Effects of Axial Solvent Coordination to Dirhodium Complexes on Reactivity and Selectivity in C–H Insertion Reactions: A Computational Study

Density functional theory calculations were used to systematically explore the effects of axial ligation by solvent molecules on the reactivity and selectivity of dirhodium tetracarboxylates with diazo compounds in the context of C–H insertion into propane. Insertions on three types of diazo compounds—acceptor/acceptor, donor/acceptor, and donor/donor—promoted by dirhodium tetraformate were tested with and without axial solvent ligation for no surrounding solvent, dichloromethane, isopropanol, and acetonitrile. Magnitudes, origins, and consequences of structural and electronic changes arising from axial ligation were characterized. The results suggest that axial ligation affects barriers for N2 extrusion and C–H insertion, the former to a larger extent.

Effects of Axial Solvent Coordination to Dirhodium Complexes on Reactivity and Selectivity in C–H Insertion Reactions: A Computational Study

Density functional theory calculations were used to systematically explore the effects of axial ligation by solvent molecules on the reactivity and selectivity of dirhodium tetracarboxylates with diazo compounds in the context of C–H insertion into propane. Insertions on three types of diazo compounds—acceptor/acceptor, donor/acceptor, and donor/donor—promoted by dirhodium tetraformate were tested with and without axial solvent ligation for no surrounding solvent, dichloromethane, isopropanol, and acetonitrile. Magnitudes, origins, and consequences of structural and electronic changes arising from axial ligation were characterized. The results suggest that axial ligation affects barriers for N2 extrusion and C–H insertion, the former to a larger extent.

Structures and Properties of 4-phpy, pyz, and 4,4′-bpy Adducts of Lantern-Type Dirhodium Complexes with µ-Formamidinato and µ-Carboxylato Bridges

Dinuclear and polymer complexes of 4-phenylpyridine (4-phpy), pyazine (pyz), and 4,4′-bipyridine (4,4′-bpy) were prepared by using cis-[Rh2(4-Me-pf)2(O2CR)2] (4-Me-pf- =N,N’-bis(4-methylphenyl)formamidinate anion; R = CF3 and CMe3) as precursor dinuclear units. The dinuclear structures of cis-[Rh2II,II(4-Me-pf)2(O2CR)2(4-phpy)2] and cis-[Rh2II,III(4-Me-pf)2(O2CCMe3)2(4-phpy)2]BF4 and polymer structures of [Rh2II,II(4-Me-pf)2(O2CR)2(L)]n (L = pyz and 4,4′-bpy) were confirmed by X-ray crystal structure analyses. In these complexes, the lantern-type dinuclear core structures with cis-(2:2) arrangement of formamidinato (4-Me-pf-) and carboxylato ligands are preserved with Rh–Rh distances of 2.44–2.47 Å, regardless of the difference in the axial ligand and oxidation state Rh2II,II or Rh2II,III. In the cyclic voltammograms (CVs) in CH2Cl2, the redox potentials for Rh2II,III/Rh2II,II were estimated as E1/2 = 0.07 V and −0.28 V (vs. Fc+/Fc) for cis-[Rh2(4-Me-pf)2(O2CCF3)2(4-phpy)2] and cis-[Rh2(4-Me-pf)2(O2CCMe3)2(4-phpy)2], respectively, negatively shifted by 0.16 and 0.12 V compared with those of corresponding parent dinuclear complexes. The results were interpreted that the axial interaction with 4-phpy ligands makes the Rh2II,II core oxidized easily. The oxidized complex cis-[Rh2(4-Me-pf)2(O2CCMe3)2(4-phpy)2]BF4 is paramagnetic, which was confirmed by effective magnetic moment value μeff = 1.90 μB at 300 K per Rh2II,III unit (S = 1/2). The polymer complexes [Rh2(4-Me-pf)2(O2CR)2(L)]n (L = pyz and 4,4′-bpy) showed Type II gas-adsorption properties for N2.

Dirhodium complexes as electrocatalysts for CO2 reduction to HCOOH: role of steric hindrance on selectivity

Structural tuning of dirhodium electrocatalysts for the selective reduction of CO2 to HCOOH.

Unsymmetrical dirhodium single molecule photocatalysts for H2 production with low energy light

New unsymmetrical dirhodium complexes for photocatalytic H2 production with red light.