Bond Alan M., Colton Ray, Gable Robert W., Mackay Maureen F., Walter Jacky N.
School of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia.
Inorg Chem. 1997 Mar 12;36(6):1181-1193. doi: 10.1021/ic961295d.
Reaction of Mn(CO)(5)X (X = Cl, Br) with Ph(2)P(CH(2))(2)P(Ph)(CH(2))(2)PPh(2) (P(2)P') in refluxing xylene led to the formation of isomerically pure cis,mer-Mn(CO)(2)(eta(3)-P(2)P')X. Cyclic voltammograms in dichloromethane (0.1 M Bu(4)NPF(6)) show a reversible one-electron oxidation (process 1, E(1/2) = 0.142 V) to give cis,mer-Mn(CO)(2)(P(2)P')X. However, in acetone (0.1 M Bu(4)NPF(6)) at room temperature, process 1 is not reversible and an additional redox process 4 (E(1/2) = 0.048 V) is observed. Process 4 is not observed at low temperatures, and at higher temperatures in acetone it merges with process 1 and also a new reversible redox couple (process 5, E(1/2) = -0.411 V) appears. A combination of electrolyses, chemical oxidation, and subsequent reduction, coupled with IR and (31)P NMR spectroscopies and electrospray mass spectrometry (ESMS), is used to show that processes 1, 4, and 5 are all associated with redox and interconversion reactions of different isomers of Mn(CO)(2)(P(2)P')X and Mn(CO)(2)(P(2)P')X. Other irreversible processes due to oxidation of the different isomers of Mn(CO)(2)(P(2)P')X are observed at very positive potentials. Reaction between Re(CO)(5)X and P(2)P' in refluxing mesitylene gives a soluble product and a small amount of precipitate. The major soluble product was identified as cis,mer-Re(CO)(2)(P(2)P')X, and the oxidative chemistry is similar to that of the manganese analogues. The precipitate consists of five compounds, one of which was cis,mer-Re(CO)(2)(P(2)P')X. The new compounds A-D were identified as follows: A is cis,mer-{Re(CO)(2)(P(2)P')X}(2), a dimeric species with bridging P(2)P' ligands. The spectroscopic data for B indicated that it was a form of cis,mer-Re(CO)(2)(P(2)P')X, but not the same as the major product. Compound C is cis,fac-Re(CO)(2)(P(2)P')X, and compound D was shown to be fac-[Re(CO)(3)(P(2)P')]X. The crystal structures of cis,mer-Re(CO)(2)(P(2)P')Cl(I) and cis,mer-Re(CO)(2)(P(2)P')Cl(II) show the compounds to be diastereoisomers with the same mer geometry of the P(2)P' ligand, which of necessity generates a cavity formed by three phenyl rings on one side of the rhenium atom. The coordination geometry of the two compounds differ only by the interchange of the mutually trans chloro and carbonyl ligands. In (I) the carbonyl ligand is within the cavity and in (II) the chloro ligand is within the cavity.
Mn(CO)(5)X（X = Cl、Br）与Ph(2)P(CH(2))(2)P(Ph)(CH(2))(2)PPh(2)（P(2)P'）在回流的二甲苯中反应，生成了异构体纯的顺式、反式-Mn(CO)(2)(η(3)-P(2)P')X。在二氯甲烷（0.1 M Bu(4)NPF(6)）中的循环伏安图显示有一个可逆的单电子氧化过程（过程1，E(1/2) = 0.142 V），生成顺式、反式-Mn(CO)(2)(P(2)P')X。然而，在室温下的丙酮（0.1 M Bu(4)NPF(6)）中，过程1不可逆，并且观察到一个额外的氧化还原过程4（E(1/2) = 0.048 V）。在低温下未观察到过程4，在丙酮中较高温度时它与过程1合并，并且还出现一个新的可逆氧化还原对（过程5，E(1/2) = -0.411 V）。通过电解、化学氧化及随后的还原，结合红外光谱、(31)P核磁共振光谱和电喷雾质谱（ESMS），表明过程1、4和5都与Mn(CO)(2)(P(2)P')X和Mn(CO)(2)(P(2)P')X不同异构体的氧化还原和相互转化反应有关。在非常正的电位下观察到由于Mn(CO)(2)(P(2)P')X不同异构体的氧化导致的其他不可逆过程。Re(CO)(5)X与P(2)P'在回流的均三甲苯中反应得到一种可溶产物和少量沉淀。主要的可溶产物被鉴定为顺式、反式-Re(CO)(2)(P(2)P')X，其氧化化学性质与锰类似物的相似。沉淀由五种化合物组成，其中一种是顺式、反式-Re(CO)(2)(P(2)P')X。新化合物A - D的鉴定如下：A是顺式、反式-{Re(CO)(2)(P(2)P')X}(2)，一种具有桥连P(2)P'配体的二聚体物种。B的光谱数据表明它是顺式、反式-Re(CO)(2)(P(2)P')X的一种形式，但与主要产物不同。化合物C是顺式、面式-Re(CO)(2)(P(2)P')X，化合物D被证明是面式-[Re(CO)(3)(P(2)P')]X。顺式、反式-Re(CO)(2)(P(2)P')Cl(I)和顺式、反式-Re(CO)(2)(P(2)P')Cl(II)的晶体结构表明这些化合物是具有相同P(2)P'配体反式几何构型的非对映异构体，这必然在铼原子一侧形成一个由三个苯环构成的空腔。这两种化合物的配位几何构型仅因相互反位的氯和羰基配体的互换而不同。在(I)中羰基配体在空腔内，在(II)中氯配体在空腔内。
