The reaction of [WO2(CN)4]4â with a series of dimethylamino- or thione-protected asymmetric dithiolenes (ene-1,2-dithiolates) has been used to synthesise [WO(dithiolene)2]2â complexes (dithiolene = âSC(H)C(R)Sâ, R = phenyl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl or quinoxalin-2-yl), which have been characterised by elemental analysis, spectroscopy and electrochemistry. The prototypical compound [PPh4]2[WO(sdt)2]·EtOH [sdt = styrenedithiolate, âSC(H)C(Ph)Sâ], crystallises in space group P21/c with a = 13.242(4), b = 31.894(8), c = 14.589(5) Ã
, β = 113.80(2)°, and Z = 4. The WOS4 moiety is square-based pyramidal with the O atom at the apex [WO 1.724(7) Ã
, WâSav 2.37 Ã
, OâWâSav 108.7°] and contains a cis geometry of the phenyl groups, although 1H NMR studies indicate that both cis and trans isomers are present in the isolated solid. The physical properties of all of the [WO(dithiolene)2]2â complexes are consistent with a retention of the WIVOS4 centre and each system undergoes a reversible electrochemical one-electron oxidation to the corresponding WV system. The variation in the dithiolene 1H NMR resonances, ν(WO) and ν(CC) (dithiolene) IR stretching frequencies, and the E½ values for the WVâWIV couple can be rationalised by a consideration of the nature of the aryl substituent. These data are compared to those of the analogous MoIV complexes and to those of the catalytic centres of the tungstoenzymes and their oxomolybdoenzyme counterparts.
[WO2(CN)4]4-与一系列
二甲氨基或
硫酮保护的不对称二
硫醇(
烯-1,2-二
硫醇)的反应已用于合成[WO(二
硫醇)2]2-配合物(二
硫烯=-SC(H)C(R)S-,R=
苯基,
吡啶-2-基,
吡啶-3-基,
吡啶-4-基或
喹喔啉-2-基),其中通过元素分析、光谱学和电
化学对其进行了表征。典型化合物 [PPh4]2[WO(sdt)2]·EtOH [sdt=二
硫代
苯乙烯, -SC(H)C(Ph)S-],在空间群 P21/c 中结晶,a = 13.242(4)、b=31.894(8)、c=14.589(5) ×、β=113.80(2)°和 Z=4。W
OS4 部分是带有 O 原子的方形锥体位于顶点 [WO 1.724(7) �, W�Sav 2.37�, O�W�Sav 108.7°] 并包含
苯基的顺式几何结构,尽管 1H NMR 研究表明顺式和反式异构体存在于分离的固体中。所有[WO(二
硫烯)2]2-配合物的物理性质与WIV
OS4中心的保留一致,并且每个系统都经历可逆的电
化学单电子
氧化至相应的WV系统。二
硫醇 1H NMR 共振、δ(WO) 和 δ(CC)(二
硫醇)IR 伸缩频率以及 WV-WIV 电对的 E 值的变化可以通过考虑芳基取代基的性质来合理化。将这些数据与类似的 MoIV 复合物的数据以及
钨酶及其
氧化钼酶对应物的催化中心的数据进行比较。