A Tour in the Chemistry of a Tricoordinate Rh(-I) Complex.

The finding of the unprecedented 16-e tricoordinate planar rhodium(-Ι) complex, K[Rh(IPr)(dvtms)] (K[1]) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolyl-2-ylidene, dvtms = divinyltretramethyldisiloxane) prompted us to explore its reactivity. K[1] reacts as a nucleophile with methyliodide to give [Rh(IPr)(dvtms)Me], a Rh(Ι) compound with an exceptional trigonal-pyramidal structure. Other haloalkanes abstract one electron from K[1] to give the previously reported [Rh0(IPr)(dvtms)] complex. K[1] also reacts with protonic acids and weak proton sources such as water and ketones to eventually give the rare tricoordinate 14-electron complex [RhI(IPr)(SiMe2OSiMe2CH = CH2)] with a Rh -Si bond. The 16-electron complex [RhI(IPr)(SiMe2OSiMe2CH = CH2)(H2C = CH2)] was characterized as an intermediate in this reaction. Furthermore, K[1] runs up to five cycles of catalytic condensation of nonenolizable aldehydes to esters, such as p-tolylaldehyde, before being fully converted into the inactive complex Rh(IPr)(η3-C3H4 ptolyl)(C2H4)] with fragmentation of the diolefin dvtms. Computational studies have provided valuable insights into the reactivity patterns and behavior of this complex, including those of the rhodium(-I)/rhodium(I) catalytic cycle.