The 2,3-dimethylbutadiene complex Tp
Me2Ir(CH
2=C(Me)C(Me)=CH
2) (
1) reacts with PhC
CPh, inC
6H
12 at 60
C, with coupling of the diene and the alkyne and formation of compound
2a, which containsan elaborated bicyclic chelating ligand with alkyl and
3-allyl functionalities. NCMe reacts reversiblywith
2a, giving rise to a mixture of the isomeric iridacyclopentenes
TpMe2Ir(CH2C(Me)(CMe=CH2)C(Ph)=C(Ph))(NCMe) (
3) and
TpMe2Ir(CH2C(Me)(cis-CPh=CHPh)C(Me)=CH)(NCMe) (
4). Complex
2adecomposes in C
6H
12 at 80
C to give a complex mixture from which an interesting substituted iridafulvene,
5, has been isolated by chromatography. All these compounds have been characterized by NMRspectroscopy and X-ray crystallography. Possible reaction mechanisms for the formation of these speciesare discussed.