Elements of the First Transitional Period

Carbonyl Compounds.—Irradiation studies on MnjCCO) have been reported by two groups. Photolysis of the carbonyl (A = 350 nm) in THF yields the paramagnetic species Mn(CO)5, identified by e.s.r. methods. The radical reacts with iodine to give Mn(CO)jI and reverts to MOjCCOl j, on storage. An e.s.r. study of y-irradiated Mn2(CO)io and Mn(CO)jBr at 77 K has led to the identification of the corresponding radical anions. The unpaired electrons are largely confined to Mn—Mn and Mn—Br a-orbitals, respectively.  

Danzer, and R. Hofer, Angew. Chem. Internat. Edn., 1973,12, 77. 

The reaction of Mn(CO)5Br with methyl isocyanide in THF has been studied under a variety of conditions. Treatment at room temperature for 48 h yields [Mn(CO)3(CNMe)2Br], refluxing for 6 h yields [Mn(CO)2(CNMe)3Br] and refluxing for 24 h gives a mixture of [Mn(CO)2(CNMe)3Br], [Mn(CO)-(CNMe)4Br], and [Mn(CO)(CNMe)g]Br. The monosubstituted product, [Mn(CO)4(CNMe)Br] is obtained from a reaction between Mn2(CO)gBr2 and CNMe and the series of cationic complexes [Mn(CO)e- c(CNMe)J from treatment of [Mn(CO)5 (CNMe) Br] with aluminium trichloride and CO(x = 1—4). The reactions of Mn(CO)sX (X = Q or Br) and CNPh in THF have been reinvestigated as part of this study. The product distribution is again found to depend on the conditions employed and the compound previously reported 

The preparation of the anion, [H2Mn3(CO) 2l as been reported. The reaction of Mn(CO)5Cl with 8-aminoquinoline, 7-azaindole, and pyrido[2,3-6]-pyrazine, all of which have structural features of adenine, yields complexes of the type [Mn(CO)3L2Cl]. The di-imine complex, trans-N2H2[(7r-Cp)Mn-( 0)2]2 has also been prepared.  

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