Tp
Me2Ir(C
2H
4)
2 (
1; Tp
Me2 = hydrotris(3,5-dimethylpyrazolyl)borate) reacts with 1 equiv ofMeO
2CC
CCO
2Me (DMAD) at 25
C, via the intermediacy of the known Ir(I) adductTp
Me2Ir(C
2H
4)(DMAD) (
2), with formation of the bis(alkenyl) derivative Tp
Me2Ir(
cis-C(R)=C(R)H)(CH=CH
2)(C
2H
4) (
3; R = CO
2Me) in ca
. 50% yield. Complex
3 slowly evolves to another alkenyl species,
TpMe2Ir(cis-C(R)=C(R)H)(CH2CH2CH=CH2) (
4), which exists as a mixture of two stereoisomers.Interestingly, complex
2 reacts with the hard Lewis base NCMe at -20
C, giving the Ir(I) adduct Tp
Me2Ir(DMAD)(NCMe) (
5) the first Ir(I) compound of the Tp
Me2Ir system with a hard ligand. The Ir-NCMebond in
5 is labile, and the acetonitrile is easily interchanged by CO, C
2H
4, and the alkynes HC
CCO
2Me (MP) and DMAD. While with CO the reaction stops at the substitution stage with formation ofTp
Me2Ir(DMAD)(CO) (
8), with C
2H
4 it gives complex
4 or the bis(alkenyl) species Tp
Me2Ir(
cis-C(R)=C(R)H)(CH=CH
2)(NCMe) (
9), depending on the concentration of NCMe in the reaction medium.With MP the known iridacyclopentadiene
TpMe2Ir(C(R)=C(H)C(R)=C(R))(NCMe) (
10) and thesymmetrical iridacycloheptatriene
TpMe2Ir(C(R)=C(H)C(R)=C(R)C(H)=C(R)(NCMe) (
11) can beobtained, while related iridacycles are formed with DMAD. Finally an iridapyrrole with the composition
TpMe2Ir(Cl)(C(R)=C(R)C(Me)=NH) (
6) is the unexpected result of heating complex
5 in a CH
2Cl
2-NCMe mixture at 120
C. All of the new compounds reported have been characterized by microanalysisand IR and NMR spectroscopy and, in addition, complexes
4 and
6 have been characterized by single-crystal X-ray studies.