Formation of manganese enediyne complexes from manganese alkynylcarbene complexes

Abstract

Dimerization of the alkynylcarbene complex (C 5H 4Me)(CO) 2MnC(Tol)CCTol ( 10) occurred at 65 °C to give a mixture of E- and Z-enediyne complexes [(C 5H 4Me)(OC) 2Mn] 2[η 2,η 2-TolCC(Tol)CC(Tol)CCTol] ( 13). Thermolysis of alkynye complexes 10 at higher (100 °C) temperature led to the formation of manganese-free E- and Z-enediynes TolCC(Tol)CC(Tol)CCTol ( 14- E and 14- Z ). Attempted synthesis of the tethered bis-(alkynylcarbene) complex Cp(OC) 2MnC(Ph)CCCH 2CH 2CH 2CCC(Ph)Mn(CO) 2Cp led instead to the cyclic enediyne complex [Cp(OC) 2Mn] 2[η 2,η 2-PhCCC(CH 2CH 2CH 2)CCCPh] ( 19), from which the metal-free enediyne 1,2-bis(phenylethynyl)cyclopentene ( 20) was released by thermolysis at 90 °C.