<p><a></a>Synthesis
of multimetallic compounds can enable placement of two or more metals in close
proximity, but efforts in this area are often hindered by reagent
incompatibilities and lack of selectivity. Here, we show that organometallic half-sandwich
[Cp*M] (M = Rh, Ir) fragments (where Cp* is <i>η</i><sup>5</sup>-pentamethylcyclopentadienyl)
can be cleanly installed into metallomacrocyclic structures based on the
workhorse diimine-monooxime-monooximato ligand system. Six new heterobimetallic
compounds have been prepared to explore this synthetic chemistry, which relies
on <i>in situ </i>protonolysis reactivity with precursor Ni(II) or Co(III) monometallic
complexes in the presence of suitable [Cp*M] species. Solid-state X-ray
diffraction studies confirm installation of the [Cp*M] fragments into the
metallomacrocyles via effective chelation of the Rh(III) and Ir(III) centers by
the nascent dioximato site. Contrasting with square-planar Ni(II) centers, the Co(III)
centers prefer octahedral geometry in the heterobimetallic compounds, promoting
bridging ligation of acetate across the two metals. Spectroscopic and
electrochemical studies reveal subtle influences of the metals on each other’s
properties, consistent with the moderate M′•••M distances of ca. 3.6–3.7 Å in
the modular compounds. The [Co,Rh] complex was found to catalyze hydrogenation
of <i>p</i>-trifluoromethylbenzaldehyde to <i>p</i>-trifluoromethylbenzyl
alcohol more cleanly than a 1:1 mixture of the individual monometallic
precursor complexes, suggesting that this family of heterobimetallic complexes could be useful in
future studies of multimetallic chemistry, especially in light of the starring
role of other [Cp*M] complexes in diverse catalytic systems.</p><br>