Aromaticity and Unsaturation of Metalladichalcogenolene Rings

[CpCo(S_2C_2X， Y)]型配合物中的金属二羟基丁香烯环是一种独特的共轭金属螯合环，具有芳香性和不饱和性。芳香性是亲电或自由基机制中取代反应的根源，而环的不饱和性质引起加成反应。本研究的目的是阐明准芳香共轭金属螯合环的独特特征。在这项工作中，我们观察到以下有趣的结果。(1)芳香性引起的反应：[CpCo(S_2C_2Ph， H)](1)与AIBN的反应导致钴二噻吩环或Cp环上的氢被1-氰基-1-甲基乙基取代。通常情况下，钴二噻吩环对自由基取代反应性更强。然而，14族元素氢化物的加入促进了Cp环(3)的反应，抑制了钴二硫烯环(2)的反应。Cp环的区域选择性（比3:2）为：Bu_3SnH (100: 0)>Bu_3GeH (75: 25)>Bu_3SiH (36: 64)>Bu_4Sn(32: 68)>无添加剂（19:81）。在苯回流条件下，钴二噻吩配合物[CpCo(S_2C_2Ph， H)]与双（苯[d]-1,3-噻唑-2-酰基）二硫化物的反应中，钴二噻吩环选择性地发生了以硫为中心的自由基取代，在乙腈回流条件下，也观察到以氮为中心的自由基或离子的产物。(2)不饱和反应：叠氮化物与[CpCo(S_2C_2Z_2)]（Z= coom）反应，在Co和Co之间形成酰亚胺桥接配合物（2组分加合物），2个等量的PPh_3与对烷基磺酰亚胺桥接配合物的反应是烷基烷桥接配合物所没有的。PPh_3与Co在室温下配位，Co- n键被劈裂，得到一个三组分加合物（ylide complex）。在苯中80℃加热后，磺酰氨基基从S环迁移到Cp环。此外，过量的PPh_3与氨基桥接配合物反应时，NTs和PPh_3基团从钴二噻吩环向Cp环发生了双重迁移。芳香性和不饱和的共存是这种准芳香环独特的反应活性或电化学行为的根源。少

The metalladichalcogenolene rings in [CpCo(S_2C_2X, Y)]-type complexes are very unique conjugated metal chelate rings which exhibit both aromaticity and unsaturation. Aromaticity is the origin of substitution reactions in electrophilic or radical mechanism, while the unsaturated character of the ring causes addition reactions. The purpose of this study is to elucidate the unique features of quasi-aromatic conjugated metal chelate rings. In this work, we observed the following interesting results.(1) Reactions due to aromaticity : The reaction of [CpCo(S_2C_2Ph, H)](1) with AIBN brings about the substitution of hydrogens with 1-cyano-1-methylethyl group either in the cobaltadithiolene ring or in the Cp ring. Normally the cobaltadithiolene ring is more reactive for the radical substitution. However, the addition of group 14 element hydride compounds promotes the reaction in the Cp ring (3) and inhibits the reaction in the cobaltadithiolene ring (2). The regio-selectivity (ratio/3 : 2) fo … More r the substitution in Cp ring changed in order of Bu_3SnH (100 : 0)>Bu_3GeH (75 : 25)>Bu_3SiH (36 : 64)>Bu_4Sn (32 : 68)>no additive (19 : 81).In the reaction of the cobaltadithiolene complex [CpCo(S_2C_2Ph, H)] with bis (benzo[d]-1,3-thiazol-2-yl) disulfide under refluxing in benzene, substitutions by sulfur-centered radicals occured selectively in the cobaltadithiolene ring and in that under refluxing in acetonitrile, the product by nitrogen-centered radicals or ions was also observed.(2) Reactions due to unsaturation : Azides react with [CpCo(S_2C_2Z_2)](Z=COOMe) to form imido-bridged complexes (2-component adducts) between Co and S.The reaction of 2 equivalents of PPh_3 with the p-tolylsulfonylimido-bridged complex showed an interesting reaction which is not observed for the alkylidene-bridged complex. The coordination of PPh_3 with Co at room temperature causes the Co-N bond cleavaged to give an ylide complex (3-component adduct). Upon heating at 80℃ in benzene, the sulfonylimido group migrates from S to the Cp ring. Further, the double migration of the NTs and PPh_3 groups to tha Cp ring from the cobaltadithiolene ring occured in the reaction of excess PPh_3 with the imido-bridged complex.The coexistence of aromaticity and unsaturation is the origin of unique reactivities or electrochemical behavior of this quasi-aromatic ring. Less