Manganese carbonyl dimer

Dimeric iron or manganese carbonyl complexes such as [CpFe(C02)]2 and Mn2(CO)io, respectively, upon irradiation photocatalytically cleave carbon-halogen bonds. This leads to carbon-centered radicals which can be reduced to hydro-... 

The reaction of metal carbonyl dimers with silicon hydrides also probably involves an initial oxidative addition step. Chiral silyl-cobalt and silyl-manganese carbonyl complexes have been obtained through the reaction of optically active organosilicon hydrides with metal carbonyls65 68 (equation 15 and 16). Phosphine-substituted cobalt complexes were similarly obtained by reaction of a chiral hydrosilane with Co2(CO)6L2 [L = PPh3, P(OPh)3, P(c-C6Hn)3]69. 

Use the 18-electron rule to rationalize why manganese carbonyl forms a dimer Mn2(CO)io containing an Mn-Mn bond, rather than a monomer Mn(CO)5. 

Ruthenium.— The oxidative addition of quinones to d and to metal centres is well documented. Now the oxidative addition of u-quinones to the d complex RuCl2(PPh3)3 has been reported. The reactions of ruthenium and iron cyclopentadienyl carbonyl dimers with azobenzene are described later (see manganese and rhenium). 

The 77-cyclopentadienyliron dicarbonyl dimer and the mixed metal carbonyl 7r-cyclopentadienyliron-manganese heptacarbonyl are protonated by strong acids to form isolatable salts, namely [CpFe(CO)2]2H +PF6 and [CpFeMn(CO)7H]+PF6 . The ruthenium dimer [CpRu(CO)2]2 behaves similarly, although no salt was isolated (63). 

It is also claimed that nitric oxide reacts in DMSO with [Mn(salen)] to yield [Mnni(salen)0]202.427 This is surprising, as an ethanolic solution of manganese(II) acetate and salenH2 is claimed to react with NO to yield [MnlII(salen)(OAc)].38 On the other hand, it has been claimed that [Mnm(salen)-CO]C104, a dimer with bridging carbonyls, can be isolated from the interaction of [Mn(salen)-(H20)2] with oxygen in 50/50 MeOH/EtOH in the presence of ClOf and NaOH.428... 

In light of the above results it is interesting to note that the reaction of diphenylcyclo-propenone dimer spirolactone with ironenneacarbonyl yields a mixture of ring-opened vinyl carbene and -vinylketene complexes, and these interconvert under addition (or removal) of CO (equation 225) . A possible pathwav to vinylketene Fe-complexes, prepared earlier from cyclopropenes and ironcarbonyls " , may thus involve initial f -coordination, followed by ring cleavage to vinyl carbene and finally carbonylation to the ketene iron // -complexes. An analogous // -manganese complex is prepared similarly by the reaction of CpMn(CO),THF with 3,3-dimethylcyclopropene complex (equation 226) . ... 

---