Synthesis of cyclopentadienyl ruthenium(II) complexes containing tethered functionalities

The reaction of [C₅H₄(CH₂)_nX]Tl (1: n = 2, X = NMe₂, OMe, CN; n = 3, X = NMe₂) with [(η⁶-C₆H₆)RuCl(μ-Cl)]₂, 2, afforded the sandwich compounds [{η⁵-C₅H₄(CH₂)_nX}Ru(η⁶-C₆H₆)]PF₆, 3, and [η⁵-C₅H₄(CH₂)_nX]₂Ru, 4. Photolytic cleavage of 3 in acetonitrile afforded the tethered products [{η⁵:κN-C₅H₄(CH₂)_nX}Ru(CH₃CN)₂]PF₆, 5.     

Cyclodiphosphazane appended with thioether functionality: Synthesis, transition metal chemistry and catalytic application in Suzuki-Miyaura cross-coupling reactions

The coordination chemistry of thioether functionalized cyclodiphosphazane ligand, cis-{^tBuNP(OCH₂CH₂SCH₃)}₂ (1) is described. The reactions of 1 with [Pd (COD)Cl₂] in 1:1, 1:2 and 2:1 M ratios afforded cis-[PdCl₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (2), cis-[{PdCl₂}₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (3) and trans-[PdCl₂{(^tBuNP(OCH₂CH₂SCH₃))₂}₂] (4), respectively. Treatment of 1 with [Pd(PEt₃)Cl₂]₂ or [PdCl(η³-C₃H₅)]₂ in appropriate molar ratios produce the mono- and binuclear complexes [PdCl₂(PEt₃{^tBuNP(OCH₂CH₂SCH₃)}₂] (5) and [{PdCl(η³-C₃H₅)}₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (6) in good yield. The reaction of 1 with [{Ru(p-cymene)Cl₂}₂] afforded the mononuclear cationic complex, [{(p-cymene)RuCl{^tBuNP(OCH₂CH₂SCH₃)}₂]Cl (7), whereas the reactions of [Rh(COD)Cl]₂, [Pt(COD)Cl₂] and [Au(SMe₂)Cl] with 1 yielded the corresponding P-coordinated neutral complexes, [RhCl(COD){^tBuNP(OCH₂CH₂SCH₃)}₂] (8)cis-[PtCl₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (9), respectively. The binuclear palladium(II) complex 3 was found to be an effective catalyst for the Suzuki-Miyaura cross-coupling reactions.     

A new cumulene diiron complex related to the active site of Fe-only hydrogenases and its phosphine substituted derivatives: synthesis, electrochemistry and structural characterization

A new cumulene diiron complex related to the Fe-only hydrogenase active site [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₆] (1) was obtained by treatment of (μ-LiS)₂Fe₂(CO)₆ with excess 1,4-dichloro-2-butyne. By controllable CO displacement of 1 with PPh₃ and bis(diphenylphosphino)methane (dppm), mono- and di-substituted complexes, namely [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₅L] (2: L = PPh₃; 3: L = dppm) and [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₄L₂] (4: L = PPh₃; 5: L = dppm) could be prepared in moderate yields. Treatment of 1 with bis(diphenylphosphino)ethane (dppe) afforded a double butterfly complex [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₅]₂(μ-dppe) (7). With dppm in refluxing toluene, a dppm-bridged complex [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₄(μ-dppm)] (6) was obtained. These model complexes were characterized by IR, ¹H, ³¹P NMR spectra and the molecular structures of 1, 2 and 5-7 were determined by single crystal X-ray analyses. The electrochemistry of 1-3 was studied and the electrocatalytic property of 1 was investigated for proton reduction in the presence of HOAc.     

Making 3d-4f hexanuclear clusters from heterotrinuclear cationic building blocks

The syntheses and crystal structures of two new hexanuclear complexes are reported: [{(LCu^II(ONO₂))(LCu^II(H₂O))Nd^III}₂(μ-C₂O₄)](NO₃)₂ · 6H₂O (1) and [{(LNi^II(H₂O))(N(CN)₂)}₂Pr^III}₂(ONO₂)](OH) · 2H₂O · 3CH₃CN (2) (L is the dianion of the Schiff-base resulted from the 2:1 condensation of 3-methoxysalyciladehyde with 1,3-propanediamine). Compounds 1 and 2 were obtained by connecting heterotrinuclear cationic complexes [{LM^II}₂Ln^III]³⁺ with oxalato or nitrato linkers. The structure of the complex cation in 1 shows two almost linear trinuclear [Cu₂Nd] moieties which are linked by a bis-chelating oxalato bridge between the neodymium ions. The hexanuclear cationic moiety in 2 is built up of two heterotrinuclear [Ni₂Pr] units that are linked by a nitrato group bridging two praseodymium(III) ions. The spectroscopic (FTIR, UV-Vis) and magnetic properties of 1 and 2 have been investigated.     

Electrochemical oxidation of ethanol using Nafion electrodes modified with heterobimetallic catalysts

Chemically modified electrodes were prepared by adsorption of Nafion/catalyst films of the type Nafion/Cp(PPh₃)Ru(μ-I)(μ-dppm)PdCl₂ (N1), Nafion/[η⁵-C₅H₄CH₂CH₂(NHMe₂)⁺]Ru(PPh₃)(μ-I)(μ-dppm)PtCl₂ (N2), Nafion/[η⁵-C₅H₄CH₂CH₂(NHMe₂)⁺]Ru(PPh₃)(μ-Cl)(μ-dppm)PdCl₂ (N3), Nafion/Cp(CO)Fe(μ-I)(μ-dppm)PdI₂ (N4) and Nafion/Cp(CO)Ru(μ-I)(μ-dppm)PtI₂ (N5) on glassy and vitreous carbon electrodes. Cyclic voltammetry and bulk electrolysis experiments were performed to assess the ability of these modified electrodes to electrocatalytically oxidize ethanol. Cyclic voltammograms using the N1-N5 modified glassy carbon electrodes displayed significant catalytic activity compared to oxidation of ethanol catalyzed by 1 in homogeneous solution. Bulk electrolysis of ethanol using electrodes coated with Nafion supported complexes 1-3 resulted in formation of the two- and four-electron oxidation products acetaldehyde and acetic acid, respectively, whilst bulk electrolysis using the complexes 4 and 5 produced only acetaldehyde.     

Diazo complexes of osmium: preparation of binuclear derivatives with bis(aryldiazene) and bis(aryldiazenido) bridging ligands

Depending on experimental conditions and the nature of the phosphite, the reaction of OsH₂P₄ [P=P(OEt)₃ and PPh(OEt)₂] with bis(aryldiazonium) salts [N₂Ar-ArN₂](BF₄)₂ [Ar-Ar=4,4^′-C₆H₄-C₆H₄, 4,4^′-(2-CH₃)C₆H₃-C₆H₃(2-CH₃), 4,4^′-C₆H₄-CH₂-C₆H₄ and 1,5-C₁₀H₆] afford the cis and the trans binuclear [{OsHP₄}₂(μ-HNNAr-ArNNH)](BPh₄)₂1, 2 aryldiazene derivatives. These complexes 1, 2 further react with the mono(diazonium) (4-CH₃C₆H₄N₂)BF₄ salt to give the bis(aryldiazene) [{Os(4-CH₃C₆H₄NNH)P₄}₂(μ-HNNAr-ArNNH)](BPh₄)₄3, 4 derivatives. Binuclear bis(aryldiazenido) [{OsP₄}₂(μ-N₂Ar-ArN₂)](BPh₄)₂ (6) [P=P(OEt)₃; Ar-Ar=4,4^′-C₆H₄-C₆H₄, 4,4^′-C₆H₄-CH₂-C₆H₄] complexes were prepared by deprotonating with NEt₃ the nitrile-diazene [{Os(4-CH₃C₆H₄CN)P₄}₂(μ-HNNAr-ArNNH)](BPh₄)₄ (5) derivatives. The aryldiazenido compounds 6 react with HCl to give the new aryldiazene [{OsClP₄}₂(μ-HNNAr-ArNNH)](BPh₄)₂ (7) derivatives. The characterisation of the complexes by IR and ¹H, ³¹P, ¹⁵N NMR data is also discussed. The reaction of the hydride OsH₂(PPh₂OEt)₄ with mono(diazonium) salts was also studied and led exclusively to the mono(aryldiazene) [OsH(ArN NH)(PPh₂OEt)₄]BPh₄ (8) (Ar=C₆H₅, 4-CH₃C₆H₄) derivatives. Spectroscopic data (¹H, ³¹P, ¹⁵N NMR) on ¹⁵N-labelled derivatives suggest the presence of two isomers with the N-bonded and the π-bonded ArNNH ligand, respectively.     

Multimetallic compounds containing cyclometalated Ir(III) units: Synthesis, structure, electrochemistry and photophysical properties

The reaction of the cyclometalated Ir^III dimer [{(ppy)₂Ir}₂(μ-Cl)₂] (ppyH = 2-phenylpyridine) with silver triflate followed by a multidentate ligand [1,4-bis[3-(2-pyridyl)pyrazolylmethyl]benzene (bppb), 1,3,5-tri[3-(2-pyridyl)pyrazolylmethyl]-2,4,6-trimethylbenzene (tppb), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz), 2-chloro-4,6-bis(dipyridin-2-ylamino)-1,3,5-triazine (cddt) or 2,4,6-tris(dipyridin-2-ylamino)-1,3,5-triazine (tdat)] afforded di- or trinuclear compounds: [{Ir(ppy)₂}₂(μ-bppb)](OTf)₂ (1), [{Ir(ppy)₂}₃(μ-tppb)](OTf)₃ (2), [{Ir(ppy)₂}₂(μ-tptz-OH)](OTf) (3), [{Ir(ppy)₂}₂(μ-cddt)](OTf)₂ (4) and [{Ir(ppy)₂}₂(μ-tdat)](OTf)₂ (5). All of these compounds contain cationic metal cores with corresponding triflate counter anions. The molecular structures of 1-4 reveal that the structural feature of the Ir(ppy)₂ center of the starting precursor is conserved in the products. Also, because of the nature of the ligands, there is virtually no electronic communication between the Ir^III centers except in 3 where a ring hydroxylation at the triazine carbon atom is effected upon metalation. Compounds 1-5 are robust in solution where they retain their structural integrity. The UV-Vis and emission spectra of 1-5 compounds are very similar to each other with the exception of 3 which seems to possess a different electronic structure. All the compounds are luminescent at room temperature. The emission bands indicate significant contribution from ³LC. Increase in the number of ‘Ir(ppy)₂’ units does not have any effect on emission color.     

Coordination chemistry of copper-molybdates with alkoxide ligands: The {Mo4O10(OMe)6} and [Mo2O4{RC(CH2O)3}2] clusters as building blocks

The reactions of the Keplerate super cluster [Mo₁₃₂O₃₇₂(CH₃CO₂)₃₀(H₂O)₇₂]⁴²⁻ with a Cu(II) source and an organonitrogen donor in methanol/DMF solutions yielded a series of bimetallic organic-inorganic oxide hybrid materials, including the molecular species [Cu(phen)₂MoO₄] (1) and [{Cu(terpy)}₂(MoO₄)₂] (2) and a series of materials constructed from the tetranuclear building block {Mo₄O₁₀(OMe)₆}²⁻: the molecular [{Cu₂(phen)₂(O₂CCH₃)₂ (MeOH)}Mo₄O₁₀(OMe)₆] (3), [{Cu(terpy)(O₂CCH₃)}₂Mo₄O₁₀(OMe)₆] (4) and [{Cu(terpy)Cl}₂Mo₄O₁₀(OMe)₆] (5), the one-dimensional phases [{Cu(bpy)(HOMe)₂}Mo₄O₁₀(OMe)₆] (6), [{Cu(bpy)(DMF)₂}Mo₄O₁₀(OMe)₆] (7), [{Cu(bpa)(DMF)₂}Mo₄O₁₀(OMe)₆] (8), [{Cu(phen)(DMF)₂}Mo₄O₁₀(OMe)₆] (9) and [{CuCl(dpa)}₂Mo₄O₁₀(OMe)₆] (10), and the two-dimensional material [{Cu₂(DMF)₂(pdpa)}{Mo₄O₁₀(OMe)₆}₂] (11). When methanol is replaced by the tridentate alkoxide tris-methoxypropane (trisp), the {Mo₂O₄(trisp)₂}²⁻ cluster building block is observed for [Cu(phen)Mo₂O₄(trisp)₂] (12), [Cu(bpa)(DMF)Mo₂O₄(trisp)₂] (13) and [{Cu(bpy)(NO₃)}₂Mo₂O₄(trisp)₂] (14).     

Synthesis of ruthenium(II) monosubstituted squarates: 1. Procedural considerations

Attempted syntheses of ruthenium(II) monosubstituted squarate complexes in acetonitrile using cis-[RuCl₂(dmso)₄] and anisole-, methoxy-, methyl- and diphenylamino-squarate ligands, respectively, resulted in the formation in each case of the monomer cis, fac-Ru(CH₃CN)Cl₂(dmso)₃ (1) with the ruthenium atom in a distorted octahedral environment. A second crop of crystals harvested from the reaction with the methoxysquarate ligand was identified as the oxalato-bridged dimer [{cis-(CH₃CN)(Cl)(dmso)₂Ru}₂(μ-C₂O₄)] (2). When cis-[RuCl₂(dmso)₄] and methylsquarate were reacted in aqueous solution instead of acetonitrile, the dimer [{fac-(Cl)(dmso)₃Ru}₂(μ-C₂O₄)] (3) was produced. The dimers 2 and 3 are formed from oxidation/ring opening of the methoxy- and methyl-squarate ligands, respectively. Use of the salts of these ligands instead of their non-ionised forms under different reaction conditions, afforded [Na] fac-[RuCl₃(dmso)₃] (4) and [(C₄H₉)₄N]₂[(C₄O₄)(C₄H₂O₄)₂] (7), respectively, which were shown to be products of competing reactions. The information acquired from these failed attempts has provided the basis for the development of a strategy to overcome these problems and lead to a successful synthetic route to ruthenium(II) monosubstituted squarates.     

Linear and bent oxo-bridged dinuclear rhenium(V) complexes with terminal and bridging pyrazole ligands

The [ReOX₃(AsPh₃)(OAsPh₃)] (X = Cl or Br) complexes react with two equivalents of 3,5-dimetylopyrazole (3,5-Me₂pzH) in acetone at room temperature to give [{Re(O)X₂(3,5- Me₂pzH)₂}₂(μ-O)] (1 and 2). In the case of [ReOBr₃(AsPh₃)(OAsPh₃)], a small quantity of the dinuclear rhenium complex [{Re(O)Br(3,5-Me₂pzH)}₂(μ-O)(μ-3,5-Me₂pz)₂] (3) has been isolated next to the main product 2. Treatment of [ReOX₃(PPh₃)₂] compounds with two equivalents of 3,5-Me₂pzH in acetone at room temperature leads to the isolation of symmetrically substituted dinuclear rhenium complexes [{Re(O)X(PPh₃)}₂(μ-O)(μ-3,5-Me₂pz)₂] (4 and 5). Refluxing of [ReO(OEt)X₂(PPh₃)₂] complexes with 3,5-Me₂pzH in ethanol affords unsymmetrically substituted dinuclear rhenium [{Re(O)X(PPh₃)}(μ-O)(μ-3,5-Me₂pz)₂{Re(O)X(3,5- Me₂pzH)}] complexes (6 and 7). The complexes obtained in these reactions have been characterised by IR, UV-Vis, ¹H and ³¹P NMR. The crystal and molecular structures have been determined for 1, 2, 3, 4, 6 and 7 complexes.     

Preparation, characterization and redox chemistry of oxo-centered triruthenium dimers linked by bis(diphenylphosphino)anthracene and -ferrocene

Diphosphine-bridged dimers of oxo-centered triruthenium-acetate cluster units, i.e., [{Ru₃O(OAc)₆(py)₂}₂(dppan)](PF₆)₂ (2) and [{Ru₃O(OAc)₆(py)₂}₂(dppf)](PF₆)₂ (3) were prepared by reaction of 2.3 equivalent [Ru₃O(OAc)₆(py)₂(CH₃OH)](PF₆) with 9,10-bis(diphenylphosphino)anthracene (dppan) or 1,1′-bis(diphenylphosphino)ferrocene (dppf), respectively. Apparent redox wave splitting is observed in complex 2, revealing the presence of electronic communication between two triruthenium units mediated through bridging dppan. The complexes were characterized by elemental analysis, IR, UV-Vis, ³¹P NMR, and ES-MS spectroscopies, and cyclic and differential-pulse voltammetry. The crystal structure of complex 3 was determined by X-ray crystallography.     

Sn-S and Ru-Ru bonds cleavage reactions between [Ph3SnS(CH2)3SSnPh3] and Ru3(CO)12: X-ray crystal structures of [Ph3SnS(CH2)3SSnPh3] and trans-[Ru(CO)4(SnPh3)2]

The organotin complex [Ph₃SnS(CH₂)₃SSnPh₃] (1) was synthesized by PdCl₂ catalyzed reaction between Ph₃SnCl and disodium-1,3-propanedithiolate which in turn was prepared from 1,2-propanedithiol and sodium in refluxing THF. Reaction of 1 with Ru₃(CO)₁₂ in refluxing THF affords the mononuclear complex trans-[Ru(CO)₄(SnPh₃)₂] (2) and the dinuclear complex [Ru₂(CO)₆(μ-κ²-SCH₂CH₂CH₂S)] (3) in 20 and 11% yields, respectively, formed by cleavage of Sn-S bond of the ligand and Ru-Ru bonds of the cluster. Treatment of pymSSnPPh₃ (pymS = pyrimidine-2-thiolate) with Ru₃(CO)₁₂ at 55-60 °C also gives 2 in 38% yield. Both 1 and 2 have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction analysis.     

Reactions of the complexes [Re2(CO)9(η-P-P)] (P-P=Ph2P(CH2)nPPh2, n=1-6) with Me3NO: formation of close-bridged complexes [Re2(CO)8(μ-P-P)] and phosphine oxide complexes [Re2(CO)9{P-P(O)}]

Reactions of [Re₂(CO)₁₀] with Me₃NO and diphosphines [Ph₂P(CH₂)_nPPh₂, n=1-6] yield mixtures of the monodentate-coordinated diphosphine complexes [Re₂(CO)₉(η¹-P-P)] (P-P=Ph₂P(CH₂)_nPPh₂, n=1-6) (yields 5-40%) and bridged dimers [{Re₂(CO)₉}₂(μ-P-P)] (5-50%). These complexes were isolated as either equatorial or axial isomers, or a mixture of two isomers. Reactions of the monodentate complexes with Me₃NO yield close-bridged complexes [Re₂(CO)₈(μ-P-P)] and phosphine oxide complexes [Re₂(CO)₉{P-P(O)}]. The structures of the close-bridged complexes 1 (n=3) and 2 (n=4), were determined by X-ray crystallography. The Re-Re bond in the close-bridged complex with the longest phosphine chain (n=6) is readily cleaved in CDCl₃ to give the complex [{cis-ReCl(CO)₄}₂(μ-dpph)] (3) as the product, the structure of which was also determined by X-ray crystallography.     

Synthesis and solid-state structures of (triphos)iridacyclopentadiene complexes as models for vinylidene intermediates in the [2 + 2 + 1] cyclotrimerization of alkynes

The iridium 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) complexes [{κ²(C¹,C⁴)-CRCRCRCR}{CH₃C(CH₂PPh₂)₃}Ir(NCMe)]BF₄ (2-NCMe, R = CO₂Me) and [{κ²(C¹,C⁴)-CRCRCRCR}{CH₃C(CH₂PPh₂)₃}Ir(CO)]BF₄ (2-CO, R = CO₂Me) serve as models for proposed iridium-vinylidene intermediates of relevance to the [2 + 2 + 1] cyclotrimerization of alkynes. The solid-state structures of 2-NCMe, 2-CO, and [κ²(C¹,C⁴)-CRCRCRCR]{CH₃C(CH₂PPh₂)₃}Ir(Cl) (2-Cl), were determined by X-ray crystallography.     

Coordination polymers derived from a bis-pyridyl-bis-amide ligand: Supramolecular structural diversities and anion binding properties

Six new coordination polymers namely [{Cu(μ-L1)(CH₃COO)₂}]_∝1a, [{Cu(μ-L1)₂(CH₃COO)₂]_∝1b, [{Cu(μ-L1)₂(H₂O)₂}(NO₃)₂]_∝2, [{Cu(μ-L1)₂(H₂O)₂}(ClO₄)₂]_∝3, [{Cu(μ-L1)(H₂O)₂(μ-SO₄)}·3H₂O]_∝4a and [{Cu(μ-L1)₂SO₄}·X]_∝4b (L1 = N,N′-bis-(3-pyridyl)terephthalamide) have been synthesized. Single crystal structures of five coordination polymers namely 1a, 2-4b and the free ligand L1 are discussed in the context of the effect of conformation dependent ligating topology of the ligands, hydrogen bonding backbone, counter anions on the resultant supramolecular structures observed in these coordination polymers. It was revealed from the single crystal X-ray structure analysis that conformation dependent ligating topology of the bis-amide ligand L1, counter anion’s ligating strength dependent metal: ligand ratio, hydrogen bonding ability of the ligand as well as counter anions are responsible for the formation of 1D zigzag, 1D looped chain, 2D corrugated sheet in 1a, 2-3, 4a−4b, respectively. By following in situ coordination polymer crystallization technique, anion binding and separation studies have also been performed; nitrate anion has been separated as neat coordination polymer crystals from a complex mixture of anions.     

Two star‐shaped tetranuclear Ru(II) complexes containing uncoordinated imidazole groups: synthesis,characterization, photophysical and pH sensing properties

Tetrapodal ligands H₄L¹ and H₄L² containing imidazole groups have been synthesized by the reaction of 1,10‐phenanthroline‐5,6‐dione with 1,2,4,5‐tetrakis[(4‐formylphenoxy)methyl]benzene and 1,2,4,5‐tetrakis[(3‐formylphenoxy)methyl]benzene, respectively, in presence of NH₄OAc. Two star‐shaped complexes [{Ru(bpy)₂}₄(μ₄‐H₄L¹)](PF₆)₈ and [{Ru(bpy)₂}₄(μ₄‐H₄L²)](PF₆)₈ (bpy = 2,2′‐bipyridine) have been prepared by refluxing Ru(bpy)₂Cl₂·2H₂O and each ligand in ethylene glycol. The deprotonated complexes [{Ru(bpy)₂}₄(μ₄‐L¹)](PF₆)₄ and [{Ru(bpy)₂}₄(μ₄‐L²)](PF₆)₄ have been obtained by the reaction of sodium methoxide with [{Ru(bpy)₂}₄(μ₄‐H₄L¹)](PF₆)₈ and [{Ru(bpy)₂}₄(μ₄‐H₄L²)](PF₆)₈, respectively, in methanol. The pH effects on the UV–vis light absorption and emission spectra of both complexes have been studied, and ground‐ and excited‐state ionization constants of both complexes have been derived. The photophysical properties of both complexes are strongly dependent on the solution pH. They act as proton‐induced off–on–off luminescent sensors through two successive deprotonation processes of imidazole groups, with a maximum on–off ratio of 8 in buffer solution at room temperature. Theoretical calculations for the highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LOMO) orbitals of bridging ligand are also presented for plausible explanations of the fluorescence changes. Copyright © 2015 John Wiley & Sons, Ltd.     

Electrochemical oxidation of methanol using alcohol-soluble Ru/Pt and Ru/Pd catalysts

The heterobimetallic Ru/Pt and Ru/Pd complexes [η⁵-C₅H₄CH₂CH₂N(CH₃)₂ · HI]Ru(PPh₃)(μ-I)(μ-dppm)PtCl₂ (7), [η⁵-C₅H₄CH₂CH₂N(CH₃)₂ · HI]Ru(PPh₃)(μ-I)(μ-dppm)PtI₂ (8), [η⁵-C₅H₄CH₂CH₂N(CH₃)₂ · HI]Ru(PPh₃)(μ-I)(μ-dppm)PdCl₂ (9), and [η⁵-C₅H₄CH₂CH₂N(CH₃)₂ · HI]Ru(PPh₃)(μ-I)(μ-dppm)PdI₂ (10) were prepared by the reaction of [η⁵-C₅H₄CH₂CH₂N(CH₃)₂ · HI]Ru(PPh₃)I(κ¹-dppm) (6) with Pt(COD)Cl₂, Pt(COD)I₂, and Pd(COD)Cl₂, respectively. Electronic interaction between the two metals is significant for the iodide-bridged compounds 7-10, as evidenced by the shifts of their redox potentials in comparison to the mononuclear complexes. The electrochemical oxidation of methanol was carried out with heterobimetallic complexes 7-10 and leads to the formation of dimethoxymethane (DMM) and methyl formate (MF) as the major oxidation products. The chloride complexes 7 and 9 are the most active catalysts, as evidenced by their TON and current efficiencies. Addition of water at the beginning of the electrolysis results in increased formation of the more oxidized product MF along with higher current efficiencies and TON.     

Formation and structural chemistry of the unusual cyanide-bridged dinuclear species [Ru2(NN)2(CN)7] (NN = 2,2′-bipyridine or 1,10-phenanthroline)

Crystallisation of simple cyanoruthenate complex anions [Ru(NN)(CN)₄]²⁻ (NN = 2,2′-bipyridine or 1,10-phenanthroline) in the presence of Lewis-acidic cations such as Ln(III) or guanidinium cations results, in addition to the expected [Ru(NN)(CN)₄]²⁻ salts, in the formation of small amounts of salts of the dinuclear species [Ru₂(NN)₂(CN)₇]³⁻. These cyanide-bridged anions have arisen from the combination of two monomer units [Ru(NN)(CN)₄]²⁻ following the loss of one cyanide, presumably as HCN. The crystal structures of [Nd(H₂O)_5.5][Ru₂(bipy)₂(CN)₇] · 11H₂O and [Pr(H₂O)₆][Ru₂(phen)₂(CN)₇] · 9H₂O show that the cyanoruthenate anions form Ru-CN-Ln bridges to the Ln(III) cations, resulting in infinite coordination polymers consisting of fused Ru₂Ln₂(μ-CN)₄ squares and Ru₄Ln₂(μ-CN)₆ hexagons, which alternate to form a one-dimensional chain. In [CH₆N₃]₃[Ru₂(bipy)₂(CN)₇] · 2H₂O in contrast the discrete complex anions are involved in an extensive network of hydrogen-bonding involving terminal cyanide ligands, water molecules, and guanidinium cations. In the [Ru₂(NN)₂(CN)₇]³⁻ anions themselves the two NN ligands are approximately eclipsed, lying on the same side of the central Ru-CN-Ru axis, such that their peripheries are in close contact. Consequently, when NN = 4,4′-^tBu₂-2,2′-bipyridine the steric bulk of the t-butyl groups prevents the formation of the dinuclear anions, and the only product is the simple salt of the monomer, [CH₆N₃]₂[Ru(^tBu₂bipy)(CN)₄] · 2H₂O. We demonstrated by electrospray mass spectrometry that the dinuclear by-product [Ru₂(phen)₂(CN)₇]³⁻ could be formed in significant amounts during the synthesis of monomeric [Ru(phen)(CN)₄]²⁻ if the reaction time was too long or the medium too acidic. In the solid state the luminescence properties of [Ru₂(bipy)₂(CN)₇]³⁻ (as its guanidinium salt) are comparable to those of monomeric [Ru(bipy)(CN)₄]²⁻, with a ³MLCT emission at 581 nm.     

Octanuclear {Co6W2} aggregate versus mixed valence {Co}3 cluster in the assembling of Co(phen)2Cl2 (phen = 1,10-phenanthroline) with octacyano metallates: A case of non-isostructurality between {W(CN)8}4− and {Nb(CN)8}4−

An unprecedented octanuclear aggregate, [{Co(phen)₂}₆{W(CN)₈}₂Cl₂] · 2Cl, 2, resulted from the assembling of {Co(phen)₂Cl₂}, 1, and {W(CN)₈}^4?. Surprisingly, the reaction with the paramagnetic {Nb(CN)₈}^4? unit did not afford the homologous {Co–Nb} cluster. Instead the latter building unit undergoes dissociation which led to the formation of a mixed-valence [{Co^II(phen)₂}{Co^III(phen)(CN)₄}₂], 3. This observation is in contrast to the usual trend that {Nb^IV(CN)₈}^4? forms compounds isostructural to that observed for {Mo^IV(CN)₈}^4? and {W^IV(CN)₈}^4?. The structures of the compounds 2 and 3 have been established by single crystal X-ray diffraction. Magnetic behaviors for compounds 1–3 are reported.     

Heteroligand copper(I) complexes of N-thiophosphorylated thioureas and phosphanes: Versatile structures and luminescence

Reaction of the potassium salts of (EtO)₂P(O)CH₂C₆H₄-4-(NHC(S)NHP(S)(OiPr)₂) (HL^I), (CH₂NHC(S)NHP(S)(OiPr)₂)₂ (H₂L^II) or cyclam(C(S)NHP(S)(OiPr)₂)₄ (H₄L^III) with [Cu(PPh₃)₃I] or a mixture of CuI and Ph₂P(CH₂)_1-3PPh₂ or Ph₂P(C₅H₄FeC₅H₄)PPh₂ in aqueous EtOH/CH₂Cl₂ leads to [Cu(PPh₃)L^I] (1), [Cu₂(Ph₂PCH₂PPh₂)₂L^II] (2), [Cu{Ph₂P(CH₂)₂PPh₂}L^I] (3), [Cu{Ph₂P(CH₂)₃PPh₂}L^I] (4), [Cu{Ph₂P(C₅H₄FeC₅H₄)PPh₂}L^I] (5), [Cu₂(PPh₃)₂L^II] (6), [Cu₂(Ph₂PCH₂PPh₂)L^II] (7), [Cu₂{Ph₂P(CH₂)₂PPh₂}₂L^II] (8), [Cu₂{Ph₂P(CH₂)₃PPh₂}₂L^II] (9), [Cu₂{Ph₂P(C₅H₄FeC₅H₄)PPh₂}₂L^II] (10), [Cu₈(Ph₂PCH₂PPh₂)₈L^IIII₄] (11), [Cu₄{Ph₂P(CH₂)₂PPh₂}₄L^III] (12), [Cu₄{Ph₂P(CH₂)₃PPh₂}₄L^III] (13) or [Cu₄{Ph₂P(C₅H₄FeC₅H₄)PPh₂}₄L^III] (14) complexes. The structures of these compounds were investigated by IR, ¹H, ³¹P{¹H} NMR spectroscopy; their compositions were examined by microanalysis. The luminescent properties of the complexes 1-14 in the solid state are reported.