谱产率在这个有趣的羟基化反应中被量化。
An intermediate (C) that is observed in both phenol hydroxylation and catechol oxidation with the side-on peroxide species [Cu2O2(DBED)2]2+(DBED =N1,N2-di-tert-butylethane-1,2-diamine) is identified as a copper(II) semiquinone species ([1]+) through independent synthesis and characterization. The reaction of the redox-active 3,5-di-tert-butylquinone ligand with [(DBED)CuI(MeCN)]+yields a copper(II) semiquinone [1]+complex with a singlet ground state and an intense purple chromophore (ε580∼ 3500 M–1cm–1). All other copper(II) semiquinone complexes characterized to date are paramagnetic and weakly colored (ε800∼ 500 M–1cm–1). Antiferromagnetic coupling between the CuIIcenter and the semiquinone radical in [1]+is characterized by paramagnetic1H NMR and SQUID magnetometry. Comparative X-ray crystal structures along with density functional theory calculations correlate the geometric structures of copper(II) semiquinone complexes with their magnetic and optical properties. The unique observable properties of [1]+originate from an increase in the overlap of the Cu 3d and semiquinone π orbitals resulting from a large rhombic distortion in the structure with a twist of 51°, attributable to the large isotropic demands of thetert-butyl substituents of the DBED ligand. Independent characterization of [1]+allows the spectroscopic yields of intermediateCto be quantified in this intriguing hydroxylation reaction.