Molecular and Electronic Structure of Square-Planar Gold Complexes Containing Two 1,2-Di(4-tert-butylphenyl)ethylene-1,2-dithiolato Ligands: [Au(2L)2]1+/0/1-&
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- 作者：Swarnalatha Kokatam ; Kallol Ray ; Joseph Pap ; Eckhard Bill ; William E. Geiger ; Robert J. LeSuer ; Philip H. Rieger ; Thomas Weyhermü ; ller ; Frank Neese ; Karl Wieghardt
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：February 19, 2007
- 年：2007
- 卷：46
- 期：4
- 页码：1100 - 1111
- 全文大小：321K
- 年卷期：v.46,no.4(February 19, 2007)
- ISSN：1520-510X
文摘
From the reaction of in situ generated 1,2-di(4-tert-butylphenyl)ethylene-1,2-dithiol, 2LH2, and Na[AuCl4]·2H2O in1,4-dioxane, green brown crystals of diamagnetic [N(n-Bu)4][AuIII(2L)2] (1) were obtained. As shown by cyclicvoltammetry, 1 is a member of an electron-transfer series comprising the dianion [AuII(2L)2]2-, the monoanion[AuIII(2L)2]-, the neutral species [AuIII(2L
)(2L)]0 
[AuIII(2L)(2L)]0, and the monocation [AuIII(2L)2]+. (2L)1- representsthe 
radical anion (Srad = 1/2) of the one-electron oxidized closed-shell dianion (2L)2-. Oxidation of 1 in CH2Cl2with ferrocenium hexafluorophosphate affords green, paramagnetic microcrystals of [AuIII(2L)(2L)] [AuIII(2L)(2L)](2) (S = 1/2). Complexes 1 and 2 have been characterized by X-ray crystallography. Both species possess square-planar monoanions and neutral molecules, respectively. From the oxidation reaction of 1 or [N(n-Bu)4][AuIII(3L)2]with 2-3 equiv of [NO]BF4 in CH2Cl2, a green solution of [AuIII(2L)2]+ and green microcrystals of [AuIII(3L)2]BF4 (3)were obtained, respectively; (3L)2- represents the dianion 1,2-di(4-diphenyl)ethylene-1,2-dithiolate, and (3L)1- isits radical monoanion. The electronic structures of this series of gold species have been elucidated by UV-vis,EPR spectroscopies, and DFT calculations. It is shown computationally by density functional theoretical (DFT)methods that the electronic structure of [AuIII(1L)2]+ is best described as a singlet diradical (St = 0); the ligandmixed valency in the neutral species 2 is of class (III) (delocalized); the monoanion in 1 contains a AuIII ion andtwo closed-shell dianionic ligands; and the corresponding dianions [Au(L)2]2- are best described as an intermediateAuII/AuIII species with a metal-ligand delocalized SOMO (25% Au 5d, 75% 3p of four S atoms). (1L)2- is thedianion 1,2-di(phenyl)ethylene-1,2-dithiolate, and (1L)1- is the radical monoanion. The neutral species [PdII(2L)2](4) has also been synthesized and characterized by X-ray crystallography. Its electronic structure is the same asdescribed for [AuIII(1L)2]+ (singlet diradical), whereas that of the monoanion [PdII(2L)(2L)]- [Pd(2L)(2L)]- correspondsto that of the neutral gold complex 2. Anodic oxidation of the analogous monoanion [AuIII(mnt)2]-, where mnt =maleonitriledithiolate, gave the neutral complex [Au(mnt)(mnt)] (E1/2 = 0.91 V vs Fc+/Fc). The optical and EPRspectroscopies of [Au(mnt)(mnt)] were consistent with those observed for the corresponding di(tert-butylphenyl)ethylenedithiolate complex 2.
)(2L)]0 [AuIII(2L)(2L)]0, and the monocation [AuIII(2L)2]+. (2L)1- representsthe radical anion (Srad = 1/2) of the one-electron oxidized closed-shell dianion (2L)2-. Oxidation of 1 in CH2Cl2with ferrocenium hexafluorophosphate affords green, paramagnetic microcrystals of [AuIII(2L)(2L)] [AuIII(2L)(2L)](2) (S = 1/2). Complexes 1 and 2 have been characterized by X-ray crystallography. Both species possess square-planar monoanions and neutral molecules, respectively. From the oxidation reaction of 1 or [N(n-Bu)4][AuIII(3L)2]with 2-3 equiv of [NO]BF4 in CH2Cl2, a green solution of [AuIII(2L)2]+ and green microcrystals of [AuIII(3L)2]BF4 (3)were obtained, respectively; (3L)2- represents the dianion 1,2-di(4-diphenyl)ethylene-1,2-dithiolate, and (3L)1- isits radical monoanion. The electronic structures of this series of gold species have been elucidated by UV-vis,EPR spectroscopies, and DFT calculations. It is shown computationally by density functional theoretical (DFT)methods that the electronic structure of [AuIII(1L)2]+ is best described as a singlet diradical (St = 0); the ligandmixed valency in the neutral species 2 is of class (III) (delocalized); the monoanion in 1 contains a AuIII ion andtwo closed-shell dianionic ligands; and the corresponding dianions [Au(L)2]2- are best described as an intermediateAuII/AuIII species with a metal-ligand delocalized SOMO (25% Au 5d, 75% 3p of four S atoms). (1L)2- is thedianion 1,2-di(phenyl)ethylene-1,2-dithiolate, and (1L)1- is the radical monoanion. The neutral species [PdII(2L)2](4) has also been synthesized and characterized by X-ray crystallography. Its electronic structure is the same asdescribed for [AuIII(1L)2]+ (singlet diradical), whereas that of the monoanion [PdII(2L)(2L)]- [Pd(2L)(2L)]- correspondsto that of the neutral gold complex 2. Anodic oxidation of the analogous monoanion [AuIII(mnt)2]-, where mnt =maleonitriledithiolate, gave the neutral complex [Au(mnt)(mnt)] (E1/2 = 0.91 V vs Fc+/Fc). The optical and EPRspectroscopies of [Au(mnt)(mnt)] were consistent with those observed for the corresponding di(tert-butylphenyl)ethylenedithiolate complex 2.