Manganese complexes, cation

The most important low-spin octahedral complex of Mn is the dark-red cyano complex, [Mn(CN)6] , which is produced when air is bubbled through an aqueous solution of Mn and CN . [MnXs] (X = F, Cl) are also known the chloro ion, at least when combined with the cation [bipyH2] +, is notable as an example of a square pyramidal manganese complex. 

The catalytic application of clays is related closely to their swelling properties. Appropriate swelling enables the reactant to enter the interlamellar region. The ion exchange is usually performed in aquatic media because the swelling of clays in organic solvents, and thus the expansion of the interlayer space, is limited and it makes it difficult for a bulky metal complex to penetrate between the layers. Nonaqueous intercalation of montmorillonite with a water-sensitive multinuclear manganese complex was achieved, however, with the use of nitromethane as solvent.139 The complex cation is intercalated parallel to the sheets. 

Chiral manganese complexes have been used to perform the enantioselective amidation of saturated C-H bonds.256-258,262 Cationic Mn(salen) 107 showed good catalytic activity and moderate enantioselectivity. Typical examples are shown in Equations (86)-(88). High enantioselectivity of 89% ee was obtained in the reaction of 1,1-dimethylindan (Equation (88)).258 Chiral manganese(m) porphyrin 106 was used in the enantioselective amidation as well nevertheless, the best enantioselectivity was only 54% (Equation (89)).256,257... 

Neutral (cyclohexadienyl)manganese complexes 71, generated by nucleophilic addition to (arene)Mn(CO)3+ cations 65, undergo ligand substitution with nitrosyl hexafluorophosphate to give the corresponding (cyclohexadienyl)Mn(CO)2NO+ cations 72 (Scheme 17)93. Attack by a wide variety of nucleophiles on cations 72... 

Photolysis of cationic alkoxycarbene iron complexes [193] or alkoxycarbene manganese complexes [194] has been used to replace carbonyl groups by other ligands. The alkylidene ligand can also be transferred from one complex to another by photolysis [195], Transfer of alkylidene ligands occurs particularly easily from diaminocarbene complexes, and has become a powerful synthetic method for the preparation of imidazoline-2-ylidene complexes [155,196]. 

Using this method, the electrophilic aromatic substitution of the electron-rich arylamine 578 by the molybdenum-complexed cation 577 affords regio- and stereoselectively the molybdenum complexes 579. Cyclization with concomitant aromatization and demetalation using activated manganese dioxide leads to the carbazole derivatives 568 (8,10,560) (Scheme 5.26). 

The synthesis of the Y zeolite-encapsulated manganese complex of the salen ligand has been reported recently [51]. It was found to have catalytic activity in the oxidation of cyclohexene, styrene, and stilbene with PhlO. Typically, 1 Mn(salen) is present per 15 supercages, resulting in catalytic turn-overs in the order of 60. The reactions investigated with the respective product yields are given in Scheme 5. Typical oxidation products are epoxides, alcohols and aldehydes. In comparison to the homogeneous case encapsulation seems to lower the reaction rate. From cyclohexene the expected oxidation product cyclohexene oxide is present in excess and is formed on the Mn(salen) site. 2-cyclohexene-l-ol is probably formed on residual Mn cations via a radical mechanism. 

Brunner has continued his studies on optically active manganese carbonyl complexes and has reported that treatment of Mn(CO)5Br with ort/to-Me2NC6H4PPh2 (PN) yields two enantiomers of/ac-[Mn(CO)3(PN)Br], Treatment of this complex with carbon monoxide in the presence of A1C13 produces the cation [Mn(CO)4(PN)] +, which was isolated as its hexafluorophosphated salt. Addition of menthoxide anions to the manganese carbonyl cation yields the diastereoisomers of Mn(CO)3(PN) (CO2C30H 9) however, these could not be separated due to their instability. Reaction of Mn(CO)5Br with the Schiff base NN (1) leads to formation of two isomers of... 

Photolysis of diethylthallium bromide in cyclohexane is a radical process involving cleavage of the thallium-carbon bond, which yields ethylcyclohexane and dicyclohexyl, as well as other products. Photoelectron transfer from benzyltributylstannanes to 10-methylacridinium ion results in cleavage of the metal-carbon bond, to give the corresponding benzyl radicals, rather than benzyl cations. Photochemical homolysis of Re- and Ru-alkyl bonds in Re(alkyl)-(CO)3(diimine) and Ru(I)(alkyl)(CO)2(diimine) complexes has been studied by Fourier transform ESR. In related manganese complexes, Mn(R)(CO)3(di-imine), elimination of CO is the predominant pathway when R = methyl, but Mn-alkyl homolysis occurs when R = benzyl. 

S.S. Kim, W. Zhang, and T.J. Pinnavaia, Catalytic Oxidation of Styrene by Manganese(II) Bipyridine Complex Cations Immobilized in Mesoporous Al-MCM-41. Catal. Lett., 1997, 43, 149-154. 

The cationic iron and manganese complexes 25 and 27 were similarly prepared by the reaction of the chloro- (24) or methoxy-substituted (26) cyclopropenylium ions with anionic carbon-ylferrate and manganate complexes. 

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