First α-ketoacyl complex with planar s-cis oxalyl configuration. Crystal structure of trans-[Pt(COCOOMe)(OH2)(PPh3)2] (CF3SO3)

The abstraction of chloride from trans-Pt(COCOOMe)(Cl)(PPh₃)₂ (1) by Ag(CF₃SO₃) yields methoxyoxalyl triflato complex trans-Pt(COCOOMe)(OTf)(PPh₃)₂ (2). Attempts to crystallize the triflato product in CH₂Cl₂/n-hexane under ambient conditions result in an cationic aquo complex, trans-[Pt(COCOOMe)(OH₂)₂](CF₃SO₃ (3). Its oxalyl carbonyls are disposed in an unprecedented nearly planar s-cis configuration in the solid-state structure.     

Photocatalytic reduction of CO2 using cis,trans-[Re(dmbpy)(CO)2(PR3)(PR’3)]+ (dmbpy=4,4′-dimethyl-2,2′-bipyridine)

Photocatalysis of biscarbonylrhenium complexes cis,trans-[Re(dmbpy)(CO)₂(PR₃) (PR′₃)]⁺ (dmbpy=4,4′-dimethyl-2,2′-bipyridine: R, R′=Ph (1a ⁺); p-FPh (1b ⁺); R=Ph, R′=OEt (1c ⁺); R, R′=O-i-Pr (1d ⁺)) is reported for the first time. The rhenium complexes with two triarylphosphine ligands (1a ⁺, 1b ⁺) efficiently photocatalyzed CO₂ reduction with triethanolamine as a sacrificial donor. On the other hand, the complexes with one or two trialkylphosphite ligand(s) (1c ⁺, 1d ⁺) had low photocatalytic abilities under the same reaction conditions.     

ESR study of reactivity of the complex (η2-C60)Os(CO)(PPh3)2(CNBut) toward free radicals

Addition of the ^·P(O)(OPrⁱ)₂, Me^·, Et^·, ^·Bu^t, and Cl₃C^· radicals to the (ν²-C₆₀)Os(CO)-(PPh₃)₂(CNBu^t) complex (1) was studied by ESR spectroscopy. The spectral parameters of the spin-adducts of these radicals with complex 1 were determined. The predominant direction of the attack by the ^·P(O)(OPrⁱ)₂, ^·Bu^t, and Cl₃C^· radicals are the cis-1 and cis-2 bonds of the fullerene molecule. The stability of the spin-adducts depends substantially on the nature of the added radical. The addition rate constants of the ^·P(O)(OPrⁱ)₂, ^·But, and Cl₃C^· radicals to complex 1 and the dimerization rate constants for these spin-adducts were determined. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 301–307, February, 2008.     

Origin of the different reactivity of the high-valent coinage-metal complexes [RCuiiiMe3]− and [RAgiiiMe3]− (R=allyl)**

High-valent tetraalkylcuprates(iii ) and -argentates(iii ) are key intermediates of copper- and silver-mediated C−C coupling reactions. Here, we investigate the previously reported contrasting reactivity of [RMⁱⁱⁱ Me₃]⁻ complexes (M=Cu, Ag and R=allyl) with energy-dependent collision-induced dissociation experiments, advanced quantum-chemical calculations and kinetic computations. The gas-phase fragmentation experiments confirmed the preferred formation of the [RCuMe]⁻ anion upon collisional activation of the cuprate(iii ) species, consistent with a homo-coupling reaction, whereas the silver analogue primarily yielded [AgMe₂]⁻, consistent with a cross-coupling reaction. For both complexes, density functional theory calculations identified one mechanism for homo coupling and four different ones for cross coupling. Of these pathways, an unprecedented concerted outer-sphere cross coupling is of particular interest, because it can explain the formation of [AgMe₂]⁻ from the argentate(iii ) species. Remarkably, the different C−C coupling propensities of the two [RMⁱⁱⁱ Me₃]⁻ complexes become only apparent when properly accounting for the multi-configurational character of the wave function for the key transition state of [RAgMe₃]⁻. Backed by the obtained detailed mechanistic insight for the gas-phase reactions, we propose that the previously observed cross-coupling reaction of the silver complex in solution proceeds via the outer-sphere mechanism.     

The oxidative addition of 1-haloalkanes to monomeric trans-[Rh(X(CO)(PR3)2] (X  Cl,Br; R  aryl) and dimeric trans-[Rh(μ-X)(CO)(PPh3)]2 (XCl,I)

The oxidative addition of 1-bromopropane to trans-[RhBr(CO){P(p-EtC₆H₄)₃}₂] has been found to follow pseudo first-order kinetics and give only an acylrhodium(III) product. The reaction is not catalysed by added bromide ion in chloroform solution, indicating that an anionic intermediate such as [RhBr₂(CO){P(p-EtC₆H₄)₃}]⁻ does not play an important part in this reaction. The oxidative addition of iodomethane to trans-[Rh(μ-X)(CO)(PPh₃)]₂ (X  Cl and I) is pseudo first-order, the reactivity increasing on replacing chloride by iodide.     

Reactions of the unsaturated anion [Re3(μ-H)4(CO)10]− with phosphines. Synthesis of the anions [Re3(μ-H)2(CO)10(PR3)2]−, and crystal structure of [NEt4][Re3(μ-H)2(CO)10(PPh3)2]

The reaction of the unsaturated cluster anion [Re₃(μ-H)₄(CO)₁₀]⁻ with tertiary phosphines at room temperature results in the substitution of two hydride ligands (eliminated as H₂) by two PR₃ ligands, leading to saturated [Re₃(μ-H)₂(CO)₁₀-(PR₃)₂]⁻ compounds. A single crystal X-ray diffraction study of the PPh₃ derivative revealed that the two phosphines occupy non-equivalent equatorial coordination sites on the triangular cluster. The rate of the reaction greatly increases with increase of the basicity of the phosphine.     

Synthesis and X-ray structure of the osmium carbonyl anion [HOs3(CO)10 · O2C · Os6(CO)20]−

The reaction of [HOs₃(CO)₁₁]⁻¹¹ with [Os₃(CO)₁₀(MeCN)₂] in acetone gives the green-blue anion [HOs₃(CO)₁₀·O₂C·Os₆(CO)₂₀]⁻ (1) amongst several other products; this anion has been structurally characterised by a single crystal X-ray study of its Bu₄P⁺ salt.     

Crystal structure of salts of the trans-[Rh(NH3)2(NO2)4]− anion with K+, Cs+, Ag+, and (CH3)4N+ cations

Complex rhodium(III) salts with the composition trans-M[Rh(NH₃)₂(NO₂)₄], where M = K⁺, Cs⁺, Ag⁺, and N(CH₃) ₄ ⁺ , are prepared and characterized. The molecular and crystal structures are determined by X-ray crystallography.     

Preparation and NMR spectroscopy of [Hg{(μ-PEt2)Cr(CO)5}3]−

The new tetranuclear phosphido-bridged compound [Hg{(μ-PEt₂)Cr(CO)₅}₃]⁻ has been obtained by reaction of [Hg{(μ-PEt₂)Cr(CO)₅}₂] with Li[Cr(CO)₅PEt₂]. The coordination of [Cr(CO)₅PEt₂]⁻ results in an unprecedented increase in J(Hg,P), whereas an increase in the number of phosphorus ligands coordinated to mercury is usually accompanied by a decrease in the magnitude of J(Hg,P). This anomaly is interpreted in terms of CrHg donor acceptor interactions.     

Novel Reaction of the [HFe3(CO)11]− reagent with alkynes: A new synthesis of cyclobutenediones

Reaction of the [HFe₃(CO)₁₁]⁻ species generated in situ using Fe(CO)₅ and NaBH₄/CH₃COOH in THF with alkynes, followed by CuCl₂.2H₂O oxidation leads to the corresponding cyclobutenediones in 60–73% yields.     

X-ray structural study of the first bicluster π-arene complex [η6-PhCo4(CO)9]2CH2 and binuclear complex [η6-PhCr(CO)3]2CH2

It has been established by X-ray structural study that the bicluster cobalt -arene complex of diphenylmethane [⁶-PhCo₄CO₉]₂CH₂ and binuclear complex [⁶-PhCr(CO)₃]₂CH₂ have ans-trans-s-trans conformation in their crystals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1111–1117, June, 1995.This work was supported by the Russian Foundation for Basic Research (Projects No. 93-03-4028 and 94-03-08338).     

Unexpected preparation and X-ray crystal structure of the dinuclear complex Mo2(μ-P(O)(OCH3)2)2(CO)4(P(OCH3)3)2(CF3COO)2

Prolonged reaction of CF₃COOH with Mo(CO)₃(P(OCH₃)₃)₃ in CH₂Cl₂ yields the dimer [Mo(CO)₂(μ(O)P(OCH₃)₂)P(OCH₃)₃CF₃COO]₂ in low yield. The complex has been characterized by the usual spectroscopic methods and by an X-ray crystal structure determination. The molybdenum atoms are linked by two OP bridges, the six-membered dimetallacycle adopting a twisted-boat conformation. Each molybdenum is seven-coordinated and has a capped trigonal prism geometry, the capping position being occupied by an oxygen atom of the bridging OP(OCH₃)₂ group. A mechanism similar to the well-known Michaelis-Arbuzov rearrangement is proposed and substantiated by the concomitant apparition of CF₃COOCH₃ during the reaction.     

Synthesis and molecular structure of the complex [Ph3Sb(NO3)]2O·Me2CO

The reaction of silver nitrate with Ph₃-SbBr₂ in an ethanol-acetone solution afforded the complex [Ph₃Sb(NO₃)]₂O·Me₂C=O (1). According to the data of X-ray diffraction study of crystals of1, molecule1 contains a nonlinear O-bridge, which links two Sb atoms. The Sb atoms have a trigonal-bipyramidal configuration. The NO₃ group and the bridging oxygen atom are in axial positions and the three Ph substituents are in equatorial positions. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 174–176, January, 1999.     

Iridium Cluster Chemistry: The Synthesis and the Solid State Structures of [HIr5(CO)12]2− and [HIr4(CO)10PPh3]−

The cluster [HIr₅(CO)₁₂]^2- (1) was prepared by condensation of [HIr₄(CO)₁₁]^- and [Ir(CO)₄]^- (molar ratio 1:1) in refluxing THF, with almost quantitative yields. Its solid state structure was determined by X-ray diffraction at low temperature on the salt [PPh₃CH₂Ph]₂[HIr₅(CO)₁₂]. The metal atoms define a trigonal bipyramidal arrangement. The hydride ligand was located indirectly as a bridge between apical and equatorial metal atoms. The phosphine-substituted cluster [HIr₄(CO)₁₀PPh₃]^- (2) was synthetized by CO displacement on [HIr₄(CO)₁₁]^-, in THF at room temperature. This reaction is selective, with no traces of polysubstitution products. In the solid state, the hydride and the triphenylphosphine are axially bound on basal iridium atoms; the terminal hydrogen atom was directly located by X-ray analysis at a Ir–H distance of 1.57(9) Å. On the contrary, two isomers are present in THF solution, and they interconvert rapidly at room temperature, as shown by¹H and ³¹P NMR spectra.     

Mixed Ruthenium–Iridium Carbonyl Cluster Complexes. Synthesis of the Anions [Ru3Ir2(CO)14]2− and [Ru3Ir2(CO)14H]− and Crystal Structures of Their [tetraphenylphosphonium]+ Salts

The reaction of Ru₃(CO)₁₂ and [Ir(CO)₄]^- (as [PPh₄]⁺ or [N(PPh₃)₂]⁺ salts) yields the anion [Ru₃Ir₂(CO)₁₄]^2- (1) which has been found to derive from the intermediate [Ru₃Ir(CO)₁₃]^- anion. Treatment of (1) with acids gives the conjugated hydrido species [Ru₃Ir₂(CO)₁₄H]^- (2). The two anions were characterized by single-crystal X-ray diffraction of their [PPh₄]⁺ salts. [PPh₄]₂[Ru₃Ir₂(CO)₁₄]: space group C2/c, Z=4, a=22.121(5) Å, b=10.546(5) Å, c=25.931(5) Å, =103.870(5)°, R=0.052 and R_w=0.130 for 3128 independent reflections with I>2(I ). [PPh₄][Ru₃Ir₂(CO)₁₄H]: space group P2₁/c, Z=8, a=22.833(5) Å, b=13.893(5) Å, c=25.810(5) Å, =92.650(5)°, R=0.070 and R_w=0.150 for 12141 independent reflections with I>2(I). Both anions 1 and 2 have a trigonal bipyramidal metal frame. There are two independent anions in the asymmetric unit of 2 differing in their ligand stereochemistry.     

A disulfide-bridged manganese carbonyl anion: synthesis,structure and reactivity of [Mn3(CO)10(μ3-S2)2]−

The reduction of Mn₂(CO)₇(μ-S₂), (1) with sodium amalgam in THF provided the new monoanion [Mn₃(CO)₁₀(μ₃-S₂)₂]⁻, (3) isolated in low yield as the [Ph₃PMe] salt. The reaction of Mn₄(CO)₁₅(μ₃-S₂)(μ₄-S₂), (2) with [Ph₃PMe]I provided the same salt [Ph₃PMe] [3] in a good yield, 68%. Anion 3 reacts [CpFe(CO)₂(acetone)]BF₄ to yield the neutral mixed metal complex CpFeMn₃(CO)₁₂(μ₃-S₂)(μ₄-S₂), (4). The structures of [Ph₃PMe] [3] and 4 were determined by single crystal X-ray diffraction analyses. The core of the structure of 3 consists of two [Mn(CO)₃] groups bridged by two disulfido ligands in a μ₂–η² fashion with an additional [Mn(CO)₄] group that bridges the two disulfido ligands. The CpFe(CO)₂ group in 4 is bonded to a sulfur atom of one of the two disulfido ligands of the anionic grouping of 3.     

Crystal structure and fluorescence spectrum of the complex [Eu(Ⅲ)(TTA)_3(phen)]

The title complex Eu(Ⅲ)(TTA)3(phen) (where TTA= thenoyltrifluoroacetone monoanion; phen = 1,10-phenanthroline) has been synthesized in mixed solvents of acetone and ethanol (1:1 volume ratio) and its crystal structure has been determined by X-ray diffraction. The complex crystals are triclinic, space group P1(#2) with cell dimensions of a = 1.3241 (2) nm, 6 = 1.5278(4) nm, c = 0.9755(3) nm, α = 92.49 (2)°, β=102.57(2)°, γ = 91.62(2)°, V=1.9268(8) nm3, Z = 2, μ(Mo Kα) = 18.77 cm-1, Dx = 1.720 g/cm3. The coordination geometry of Eu atom is a distorted square antiprism, and the encapsulated structure that can meet the structural requirement of the typical europium luminescent sensor. The fluorescence spectrum suggests that the complex is a strong photoluminescent material.     

Transformations of [Au(CN)2]− at the contact with activated carbon surface

We have studied the processes occurring when alkaline aqueous solution of Na[Au(CN)₂] is brought in contact with activated carbon surface. It has been shown that the adsorption of the gold cyanide complex occurs via several independent routes, one of them being accompanied with the partial breakdown of the inner sphere of the compound and free cyanide ions release into the solution. The latter process decreases the gold recovery by aqueous NaOH during the high-temperature (150°C) desorption. A prolonged storage of the adsorbent saturated with [Au(CN)₂]^? in air produces a similar result. The reasons of the observed phenomena have been discussed.     

Oxidative addition of 2,2′-dithiosalicylic acid to the cluster [Os3(CO)10)(CH3CN)2]

The reaction of 2,2'-dithiosalicylic acid with two equivalents of [Os₃(CO)₁₀ (CH₃CN)] in THF at –78°C yields yellow crystals of [{Os₃(CO)₁₀(-H)}₂ (O₂CC₆H₄S)₂] 1 in moderate yield. Hydrogenetaion of 1 in refluxing CHCl₃ affords [Os₃(CO)₁(-H)(O₂CC₆H₅)] 2 in good yield. Structures of 1 and 2 have been established by single crystal X-ray structure analysis.