Chemistry of the metal carbonyls. Part LXVIII. Complexes of manganese, iron, and ruthenium containing the cyclic carbene 2-oxacyclopentylidene

Addition of [Mn(CO)5]– to an excess of 4-chlorobutyryl chloride affords [Mn(COCH2·CH2·CH2Cl)(CO)5](I), which reacts with [Mn(CO)5]– or I– to afford respectively the carbene complexes [Mn(X)[graphic omitted]H2(CO)4][X = Mn(CO)5 or I]. Thermal decacarbonylation of (I) gives [Mn(CH2·CH2·CH2Cl)(CO)5](II), which rapidly reacts with lithium iodide to give cis-[Mn(I)([graphic omitted]H2)(CO)4]. Treatment of (II) with the ligands L [L = P(OCH2)3CMe, P(OMe)3, PMe2Ph, P(OMe)2Ph, or AsMe2Ph] gives cis-[Mn(COCH2·CH2·CH2·Cl)(CO)4L], which cyclise on treatment with AgBF4 to give the cationic carbene complexes cis-[Mn[graphic omitted]H2(CO)4L]+. Thermal decarbonylation of cis-[Mn(COCH2·CH2·CH2Cl)(CO)4{P(OCH2)3CMe}] gives cis-[Mn(CH2·CH2CH2Cl)(CO)4{P(OCH2)3CMe}] which forms the carbene complex fac-[Mn(I)[graphic omitted]H2(CO)3{P(OCH2)3CMe}] with lithium iodide. The corresponding reaction, starting with 5-chlorovaleryl chloride, affords only a low yield of the 2-oxacyclohexylidene complex cis-[Mn(I)[graphic omitted]H2(CO)4]. The formation of the cationic carbene complexes [M[graphic omitted]H2(CO)2(π-C5H5)]+(M = Fe or Ru) is also described.