The Ir(I)-butadiene complex Tp
Me2Ir(
4-CH
2=C(Me)C(Me)=CH
2) (
1) (Tp
Me2 = hydrotris(3,5-dimethylpyrazolyl)borate) reacts with
3 equiv of DMAD (RC
CR, R = CO
2Me) in CH
2Cl
2 at 60
C,in the presence of adventitious water, with formation of the iridacycloheptatriene
TpMe2Ir(C(R)=C(R)C(R)=C(R)C(R)=C(R))(H2O) (
2), by the oxidative coupling of three molecules of DMAD in the metalcoordination sphere. In a related process, Tp
Me2IrPh
2(N
2) (
4) gives two benzoannelated iridacycloheptatrienes, the symmetrical species
TpMe2Ir(C(R)=C(R)-o-C6H4C(R)=C(R))(H2O) (
5) and the unsymmetricalone
TpMe2Ir(C(R)=C(R)C(R)=C(R)-o-C6H4)(H2O) (
6). The water ligand in these complexes is labile,and derivatives substituted with CO, PMe
3, and NCMe have been obtained.
2,
5, and
6 react, at 25
C,with oxo-transfer oxidizing reagents such as
tBuOOH with formation of the keto-metallabicyclic products
7-
9, which result from the selective oxo attack to the
,
-C=C double bond, irrespective of this beingof the benzo or the (R)C=C(R) type. In the latter case, further oxidation takes place with
tBuOOH, atambient temperature, with formation of an iridabenzene (
11) and an iridanaphthalene (
12) (with five andthree electron-withdrawing CO
2Me substituents, respectively) in which the carboxylate MeO
2CCO
2- ligandcompletes the metal coordination sphere. Interestingly, substitution of this group by OH
- or MeO
- allowsthe formation of Jackson-Meisenheimer complexes, reflecting the inherent aromaticity of these electron-deficient metalloaromatics. Finally, the hydrogenation of the iridacycloheptatrienes has been studied. Allnew compounds have been fully characterized by microanalysis, IR and NMR spectroscopies, and, insome cases, single-crystal X-ray diffraction studies.