A selective and convenient ruthenium mediated method for the synthesis of mixed acetals and orthoesters

Addition of alcohols and phenols to O-allyl compounds (allyl ethers and acrolein acetals), catalyzed by [RuCl₂(PPh₃)₃], was examined. Intramolecular addition of an OH group, leading to the formation of cyclic acetals and orthoesters, was also investigated. As a result, a new, selective and convenient method for the synthesis of symmetrical and unsymmetrical (mixed) acetals and orthoesters was developed.     

A selective convenient ruthenium-mediated synthesis of mixed acetals

Addition of alcohols and phenols to allyl ethers catalyzed mainly by ruthenium complexes was studied. Complexes of ruthenium generated in situ from precursors such as {[RuCl₂(1,5-COD)]_x} or [Ru₃(CO)₁₂] and from external ligands such as phosphines (e.g. PPh₃, PBu₃, BINAP) or phosphites (e.g. P(OPh)₃, P(OMe)₃) were found to be particularly efficient catalysts of the studied reactions. Transacetalization reaction could be practically completely eliminated by the addition of a base (particularly Na₂CO₃) to the catalytic systems. It was observed that the selectivity of mixed acetals formation increases with increasing value of Θ parameter of phosphines. Especially interesting results (0–5% of transacetalization) have been obtained for catalytic systems generated from {[RuCl₂(1,5-COD)]_x} or [Ru₃(CO)₁₂], phosphines (PPh₃, BINAP, dppe, tris(2,4,6-tri-metylphenyl)phosphine, or dppf) and Na₂CO₃. The mechanism of mixed acetals formation has been investigated using deuterated reagents. It is postulated that the examined reaction is a nucleophilic addition of ROH to a hydrido-π-allyl complex formed during oxidative addition of allyl substrate to metal complex. As a result, a new, selective, and convenient method of the synthesis of symmetrical and, in particular, unsymmetrical (mixed) acetals has been developed. Mixed acetals CH₃CH₂CH(OR¹)(OR²) may be obtained in the reaction of R¹-O-allyl with R²OH or R¹OH with R²-O-allyl, depending on the structure of R¹ and R².     

Synthesis and catalytic activity of some π-allylic bis(trifluorophosphine)(triphenylphosphine)cobalt(I) complexes

The syntheses of Co(π-all)(PF₃)₂(PPh₃) complexes (π-all = π-allyl, anti-1-Me-π-allyl, syn-1-Me-π-allyl, 1,1-dimethyl-π-allyl, anti-1,2-diMe-π-allyl, syn,syn-1,3-diMe-π-allyl, 2Et-π-allyl, π-cyclooctenyl, h³-π-cycloheptadienyl) are described. ¹H and ¹⁹F NMR data are presented and discussed in relation to the structures of the complexes. The compound Co(π-C₅H₉)(PF₃)(PPh₃)₂ is also reported. Several of the π-allylic complexes are found to be active catalysts for the isomerisation of 1-octene to 2-octene under a hydrogen atmosphere.     

Synthesis of 2‐aminomethylpiperidine ruthenium(II) phosphine complexes and their applications in transfer hydrogenation of aryl ketones

The complex trans,cis‐[RuCl₂(PPh₃)₂(ampi)] (2) was prepared by reaction of RuCl₂(PPh₃)₃ with 2‐aminomethylpiperidine(ampi) (1). [RuCl₂(PPh₂(CH₂)_nPPh₂)(ampi) (n = 3, 4, 5)] (3–5) were synthesized by displacement of two PPh₃ with chelating phosphine ligands. All complexes (2–5) were characterized by ¹ H, ¹³C, ³¹P NMR, IR and UV‐visible spectroscopy and elemental analysis. They were found to be efficient catalysts for transfer hydrogen reactions. Copyright © 2012 John Wiley & Sons, Ltd.     

Chemistry of the CARBEX process: Identification of absorption bands of the ligands in the electronic spectra of aqueous solutions of Na<Subscript>4</Subscript>[UO<Subscript>2</Subscript>(O<Subscript>2</Subscript>)CO<Subscript>3</Subscript>)<Subscript>2</Subscript>]

On the basis of consideration of dissociation, hydration, association, and ligand exchange, the assignment of absorption bands in the electronic spectra of aqueous solutions of the Na₄[UO₂(O₂)CO₃)₂] complex has been performed. It has been demonstrated that the absorption in the range 190–400 nm is caused by the oxygen atoms of the O₂^2- and CO₃^2- groups and hydration water molecules of dissociated and neutral complex species Na₃[UO₂(O₂)(CO₃)₂]^–, Na₂[UO₂(O₂)(CO₃)₂]^2–, and Na₄[UO₂(O₂)(CO₃)₂].     

The kinetics and thermodynamics of a novel efficient mixed water–1,4-dioxan solvent for the effective complexation of a neutral ruthenium complex with carbon monoxide at atmospheric pressure

Kinetic and thermodynamic investigations were performed for a mixed aqueous-organic, 1:1 (v/v) water–1,4-dioxane medium, which was found to be an efficient solvent for the interaction of a neutral dichlorotris(triphenylphosphine) ruthenium(II), RuCl₂(PPh₃)₃ complex with carbon monoxide at atmospheric pressure. During the interaction, RuCl₂(PPh₃)₃ dissociates to a neutral complex dichlorobis(triphenylphosphine) ruthenium(II), RuCl₂(PPh₃)₂, by losing a coordinated PPh₃ ligand and RuCl₂(PPh₃)₂ coordinates with CO to form an in situ carbonyl complex RuCl₂(CO)(PPh₃)₂. The in situ formed carbonyl complex RuCl₂(CO)(PPh₃)₂ was thoroughly characterized by equilibrium, spectrophotometric, IR, and electrochemical techniques. Under equilibrium conditions, the rate and dissociation constants for the dissociation of PPh₃ from RuCl₂(PPh₃)₃ were found to be favorable for the formation of the carbonyl complex RuCl₂(CO)(PPh₃)₂. The rates of complexation for the formation of RuCl₂(CO)(PPh₃)₂ were found to follow an overall second-order kinetics being first order in terms of the concentrations of both carbon monoxide and RuCl₂(PPh₃)₂. The determined activation parameters corresponding to the rate constant (ΔH^# = 35.9 ± 2.5 kJ mol⁻¹ and ΔS^# = −122 ± 6 J K⁻¹ mol⁻¹) and thermodynamic parameters corresponding to the formation constant (ΔH° = −33.5 ± 4.5 kJ mol⁻¹, ΔS° = −25 ± 8 J K⁻¹ mol⁻¹, and ΔG° = −25.7 ± 2.0 kJ mol⁻¹) were found to be highly favorable for the formation of the complex RuCl2(CO)(PPh3)2. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 359–369, 2008     

Corrigendum

Reactions of NaMn(CO)₃ with RuCl₂(PMe₃)₄, RuCl₂(dppm)₂ and RuCl₂(PPh₃)₃ lead either to an ionic species [Ru₂Cl₃(PMe₃)₆]+[Mn(CO)₅]^? or to metal—metal bonded RuMn compounds such as RuMn(μ-CO)₂(CO)₃(μ-dppm)₂ Cl, and, quite unexpectedly, to the μ-phosphido complex RuMn(μ-PPh₂)(CO)₆(PPh₃)₂ via a hydride intermediate.     

Metathetical reactions of carbonylate anions with dichlororuthenium complexes: Preparation and characterization of ruthenium—molybdenum and ruthenium—manganese complexes

The possibility of making metal—metal bonded heterobimetallic species by metathesis of ruthenium dichlorides with anionic carbonylates is demonstrated by the isolation of MoRu(μ-Cl)(μ-CO)(CO)₂(PPh₃)₂(η-C₅H₅) (1) and MnRuCl(μ-CO)₂(CO)₃(μ-dppm)₂ (2), obtained by action of [Mo(CO)₃(η-C₅H₅]^? on RuCl₂(PPh₃)₃ and of Mn(CO)₅^? on RuCl₂(dppm)₂, respectively. In contrast, reaction of Mn(CO)₅^? with RuCl₂(PMe₃)₄ yielded an ionic species 3 containing the diruthenium cation Ru₂Cl₃(PMe₃)₆⁺. More interestingly, the action of Mn(CO)₅^? on RuCl₂(PPh₃)₃ resulted in the formation of the unexpected complex MnRu(μ-PPh₂)(CO)₆(PPh₃)₂ (4) in which the phosphido group PPh₂ bridges the two metals; this process is shown to involve a hydride intermediate, and elimination of a molecule of benzene, both identified in the reaction mixture.     

Two pseudo-N3 ligands and the catalytic activity of their ruthenium(II) complexes in transfer hydrogenation and hydrogenation of ketones

Complex RuCl₂(PPh₃)(iBu-BTP) (5) was synthesized by the reaction of 2,6-bis(5,6-bis(iso-butyl)-1,2,4-triazin-3-yl)pyridine (iBu-BTP) and RuCl₂(PPh₃)₃ in refluxing toluene, and its molecular structure was confirmed by X-ray crystallographic determination. Complex 5 was applied as a catalyst for transfer hydrogenation of ketones and exhibited catalytic activity comparable to RuCl₂(PPh₃)(Me₄BPPy) (1) (Me₄BPPy = bis(3,5-dimethylpyrazol-1-yl)pyridine) in some cases. The difference between the catalytic activity of 5 and 1 is attributed to the significantly different arrangement and positions of the PPh₃ and chlorides and also to the different electron density on the N-heterocycles. Complex 1 exhibited good to excellent catalytic activity in hydrogenation of ketones under mild conditions. These results have suggested new applications of iBu-BTP and Me₄BPPy as promising planar tridentate pseudo-N₃ ligands to construct highly active transition-metal catalysts.     

Coordination,oligomerisation and transfer hydrogenation of acetylenes by some ruthenium and osmium carboxylates: Crystal and molecular structures of bis(trifluoroacetato)carbonyl-(methanol) bis(triphenylphosphine)ruthenium(II) and (1,4-diphenylbut-1-en-3-yn-2-yl)trifluoroacetato-(carbonyl) bis(triphenylphosphine)ruthenium(II)

The hydrides [MH(O₂CCF₃)(CO)(PPh₃)₂] (M = Ru or Os) react with disubstituted acetylenes PhCCPh and PhCCMe to afford vinylic products [M{C(Ph)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] and [M{C(Ph)CHMe}(O₂CCF₃)(CO) (PPh₃)₂]/[M{C(Me)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] respectively. Acidolysis of these products with trifluoroacetic acid in cold ethanol liberates cis-stilbene and cis-PhHCCHMe respectively thus establishing the cis-stereochemistry of the vinylic ligands. The complexes [M(O₂CCF₃)₂(CO)(PPh₃)₂] formed during the acidolysis step undergo facile alcoholysis followed by β-elimination of aldehyde to regenerate the parent hydrides [MH(O₂CCF₃)(CO)(PPh₃)₂] and thereby complete a catalytic cycle for the transfer hydrogenation of acetylenes. The molecular structure of the methanol-adduct intermediate, [Ru(O₂CCF₃)₂(MeOH)(CO)(PPh₃)₂] has been determined by X-ray methods and shows that the coordinated methanol is involved in H-bonding with the monodentate trifluoroacetate ligand [MEO-H---OC(O)CF₃; O...O = 2.54 Å]. The hydrides [MH(O₂CCF₃)(CO) (PPh₃)₂]react with 1,4-diphenylbutadiyne to afford the complexes [M{C(CCPh)CHPh} (O₂CCF₃)(CO)(PPh₃)₂]. The ruthenium product, which has also been obtained by treatment of [RuH(O₂CCF₃)(CO)(PPh₃)₂] with phenylacetylene, has been shown by X-ray diffraction methods to contain a 1,4-diphenylbut-1-en-3-yn-2-yl ligand. The osmium complexes [Os(O₂CCF₃)₂(CO)(PPh₃)₂], [OsH(O₂CCF₃)(CO)(PPh₃)₂] and [Os{C(CCPh)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] all serve as catalysts for the oligomerisation of phenylacetylene. Acetylene reacts with [Ru(O₂CCF₃)₂(CO)(PPh₃)₂] in ethanol to afford the vinyl complex [Ru(CHCH₂)(O₂CCF₃)(CO)(PPh₃)₂].     

Propionyl complexes of ruthenium derived from the reaction of ethylene with RuHCl(CO)2(PPh3)2

RuHCl(CO)₂(PPh₃)₂ reacts with ethylene under mild conditions (25 psi, 80°C) to yield a propionyl derivative RuCl(C[O]C₂H₅)(CO)(PPh₃)₂ which is believed to be coordinatively unsaturated. Unlike the acetyl analogue, RuCl[C[O]C₂H₅(CO)-(PPh₃)₂ does not isomerize to RuCl(C₂H₅)(CO)₂(PPh₃)₂ in solution. Under one atmosphere of carbon monoxide, RuCl(C[O]C₂H₅(CO)(PPh₃)₂ exists in equilibrium with two species believed to be RuCl(C[O]C₂H₅)(CO)₂(PPh₃)₂ and [Ru(C[O]C₂H₅)(CO)₃(PPh₃)₂]Cl. RuCl(C[O]C₂H₅)(CO)(PPh₃)₂ reacts with CO/ AgClO₄ to give mer-[Ru(C[O]C₂H₅)(CO)₃(PPh₃)₂]ClO₄, p-tolylisocyanide (RNC) and NaClO₄ to give cis-[Ru(C[O]C₂H₅)(CO)(CNR)₂(PPh₃)₂ClO₄, and hydrochloric acid to yield the hydroxycarbene complex, RuCl₂(CO)(C[OH]C₂H₅)(PPh₃)₂.     

15N NMR spectroscopy as a probe for the geometry of diazenido ligands

A useful criterion of linear or bent geometry at N_α of diazenido (-N_αN_βR) ligands is afforded by ¹⁵N NMR. A very large downfield shift (ca. 350 ppm) of the N_α resonance is reported for the “doubly-bent” diazenido ligands in [RhCl₂(¹⁵NNC₆H₄R-4)(PPh₃)₂] (R = H or NO₂) compared with the “singly-bent” diazenido ligands in trans-[MX(¹⁵N₂R¹)(dppe)₂] (M = Mo or W, X = Cl or Br, R¹ = Et or COMe), [ReCl₂(¹⁵N₂COC₆H₅)(C₅H₅N)(PPh₃)₂] and [RuCl₃(¹⁵NNC₆H₅)(PPh₃)₂].     

Synthesis,Structures, and Reactivities of Pincer‐Type Ruthenium Complexes Bearing Two Proton‐Responsive Pyrazole Arms

A new metal–ligand bifunctional, pincer‐type ruthenium complex [RuCl( L1‐H2 )(PPh₃)₂]Cl ( 1 ; L1‐H2 =2,6‐bis(5‐tert‐butyl‐1H‐pyrazol‐3‐yl)pyridine) featuring two proton‐delivering pyrazole arms has been synthesized. Complex 1 , derived from [RuCl₂(PPh₃)₃] with L1‐H2 , underwent reversible deprotonation with potassium carbonate to afford the pyrazolato–pyrazole complex [RuCl(L1‐H)(PPh₃)₂] ( 2 ). Further deprotonation of 1 and 2 with potassium hexamethyldisilazide in methanol resulted in the formation of the bis(pyrazolato) complex [Ru(L1)(MeOH)(PPh₃)₂] ( 3 ). Complex 3 smoothly reacted with dioxygen and dinitrogen to give the side‐on peroxo complex [Ru(L1)(O₂)(PPh₃)₂] ( 4 ) and end‐on dinitrogen complex [Ru(L1)(N₂)(PPh₃)₂] ( 5 ), respectively. On the other hand, the reaction of [RuCl₂(PPh₃)₃] with less hindered 2,6‐di(1H‐pyrazol‐3‐yl)pyridine ( L3‐H2 ) led to the formation of the dinuclear complex [{RuCl₂(PPh₃)₂}₂(μ₂‐ L3‐H2 )₂] ( 6 ), in which the pyrazole‐based ligand adopted a tautomeric form different from L1‐H2 in 1 and the central pyridine remained uncoordinated. The detailed structures of 1 , 2 , 3 , 3.MeOH , 4 , 5 , 6 were determined by X‐ray crystallography.     

Synthesis and structural characterization of ruthenium complexes with 1-aryl-imidazole-2-thione

Treatment of [RuCl₂(PPh₃)₃] with 2 equiv. Himt^MPh (Himt^MPh?=?1-(4-methyl-phenyl)-imidazole-2-thione) in the presence of MeONa afforded cis-[Ru(κ ²-S,N-imt^MPh)₂(PPh₃)₂] (1), while interaction of [RuCl₂(PPh₃)₃] and 2 equiv. Himt^MPh in tetrahydrofuran (THF) without base gave [RuCl₂(κ ¹-S-Himt^MPh)₂(PPh₃)₂] (2). Treatment of [RuHCl(CO)(PPh₃)₃] with 1 equiv. Himt^MPh in THF gave [RuHCl(κ ¹-S-Himt^MPh)(CO)(PPh₃)₂] (3), whereas reaction of [RuHCl(CO)(PPh₃)₃] with 1 equiv. of the deprotonated [imt^MPh]^? or [imt^NPh]^? (imt^NPh?=?1-(4-nitro-phenyl)-2-mercaptoimidazolyl) gave [RuH(κ ²-S,N-imt^RPh)(CO)(PPh₃)₂] (R?=?M 4a, R?=?N 4b). The ruthenium hydride complexes 4a and 4b easily convert to their corresponding ruthenium chloride complexes [RuCl(κ ²-S,N-imt^MPh)(CO)(PPh₃)₂] (5a) and [RuCl(κ ²-S,N-imt^NPh)(CO)(PPh₃)₂] (5b), respectively, in refluxing CHCl₃ by chloride substitution of the RuH. Photolysis of 5a in CHCl₃ at room temperature afforded an oxidized product [RuCl₂(κ ²-S,N-imt^MPh)(PPh₃)₂] (6). Reaction of 6 with excess [imt^MPh]^? afforded 1. The molecular structures of 1·EtOH, 3·C₆H₁₄, 4b·0.25CH₃COCH₃, and 6·2CH₂Cl₂ have been determined by single-crystal X-ray crystallography.     

Metallacyclic complexes with ortho-silylated triphenylphosphine ligands, LnOs(κ(Si,P)-SiMe2C6H4PPh2), derived from thermal reactions of the coordinatively unsaturated trimethylsilyl, methyl complex, Os(SiMe3)(Me)(CO)(PPh3)2

Reaction between Os(SiCl₃)Cl(CO)(PPh₃)₂ and five equivalents of MeLi produces a colourless intermediate, tentatively formulated as the lithium salt of the six-coordinate, dimethyl, trimethylsilyl-containing complex anion, Li[Os(SiMe₃)(Me)₂(CO)(PPh₃)₂]. Reaction of this material with ethanol releases methane and gives the red, coordinatively unsaturated methyl, trimethylsilyl-containing complex, Os(SiMe₃)(Me)(CO)(PPh₃)₂ (1). An alternative synthesis of 1 is to add one equivalent of MeLi to Os(SiMe₃)Cl(CO)(PPh₃)₂, which in turn is obtained by adding three equivalents of MeLi to Os(SiCl₃)Cl(CO)(PPh₃)₂. Treatment of 1 with p-tolyl lithium, again gives a colourless intermediate which may be Li[Os(SiMe₃)(Me)(p-tolyl)(CO)(PPh₃)₂], and reaction with ethanol gives the red complex, Os(SiMe₃)(p-tolyl)(CO)(PPh₃)₂ (3). Complexes 1 and 3 are readily carbonylated to Os(SiMe₃)(Me)(CO)₂(PPh₃)₂ (2) and Os(SiMe₃)(p-tolyl)(CO)₂(PPh₃)₂ (4), respectively. Heating Os(SiMe₃)Cl(CO)(PPh₃)₂ in molten triphenylphosphine results only in loss of the trimethylsilyl ligand and formation of the previously known complex containing an ortho-metallated triphenylphosphine ligand, Os(κ²(C,P)-C₆H₄PPh₂)Cl(CO)(PPh₃)₂. In contrast, heating the five-coordinate osmium-methyl complex, Os(SiMe₃)(Me)(CO)(PPh₃)₂ (1), in the presence of triphenylphosphine results mainly, not in tetramethylsilane elimination, but in ortho-silylation as well as ortho-metallation of different triphenylphosphine ligands giving, Os(κ²(Si,P)-SiMe₂C₆H₄PPh₂)(κ²(C,P)-C₆H₄PPh₂)(CO)(PPh₃) (5). A byproduct of this reaction is the non-silicon containing di-ortho-metallated complex, Os(κ²(C,P)-C₆H₄PPh₂)₂(CO)(PPh₃) (6). A similar reaction occurs when Os(SiMe₃)(Me)(CO)(PPh₃)₂ (1) is heated in the presence of tri(N-pyrrolyl)phosphine producing Os(κ²(Si,P)-SiMe₂C₆H₄PPh₂)(κ²(C,P)-C₆H₄PPh₂)(CO)[P(NC₄H₄)₃] (7) but a better synthesis of 7 is to treat 5 directly with tri(N-pyrrolyl)phosphine. Heating the six-coordinate complex, Os(SiMe₃)(Me)(CO)₂(PPh₃)₂ (2), gives two complexes both containing ortho-metallated triphenylphosphine, one with loss of the trimethylsilyl ligand, giving the known complex, Os(κ²(C,P)-C₆H₄PPh₂)H(CO)₂(PPh₃), and the other with retention of the trimethylsilyl ligand, giving Os(SiMe₃)(κ²(C,P)-C₆H₄PPh₂)(CO)₂(PPh₃) (8). Crystal structure determinations for 5, 6, 7 and 8 have been obtained.     

Syntheses,characterization, and crystal structures of ruthenium(II)/(III) complexes with tridentate salicylaldiminato ligands

Treatment of [Ru(PPh₃)₃Cl₂] with one equivalent of tridentate Schiff base 2-[(2-dimethylamino-ethylimino)-methyl]-phenol (HL) in the presence of triethylamine afforded a ruthenium(III) complex [RuCl₃(κ²-N,N-NH₂CH₂CH₂NMe₂)(PPh₃)] as a result of decomposition of HL. Interaction of HL and one equivalent of [RuHCl(CO)(PPh₃)₃], [Ru(CO)₂Cl₂] or [Ru(tht)₄Cl₂] (tht = tetrahydrothiophene) under different conditions led to isolation of the corresponding ruthenium(II) complexes [RuCl(κ³-N,N,O-L)(CO)(PPh₃)] (2), [RuCl(κ³-N,N,O-L)(CO)₂] (3), and a ruthenium(III) complex [RuCl₂(κ³-N,N,O-L)(tht)] (4), respectively. Molecular structures of 1·CH₂Cl₂, 2·CH₂Cl₂, 3 and 4 have been determined by single-crystal X-ray diffraction.     

The tris(triphenylphosphine)osmium zerovalent complexes Os(CO)2(PPh3)3, .Os(CO)(CNR)(PPh3)3, Os(CO)(CS)(PPh3)3, Os(CS)(cNR)(PPh3)3 and derived compounds

Detailed procedures for the syntheses of Os(CO)₂(PPh₃)₃, Os(CO)(CNR)-(PPh₃)₃ (R = p-tolyl), Os(CO)(CS)(PPh₃)₃ and Os(CS)(CNR)(PPh₃)₃, together with the derived complexes Os(CO)₂(CS)(PPh₃)₂, Os(CO)(CS)(CNR)(PPh₃)₂, Os(η²-C₂H₄)(CO)(CNR)(PPh₃)₂, Os(η²-C₂H₄)(CO)(CS)(PPh₃)₂, Os(η²CS₂)(CO)₂-(PPh₃)₂, Os(η²CS₂)(CO)(CS)(PPh₃)₂, Os(η²-CS₂)(CO)(CNR)(PPh₃)₂, Os(η²PhC₂Ph)(CO)₂(PPh₃)₂ and OsH(C2Ph)(CO)₂(PPh₃)₂ are described.     

Metallorganische lewissäuren: XXV. Übergangsmetallkomplexe mit o-koordiniertem perrhenat

The O-perrhenato complexes L_nMOReO₃ (L_nM = Re(CO)₅, Rh(PPh₃)₂(CO), Ir(PPh₃)₂(CO), Pt(PPh₃)₂(H), Ru(η⁵-C₅H₅)(PPh₃)₂, Os(PPh₃)₃(CO)(H), Ir(PPh₃)₂(CO)(H)(Cl) have been prepared from the corresponding halogeno compounds with AgReO₄ or NaReO₄, respectively. The spectroscopic data (IR, ¹H NMR) indicate that ReO₄⁻ is a stronger ligand compared to ClO₄⁻, SO₃CF₃⁻ and BF₄⁻.     

Study on molecular and electronic structures, and spectroscopic properties of azide ruthenium complexes with pyridine and β-picoline ligands

The [Ru(N₃)₂(PPh₃)(py)₃] and [Ru(N₃)₂(PPh₃)₂(β-pic)₂] complexes have been prepared and studied by IR, NMR, UV-Vis spectroscopy and X-ray crystallography. The complexes were prepared in the reactions of [RuCl₂(PPh₃)₃] with pyridine, β-picoline and NaN₃ in methanol solutions. The electronic structures of the obtained complexes have been calculated using the DFT/TD-DFT method. The trans effect of triphenylphosphine on the pyridine molecule has been studied using NBO and molecular orbital terms, and impact of the acceptor properties of the halide/pseudohalide co-ligands was indicated.     

Octahedral carbyneosmium(II) complexes

The zerovalent carbyneosmium complex, OsCl(CC₆H₄NMe₂)(CO)(PPh₃)₂, reacts with molecular oxygen giving a 1/1 adduct which is formulated as a divalent, octahedral complex retaining the unchanged carbyne ligand, and with a dihapto-peroxycarbonyl ligand, O$\text{s(O}{}_2\text{C}$O)Cl(CC₆H₄NMe₂)(PPh₃(₂. Reaction with HCl liberates CO₂ and forms [OsCl₂(CC₆H₄NMe₂)(H₂O)(PPh₃)₂]⁺ from which have been derived, and structurally characterised by X-ray crystallography, the two octahedral complexes, OsCl₂(NCS)(CC₆H₄NMe₂)(PPh₃)₂ and [OsCl₂(CC₆H₄NMe₂)(CNR)(PPh₃)₂]⁺. The Os—carbyne distances in these two species are, respectively, 1.75(1) and 1.78(1) Å.