Voltammetry of rhodium-1,10-phenanthroline complexes

Abstract

50) The question of "What is the radius of an ion In solution?", is a vexed one; and not only because of the difficulty of precise definition and the uncertainty of the exact meaning of any value calculated from experimental data, or otherwise. There is also the problem of selecting the value that is most appropriate for a particular application. In the present context, the distance of closest approach of a nonpolar nonelectrolyte to an ion seems best defined In terms of the size of an ion plus the very small number of tightly bound water molecules which could be described as "having lost their own degrees of translation freedom and have those of the Ion".45 Bockris and Saluja42•45 define this number of water molecules of the solvation number of an ion. A set of radii of hydrated ions approximately corresponding to this extent of hydration have been used.

Stable mononuclear rhodium(II) polypyridyl complexes: synthesis, spectroscopic and structural characterisation

“…8-16 However, using poly(pyridyl) ligands a few dimeric Rh() complexes have been isolated 5,17 but no stable monomer has been reported with the exception [Rh(bipy) 2 ][NO 3 ]. 18 However, short-lived Rh II mononuclear complexes were generated by one-electron reduction of the corresponding Rh III complexes either photochemically 19-21 or electrochemically 22, 23 and their properties were studied in solution. Generally, when mononuclear octahedral Rh III complexes are reduced to Rh II they undergo ligand labilization, which results in the loss of one ligand and either dimerization or disproportionation to Rh III and Rh I species.…”

Mechanistic Insight into the Electronic Influences Imposed by Substituent Variation in Polyazine‐Bridged Ruthenium(II)/Rhodium(III) Supramolecules

“…This is indicative of Rh reduction followed by halide loss occurring on the CV timescale 5b–d. 6a,b,d, 8 Changing TL′ from t Bu 2 bpy to Ph 2 phen gave orbital inversion with a dpp(π*) or Rh(dσ*)‐based LUMO, respectively.…”

“…The Rh III/II reduction promotes fast halide loss, followed by Rh II/I reduction and a second halide loss resulting in an ECEC mechanism (E=electrochemical or C=chemical step) 6a. b…”

Photochemistry and Photophysics of Coordination Compounds: Rhodium

“…Here, however, a relevant aspect is also the presence a Rh(III) moiety with of coordinated chloride ligands. In fact, contrary to what happens for common Rh(III) polypyridine units (e.g., Rh(bpy) 3 3+ , Rh(phen) 3 3+ ) where one-electron reduction is a quasi-reversible process, mixed-ligand units containing halide ions (e.g., Rh(bpy) 2 Cl 2 + , Rh(phen) 2 Cl 2 + ) undergo strongly irreversible two-electron reductions accompanied by prompt halide ligand loss [78,104]. While the use of these units as electron acceptors can be of interest towards photoinduced electron collection and multi-electron catalysis (see Sect.…”

“…4, where Rh(III), * Rh(III), and Rh(II) represent the ground state, the triplet LC excited state (see Sect. 2.1), and the one-electron reduced form, respectively, and the values of excitedstate energy [31] and reduction potential [78] refer to Rh(phen) 3…”