Radiation reduction of binuclear Rh(II) complexes in aqueous-methanol solutions

Abstract

Radiation reduction of binuclear [Rh2(OAc)2(phen)2(H20)2](OAc)2, [Rh2(OAc)(tpy)2C12]C1.2H20 and [Rh2C12(HCOO)2(bpy)2].4H20 complexes in aqueous-methanol solution have been studied. The reduction yields as equal to ca. 6 equiv/100 eV and the rate constants of reactions: complex+esolv as equal to 2.9.1010, 3.2.10 l~ and 3.7.10 l~ M 1.s 1, respectively, have been determined. On the basis of electronic spectra it has been shown that Rh(II) compounds were reduced giving several Rh(I) complexes being in equilibrium. The mechanism of the processes has been discussed.

Rhodium-Based Metal–Organic Polyhedra Assemblies for Selective CO2 Photoreduction

“…68,69 Thus, PDF analysis provides strong evidence that the Rh 0 resting state observed by XPS analysis is located in a reduced [Rh 2 II,0 ] or [Rh 2 0,0 ] paddlewheel, but not caused by the formation of Rh 0 clusters. In summary, the combined XPS and PDF investigation of spent catalysts exclude any degradation into Rh 0 clusters or particles, 70 or into unimolecular or polymeric Rh I species, [71][72][73] which, in contrast, was observed in the case of photocatalysis with [Rh 2 (OAc) ] as catalyst (Figure S24b) and has been reported for different molecular Rh 2 II,II carboxylates. [70][71][72][73] Thus the fixation of the Rh 2 paddlewheel into a solid scaffold prevents these undesired side reactions.…”

“…In summary, the combined XPS and PDF investigation of spent catalysts excludes any degradation into Rh 0 clusters or particles or into unimolecular or polymeric Rh I species, − which, in contrast, was observed in the case of photocatalysis with [Rh 2 (OAc) 4 ] as the catalyst (Figure S29b) and has been reported for different molecular Rh 2 II,II carboxylates. − Thus, the fixation of the Rh 2 paddlewheel into a rigid scaffold prevents these undesired side reactions . In other words, the Rh-MOP structure remains the same upon catalysis, and the reduced Rh atoms detected by XPS remain at the same positions, part of the Rh-MOP structure.…”