Temperature Of Acetone Research Articles

High-nuclearity ruthenium carbonyl cluster chemistry. 9. Ligand substitution at decaruthenium carbonyl clusters

The mono- to tri-substituted decaruthenium cluster anions [Ru10(μ-H)(μ6-C)(CO)24–x(L)x]- [L = P(C6H4Me-4)3, AsPh3, SbPh3, x = 1–3] were prepared as their [PPh4]+ salts in moderate to good yields from reaction of [PPh4][Ru10(μ-H)(μ6-C)(CO)24] with the corresponding group 15 ligands at room temperature in acetone. The tetrakis-substituted cluster Ru10(μ6-C)(μ3-CO)(μ-CO)(CO)19{P(C6H4Me-4)3}4 was obtained in high yield from [PPh4]2[Ru10(μ6–C)(CO)24] and an excess of the phosphine under the same conditions; a single-crystal X-ray diffraction study revealed that the phosphines ligate at the vertices of the “giant tetrahedral” core. Kinetics studies of the formation of [PPh4][Ru10(μ-H)(μ6-C)(AsPh3)2(CO)22] from [PPh4][Ru10(μ-H)(μ6-C)(AsPh3)(CO)23] shows that ligand substitution at these giant tetrahedral clusters proceeds via a strongly associative pathway with the likely intermediacy of a Ru-Ru bond-cleaved intermediate.

Mild synthesis of 5-(9-ethyl-9H-carbazol-3-yl)-N-aryl-1,3,4-thiadiazol-2-amines

An efficient synthetic method for heterocycles containing both carbazole and 1,3,4-thiadiazole moieties is described. 9-Ethyl-9H-carbazol-3-carbaldehyde reacted with 4-arylthiosemicarbazides, with acetic acid as catalyst, to give 1-(9-ethyl-9H-carbazol-3-yl)methylene-4-arylthiosemicarbazides, which were further treated with manganese dioxide at room temperature in acetone to give 5-(9-ethyl-9H-carbazol-3-yl)-N-aryl-1,3,4-thiadiazol-2-amines in good to high yield. This procedure has the advantages of mild conditions, easy separation, and simple manipulation.

Selectivity Manipulation of Bicyclization Reactions of 1,5‐Bis(1,2‐allenylketone)s: Pd versus Rh and Electronic Effect

Select Rh! The rhodium(I)-catalyzed double cyclization of 1,5-bis(1,2-allenylketone)s gives TNF-α inhibitor (A)-type skeletons at room temperature in acetone or 1,2-dichloroethane (DCE, see scheme; Ts=Tosyl). Compared with [PdCl2(MeCN)2], [RhCl(CO)2]2 shows excellent selectivity towards the nonaromatic CC bond. The selectivity of unsymmetrical substrates can be controlled by the electronic effect.

Enhancement of thermal stability of multiwalled carbon nanotubes via different silanization routes

This work presents an effect of two different silanization procedures on thermal and structural properties of oxidized and oxidized followed by sodium borohydrate (NaBH 4) reduction of multiwalled carbon nanotubes (MWCNTs). Purified sample was oxidized in a mixture of nitric and sulfuric acids in a reflux. An oxidized material was divided into two batches. The first batch underwent a silanization procedure directly, while the second batch was reduced by NaBH 4 treatment prior to the silanization. The silanization experiments were performed: (A) with γ-aminopropyltriethoxysilane (APTES) at room temperature in acetone (pH ∼7) and (B) with condensated γ-aminopropyltriethoxysilane at 40 °C in water (pH 4). The extent of the functionalization of the samples after each procedure was examined by Raman spectroscopy. The vibrational properties of the materials were studied via Fourier transform infrared spectroscopy. Boehms titration technique was applied to quantify the amount of the functional groups on MWCNTs. The morphology of the pristine and functionalized carbon nanotubes was exposed to high-resolution transmission electron microscopy analysis. The energy dispersive X-ray (EDX) analysis was used to characterize the elemental composition of each sample. The effect of the silanization process on the thermal properties of MWCNTs was investigated by thermogravimetry analysis. Interestingly, the significant increase of the thermal stability of silanized MWCNTs samples in respect to the pristine MWCNTs was observed.

The Direct Conversion of Ethanol to Ethyl and Methyl Acetates Catalyzed by Iridium Complex

Abstract Ethanol was efficiently converted to ethyl and methyl acetates by [Cp*IrCl2]2 combined with 2-(methylamino)ethanol and a base like Cs2CO3 at room temperature in acetone in high yield, which provides the first Ir-catalyzed direct route to ethyl and methyl acetates from ethanol.

Influence of nucleation on the flow boiling heat transfer coefficient of a refrigerant mixture under varied heat flux conditions

The influence of nucleation on the flow boiling heat transfer coefficient of R-134a/R-290/R-600a refrigerant mixture is experimentally studied in a smooth horizontal tube of 12.7 mm diameter. The heat transfer coefficients are experimentally measured for stratified flow patterns under a varied heat flux condition; a condition found in the evaporator of refrigerators and deep freezers. The experiments are conducted in a counter-current heat exchanger test section. By regulating the flow rate and inlet temperature of acetone, which is the heating fluid flowing in the outer tube, a varied heat flux is provided to the refrigerant flowing in the inner tube. The refrigerant mass flow rate is fixed between 3 and 5 g s−1 and its inlet temperature between −8.59 and 5.33°C, which corresponds to a pressure of 3.2 to 5 bar. The significance of nucleate boiling prevailing in the above-mentioned evaporators is highlighted. The experimental heat transfer coefficients are also compared with well known heat transfer correlations.

Binuclear Intermediates in Oxidation Reactions: [(Me3SiC≡C)Me2(bipy)Pt−PtMe2(bipy)]+ in the Oxidation of PtIIMe2(bipy) (bipy = 2,2′-Bipyridine) by IPh(C≡CSiMe3)(OTf) (OTf = Triflate)

A study of the reaction of PtMe(2)(bipy) with IPh(C[triple bond]CSiMe(3))(OTf) at low temperature in acetone, leading to detection of the Pt-Pt-bonded cation [Pt(2)Me(4)(C[triple bond]CSiMe(3))(bipy)(2)](+), an intermediate in the oxidation of Pt(II) to Pt(IV), is reported. The cation is assessed as Pt(III)-Pt(III) <--> Pt(IV)-Pt(II), and at the other extreme may be regarded as a cationic alkynylplatinum(IV) center, "[Pt(IV)Me(2)(C[triple bond]CSiMe(3))(bipy)](+)", stabilized by "Pt(II)Me(2)(bipy)" as a donor ligand. The detection and isolation of the [Pt(2)Me(4)(C[triple bond]CSiMe(3))(bipy)(2)](+) cation provides a number of insights into the mechanisms of oxidation reactions.

Mild and Efficient Catalytic Protocol for Tetrahydropyranylation of Alcohols Using Acidic Keggin and Wells‐Dawson Structures

AbstractA simple, mild and effective procedure is reported to the generation of 2‐tetrahydropyranyl acetals from alcohols. Keggin and Wells‐Dawson heteropolyoxometalates were used as catalysts at ambient temperature in acetone as solvent with good yields and high selectivities in a short reaction time. Different reaction parameters affecting efficiency of the protocol were also studied. The use of these acid catalysts allows replacing the usual soluble inorganic acids, contributing to waste reduction.

Synthesis and Stable‐Ion Studies of Regioisomeric Acetylnitropyrenes and Nitropyrenyl Carbinols and GIAO‐DFT Study of Nitro Substituent Effects on α‐Pyrenyl Carbocations

AbstractSeveral regioisomeric acetylnitropyrenes were synthesized from isomeric acetylpyrenes by mild protic nitration. Nitration of 1‐acetylpyrene gave the 3‐, 6‐, and 8‐nitro derivatives (with 8‐nitro as the major isomer), from which the corresponding carbinols [NO2‐Py‐CH(OH)CH3; Py = pyrene] were synthesized. Isomeric 4‐acetylnitropyrenes and their corresponding carbinols were synthesized by starting from hexahydropyrene through nitration/aromatization/reduction or aromatization/nitration/reduction sequences. The molecular structures of 4‐acetyl‐3‐nitropyrene and 1‐(6‐nitropyren‐1‐yl)ethanol were established by X‐ray analysis. Tetrahydropyrene was the starting point for the synthesis of isomeric nitro‐2‐acetylpyrenes. Low‐temperature protonation of 1‐acetyl‐8‐nitropyrene, 4‐acetyl‐3‐nitropyrene, and 2‐acetyl‐6‐nitropyrene in FSO3H/SO2ClF or in FSO3H/SbF5 (1:1)/SO2ClF resulted in the formation of onium dications (by C=O and NO2 protonation). Charge delocalization (pyrenium ion character) in the carboxonium ions is strongly influenced by the position of the carboxonium group, with the 4‐acetyl‐3‐nitropyrene dication being the most delocalized. Superacid protonation of 1‐(3‐nitropyren‐4‐yl)ethanol gave a persistent onium dication rather than an α‐pyrenyl carbocation. With all other isolated nitropyrenyl carbinol isomers, low‐temperature protonation (with FSO3H/SO2ClF) led to polymerization within 5 min standing at dry‐ice–acetone temperature. For these cases, nitro substituent effects on the α‐pyrenyl carbocations were gauged by DFT and GIAO‐DFT studies. An interesting relationship between the computed nitro tilt angles and the GIAO‐derived charge delocalization modes was observed.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2008)

Cp*Ir Complex‐Catalyzed Hydrogen Transfer Reactions Directed Toward Environmentally Benign Organic Synthesis

AbstractFor Abstract see ChemInform Abstract in Full Text.

Ruthenium‐Catalyzed Enyne Cycloisomerizations. Effect of Allylic Silyl Ether on Regioselectivity.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Cp*Ir Complex-Catalyzed Hydrogen Transfer Reactions Directed toward Environmentally Benign Organic Synthesis

Catalytic activity of Cp*Ir complexes toward hydrogen transfer reactions are discussed. Three different types of reactions have been developed. The first is Oppenauer-type oxidation of alcohols. This reaction proceeds under quite mild conditions (room temperature in acetone) catalyzed by [Cp*IrCl2]2/K2CO3, and both primary and secondary alcohols can be used as substrates. Introduction of a N-heterocyclic carbene ligand to the catalyst considerably enhances the catalytic activity, and a very high turnover number of 950 has been obtained in the oxidation of 1-phenylethanol. The ­second is the N-alkylation of amines with alcohols. A new effective catalytic system consisting of [Cp*IrCl2]2/K2CO3 for the N-alkylation of primary amines with alcohols has been developed. Synthesis of indoles and 1,2,3,4-tetrahydroquinolines via intramolecular N-alkylation of amino alcohols and synthesis of nitrogen heterocycles via intermolecular N-alkylation of primary amines with diols catalyzed by a Cp*Ir complex have been also achieved. The third is the regio- and chemoselective transfer hydrogenation of quinolines. An efficient method for the transfer hydrogenation of quinolines catalyzed by [Cp*IrCl2]2/HClO4 using 2-propanol as a hydrogen source has been realized. A variety of 1,2,3,4-tetrahydroquinoline derivatives can be synthesized by this method. These results show that Cp*Ir complexes can be useful catalysts for hydrogen transfer ­reactions from the viewpoint of developing environmentally benign organic synthesis.

Ruthenium-Catalyzed Enyne Cycloisomerizations. Effect of Allylic Silyl Ether on Regioselectivity

The ruthenium-catalyzed cycloisomerization of 1,6- and 1,7-enynes substituted in the terminal allylic position with a tert-butyldimethylsilyl ether group emerges as an effective reaction to form unprecedented five- or six-membered rings possessing a geometrically defined enol silane. Straightforward synthetic access to a variety of achiral 1,6- and 1,7-enynes, as well as chiral ones, is presented. Ruthenium catalysts effect efficiently such single-step cycloisomerization at room temperature in acetone under neutral conditions. The cycloisomerization functions with (E) or (Z) 1,2-disubstituted alkenes. Parameters influencing the enol silane geometry are discussed. The level of selectivity depends on the alkyne substitution, the geometry of the double bond, and the nature of the catalyst. Furthermore, examples of stereoinduction are shown and lead to highly substituted carbo- and heterocycles with excellent diastereocontrol.

Reactivity of Diaryliodine(III) Triflates toward Palladium(II) and Platinum(II): Reactions of C(sp2)−I Bonds to Form Arylmetal(IV) Complexes; Access to Dialkyl(aryl)metal(IV), 1,4-Benzenediyl-Bridged Platinum(IV), and Triphenylplatinum(IV) Species; and Structural Studies of Platinum(IV) Complexes

Diphenyliodine(III) triflate is able to transfer Ph+ to Pd(II) and Pt(II) with cleavage of a phenyl−iodine bond and formation of metal(IV) species, leading to the first identified transfer of Ph+ to Pd(II) from an aryl−halogen bond, and, for platinum, a methodology providing a facile route to dimethyl(aryl)platinum(IV) and 1,4-arenediyl-bridged Pt(IV) species and the first archetypal triarylplatinum(IV) complex. Thus, [IPh2][OTf] reacts with PtMe2(bpy) (bpy = 2,2‘-bipyridine) at −50 °C to form iodobenzene and the Pt(IV) complex trans-PtIV(OTf)Me2Ph(N∼N) (1b) (Ph trans to OTf), and on addition of NaI, the species PtIMe2Ph(bpy) (2a (Ph cis to I) and 2b (Ph trans to I) in 2:1 ratio) may be isolated at −20 °C. Similarly, metalla(II)cyclopentane complexes M(C4H8)(bpy) react with [IPh2][OTf] to form trans-Pt(OTf)(C4H8)Ph(bpy) (3b) and a 1:1 ratio of cis- (4a) and trans-Pd(OTf)(C4H8)Ph(bpy) (4b); addition of halide ion gives trans-PtI(C4H8)Ph(bpy) (5b) and a 1:3 ratio of cis and trans isomers for PdI(C4H8)Ph(bpy) (6a, 6b) and PdCl(C4H8)Ph(bpy) (7a, 7b). Complex 5b isomerizes to form a 2:1 mixture of cis-PtI(C4H8)Ph(bpy) (5a) and 5b at ambient temperature in acetone. Dimethyl(2,2‘-bipyridine)palladium(II) reacts with [IPh2][OTf] to form Pd(OTf)Me2Ph(bpy), followed by transfer of a methyl group from Pd(IV) to Pd(II), to form trimethylpalladium(IV) species. Dimethyl(2,2‘-bipyridine)platinum(II) reacts with [IPh(C6H4-4-I)][OTf], followed by addition of sodium iodide, to form a 1:1 mixture of trans-PtIMe2Ph(bpy) (2b) and trans-PtIMe2(C6H4-4-I)(bpy) (8b), and with [IPh(C6H4-4-IPh)][OTf]2 to form the 1,4-arenediyl complex trans-1,4-{PtIMe2(bpy)}2C6H4 (9b). Diphenyl{di(tert-butyl)-2,2‘-bipyridine}platinum(II) reacts with [IPh2][OTf] at 25 °C over 2 days to form the triphenylplatinum(IV) complex Pt(OTf)Ph3(But2bpy) (10), and addition of iodide ion results in isolation of PtIPh3(But2bpy) (11). Structural studies of trans-PtIMe2Ph(bpy) (2b) and trans-Pt(C4H8)Ph(bpy) (5b) reveal distorted octahedral geometry and the fac-PtC3 configuration expected for all of the metal(IV) complexes. The compound [IPh(C6H4-4-I)][OTf] has two sets of cation−anion pairs with a complex array of weak interactions, and the cations have C−I−C angles close to 90°.

A novel L-neopentylglycine derivative as auxiliary for copper-catalyzed asymmetric Michael reactions.

L-Neopentylglycine diethylamide (4a). was prepared from the new unnatural amino acid L-neopentylglycine (1). The utilization of amide 4a as a chiral auxiliary in the copper(II)-catalyzed asymmetric Michael reaction was investigated in comparison with L-valine diethylamide (4b). Cyclic beta-oxocarboxylates 7 react with 4a and 4b to give the respective enaminoesters 8, which were converted with methyl vinyl ketone (9) in the presence of 10 mol% Cu(OAc)(2). H2O at room temperature in acetone to yield the optically active Michael addition products (R)-10a, b with high selectivity independent of the starting enamine. In the case of the seven-membered beta-oxocarboxylate 7c, however, the valine-derived enamine 8f led to higher enantioselectivity for product 10c. Despite the bulkiness of the neopentyl group, the isopropyl group with an alpha-branch has a better stereoinducing effect.

Mechanistic dichotomy in CpRu(CH(3)CN)(3)PF(6) catalyzed enyne cycloisomerizations.

Enynes are easily accessible building blocks as a result of the rich chemistry of alkynes and thus represent attractive substrates for ring formation. A ruthenium catalyst for cycloisomerization effects such reaction of 1,6- and 1,7-enynes typically at room temperature in acetone or DMF under neutral conditions. The reaction is effective for forming five- and six-membered rings of widely divergent structure. The alkyne may bear both election-donating and election-withdrawing substituents. The alkene may be di- or trisubstituted. Introduction of a quaternary center at the propargylic position of an ynoate, however, completely changes the nature of the reaction. In the case of a 1,6-enynoate, a seven-membered ring forms in excellent yield under equally mild conditions. Evidence is presented to indicate a complete change in mechanism. In the former case, the reaction involves the intermediacy of a ruthenacyclopentene. In the latter case, a C-H insertion to form a pi-allylruthenium intermediate is proposed and supported by deuterium-labeling studies. A rationale is presented for the structural dependence of the mechanism.

Synthesis, Chemistry, and Catalytic Activity of Ruthenium Diaminodiphosphane Complexes − Crystal Structures of trans-[RuCl2{κ3-Ph2PC6H4CH=NC6H10N(H)CH2C6H4PPh2}(PPh3)] and cis-[RuCl2{κ4-Ph2PC6H4CH=NC6H10N(H)CH2C6H4PPh2}

The interaction of [RuCl2(PPh3)3] with one equivalent of N,N′-bis[2-(diphenylphosphanyl)benzyl]-1R,2R-cyclohexanediamine [1R,2R-P(NH)(NH)P] in dichloromethane at room temperature gave trans-[RuCl2{κ3-1R,2R-P(NH)(NH)P}(PPh3)] (1). When heated under reflux in toluene under a nitrogen atmosphere, 1 was converted into trans-[RuCl2{κ4-1R,2R-P(NH)(NH)P}] (2). However, when 1 was stirred at room temperature in air, it was oxidized to trans-[RuCl2{κ3-1R,2R-PN(NH)P}(PPh3)] (3). Depending on the reaction conditions, 3 was converted into trans-[RuCl2{κ3-1R,2R-P(NH)(NH)P=O}(PPh3)] (4) when heated to 80 °C in toluene in air, to cis-[RuCl2{κ4-1R,2R-PN(NH)P}] (5) when stirred at room temperature in acetone in air, or to trans-[RuCl2{κ4-1R,2R-PN(NH)P}] (6) when heated under reflux in acetone under a nitrogen atmosphere. When heated under reflux in toluene under a nitrogen atmosphere, 5 isomerized to 6 quantitatively. When heated under reflux in mesitylene under a nitrogen atmosphere, 6 was slowly reduced to 2. The solid state structures of 3 and 5 were ascertained by X-ray crystallography. Catalytic studies showed that 1 could catalyze the oxidation of alkanes and alkenes with molecular oxygen.

Synthesis, Chemistry, and Catalytic Activity of Ruthenium Diaminodiphosphane Complexes − Crystal Structures oftrans-[RuCl2{κ3-Ph2PC6H4CH=NC6H10N(H)CH2C6H4PPh2}(PPh3)] andcis-[RuCl2{κ4-Ph2PC6H4CH=NC6H10N(H)CH2C6H4PPh2}

The interaction of [RuCl2(PPh3)3] with one equivalent of N,N′-bis[2-(diphenylphosphanyl)benzyl]-1R,2R-cyclohexanediamine [1R,2R-P(NH)(NH)P] in dichloromethane at room temperature gave trans-[RuCl2{κ3-1R,2R-P(NH)(NH)P}(PPh3)] (1). When heated under reflux in toluene under a nitrogen atmosphere, 1 was converted into trans-[RuCl2{κ4-1R,2R-P(NH)(NH)P}] (2). However, when 1 was stirred at room temperature in air, it was oxidized to trans-[RuCl2{κ3-1R,2R-PN(NH)P}(PPh3)] (3). Depending on the reaction conditions, 3 was converted into trans-[RuCl2{κ3-1R,2R-P(NH)(NH)P=O}(PPh3)] (4) when heated to 80 °C in toluene in air, to cis-[RuCl2{κ4-1R,2R-PN(NH)P}] (5) when stirred at room temperature in acetone in air, or to trans-[RuCl2{κ4-1R,2R-PN(NH)P}] (6) when heated under reflux in acetone under a nitrogen atmosphere. When heated under reflux in toluene under a nitrogen atmosphere, 5 isomerized to 6 quantitatively. When heated under reflux in mesitylene under a nitrogen atmosphere, 6 was slowly reduced to 2. The solid state structures of 3 and 5 were ascertained by X-ray crystallography. Catalytic studies showed that 1 could catalyze the oxidation of alkanes and alkenes with molecular oxygen.

Synthesis of 1,1-disubstituted alkenes via a Ru-catalyzed addition.

The synthesis of 1,1-disubstituted alkenes typically involves reactions that lack atom economy such as olefination protocols. The use of various ruthenium complexes to effect the addition of terminal alkynes to alkenes is explored as an atom economical strategy. Two new ruthenium complexes have been discovered that effect this reaction at ambient temperature, cyclopentadienylruthenium (triphenylphosphine) camphorsulfonate and cyclopentadienylruthenium tris(acetonitrile) hexafluorophosphate. Using these complexes as catalysts, reactions proceed at ambient temperature in acetone or DMF, respectively. Regioselectivity favoring the formation of a 1,1-disubstituted over a 1,2-disubstituted alkene typically ranges from 9:1 to >25:1. The reaction demonstrates extraordinary chemoselectivity-even di- and trisubstituted alkenes such as present in the products do not compete with the starting monosubstituted alkene. Free hydroxyl groups as well as silyl and PMB ethers are tolerated as are ketones, esters, and amides. The mechanism of the reaction is believed to invoke formation of a metallacyclopentene. To account for the chemo- and regioselectivity, the initial formation of the metallacycle is believed to be reversible. While formation of the 2,5-disubstituted ruthenacyclopentene, which produces the linear product, is believed to be kinetically preferred, the rate of beta-hydrogen elimination from the 2,4-disubstituted ruthenacyclopentene, which produces the branched product, is believed to be faster. Thus, the competition between the rate of beta-hydrogen elimination and cycloreversion rationalizes the results.

Axial ligand substitution and photoisomerization reactions in ruthenium(II) trans mixed-chelate complexes containing the ligands 1,2-phenylenebis(dimethylarsine) and 2,2′-bipyridine or 1,10-phenanthroline

The nitrosyl complex in trans-[RuCl(pdma)(bpy)(NO)][PF 6] 2 (pdma=1,2-phenylenebis(dimethylarsine), bpy=2,2′-bipyridine) reacts at room temperature with stoichiometric NaN 3, followed by an excess of a neutral ligand L 1 in 2-butanone under reflux, to afford high yields of the mono-substituted derivatives trans-[RuCl(pdma)(bpy)L 1]PF 6 (L 1=pyridine (py) 1, triphenylphosphine (PPh 3) 2, N-methylimidazole (mim) 3, acetonitrile (MeCN) 4, dimethylsulfoxide (dmso) 5 or pyrazine (pyz) 6). The related compound trans-[RuCl(pdma)(phen)(NO)][PF 6] 2 (phen=1,10-phenanthroline) reacts similarly to yield trans-[RuCl(pdma)(phen)L 1]PF 6 (L 1=py 8, PPh 3 9, mim 10 or pyz 11). The pyrazine complexes in 6 and 11 react with MeI at room temperature in acetone to afford trans-[RuCl(pdma)(L–L)(mpyz +)][PF 6] 2 (mpyz += N-methylpyrazinium, L–L=bpy 7 or phen 12, respectively). 3 reacts with an excess of a neutral ligand L 2 in the presence of stoichiometric AgCF 3CO 2 in water/acetone under reflux to afford high yields of the di-substituted derivatives trans-[Ru(pdma)(bpy)mim(L 2)][PF 6] 2 (L 2=mim 13, py 14 or MeCN 15) and 2 reacts similarly with AgCF 3CO 2 in water/MeCN to give trans-[RuCl(pdma)(bpy)PPh 3(MeCN)][PF 6] 2 ( 16). The complexes in 1– 16 exhibit intense d π(Ru II)→π*(L–L) and d π(Ru II)→π*(L 1/L 2) (L 1/L 2=py, pyz or mpyz +) metal-to-ligand charge-transfer absorption bands in the near-UV–visible region and are mildly photosensitive in solution. Solar irradiation leads to isomerization; for example 3 is converted into cis-[RuCl(pdma)(bpy)mim]PF 6 ( 17) over a period of ca. 100 h exposure to diffuse sunlight in acetone. Single crystal X-ray structures have been determined for 1, 2·DMF, 3, 12·3MeCN, 14·DMF and 17.