Manganese complexes diols

In other examples, compounds in which a metal atom is already coordinated in a molecule can be used as a comonomer in an addition polymerization. Two examples involve the ferrocenes discussed in Chapter 6. The vinyl ferrocene molecule is shown in 7.14, and a similar vinyl manganese complex in 7.15.30 An alternative approach involves condensation polymerization. For example, if the R group in the ferrocene unit shown in 7.16 contains a hydroxyl group, it can be copolymerized with a diacid chloride. If it is an acid chloride, it can be copolymerized with a diamine. (This type of polymer is called a heteroannular chain if only one of the rings in the repeat unit is in the backbone, the polymer is called homoannular.)7 Similarly, the titanium complex shown in 7.17 is copolymerized with diacids or diols.30 Numerous other examples involving ferrocenes are discussed in Chapter 6. 

Manganese An asymmetric c -dihydroxylation of electron-deficient alkenes with oxone, catalysed by a manganese complex bearing a chiral tetradentate N4-donor ligand (2-5 mol%), has been developed the resulting diols were of <96% ee. Analysis of the reaction mixture by high-resolution ESI-MS revealed the formation of a cis-dioxomanganese(V) intermediate. ... 

Manganese(iii) was detected spectrophotometrically as a short-lived intermediate in the oxidation of cw-but-2-ene-l,4-diol (CBD). Addition of pyrophosphate traps Mn ii by forming the stable pyrophosphatomanganate(ra) complex. In the presence of this reagent, the rate of oxidation may be described by... 

More recently, the use of glyoxylic acid methyl ester hemiacetal as a cocatalyst was shown to afford an even more effective epoxidation catalyst, enabling high conversions with only a 30% excess of hydrogen peroxide. Interestingly, the corresponding cfs-diols were observed as by-products in many cases and a concerted mechanism via a manganese(III)-cfs-diol complex was proposed to explain their formation. 

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