Heterobimetallic Cu(I)–Rh(I) and Cu(I)–Ir(I) Complexes: Synthesis, Catalytic Applications in Transfer Hydrogenation, and Photophysical Properties

The syntheses and structural characterization of Cu(I)–Rh(I) and Cu(I)–Ir(I) complexes are reported. These complexes are synthesized via the reaction of a previously reported copper amidinate complex, Cu$_2$L$_2$ (L= Ph$_2$PC≡CC(NDipp)$_2$}, Dipp = N,N0-2,6-diisopropylphenyl), with [M(cod)Cl]$_2$, (M= Rh, Ir; cod = 1,5-cyclooctadiene) yielding complexes [{(M(cod)Cl)Ph$_2$PC≡CC(NDipp)$_2$}$_2$Cu$_2$] (M= Rh, Ir). Additionally, an alternative one-pot synthetic route is explored by the reaction of lithium salt of the ligand, [M(cod)Cl]2, (M= Rh, Ir), and CuCl, resulting in improved yields of [{(M(cod)Cl)Ph$_2$PC≡CC(NDipp)$_2$}$_2$Cu$_2$]. Further, reaction of lithium salt of the ligand with [M(cod)Cl]2, (M= Rh, Ir) leads to the formation of intermediate complexes [{(M(cod)Cl) Ph$_2$PC≡CC(NDipp)$_2$}Li(thf)$_3$] (M= Rh, Ir), which upon hydrolysis, yielded protonated amidinate derivatives [(M(cod)Cl)Ph$_2$PC≡CC(NDipp)(NHDipp)] (M= Rh, Ir). In the second pathway, lithium salt of the ligand is hydrolyzed to obtain [Ph$_2$PC≡CC(NDipp)(NHDipp)]$_2$ and further reaction with [M(cod)Cl]$_2$, (M= Rh, Ir) yields [(M(cod)Cl) Ph$_2$PC≡CC(NDipp)(NHDipp)] via an alternative reaction pathway. ... mehrThe catalytic potential of Cu(I)–Ir(I) complex [{(Ir(cod)Cl) Ph$_2$PC≡CC(NDipp)$_2$}$_2$Cu$_2$] is evaluated for transfer hydrogenation (TH) of aryl aldehydes using isopropanol as a hydrogen transfer
source. Furthermore, the Ir complexes [{(Ir(cod)Cl)Ph$_2$PC≡CC(NDipp)$_2$}$_2$Cu$_2$] and [(Ir(cod)Cl)Ph$_2$PC≡CC(NDipp)(NHDipp] are
found to be luminescent in the solid state at 77 K with an emission maximum around 580 nm.