Novel Hydridoirida-β-diketones Containing Small Molecules, CO, or Ethylene: Their Behavior in Coordinating Solvents Such as Dimethylsulfoxide or Acetonitrile

New hydridoirida-β-diketones [IrH{(PPh2(o-C6H4CO))2H}(CO)]ClO4 2 and [IrH{(PPh2(o-C6H4CO))2H}(olefin)]BF4 (olefin
= C2H4, 5; 1-hexene, 10) have been prepared. These complexes may afford new diacylhydridoiridium(III) derivatives.
In chloroform solution, complex 2 is in equilibrium with the deprotonated diacylhydride trans-[IrH(PPh2(o-C6H4CO))2(CO)] complex 3. In DMSO, deprotonation of 2 occurs to yield the kinetically favored product 3, which isomerizes
to the thermodynamically favored complex cis-[IrH(PPh2(o-C6H4CO))2(CO)] 4. Reprotonation of 4 with HBF4 in
chlorinated solvents gives the cation in 2. In coordinating solvents such as dimethyl sulfoxide or acetonitrile, complex
5 undergoes displacement of ethylene to afford [IrH{(PPh2(o-C6H4CO))2H}(L)]BF4 (L = DMSO, 7; CH3CN, 9).
Complexes 5 and 7 undergo deprotonation by NEt3 to give the corresponding diacylhydrides. The ethylene complex
gives only trans-[IrH(PPh2(o-C6H4CO))2(C2H4)] 6, while the dimethyl sulfoxide derivative affords a mixture of trans-
and cis-[IrH(PPh2(o-C6H4CO))2(DMSO)] 8. Complex 10 shows inhibited alkene rotation around the Ir−olefin axis.
All of the complexes were fully characterized spectroscopically. Single-crystal X-ray diffraction analysis was performed
on complexes 3, 4, and 9. The 13C NMR and X-ray data point to a carbenoid character in the carbon atoms
bonded to iridium in the irida-β-diketone fragment, so that it can be considered as an acyl(hydroxycarbene) moiety.