Study of nitrosation of hexaammineruthenium(II): Crystal structure of <Emphasis Type="Italic">trans</Emphasis>-[RuNO(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>Cl]Cl<Subscript>2</Subscript>

The nitrosation of [Ru(NH₃)₆]²⁺ in hydrochloric acid and alkaline ammonia media has been studied; the patterns of interconversion of ruthenium complexes in reaction solutions have been proposed. In both cases, nitrogen(II) oxide acts as the nitrosation agent. The procedure for the synthesis of [Ru(NO)(NH₃)₅]Cl₃ · H₂O (yield 75–80%), the main nitrosation product of [Ru(NH₃)₆]²⁺, has been optimized. Thermolysis of [Ru(NO)(NH₃)₅]Cl₃ · H₂O in a helium atmosphere has been studied; the intermediates have been identified. One of these products is polyamidodichloronitrosoruthenium(II) whose subsequent decomposition gives an equimolar mixture of ruthenium metal and dioxide. The structure of trans-[RuNO(NH₃)₄Cl]Cl₂, formed in the second stage of thermolysis and as a by-product in the nitrosation of [Ru(NH₃)₆]Cl₂, has been determined by X-ray diffraction.     

Decomposition thermique du trichlorure de ruthenium hexammine

The thermal decomposition of [Ru(NH₃)₆]Cl₃ leads between 200 and 400° in inert gas to metallic ruthenium through the intermediates [Ru(NH₃)₅Cl]Cl₂, [Ru(NH₃)₄Cl₂]Cl and [Ru(NH₃)₃Cl₃]. In the total decomposition $$[Ru(NH_3 )_6 ]Cl_3 \to Ru + 1/2N_2 + 3NH_3 + HCl + 2NH_4 Cl$$ finely divided ruthenium is obtained above 240°. In oxygen the same intermediates are formed, the final product, however, being the metal and its dioxide.     

X-ray diffraction study of [Ru(NH3)5Cl][ReCl6] and [Ru(NH3)5Cl]2[ReCl6]Cl2 and their thermolysis products. Crystal-chemical analysis of the Ru-Re system

Binary complex salts [Ru(NH₃)₅Cl][ReCl₆] and [Ru(NH₃)₅Cl]₂[ReCl₆]Cl₂ were synthesized and characterized. An X-ray diffraction analysis showed that they were isostructural with the previously obtained isoformula salts [Rh(NH₃)₅Cl][OsCl₆] and [Ir(NH₃)₅Cl]₂[PtCl₆]Cl₂, respectively. Thermolysis of these compounds under hydrogen and helium was studied. According to X-ray phase analysis data, bimetallic solid solutions Ru_0.67Re_0.33 and Ru_0.50Re_0.50 were the final products of thermolysis. Their unit cell parameters correspond to the characteristics of alloys with similar compositions. Original Russian Text Copyright ? 2009 by S. A. Martynova, K. V. Yusenko, I. V. Korolkov, I. A. Baidina, and S. V. Korenev __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 1, pp. 126–132, January–February, 2009.     

Double complex salts with [Ru(NH3)5Cl]2+ cation and [OsCl6]2? anion: Synthesis and properties. Crystal structure of [Ru(NH3)5Cl]2[OsCl6]Cl2

Double complex salts [Ru(NH₃)₅Cl][OsCl₆] and [Ru(NH₃)₅Cl]₂[OsCl₆]Cl₂ were prepared and characterized. An X-ray diffraction study showed that [Ru(NH₃)₅Cl][OsCl₆] is isostructural to the previously synthesized [Rh(NH₃)₅Cl][OsCl₆]. The structure of [Ru(NH₃)₅Cl]₂[OsCl₆]Cl₂ was solved by X-ray diffraction (a = 11.1849(8) ?, b = 7.9528(6) ?, c = 13.4122(9) ?; β = 99.765(2)°; V= 1175.75 ?³; space group C2/m; Z = 2). Thermolysis of the compounds under hydrogen and helium was studied. According to X-ray diffraction, nanosized metallic powders of the corresponding alloys are formed as the final products of thermolysis. The compositions of the obtained solid solutions are consistent with the phase diagram of the Ru-Os system.     

Synthesis, properties, and thermal decomposition products of [Ru(NH3)5Cl][PtCl6] and [Ru(NH3)5Cl]2[PtCl6]Cl2

The double complex salts [Ru(NH₃)₅Cl][PtCl₆] (I) and [Ru(NH₃)₅Cl]₂[PtCl₆]Cl₂ (II) were synthesized and studied by X-ray diffraction. They were found to be isostructural to the previously synthesized [Rh(NH₃)₅Cl][OsCl₆] and [Ir(NH₃)₅Cl]₂[PtCl₆]Cl₂. The thermolysis of the complexes in the atmosphere of hydrogen and helium was studied by the powder X-ray diffraction analysis. The product of the salt I thermolysis is a single-phase solid solution Ru_0.5Pt_0.5 (a = 3.857(3) ?), the thermolysis of salt II results in a double-phase metallic powder. Original Russian Text ? S.A. Martynova, K.V. Yusenko, I.V. Korol’kov, S.A. Gromilov, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 7, pp. 541–545.     

Solid solutions Ru<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ir<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript> synthesized by thermolysis of coordination compounds

The double complex salts [Ir(NH₃)₅Cl][IrCl₆], [Ru(NH₃)₅Cl][IrCl₆], and [Ru(NH₃)₅Cl]₂[IrCl₆]Cl₂ have been synthesized and characterized. An X-ray diffraction study demonstrated that these salts are isostructural with [Rh(NH₃)₅Cl][OsCl₆] and [Ir(NH₃)₅Cl]₂[PtCl₆]Cl₂ synthesized earlier. Thermolysis of these salts in hydrogen and helium has been studied. X-ray powder diffraction analysis show that thermolysis yields stoichiometric solid solutions of metals as the final products. The unit cell parameters of these products correspond to equilibrium phases.     

Synthesis of nonequilibrium Ir<Subscript>x</Subscript>Re<Subscript>1-x</Subscript> solid solutions. Crystal structure of [Ir(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl]<Subscript>2</Subscript>[ReCl<Subscript>6</Subscript>]Cl<Subscript>2</Subscript>

Synthesis of five binary complex salts with an [Ir(NH₃)₅Cl]²⁺ complex cation is described. The counterions are [ReCl₆]^2–, [IrCl₆]^2–, [ReBr₆]^2–, and Cl^–. A polycrystal X-ray diffraction study has been performed for [Ir(NH₃)₅Cl]₂[ReCl₆]Cl₂, and its crystal structure has been determined. A series of Ir _x Re_1–x phases (0.5 x > 1) were obtained by reductive thermolysis. For the Ir-Re system, the history of the V/Z(x) dependence has been refined.Original Russian Text Copyright © 2004 by S. A. Gromilov, S. V. Korenev, I. V. Korolkov, K. V. Yusenko, and I. A. BaidinaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 508–515, May–June 2004.     

Darstellung und Kristallstruktur von (NH4)2[V(NH3)Cl5]. Die Kristallchemie der Salze (NH4)2[V(NH3)Cl5], [Rh(NH3)5Cl]Cl2 und M2VXCl5 mit M = K,NH4, Rb,Cs und X = Cl,O

Preparation and Crystal Structure of (NH₄)₂[V(NH₃)Cl₅]. The Crystal Chemistry of the Compounds (NH₄)₂[V(NH₃)Cl₅], [Rh(NH₃)₅Cl]Cl₂, and M₂VXCl₅ with M = K, NH₄, Rb, Cs and X ? Cl, O (NH₄)₂[V(NH₃)Cl₅] crystallizes like [Rh(NH₃)₅Cl]Cl₂ in the orthorhombic space group Pnma with Z = 4. The compounds are built up by isolated NH₄⁺ or Cl^? and complex MX₅Y ions. The following distances have been observed: V? N: 213.8, V? Cl: 235.8–239.1, Rh? N: 207.1–208.5, Rh? Cl: 235.5 pm. Both structures differ from the K₂PtCl₆ type mainly in the ordering of the MX₅Y polyhedra. The compounds M₂VCl₆ and M₂VOCl₅ with M = K, NH₄, Rb, and Cs crystallize with exception of the orthorhombic K₂VOCl₅ in the K₂PtCl₆ type. The ordering of the MX₅Y polyhedra in the compounds (NH₄)₂[V(NH₃)Cl₅], [Rh(NH₃)₅Cl]Cl₂ and K₂VOCl₅ enables a closer packing.     

[M(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl][AuCl<Subscript>4</Subscript>]Cl · <Emphasis Type="Italic">n</Emphasis>H<Subscript>2</Subscript>O (M = Rh,Ru, or Cr): Synthesis,crystal structure,and thermal properties

Double complex salts [M(NH₃)₅Cl][AuCl₄]Cl · nH₂O (M = Rh, Ru, or Cr) were synthesized and structurally studied. These compounds are isostructural; space group C2/m. Their crystal structure is built of [M(NH₃)₅Cl]²⁺ complex cations, [AuCl₄]^? complex anions, Cl^? anions, and molecules of water of crystallization. The compounds were characterized by X-ray crystallography, X-ray powder diffraction, IR spectroscopy, and thermal analysis.     

Electronic structure of metastable isomers of Ru nitroso complexes

Geometrical structures of nitroso complexes trans- [Ru(NO)(NH₃)₄(Cl)]²⁺, trans-[Ru(NO)(NH₃)₄(H2O)]³⁺, [Ru(NO)(Cyclam)(Cl)]²⁺(Cyclam is 1,4,8,11-tetraazocyclodecane), and [Ru(NO)(Bipy)₂(Cl)]²⁺ (Bipy is 2,2-bipyridine) are optimized using the density functional method. The potential energy surface of all four complexes was found to contain local minima corresponding to a stable state with the ¹-coordination of NO through the N atom and to two metastable isomers with the ¹-O and ²-NO coordination. For [Ru(NO)Cl₅)]^2-, trans-[Ru(NO)(NH₃)₄(Cl)]²⁺, and trans-[Ru(NO)(NH₃)₄(H₂O)]³⁺, the lowest electronically excited triplet states are calculated, as well as the reduced complexes with one additional electron. It is shown that the electron excitation and reduction are accompanied by bending of the RuNO group with a substantial elongation of the Ru-O and N-O bonds, which makes this group unstable. These processes do not cause any significant changes in the metal or in the nitroso ligand oxidation states because of the electron density delocalization in the RuNO group.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 1, 2005, pp. 32–42.Original Russian Text Copyright © 2005 by Sizova, Lubimova.     

Synthese und Struktur von Ammin- und Amidokomplexen des Iridiums

Synthesis and Structure of Ammine and Amido Complexes of Iridium The reaction of (NH₄)₂[IrCl₆] with NH₄Cl at 300 °C in a sealed glass ampoule yields the iridium(III) ammine complex (NH₄)₂[Ir(NH₃)Cl₅], which crystallizes isotypically with K₂[Ir(NH₃)Cl₅] in the orthorhombic space group Pnma with Z = 4, and a = 1350.0(2); b = 1028.5(3); c = 689.6(2) pm. The reaction of (NH₄)₂[IrCl₆] with NH₃ at 300 °C, however, gives the already known [Ir(NH₃)₅Cl]Cl₂ beside a small amount of [Ir(NH₃)₄Cl₂]Cl₂. In pure form [Ir(NH₃)₅Cl]Cl₂ is obtained by ammonolysis of (NH₄)₂[Ir(NH₃)Cl₅] at 300 °C with NH₃. [Ir(NH₃)₄Cl₂]Cl₂ crystallizes triclinic (P1, Z = 1, a = 660,2(3); b = 680,4(3); c = 711,1(2) pm; α = 103,85(2)°, β = 114,54(3)°, γ = 112,75(2)°). The structure contains Cl^– anions and [Ir(NH₃)₄Cl₂]²⁺ cations with a trans position of the Cl atoms. Upon reaction of [Ir(NH₃)₅Cl]Cl₂ with Cl₂ one ammine ligand is eliminated yielding [Ir(NH₃)₄Cl₂]Cl, which is transformed to orthorhombic [Ir(NH₃)₄(OH₂)Cl]Cl₂ (Pnma, Z = 4, a = 1335,1(3); b = 1047,9(2); c = 673,4(2) pm) by crystallization from water. In the octahedral complex [Ir(NH₃)₄(OH₂)Cl]²⁺ the four ammine ligands have an equatorial position, whereas the Cl atom and the aqua ligand are arranged axial. Oxidation of (NH₄)₂[Ir(NH₃)Cl₅] with Cl₂ at 330 °C affords the tetragonal Ir^IV complex (NH₄)[Ir(NH₃)Cl₅] (P4nc, Z = 2, a = 702.68(5); c = 912.89(9) pm). Its structure was determined using the powder diagram. Oxidation of (NH₄)₂[Ir(NH₃)Cl₅] with Br₂ in water, on the other hand, gives (NH₄)₂[IrBr₆] crystallizing in the K₂[PtCl₆] type. Oxidation of (PPh₄)₂[Ir(NH₃)Cl₅] with PhI(OAc)₂ in CH₂Cl₂ affords the Ir^V amido complex (PPh₄)[Ir(NH₂)Cl₅].     

Reactions of hydrosulfido- and hydroselenido-bridged dinuclear Ir, Rh, and Ru complexes with SbCl3 and BiCl3 affording mixed-metal sulfido and selenido clusters containing both noble metals and Group 15 metals

A new versatile method to synthesize a series of noble metal-Group 15 metal chalcogenido clusters has been found. Thus, treatment of the hydrosulfido- or hydroselenido-bridged dinuclear complexes [Cp*MCl(μ-EH)₂MCp*Cl] (M=Ir, Rh; E=S, Se; Cp*=η⁵-C₅Me₅), [Cp°RuCl(μ-SH)₂RuCp°Cl] (Cp°=η⁵-C₅EtMe₄), and [Ru(L)Cl(μ-SH)₂Ru(L)Cl] (L=η⁶-C₆Me₅H) with M^′Cl₃ (M^′=Sb, Bi) in THF at room temperature afforded smoothly the clusters [Cp*MCl(μ-EM^′Cl₂)₂MCp*Cl], [Cp°RuCl(μ-SM^′Cl₂)₂RuCp°Cl], and [Ru(L)Cl(μ-SM^′Cl₂)₂Ru(L)Cl] through dehydrochlorination. The X-ray analyses of eleven new clusters clarified the details of their structures consisting of the cubane-type M₂M^′₂E₂Cl₂ cores resulting from the presence of weak MCl?M^′ bonding interactions in addition to the normal M-E, M-Cl, and M^′-E bonds.     

First example of ruthenium nitroso monoammine complex. Crystal structure of [Ru(NO)(NH3)3(H2O)Cl] × [Ru(no)(NH3)3(OH)Cl][Ru(NO)(NH3)Cl4]2Cl·2H2O

The structure of the interaction products of (NH₄)₂[Ru(NO)Cl₅] solution with ammonium acetate on heating is studied. The crystal structure of the [Ru(NO)(NH₃)₃(H₂O)Cl][Ru(NO)(NH₃)₃(OH)Cl] × [Ru(NO)(NH₃)Cl₄]₂Cl-2H₂O compound (compound I) containing a previously unknown anion of the nitrosomonoammine series is determined: Cc space group; a = 33.530(7) ?, b = 8.202(2) ?, c = 11.844(2) ?; β= 101.54(3)°.     

Crystal structure of [Ir(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl]<Subscript>2</Subscript>[OsCl<Subscript>6</Subscript>]Cl<Subscript>2</Subscript>. Crystal-chemical analysis of the iridium-osmium system

The [Ir(NH₃)₅Cl]₂[OsCl₆]Cl₂ binary complex salt has been prepared, and its structure was investigated by single crystal X-ray diffraction. Crystal data: a = 11.1901(13) Å, b = 7.9138(13) Å, c = 13.4384(18) Å; β = 99.640(3)°, V = 1190.0(2), space group C2/m, Z = 2, FW = 1099.47, d _x = 3.068 g/cm³. Thermolysis products of [Ir(NH₃)₅Cl]₂[OsCl₆]Cl₂, [Ir(NH₃)₅Cl][OsBr₆], (NH₄)₂[OsCl₆]_x[IrCl₆]_1?x , and K₂[OsCl₆]_x[IrCl₆]_1?x were studied by X-ray phase analysis; the unit cell parameters were refined, and the dependence of volume per atom (V/Z) on the composition of the Ir Os_1?x solid solution has been plotted.     

Ruthenium(III) complexes with N-(acetyl)-N′-(5-R-salicylidene)hydrazines: Syntheses,structures and properties

The reactions of 1 mol equiv. each of [Ru(PPh₃)₃Cl₂] and N-(acetyl)-N′-(5-R-salicylidene)hydrazines (H₂ahsR, R = H, OCH₃, Cl, Br and NO₂) in alcoholic media afford simultaneously two types of complexes having the general formulae [Ru(HahsR)(PPh₃)₂Cl₂] and [Ru(ahsR)(PPh₃)₂Cl]. The complexes have been characterized by elemental analysis, magnetic, spectroscopic and electrochemical measurements. Molecular structures of [Ru(HahsH)(PPh₃)₂Cl₂] and [Ru(ahsH)(PPh₃)₂Cl] have been confirmed by X-ray crystallography. In both species, the PPh₃ ligands are trans to each other. The bidentate HahsH⁻ coordinates to the metal ion via the O atom of the deprotonated amide and the imine–N atom in [Ru(HahsH)(PPh₃)₂Cl₂]. In HahsH⁻, the phenolic OH is involved in a strong intramolecular hydrogen bond with the uncoordinated amide N atom forming a seven-membered ring. In [Ru(ahsH)(PPh₃)₂Cl], the tridentate ahsH²⁻ binds to the metal ion via the deprotonated amide O, the imine N and the phenolate O atoms. In the electronic spectra, the green [Ru(HahsR)(PPh₃)₂Cl₂] and brown [Ru(ahsR)(PPh₃)₂Cl] complexes display several absorptions in the ranges 385–283 and 457–269 nm, respectively. Both complexes are low-spin and display rhombic EPR spectra in frozen solutions. Both types of complexes are redox active and display a quasi-reversible ruthenium(III) to ruthenium(II) reduction which is sensitive to the polar effect of the substituent on the chelating ligand. The reduction potentials are in the ranges −0.21 to −0.12 and −0.42 to −0.21 V (versus Ag/AgCl) for [Ru(HahsR)(PPh₃)₂Cl₂] and [Ru(ahsR)(PPh₃)₂Cl], respectively.     

Double complex salts [M(NH3)5Cl][M′Br4] (M = Rh, Ir, Co, Cr, Ru; M′ = Pt, Pd): Synthesis, x-ray diffraction characterization, and thermal properties

Double complex salts (DCSs) with [M(NH₃)₅Cl]²⁺ (M = Rh, Ir, Co, Cr, Ru) cations and [PtBr₄]^2? anions were prepared in high yields. The salts were two-phase mixtures of the anhydrous and monohydro DCSs. Anhydrous analogues containing [PdBr₄]^2? anions with M = Cr or Ru were synthesized. All the compounds were characterized using a set of physicochemical methods. The crystal structure of chloropentaamminechromium(III) tetrabromopalladate(II) was solved: space group Pnma, Z = 4, a = 17.068(2) Å, b = 8.315(12) Å, c = 9.653(14) Å. The [M(NH₃)₅Cl][M′X₄] (M = Rh, Ir, Co, Cr, Ru; M′ = Pd, Pt; X = Cl, Br) compounds were shown to be isostructural. The [M(NH₃)₅Cl][PtBr₄] · H₂O monohydrates are isostructural to the [M(NH₃)₅Cl][PdCl₄] · H₂O monohydrates (space group P2₁/c, z = 4). The properties of the compounds were comparatively analyzed. The tendencies of the thermal stability of the complexes were elucidated. The thermolysis products of the double complex salts obtained under a helium or hydrogen atmosphere were studied.     

Synthesis and Characterization of Some Ru( tmeda ) Complexes Containing Chloride, Hydride, and Vinylidene Ligands

 The polymeric compound [Ru(cod)Cl₂] _x (cod = cyclooctadiene) reacts with 2 equivalents of tmeda (N,N,N′,N′-tetramethylethylenediamine) in refluxing MeOH to afford trans-[Ru(cod)(tmeda)(Cl)(H)] (1), which upon treatment with CHCl₃ is readily converted to the dichloro complex trans-[Ru(cod)(tmeda)Cl₂] (2). When [Ru(cod)Cl₂] _x is reacted with tmeda under an atmosphere of H₂ (3 bar), the bis-tmeda complex trans-[Ru(tmeda)₂Cl₂] (3) is obtained in 80% yield. DFT calculations revealed that 3 is by 52 kJ/mol more stable than the corresponding cis isomer. Attempts to prepare the coordinatively unsaturated complex [Ru(tmeda)₂Cl]⁺ by reacting 1 with TICF₃SO₃ were unsuccessful. According to DFT calculations, however, such a complex should be stable and, interestingly, should adopt a square pyramidal rather than a trigonal bipyramidal structure. If halide abstraction of 3 is performed in the presence of terminal alkynes HC*CR (R*t-Bu, n-Bu), the cationic vinylidene complexes [Ru(tmeda)₂(Cl)(*C*CHR)]⁺ (4a,b) are obtained.     

New method for the synthesis of trans-hydroxotetraamminenitrosoruthenium(II) dichloride and its characterization

A procedure for the synthesis of mpa h c-[Ru(NO)(NH₃)₄(OH)]Cl₂ in a nearly quantitative yield (～95%) comprising treatment of a solution of (NH₄)₂[Ru(NO)Cl₅] with ammonium carbonate at t ～80°C was developed. It was found that [Ru(NO)(NH₃)₄(H₂O)]Cl₃·H₂O and trans-[Ru(NO)(NH₃)₄Cl]Cl₂ formed in the reaction of [Ru(NO)(NH₃)₄(OH)]Cl₂ with hydrochloric acid at various temperatures most often contain some initial hydroxy complex. The former compound is unstable, even at room temperature, it slowly eliminates water and HCl. A procedure for preparing the latter compound in a pure state in 85–90% yield was proposed. The acidity constant of the complex trans-[Ru(NO)(NH₃)₄(H₂O)]³⁺ at room temperature (K _a = (4 ± 1) × 10^?2) was estimated by ¹⁴N NMR spectroscopy.     

Thermal decomposition of [Co(NH3)5Cl]Cl2

The thermal decomposition of [Co(NH₃)₅Cl]Cl₂ was studied under non-isothermal conditions, in dynamic air and argon atmospheres. The kinetics of the particular stages of [Co(NH₃)₅Cl]Cl₂ thermal decomposition were evaluated from the dynamic weight loss data by means of the modified Coats-Redfern method. TheD _n andR _n models were selected as the models best fitting the experimental TG curves. These models suggest that the kinetics and macromechanism of [Co(NH₃)₅Cl]Cl₂ decomposition can be governed by diffusive and/or phase boundary processes. The values of the activation energy,E _a, and the pre-exponencial factor,A, of the particular stages of the thermal decomposition were calculated.     

Photocatalytic degradation of chloroform by bis (bipyridine)dichlororuthenium(III/II)

Broadband (λ > 320 nm) irradiation of chloroform solutions of either [Ru(bpy)₂Cl₂] or [Ru(bpy)₂Cl₂]Cl exposed to air led to a photostationary state, in which [Ru(bpy)₂Cl₂]⁺ predominated, and to the continuous decomposition of CHCl₃, as evidenced by the accumulation of HCl, hydroperoxides (CCl₃OOH and CHCl₂OOH), and tetra-, penta-, and hexachloroethane. The addition of Cl^? increased the rate of photodecomposition, while the replacement of Cl^? by F^? greatly decreased the rate. The observations are consistent with a photocatalytic cycle in which [Ru(bpy)₂Cl₂]⁺ is photochemically reduced to [Ru(bpy)₂Cl₂], which is thermally reoxidized by CCl₃OO or CCl₃OOH. In the absence of air a much slower photodecomposition reaction takes place leading to continuously increasing concentrations of chloroethanes. The data are consistent with a catalytic cycle in which [Ru(bpy)₂Cl₂]⁺ is photoreduced, as in aerated solutions, while [Ru(bpy)₂Cl₂] is photooxidized with chloroform as the substrate.