Manganese complexes diketones

Epoxidation of olefins was catalyzed by the ruthenium(II) complex of the above perfluorinated y3-diketone in the presence of 2-methylpropanal (Scheme 50). Unfunctionalized olefins were epoxidized with a cobalt-containing porphyrin complex, and epoxidation of styrene derivatives was catalyzed by chiral salen manganese complexes (248) (Scheme 50). In the latter case, chemical yields were generally high, however, the products showed low enantiomeric excess with the exception of indene (92% ee). [Pd(C7Fi5COCHCOC7Fi5)2] efficiently catalyzed the oxidation of terminal olefins to methyl ketones with f-butylhydroperoxide as oxidant in a benzene-bromoperfluoro-octane solvent system (Scheme 50). In all these reactions, the product isolation and efficient catalyst recycle was achieved by a simple phase separation. 

It is quite often possible to prepare hydroxypyridinone complexes directly by one-pot synthesis from the appropriate hydroxypyranone, amine, and metal salt 90-92). They can also be prepared by reacting complexes such as P-diketonates with hydroxypyridinones (see e.g., Ce, Mo later). Several maltolate complexes, of stoichiometry ML2, ML3, ML4, or MOL2, have been prepared by electrochemical oxidation of the appropriate metal anode, M — a first-row d-block metal (Ti, V, Cr, Mn, Fe, Co, Ni), In, Zr, or Hf, in a solution of maltol in organic solvent mixtures 92). Preparations of, e.g., manganese(III), vanadium(III), or vanadium(V) complexes generally involve oxidation... 

Another type of polynuclear complex has been developed by Lukehart and his students.15 Starting with manganese pentacarbonyl, for example, they have prepared complexes of the type (5). Formally, these resemble the complexes of 1,2-diketones and, indeed, they have some of the properties of those substances. 

There are now numerous, metal-linked oligomeric (and polymeric) systems that fall into this category. For example, the acetylacetonates of manganese(II), nickel(II) and zinc(II) have long been known to be trimeric while the cobalt(II) complex is tetrameric, with three (3-diketonate oxygen atoms bridging adjacent metal centres in a linear array in each case. Other more recent examples include systems built... 

It was found that octahedral iron(lll), manganese(III) or chromium(lll) ions produced mesomorphic complexes when complexed with three -diketonate ligands, presumably with the molecules associating as in Figure 88 [167],... 

Thermal decomposition of MMn(P-dik)3 starts with formation of Mn(p-dik)2 and M(p-dik) (P-dik = p-diketone). Introduction of CF3 groups into the ligand increases the thermal stability of these anionic chelates. Manganese(ii) complexes of polymeric p-diketones have been prepared. o)-Benzoyl-2-acetylfuran and o)-(2-theonyl)-... 

Cartoni et al. [88] studied perspective of the use as stationary phases of n-nonyl- -diketonates of metals such as beryllium (m.p. 53°C), aluminium (m.p. 40°C), nickel (m.p. 48°C) and zinc (liquid at room temperature). These stationary phases show selective retention of alcohols. The retention increases from tertiary to primary alcohols. Alcohols are retained strongly on the beryllium and zinc chelates, but the greatest retention occurs on the nickel chelate. The high retention is due to the fact that the alcohols produce complexes with jS-diketonates of the above metals. Similar results were obtained with the use of di-2-ethylhexyl phosphates with zirconium, cobalt and thorium as stationary phases [89]. 6i et al. [153] used optically active copper(II) complexes as stationary phases for the separation of a-hydroxycarboxylic acid ester enantiomers. Schurig and Weber [158] used manganese(ll)—bis (3-heptafiuorobutyryl-li -camphorate) as a selective stationary phase for the resolution of racemic cycUc ethers by complexation GC. Picker and Sievers [157] proposed lanthanide metal chelates as selective complexing sorbents for GC. Suspensions of complexes in the liquid phase can also be used as stationary phases. Pecsok and Vary [90], for example, showed that suspensions of metal phthalocyanines (e.g., of iron) in a silicone fluid are able to react with volatile ligands. They were used for the separation of hexane-cyclohexane-pentanone and pentane-water-methanol mixtures. 

Optically active manganese (III) complex, Cyclo-Salen-Mn (III)Cl, was prepared by the reported method and purified with column chromatography on silica-gel or washing its benzene solution with aqueous lithium chloride solution. Ph-P-diketone-... 

Both six- and five-coordinate species are involved in jS-diketone exchange reactions of manganese(III)-chloride-j3-diketone complexes. Kinetic data have been obtained in dichloromethane solution the starting complex contains five-coordinate manganese in this solvent, but six-coordinate in donor solvents. 

A preliminary report has appeared which demonstrates that the chloride ion has a substantial trans-labilizing effect in (tetraphenylpor-phinato)chromium(III) chloride, and the first kinetic study on substitution at five-coordinate manganese(III) [involving the reaction of chlorobis(/8-diketonato)Mn(III) complexes with other 3-diketones] has been published. ... 

Iron, manganese and chromium tris-)3-diketonate complexes... 

---