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Item Thermal reactions of perfluoromethyl and perfluoroacetyl manganese pentacarbonyls. Part 2.—Initiation of free-radical polymerization and formation of methyl(2-methyl 4-oxo-5,5,5-trifluoropentanoate)(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (07), 1978) Bamford, Clement H.; Mullik, Sanam U.This paper continues the study of the thermal reactions of low-molecular-weight analogues of macroinitiators carrying terminal Mn(CO)5 groups e.g. [graphic omitted]CF2 CF2 Mn(CO)5. The reactions of CF3Mn(CO)5 and CF3COMn(CO)5 in methylmethacrylate solution at 100°C have been examined. Both derivatives initiate free-radical polymerization; retardation is less marked than with the unfluorinated analogues, especially in the case of CF3Mn(CO)5. Rates of polymerization ω are increased by the presence of “halide” and “non-halide” type additives; with CF3Mn(CO)5 the increase corresponds to a factor of 2 in the rate of initiation. The dependence of ω on [CCl4] is very sharp and a plateau value is reached for [CCl4] > 5 × 10–3 mol dm–3. The reaction of CF3COMn(CO)5 yields methyl(2-methyl-4-oxo-5,5,5-trifluoropentanoate), CF3COCH2CH(CH3)COOCH3. Reaction in the presence of D2O yields CF3COCH2CD(CH3)COOCH3, indicating that the mechanism is of a polar type involving intramolecular attack by a CF3CO anion on a coordinated monomer molecule, with subsequent acquisition of a proton from water present in trace quantities. No corresponding reaction with CF3Mn(CO)5 has been observed under similar conditions. On heating these derivatives in methyl methacrylate at 100°C a peak with λmax= 342 nm slowly develops in the u.v.-visible spectrum and represents the formation of Mn2(CO)10. In the presence of added water a peak near 385 nm appears, attributable to Mn(CO)5OH. The bearing of these results on the use of macroinitiators for block-copolymer synthesis is discussed.Item Thermal reactions of methyl and acetyl manganese pentacarbonyls. Part 1.—Initiation of free-radical polymerization and formation of methyl(2-methyl 4-oxopentanoate)(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (07), 1978) Bamford, Clement H.; Mullik, Sanam U.The manganese pentacarbonyl derivatives CH3Mn(CO)5 and CH3COMn(CO)5 are low-molecular-weight analogues of macroinitiators which carry terminal Mn(CO)5 groups and their thermal reactions in methyl methacrylate at 100°C have been studied from this aspect. Under these conditions isomerization reactions are rapid and the two compounds behave similarly. The derivatives initiate free-radical polymerization above 60°C but give rise to marked retardation except at very low concentrations. The rate of polymerization ω is increased by the presence of “halide” or “non-halide” additives and at the same time retardation is greatly reduced. The dependence of ω upon additive concentration is of the familiar form showing a plateau value at high concentrations. The rate of polymerization is depressed by the presence of carbon monoxide. However, initiation of polymerization is only a minor component of the overall reaction at 100°C, the major process (∼90%) being formation of methyl(2-methyl 4-oxopentanoate), CH3COCH2CH (CH3)COOCH3. This reaction follows a non-radical route. A mechanism is suggested involving intramolecular interaction between an acetyl anion and the coordinated monomer (M) in CH3COMn(CO)4M; the process is completed by proton transfer from water present in the system in trace quantities. This mechanism is strongly supported by investigations with D2O. Spectral (u.v.-visible) changes accompanying these transformations are recorded. Thermal decomposition of CH3Mn(CO)5 and CH3COMn(CO)5 in benzene yields Mn2(CO)10; in methyl methacrylate an additional peak develops at 385 nm which we attribute to Mn(CO)5OH. This peak is not much affected by the presence of CCl4 or CO.