The use of the borocaptate anion as a ligand. Synthesis and X-ray crystal structure of pentaammine (1-thiolato-closo-undecahydrododecaborane)ruthenium(III) dihydrate

The complex [Ru(SB₁₂H₁₁)(NH₃)₅]·2H₂O has been prepared by the reaction of Cs₂B₁₂H₁₁SH with [RuCl(NH₃)₅]Cl₂ in aqueous solution. The complex represents the first reported example of the borocaptate anion acting as a ligand. The structure of the complex has been determined by single crystal X-ray diffraction analysis. The crystal parameters are monoclinic, space group P2₁/c, A = 8.056(1), B = 14.240(2), C = 15.172(2) Å, β=98.48° and Z = 4. The ruthenium atom has a distorted octahedral coordination. The distortion is probably due to the high (3⁻) charge and the large bulk of the borocaptate ligand. These features can also be observed in the spectroscopic properties of the complex.     

Direct nitration of aryl groups σ-bound to ruthenium(II)

A new method has been developed for the preparation of nitroaryl transition metal complexes using copper(II) nitrate in the presence of acetic anhydride (Menke conditions) to directly nitrate an aryl group which is already σ-bound to a transition metal centre. Under these conditions ruthenium(II) aryl complexes of the type: (where R₁=R₂=H; R₁=H, R₂=CH₃; R₁=CH₃, R₂=H) react to yield three distinct types of nitroaryl-containing products (I–III).

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The preparation and characterisation of these compounds are described. X-ray crystallographic data for one example of each of the three types of compound, are also reported. The compounds that have been studied crystallographically are Ru(C₆H₄NO₂-4)(η²-O₂CCH₃)(CO)(PPh₃)₂ (1a), C₄₅H₃₇NO₅P₂Ru·(CH₂Cl₂)_0.5, a = 20.254(5), b=19.437(8), c=22.629(3) Å, β=115.390(10)°, monoclinic, space group C2/c, Z=8; Ru(C6H4N[O]O-2)- Cl(CO)(PPh₃)₂ (4a), C₄₃H₃₄ClNO₃P₂Ru, a=9.331(3), b=12.443(2), c=16.346(3) Å, =82.81(2), β=85.03(2), γ=74.76(2)°, triclinic, space group P , Z=2; Ru(C₆H₂CH₃-2,NO₂-4,N[O]O-6)Cl(CO)(PPh₃)₂ (5b), C₄₄H₃₅Cl- N₂O₅P₂Ru·(CH₂Cl₂)₂, a=19.497(3), b=14.502(3), c=19.340(5) Å, β=122.79(1)°, monoclinic, space group Cc, Z=4.     

Preparation of ruthenium(II) chloride complexes of polybasic amines

The reactions of RuCl₂[P(C₆H₅)₃]₃, RuCl₂(tmeda)₂, and RuCl₂(1,5-COD)(tmeda) with polybasic amines such as pyrazole have been studied. From the phosphine complex, a binuclear complex has been isolated in which one pyrazole has been incorporated, while reactions of the latter two with excess pyrazole lead to the replacement of a tmeda ligand by two pyrazoles.     

Control of the migratory aptitudes of vinyl and aryl ligands in ruthenium(II) complexes

Complexes Ru(CO)₂ (CH=CHR) (C₆H₄X-4)L₂ (R=^tBu, Ph, OEt; X=H, Cl, OMe; L=PMe₃, PMe₂Ph, P(OMe)₂Ph) in which the two phosphorus ligands are mutually cis (isomer 1) react readily with ligands ^tBuNC, CO and P(OMe)₃ to give complexes in which one of the organic ligands has migrated onto a carbonyl ligand. Vinyl migration products (5) retain the mutually cis geometry of the phosphorus ligands, and are unstable: one of the decomposition products is the ketone RCH=CHC(O)C₆H₄X-4. Phenyl migration products (4) are stable and have the phosphorus ligands in mutually trans positions; an X-ray crystal structure of Ru(CO) (CN^tBu) {C(O)Ph} (CH=CHPh) (PMe₂Ph)₂ was obtained. In both cases, the incoming ligand enters trans to the newly formed acyl ligand. Vinyl migration is favoured over aryl migration by electron-donating substituents on the vinyl ligand, electron-withdrawing substituents on the aryl ligand, good σ-donor phosphorus ligands and use of ^tBuNC as the incoming ligand. The rate of phenyl migration in Ru(CO)₂(CH=CHPh)Ph(PMe₂Ph)₂ is independent of ^tBuNC concentration: k=1.5 × 10⁻³ s⁻¹ at 20°C. Isomer 3 of complexes Ru(CO)₂(CH=CHR) (C₆H₄X-4)L₂ in which the phosphorus ligands are mutually trans is much less reactive towards migration reactions. The reactivity of isomer 1 is attributed to the steric strain of two mutually cis phosphorus ligands.     

Syntheses, spectra and crystal structures of ruthenium(II) complexes with polypyridyl: [Ru(bipy)2(phen)](ClO4)2 · H2O and [Ru(bipy)2(Me-phen)](ClO4)2

Two ruthenium(II) complexes with polypyridyl, Ru(bipy)₂(phen)](ClO₄)₂·H₂O (1) and [Ru(bipy)₂(Me-phen)](ClO₄)₂ (2), (phen = 1,10-phenanthroline, bipy = 2,2′-bipyridine, Me-phen = 5-methyl-1,10-phenanthroline), were synthesized and characterized by IR, MS and NMR spectra. Their structures were determined by single crystal X-ray diffraction techniques. The strong steric interaction between the polypyridyl ligands was relieved neither by the elongation of the Ru---N bonds nor increase of the N---Ru---N bite angles. The coordination sphere was distorted to relieve the ligand interaction by forming specific angles (δ) between the polypyridyl ligand planes and coordination planes (N---Ru---N), and forming larger twisted angles between the two pyridine rings for each bipy. The bond distances of Ru---N(bipy) and Ru---N(phen) were virtually identical with experimental error, as expected of π back-bonding interactions which statistically involve each of the ligands present in the coordination sphere.     

Synthesis and characterization of new ruthenium(II) complexes containing coupled di(2-pyridyl) and 1,3-dithiole units

Two new ruthenium (II) complexes containing coupled di(2-pyridyl) and 1,3-dithiole units, cis-[Ru(Medpydt)₂(NCS)₂] (2, Medpydt = dimethyl 2-(di(2-pyridyl)methylene)-1,3-dithiole-4,5-dicarboxylate) and cis-[Ru(H₂dpydt)₂(NCS)₂] (3, H₂dpydt = 2-(di(2-pyridyl)methylene)-1,3-dithiole-4,5-dicarboxylate), have been synthesized and characterized. The structure of complex 2 has been determined by X-ray crystallography. There exist intermolecular H-bonding interactions between carbomethoxy groups on neighboring pyridine rings giving rise to 2D H-bonded arrays. The metal-to-ligand charge-transfer (MLCT) absorptions were observed around 480 nm. Redox properties of ruthenium complexes have been investigated by cyclic voltammetry. Solar cells involving thin films of anatase TiO₂ impregnated with cis-[Ru(H₂dpydt)₂(NCS)₂] were prepared, and the photovoltaic performance was preliminarily investigated.     

Synthesis, chemical- and electrochemical properties of ruthenium(II) complexes bearing 2,6-bis(2-naphthyridyl)pyridine

Ruthenium complexes with a terpyridine-analogous ligand, 2,6-bis(2-naphthyridyl)pyridine (bnp), have been synthesized and their chemical and electrochemical properties investigated. The structures of [Ru(bnp)(tpy)](PF₆)₂ (1) and [Ru(bnp)₂](PF₆)₂ (2) were determined by the X-ray structure analysis. The bnp localized redox potentials of 1 and 2 showed significant positive shift by 260-290 mV relative to the analogous Ru-terpyridine complexes.     

Synthesis, characterization and reactivity of polypyridyl ruthenium(II) carbonyl complexes with phosphine derivatives: Ruthenium-carbon bond labilization based on steric and electronic effects

Ruthenium phosphine complexes with a CO ligand [Ru(tpy)(PR₃)(CO)Cl]⁺ (tpy = 2,2′:6′,2″-terpyridine, R = Ph or p-tolyl), were prepared by introduction of CO gas to the corresponding dichloro complexes at room temperature. New carbonyl complexes were characterized by various methods including structural analyses. They were shown to release CO following the addition of several N-donors to form the corresponding substituted complexes. The kinetic data and structural results observed in this study indicated that the CO release reactions proceeded in an interchange mechanism. The molecular structures of [Ru(tpy)(PPh₃)(CO)Cl]PF₆, [Ru(tpy)(P(p-tolyl)₃)(CO)Cl]PF₆ and [Ru(tpy)(PPh₃)(CH₃CN)Cl]PF₆ were determined by X-ray crystallography.     

Synthesis and characterization of polypyridineruthenium(II) complexes containing a linear ambidentate ligand, NCO or NCS, and reaction of isocyanato complexes under acidic conditions

Isocyanato and isothiocyanatopolypyridineruthenium complexes, [Ru(NCX)Y(bpy)(py)₂]ⁿ⁺ (bpy=2,2′-bipyridine, PY=pyridine; X=O, Y=NO₂ for n=0, and Y=py for n=1; X=S, Y=NO₂ for n=0, Y=NO for n=2, and Y=py for n=1), were synthesized by the reaction of polypyridineruthenium complexes with potassium cyanate or sodium thiocyanate salt. Isocyanatoruthenium(II) complexes, [Ru(NCO)(NO₂)(bpy)(py)₂] and [Ru(NCO)(bpy)(py)₃]⁺, react under acidic conditions to form the corresponding ammineruthenium complexes, [Ru(NO)(NH₃)(bpy)(py)₂]³⁺. The molecular structures of [Ru(NCO)(bpy)(py)₃]ClO₄, [Ru(NCS)(NO)(bpy)(py)₂](PF₆)₂ and [Ru(NO)(NH₃)(bpy)(py)₂](PF₆)₃ were determined by X-ray crystallography.     

Bis(mercapto) and hydrido(thiolate) complexes of Ru(II)–dppm (dppm=Ph2PCH2PPh2)

From a mixture of cis- and trans-Ru(SH)₂(dppm)₂ (4), formed from reaction of H₂S with trans-Ru(H)Cl(dppm)₂ (2), a crystal of cis-4 has been isolated and its structure determined by X-ray analysis. The mercapto protons are located within the centrosymmetric structure, although the S-atoms are partially disordered (S–H1.06 Å). The thiolate complexes, trans-Ru(H)SR(dppm)₂ (R=Ph, 5a; C₆F₅, 5b), have been isolated from reaction of trans-2 with 1 equiv. of RSH. trans-Ru(H)SH(dppm)₂ (3) has been isolated from reaction of H₂S with a mixture of cis- and trans-Ru(H)₂(dppm)₂ (1). An improved synthetic route for 1 is presented.     

Synthesis and properties of the dichloro [tetramethyl (trifluoromethyl)cyclopentadienyl]ruthenium dimer: X-ray structure of [M2(η-C5Me4CF3)2Cl2(μ-Cl)2] (M=Ru, Rh)

The reaction of RuCl₃(H₂O), with C₅Me₄CF₃J in refluxing EtOH gives [Ru₂(η⁵-C₅Me₁CF₂)₂ (μ-Cl₂] (20 in 44% yield. Dimer 2 antiferromagnetic (−2J=200 cm¹). The crystal structures of 2 (rhombohedral system, R3 space group, Z=9, R=0.0589) and [Rh₂(η⁵-C₅Me₄CF₃(₂Cl₂(μ-Cl)₂] (3) (rhombohedral system. space group, Z = 9, R = 0.0641) were solved; both complexes have dimeric structures with a trans arrangement of the η⁵-C₅Me₄CF₄ rings. Comparison of the geometry of 2 and 3 with those of the corresponding η⁵-C₅Me₅ complexes shows that lowering the ring symmetry causes significant distortion of the M₂(μ-Cl)₂ moiety. The analysis of the MCl₃ fragment conformations in 2 and 3 and in the η⁵-C₅ME₅ analogues shows that they are correlated with the M---M distances. The Cl atoms are displaced by Br on reaction of 2 with KBr in MeOH to give the diamagnetic dimer [Ru₂(η⁵-C₅Me₄CF₃)₂Br₂ (μ-Br₂] (4). Complex 2 reacts with O₂ in CH₂Cl₂ solution at ambient temperature to form a mixture of isomeric η⁶-fulvene dimers [Ru₂(η⁶-C₅Me₃CF₃ = CH₂)₂Cl₂(μ-Cl)₂] (5). Reactions of 5 with CO and allyl chloride give Ru(η⁵-C₅Me₃CF₃CH₂Cl)(CO)₂Cl (6) and Ru(η⁵-C₅Me₃CF₃CF₃CH₂Cl)(η³-C₃H₅)Cl₂ (7) respectively.     

Heterobimetallic chloro bridgedcomplexes of (η:η−C10H16)-ruthenium(IV) with palladium(II), platinum(II), rhodium(III), iridium(III), copper(I) and rhodium(I)

Metathesis of [(η³:η³−C₁₀H₁₆)Ru(Cl) (μ−Cl)]₂ (1) with [R₃P) (Cl)M(μ-Cl)]₂ (M = Pd, Pt), [Me₂NCH₂C₆H₄Pd(μ-Cl)]₂ and [(OC)₂Rh(μ-Cl)]₂ affords the heterobimetallic chloro bridged complexes (η³:η³-C₁₀H₁₆) (Cl)Ru(μ-Cl)₂M(PR₃)(Cl) (M = Pd, Pt), (η³:η³-C₁₀H₁₆) (Cl)Ru(μ-Cl)₂PdC₆H₄CH₂NMe₂ and (η³:η³-C₁₀H₁₆) (Cl)Ru(μ-Cl)₂Rh(CO)₂, respectively. Complex 1 reacts with [Cp^*M(Cl) (μ-Cl)]₂ (M = Rh, Ir), [p-cymene Ru(Cl) (μ-Cl]₂ and [(Cy₃P)Cu(μ-Cl)]₂ to give an equilibrium of the heterobimetallic complexes and of educts. The structures of (η³:η³-C₁₀H₁₆)Ru(μ-Cl)₂Pd(PR₃) (Cl) (R = Et, Bu) and of one diastereoisomer of (η³:η³-C₁₀H₁₆)Ru(μ-Cl)₂IrCp^*(Cl) were determined by X-ray diffraction.     

Pyrazolonato complexes of lead. Crystal structures of bis(1-phenyl-3-methyl-4-acetyl pyrazolonato)lead(II) and bis(1-phenyl-3-methyl-4-butanoylpyrazolonato)lead(II)

The structures of the complexes [PbL₂], L = 1-phenyl-3-methyl-4-acylpyrazolonato, RCOC₁₀H₈N₂O, R = Me (2) or Pr (3), have been determined by X-ray diffraction studies. Compound 2 is monoclinic, space group P2₁, A = 11.285(4), B = 14.727(4), C = 20.749(5) Å, β = 95.83(3)°, R = 0.039 for 4486 reflections, and 3 is monoclinic, space group C2/c, A = 27.528(11), B = 7.245(11), C = 14.264(7) Å, β = 113.6(3)°, R = 0.021 for 2118 reflections. There are three different lead environments in 2 but only one in 3. In each case the lead atom makes four strong bonds to oxygen and two weaker bonds to either oxygen or nitrogen in adjacent molecules.     

Complexes of copper(II) dihalide with 2,2′-dipyridylamine. X-ray diffraction structures of the [dibromo-bis(dipyam)copper(II)]–water (1:2) and di[chloro-bis(dipyam)copper(II)]diiodide–acetonitrile (1:2) complexes

The formation of complexes between copper(II) halides and 2,2′-dipyridylamine (dipyam) has been studied systematically. Only complexes with a 1:1 and 1:2 metal-to-ligand ratio are formed. Some mixed chloro–iodide and halide–PF₆ compounds have also been isolated. The X-ray diffraction structures of the [Cu(dipyam)₂Br₂] · 2H₂O (I) and the [Cu(dipyam)₂Cl]₂I₂ · 2CH₃CN (II) complexes are reported. I is a rare example of an octahedral coordination among the copper(II) halide complexes of dipyam. The two bromo atoms, which occupy the apical positions, are H-bonded to the water molecules of crystallization. II is a dimer, where each copper forms a cationic chloro-complex of approximately trigonal bipyramidal geometry, the dimerization being due to hydrogen bonds formed by the NH group of one of the two dipyams coordinated to each metal atom with the chlorine atom of the centrosymmetric cationic complex. The iodide anions are hydrogen-bonded to the NH groups of the dipyams not involved in the dimerization.     

Structure and spectroscopic studies of cis-bis(bipyridine) ruthenium(II) complexes of phenylcyanamide ligands

New ruthenium(II) complexes with cyanamide ligands, cis-[Ru(bpy)₂(Ipcyd)₂] (1) and [Ru(bpy)₂(OHpcyd)₂] (2) (bpy = 2,2′-bipyridine, Ipcyd = 4-iodophenylcyanamide anion, OHpcyd = 4-(3-hydroxy-3-methylbut-1-ynil)phenylcyanamide), have been prepared and characterized by UV-Vis, IR and ¹H NMR spectroscopies as well as electrochemical technique (CV). The complex cis-[Ru(bpy)₂(Ipcyd)₂] (1) crystallized with empirical formula of C₃₄H₂₄I₂N₈Ru in a monoclinic crystal system and space group of P2₁/c with a = 11.769(7) Å, b = 24.188(12) Å, c = 11.623(2) Å, β = 91.63(3)°, V = 3308(3) ų and Z = 4.     

Reactivity of cationic carbonyl/phosphine ruthenium(II) compounds

Cis(or trans)-[RuCl₂(CO)₂(PPh₃)₂] react with two and one equivalents of AgBF₄ to give the recently reported [Ru(CO)₂(PPh₃)₂][BF₄]₂·CH₂Cl₂ (1) and novel [RuCl(CO)₂(PPh₃)₂][BF₄] · 1/2 CH₂Cl₂ (2), respectively. Cis-[RuCl₂(CO)₂(PPh₃)₂] also reacts with two equivalents of AgBF₄ in the presence of CO to give [Ru(CO)₃(PPh₃)₂][BF₄]₂ (3). Reactions of 1 and 2 with NaOMe and CO at 1 atm produce the carbomethoxy species [Ru(COOMe)₂(CO)₂(PPh₃)₂] (4) and [RuCl(COOMe)(CO)₂(PPh₃)₂] (5), respectively. Complex 4 can also be formed from the reaction of 3 with NaOMe and CO. Alternatively, 4 is formed from cis-[RuCl₂(CO)₂(PPh₃)₂] with NaOMe and CO at elevated pressure (10 atm); if these reactants are refluxed under 1 atm of CO, [Ru(CO)₃(PPh₃)₂] is the product. The reaction of [RuCl(CO)₃(PPh₃)₂][AlCl₄] with NaOMe provides an alternative route to the preparation of 5, but the product is contaminated with [RuCl₂(CO)₂(PPh₃)₂]. Compounds 1. 2, 4 and 5 have been characterised by IR, ¹H NMR and analysis, whilst the formulation of 3 is proposed from spectroscopic data only. This account also examines the reactivity of [Ru(CO)₂(PPh₃)₂][BF₄]₂ · CH₂Cl₂ with NaBH₄, conc. HCl, KI and, finally, MeCOONa in the presence of CO. The products of these reactions, namely cis-[RuH₂(CO)₂(PPh₃)₂], cis-[RuCl₂(CO)₂(PPh₃)₂], cis-[RuI₂(CO)₂(PPh₃)₂] and [Ru(OOCMe)₂(CO)₂(PPh₃)₂], have been identified by comparison of their spectra with previous literature.     

Ligand connected metal clusters. The molecular structures and solid state packing of {Ru3(CO)11}2(bis(diphenylphosphino)ethane) and {Ru3(CO)11}2(1,4-bis(diphenylphosphino)benzene)

The preparation and structural characterization of {Ru₃(CO)₁₁}₂(1,4-bis(diphenylphosphino)benzene), a modified synthesis of 1,4-bis(diphenylphosphino)benzene, and the structural characterization of {Ru₃(CO)₁₁}₂(bis(diphenylphosphino)ethane) are reported. In both compounds two metal cluster units are connected through ditertiary-phosphine ligands. Both molecules consist of centrosymmetric units in which the diphosphine ligands are largely covered by the triangular ruthenium clusters. No direct interaction between the two cluster units occurs within individual molecules. Molecular packing in the solid state is dominated by interactions between sets of carbon monoxide ligands in motifs that were previously identified in the solid state structure of the parent cluster, Ru₃(CO)₁₂.     

Reactions between ruthenium cluster carbonyls and 1,4-diphenylbuta-1,3-diyne

The complexes RuC(CCPh)=CPhC(CCPh)=CPh(CO)₃(NMe₃) (3), Ru₂μ-C(CCPh)=CPhC(CCPh)=CPh(CO)₆ (1), Ru₂μ-[C(CCPh)=CPh]₂CO(CO)₆ (2), Ru₃(μ₃-PhC₂CCPh)(μ-CO)(CO)₉ (4) and Ru₄(μ₄-PhC₂CCPh)(CO)₁₂ (5) have been isolated from reactions between PhC₂C₂Ph and Ru₃(CO)₁₂ or RU₃(CO)₁₀(NCMe)₂. The molecular structures of complexes 1, 2, 3 and 5 have been determined from single-crystal X-ray studies. All complexes have precedents in similar products obtained from reactions involving mono-ynes; in the present cases, each alkyne fragment retains a phenylethynyl (PhCC---) group as a non-coordinated substituent.     

Relationship between pKa of 8-quinolinol derivatives and a π-donor ability of the 8-quinolinolato oxygen in linear nitrosylruthenium(II) complexes

The relationship between the pK_a of 8-quinolinol derivatives {8-quinolinol (Hqn), 2-methyl- (H2-Meqn), 2,4-dimethyl- (H2,4-diMeqn), 5-chloro- (H5-Clqn) and 5,7-dichloro-8-quinolinols (H5,7-diClqn)} and a π-donor ability of the 8-quinolinolato oxygens has been investigated by the identification of the structures of the major products, [RuCl(QN)(QN′)NO] (HQN=8-quinolinol derivative; HQN′=different 8-quinolinol derivatives), obtained by the reaction of [RuCl₃(QN or QN′)NO]⁻ with HQN′ or HQN. The results obtained clearly showed that the oxygen of the 8-quinolinol derivative that has a higher pK_a predominantly coordinates in the trans position to the NO ligand and is a better π-electron donor. The order of the π-electron donor ability for the oxygen of the 8-quinolinol derivatives is as follows: H2-Meqn≥H2,4-diMeqn>Hqn≥H5-Clqn>H5,7-diClqn, almost agreeing with the magnitude of the pK_a values of the corresponding 8-quinolinols. The structures of cis-1 [RuCl(5,7-diClqn)₂NO] and cis-1 [RuCl(5,7-diClqn)(2-Meqn)NO] were determined by X-ray diffraction.     

Spectroelectrochemical studies of some ruthenium(II) complexes with polypyridyl bridging ligands

Ruthenium(II) bis(2,2″-pyridyl) complexes with bridging ligands: 6,7-dichloro-2,3-di(2-pyridyl)quinoxaline; 2,3-di(2-pyridyl)-quinoxaline; 5-methyl-2,3-di(2-pyridyl) quinoxaline; 6,7-dibenzo-2,3-di(2-pyridyl)quinoxaline have been prepared. The electrochemical and spectroscopic properties of these complexes are reported. The resonance Raman spectroelectrochemical results indicate the presence of oxidation state sensitive marker bands in the resonance Raman spectra of the oxidized complexes. The spectroscopic data for the reduced complexes is similar for all four species. The resonance Raman data for the reduced species are dominated by 2,2″-bipyridyl vibrations.