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

Abstract

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.