Muresan Nicoleta, Chlopek Krzysztof, Weyhermüller Thomas, Neese Frank, Wieghardt Karl
Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
Inorg Chem. 2007 Jun 25;46(13):5327-37. doi: 10.1021/ic700407m. Epub 2007 May 27.
From the reaction of Ni(COD)(2) (COD = cyclooctadiene) in dry diethylether with 2 equiv of 2-phenyl-1,4-bis(isopropyl)-1,4-diazabutadiene (L(Ox))(0) under an Ar atmosphere, dark red, diamagnetic microcrystals of [Ni(II)(L*)(2)] (1) were obtained where (L*)(1-) represents the pi radical anion of neutral (L(Ox))(0) and (L(Red))(2-) is the closed shell, doubly reduced form of (L(Ox))(0). Oxidation of 1 with 1 equiv of ferrocenium hexafluorophosphate in CH(2)Cl(2) yields a paramagnetic (S = 1/2), dark violet precipitate of Ni(I)(L(Ox))(2) (2) which represents an oxidatively induced reduction of the central nickel ion. From the same reaction but with 2 equiv of Fc in CH(2)Cl(2), light green crystals of Ni(II)(L(Ox))(2)(FPF(5)) (3) (S = 1) were obtained. If the same reaction was carried out in tetrahydrofuran, crystals of Ni(II)(L(Ox))(2)(THF)(FPF(5)) x THF (4) (S = 1) were obtained. Compounds 1, 2, 3, and 4 were structurally characterized by X-ray crystallography: 1 and 2 contain a tetrahedral neutral complex and a tetrahedral monocation, respectively, whereas 3 contains the five-coordinate cation Ni(II)(L(Ox))(2)(FPF(5)) with a weakly coordinated PF(6)(-) anion and in 4 the six-coordinate monocation Ni(II)(L(Ox))(2)(THF)(FPF(5)) is present. The electro- and magnetochemistry of 1-4 has been investigated by cyclic voltammetry and SQUID measurements. UV-vis and EPR spectroscopic data for all compounds are reported. The experimental results have been confirmed by broken symmetry DFT calculations of Ni(II)(L*)(2), Ni(I)(L(Ox))(2), and Ni(II)(L(Ox))(2) in comparison with calculations of the corresponding Zn complexes: Zn(II)((t)L(Ox))(2), Zn(II)((t)L(Ox))((t)L*), Zn(II)((t)L*)(2), and Zn(II)((t)L*)((t)L(Red)) where ((t)L(Ox))(0) represents the neutral ligand 1,4-di-tert-butyl-1,4-diaza-1,3-butadiene and ((t)L*)(1-) and ((t)L(Red))(2-) are the corresponding one- and two-electron reduced forms. It is clearly established that the electronic structures of both paramagnetic monocations Ni(I)(L(Ox))(2) (S = 1/2) and Zn(II)((t)L(Ox))((t)(L*) (S = 1/2) are different.
在氩气氛围下，将Ni(COD)₂（COD = 环辛二烯）在干燥的二乙醚中与2当量的2-苯基-1,4-双（异丙基）-1,4-二氮杂丁二烯（L(Ox)）₀反应，得到暗红色、抗磁性的[Ni(II)(L*)₂]（1）微晶，其中（L*）¹⁻代表中性（L(Ox)）₀的π自由基阴离子，（L(Red)）²⁻是（L(Ox)）₀的闭壳层、双还原形式。在二氯甲烷中用1当量的六氟磷酸二茂铁氧化1，得到顺磁性（S = 1/2）、深紫色沉淀Ni(I)(L(Ox))₂（2），这代表中心镍离子的氧化诱导还原。在相同反应中，但在二氯甲烷中使用2当量的Fc，得到浅绿色晶体Ni(II)(L(Ox))₂(FPF₅)（3）（S = 1）。如果在四氢呋喃中进行相同反应，则得到Ni(II)(L(Ox))₂(THF)(FPF₅)·THF（4）（S = 1）的晶体。通过X射线晶体学对化合物1、2、3和4进行了结构表征：1和2分别包含一个四面体中性配合物和一个四面体单阳离子，而3包含五配位阳离子[Ni(II)(L(Ox))₂(FPF₅)]⁺以及一个弱配位的PF₆⁻阴离子，在4中存在六配位单阳离子[Ni(II)(L(Ox))₂(THF)(FPF₅)]⁺。通过循环伏安法和SQUID测量研究了1 - 4的电化学和磁化学性质。报告了所有化合物的紫外可见光谱和电子顺磁共振光谱数据。通过与相应锌配合物：[Zn(II)((t)L(Ox))₂]²⁺、[Zn(II)((t)L(Ox))((t)L*)]⁺、[Zn(II)((t)L*)₂]⁰和[Zn(II)((t)L*)((t)L(Red))]⁻（其中((t)L(Ox))₀代表中性配体1,4 - 二叔丁基 - 1,4 - 二氮杂 - 1,3 - 丁二烯，((t)L*)¹⁻和((t)L(Red))²⁻是相应的单电子和双电子还原形式）的破缺对称性密度泛函理论计算，证实了实验结果。明确确定顺磁性单阳离子[Ni(I)(L(Ox))₂]⁺（S = 1/2）和[Zn(II)((t)L(Ox))((t)(L*)]⁺（S = 1/2）的电子结构是不同的。
