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• 110-86-1 pyridine 
• 138459-71-9 [Rh₂(OCOCH₃)3(P(C₆H₅)3)(C₆H₄)P(C₆H₅)2]*H₂O 
• 91837-70-6 {Rh2(μ-O2CMe)2{(C6H4)PPh2}{(C6H4)P(C6H5)2}(HO2CMe)2} 

Relevant academic research and scientific papers

A unified mechanistic view obtained from the temperature and pressure dependence of the spontaneous, acid-, and base-assisted cyclometallation reactions of dirhodium(II) complexes

The reaction of compounds [Rh2(O2CMe)(μ-O2CMe) 2{μ-(XC6H3)P(C6H 4X-p)2}{P(C6H4X′-p) 3}] (X = H, X′ = H or Me; X = Me, X′ = H or Me), having a metallated and an equatorial phosphine in a head-to-tail cisoid configuration, to produce the corresponding doubly metallated compounds [Rh2(μ-O2CMe)2· {μ-(XC6H3)P(C6H4X-p) 2}2], has been studied in detail. The thermal, acid-, and base-assisted conditions include toluene solution, neat acetic acid, and different bases [PPh3, P(C6H4Me-p)3 or pyridine] in toluene solution and as a function of temperature, pressure and base concentration (when applicable). The doubly metallated compounds always show retention of the head-to-tail cisoid configuration according to 31P NMR spectroscopy. The reported activation parameters allow a clear differentiation between the spontaneous, acid-assisted and base-assisted processes, some of which had been previously studied (ΔH? = 80 ± 5, 68 ± 1, 38 ± 3 kJ mol-1; ΔS? = -105 ± 15, -85 ± 3, -150 ± 30 J K-1 mol-1; ΔV? = -22.7 ± 0.2, -15.3 ± 0.2, -35.0 ± 0.5 cm3 mol-1 respectively, for the compound with X, X′ = H). For the reactions under base-assisted conditions, when long reaction times and/or high added Lewis-base concentrations were applied, the non-metallated phosphine was displaced from equatorial to axial co-ordination. Under these conditions a mixture of the bis adducts of the monometallated [Rh2(μ-O2CMe)3{μ-(XC6H 3)P(C6H4X-p)2}], and the doubly-metallated compounds was detected by 31P NMR spectroscopy. The activation parameters obtained for this slower process agree with those expected for substitution reactions and are interpreted in terms of the steric demands of the mono and bis adducts formed immediately on mixing the reaction solutions.

Structural and electrochemical characterization of the novel ortho-metalated dirhodium(II) compounds Rh2(O2CCH3)2[(C6H 5)2P(C6H4)]2·2L

The complex Rh2(O2CCH3)2[(C6H 5)2P(C6H4)] 2·2CH3CO2H, 1, was obtained by reaction of Rh2-(O2CCH3)4·2MeOH with triphenylphosphine in acetic acid. The purple crystals belong to the monoclinic system, space group C2/c with unit cell dimensions of a = 10.111 (3) A?, b = 19.653 (10) A?, c = 21.033 (8) A?, β = 97.63 (3)°, V = 4142 (3) A?3, and Z = 4. The molecule consists of a dirhodium unit bridged by two cisoid acetate ligands and by triphenylphosphine ligands in which orthometalation has occurred at one of the phenyl rings on each phosphine, with a molecule of acetic acid in each axial site. The electrochemical reactivity of this novel dirhodium(II) compound was investigated in three organic solvents in the presence of potential donor ligands, such as pyridine, p-dithiane, and PMe2Ph. In each experiment a one-electron oxidation was observed at potentials between +0.25 and +1.04 V vs. Ag-AgCl. In addition, two ill-defined reductions were observed at potentials in excess of -0.60 V. The pyridine adduct Rh2(O2CCH3)2[(C6-H 5)2P(C6H4)] 2·2C5H5N, 2, was prepared independently and was shown, by X-ray crystallography, to contain the same general arrangement of ligands. It too forms monoclinic crystals in space group C2/c with unit cell dimensions a = 24.289 (4) A?, b = 10.391 (3) A?, c = 23.056 (5) A?, β = 131.85 (2)°, V = 4334 (2) A?3 and Z = 4. Both compounds are unusual in that the Rh-Rh distances, 2.508 (1) A? in 1 and 2.556 (2) A? in 2, are significantly greater than those reported for any of the dirhodium tetracarboxylates Rh2(O2CR)4·2L. Rh2(O2CR)4·2L.