By manganese carbonyl

The disproportionation of manganese carbonyl with nitrogen ligands is reviewed by Hieber et al. (122). Calderazzo has investigated the catalytic carbonylation of amines by manganese carbonyl (30). The corresponding chemistry of rhenium carbonyl remains to be investigated. 

Another reaction of type 3 is the formation of sym-dialkylureas from primary amines and CO catalyzed by manganese carbonyl complexes ... 

Friestad, G.K. and Qin, J., Intermolecular alkyl radical addition to chiral N-acylhydrazones mediated by manganese carbonyl,/. Am. Chem. Soc., 123, 9922, 2001. 

Methylcyclopentadienyl manganese tricarbonyl that has been suggested as a fuel additive is decomposed primarily by photolysis in aqueous medium. This resulted in the formation of methylcyclopentadiene that may plausibly be presumed to polymerize, and a manganese carbonyl that decomposed to Mn304 (Garrison et al. 1995). 

Group VIIA (Mn, Tc. Re). A number of mononuclear manganese carbonyl derivatives have been y- irradiated and examined by e.s.r. spectroscopy. The motivation behind much of this effort was the search for the elusive radical Mn(CO)s. The e.s.r. spectrum of this species is now firmly (35-37) established (Figure 4), although there is still some suggestion that the true "naked Mn(CO)s has yet to be observed (37). 

When propylene chemisorbs to form this symmetric allylic species, the double-bond frequency occurs at 1545 cm-1, a value 107 cm-1 lower than that found for gaseous propylene hence, by the usual criteria, the propylene is 7r-bonded to the surface. For such a surface ir-allyl there should be gross similarities to known ir-allyl complexes of transition metals. Data for allyl complexes of manganese carbonyls (SI) show that for the cr-allyl species the double-bond frequency occurs at about 1620 cm-1 formation of the x-allyl species causes a much larger double-bond frequency shift to 1505 cm-1. The shift observed for adsorbed propylene is far too large to involve a simple o--complex, but is somewhat less than that observed for transition metal r-allyls. Since simple -complexes show a correlation of bond strength to double-bond frequency shift, it seems reasonable to suppose that the smaller shift observed for surface x-allyls implies a weaker bonding than that found for transition metal complexes. 

Herrmann and coworkers183 reported a series of Cp-manganese carbonyl complexes which bind Ge, Sn and Pb as central atoms linearly coordinated in clusters, to two Mn atoms in one series and trigonal-planar coordinated to three Mn atoms in another series 8 and 9. The group 14 atoms are double-bonded to two Mn atoms in these compounds, or carry one double bond and two single bonds to three Mn atoms. Potentiometric measurements of these compounds show irreversible reductions and oxidation by CV. No products could be isolated from either reduction or oxidation. The exceptionally high oxidation potential of (/i-Pb) r/ -CsHs )Mn(CO)2]2 as compared to the apparently similar Sn compound is noteworthy (Table 15). 

W. D. Good, D. M. Fairbrother, G. Waddington. Manganese Carbonyl Heat of Formation by Rotating-Bomb Calorimetry. J. Phys. Chem. 1958, 62, 853-856. 

Nano-sized manganese-carbonyl subspecies on MCM-41 have been prepared by impregnation of Mn2(CO)io under UV irradiation followed by an ultrasound treatment. From XANFS characterization, the formation of highly dispersed species with a formal oxidation state of -t-2.2 is proposed. These systems could be used as nanometric reactors [23]. 

Synthetically especially valuable is the oxidation of carbonyl compounds and nitroalkanes by manganese(III) salts to form carboxymethyl and nitromethyl radicals, respectively. These radicals can be trapped by olefins like 1,3-butadiene or aromatic compounds to yield synthetically interesting products. In this case it is very advantageous to generate and regenerate the oxidizing species in situ by indirect electrolysis. This was the basis for the development of a process for the synthesis of sorbic acid viay-vinyl-y-butyrolactone Equations (31)—(35) summarize the im-... 

Bromopentacarbonylmanganese, Mn(CO)5Br (1). This yellow metal carbonyl halide is obtained in 73% yield by reaction of manganese carbonyl with Br2 in CC14 at 40°.1... 

Manganese KJ) compounds are exemplilied by the carbonyls discussed below. 

One-electron oxidation systems can also generate radical species in non-chain processes. The manganese(III)-induced oxidation of C-H bonds of enolizable carbonyl compounds [74], which leads to the generation of electrophilic radicals, has found some applications in multicomponent reactions involving carbon monoxide. In the first transformation given in Scheme 6.49, a one-electron oxidation of ethyl acetoacetate by manganese triacetate, yields a radical, which then consecutively adds to 1-decene and CO to form an acyl radical [75]. The subsequent one-electron oxidation of an acyl radical to an acyl cation leads to a carboxylic acid. The formation of a y-lactone is due to the further oxidation of a carboxylic acid having an active C-H bond. As shown in the second equation, alkynes can also be used as substrates for similar three-component reactions, in which further oxidation is not observed [76]. 

Evidence on the probable mechanism of the carbonyl insertion in Eq. (19) or Eq. (20) has come from a study of manganese carbonyls. It had previously been established by 14C labeling that in the equilibrium... 

Under a nitrogen atmosphere 85 % phosphoric acid is added to the green solution, which changes first to purple subsequently the product precipitates as an orange-red solid. It is separated by filtration, washed with water until the washings are neutral, and dried in vacuo. Any unreacted manganese carbonyl may be removed by sublimation under reduced pressure at room temperature (1 mm./20°C.). The pure compound is then obtained as deep orange-red crystals by sublimation (1 mm./ 60°C.). The yield is 0.3-0.35 g. (64-74%). Anal. Found C, 28.6 H, 0.79 O, 37.7 Mn, 32.1. Calcd. for H Mn,(CO)12 C, 28.60 H, 0.56 O, 38.10 Mn, 32.70. 

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