The Structure of Pd2(CH≡CC6H5)2(C5H7O2)3(BF3)2BF4

IR and NMR data showed that the ionic complex Pd₂(CHCC₆H₅)₂(C₅H₇O₂)₃(BF₃)₂BF₄ isolated in the reaction Pd(Acac)₂ + PA + 5BF₃OEt₂ (Acac is C₅H₇O₂, PA is phenylacetylene) is an adduct of two complexes, namely, (Acac)PdBF₄ and [(PA)₂Pd(C³-Acac · BF₃)]⁺(Acac · BF₃)^– (coordinatively unsaturated). On dissolution in deuteroacetone or deuteromethanol, the [(Acac)PdF₂BF₂Pd(C³-Acac · BF₃)(PA)₂]⁺(Acac · BF₃)^– adduct decomposed to Pd(Acac)₂, 2BF₃ · L (L = (CD₃)₂CO, CD₃OD) and the [L(PA)₂Pd(C³-Acac]⁺BF₄ ^– complex.     

Reactions of ((i)PrO)3M≡M(O(i)Pr)3 (M = Mo, W) with low-coordinate phosphorus compounds. Formation of the first four-membered planar metallacycles, containing an M≡M triple bond

The low-coordinate phosphorus compounds (Me(3)Si)(2)N-P=NSiMe(3), (Me(3)Si)(2)N-P(=S)=N(t)Bu and (Me(3)Si)(2)N-P(=NSiMe(3))(2) react with ((i)PrO)(3)M≡M(O(i)Pr)(3) (M = Mo, W) to form four- and five-membered metallacycles with intact endocyclic or exocyclic M≡M triple bonds. The first four-membered planar metallacycles, containing an M≡M triple bond were obtained in reaction with (Me(3)Si)(2)N-P=NSiMe(3).     

Synthesis and characterization of stable osmafuran starting from HC≡CCH(OH)C≡CH and OsHCl(CO)(PPh3)3

This paper presents a new convenient route to prepare osmafuran starting from readily accessible HC≡CCH(OH)C≡CH and OsHCl(CO)(PPh₃)₃. Treatment of a solution of OsHCl(CO)(PPh₃)₃ in dichloromethane with HC≡CCH(OH)C≡CH, followed by the addition of acetic acid, produced osmafuran [Os(CHC(PPh₃)CO(CH₂CH₃))Cl(CO)(PPh₃)₂]Cl (2). 2 has been isolated in good yield and fully characterized. ¹H and ¹³C NMR spectra show the characteristic downfield chemical shifts of the ring hydrogen and carbon atoms. NMR and X-ray diffraction data provide strong evidence for the aromatic nature of 2. Probably due to the effect of the phosphonium substituent, 2 exhibits remarkable thermal stability, air stability and lower reactivity.

     

Reaction of N≡W(O(t)Bu)3 with σ3λ5-phosphoranes. The [2 + 2] cycloaddition across the W≡N triple bond results in the first representative of an inorganic four-membered metallacycle with conjugated endo- and exocyclic double bonds

The reactions of N≡W(O(t)Bu)(3) with the low-coordinate phosphorus compounds (Me(3)Si)(2)NP(NSiMe(3))(2) (I) and (Me(3)Si)(2)NPS(N(t)Bu) (II) were studied. Quantum chemical calculations were used to determine why Mo- and W-containing compounds with the same composition have different molecular structures.     

A new disilene with π-accepting groups from the reaction of disilyne RSi≡SiR (R = Si(i)Pr[CH(SiMe3)2]) with isocyanides

The reaction of 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diisopropyltetrasila-2-yne (1) with tert-butylisocyanide or tert-octylisocyanide produced the corresponding disilyne-isocyanide adducts [RSiSiR(CNR')(2)] (R = Si(i)Pr[CH(SiMe(3))(2)](2), R' = (t)Bu (2a) or CMe(2)CH(2)(t)Bu (2b)), which are stable below -30 °C and were characterized by spectroscopic data and, in the case of 2a, X-ray crystallography. Upon warming to room temperature, 2 underwent thermal decomposition to produce 1,2-dicyanodisilene R(NC)Si═Si(CN)R (3) and 1,2-dicyanodisilane R(NC)HSiSiH(CN)R (4) via C-N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative 3 was characterized by X-ray crystallography.     

Photochemical reaction of the heterometallic complex (μ-H)Os3{μ-O2CC5H4Mn(CO)3}(CO)10 with triphenylphosphine

Photolysis of the heterometallic complex (μ-H)Os₃{μ-O₂CC₅H₄Mn(CO)₃}(CO)₁₀ together with PPh₃ results in replacement of the CO groups by PPh₃ both at the Mn atom and in the Os₃ metallocycle to afford the complexes (μ-H)Os₃{μ-O₂CC₅H₄Mn(CO)₂PPh₃}(CO)₁₀, (μ-H)Os₃{μ-O₂CC₅H₄Mn(CO)₃}(CO)₉}(CO)₉PPh₃, and (μ-H)Os₃{μ-O₂CC₅H₄Mn(CO)₂PPh₃}(CO)₉PPh₃ (two isomers). The reaction is also accompanied by the partial removal of the Mn(CO)₃ group followed by the protonation of the cyclopentadienyl group and formation of triosmium clusters (μ-H)Os₃(μ-O₂CC₅H₄R}(CO)₁₀ (R=H, Et). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 746–751, April, 2000.     

Theoretical Investigation for the Abstraction Reaction of H with (CH_3)_3GeH

The reaction of H atom with (CH3)3GeH is considered to play important role in chemical vapor deposition (CVD) processes used in the semiconductor industry 1-2. The reaction mechanism and kinetics nature for this reaction are therefore essential input data for computer-modelling studies directed towards obtaining an understanding of the factors controlling CVD processes. However, despite its importance, the kinetics work about this reaction was very limited. Only two groups studied exper…     

Theoretical studies of the reactions of O(~3p) with halogenated methyl (Ⅰ)——Reaction mechanism of the O(~3p) CH_2Cl reaction

The reaction of O(~3P) with CH_2Cl radical has been studied using ab initio molecular orbital theory. G2 (MP2) method is used to calculate the geometrical parameters, vibrational frequencies and energies of various stationary points on the potential energy surface. The reaction mechanism is revealed. The addition of O(~3P) with CH_2Cl leads to the formation of an energy rich intermediate OCH_2Cl which can subsequently undergo decomposition or isomerization to the final products. The calculated heat of reaction for each channel is in agreement with the experimental value. The production of H CHClO and Cl CH_2O are predicted to be the major channels. The overall rate constants are calculated using transition state theory on the basis of ab initio data. The rate constant is pressure independent and exhibits negative temperature dependence at lower temperatures, in accordance with the experimental results.     

Reaction of the heteronuclear cluster RuOs3(μ-H)2(CO)13 with azulenes

Reaction of the heteronuclear cluster RuOs₃(μ-H)₂(CO)₁₃ (1) with azulene under thermal activation afforded the novel clusters RuOs₃(μ-H)(CO)₉(μ₃,η⁵:η²:η²-C₁₀H₉) (3) and Ru₂Os₃(μ-H)₂(CO)₁₃(μ-CO)(μ₃,η⁵:σ²-C₁₀H₈) (5a), with 4,6,8-trimethylazulene to give RuOs₃(μ-H)(CO)₈(μ-CO)(μ,η⁵:η⁴-C₁₀H₆Me₃) (4) and Ru₂Os₃(μ-H)₂(CO)₁₃(μ-CO)(μ₃,η⁵:σ²-C₁₀H₅Me₃) (5b), and with guaiazulene to give Ru₂Os₃(CO)₁₁(μ₃,η⁵:η³:η³-C₁₀H₅Me₂ⁱPr) (6), respectively. In 3–5, cluster-to-ligand hydrogen transfer appears to have taken place, with the organic moiety capping a trimetallic face in 3, bridging a metal–metal bond in 4 and via a μ₃,η⁵:σ² bonding mode in 5a and 5b. Cluster 6 contains a trigonal bipyramidal metal framework with the guaiazulene ligand over a triangular metal face. All five clusters have been completely characterised, including by single-crystal X-ray diffraction analysis.     

Structural relationships between dicopper diacetylide (Cu-C≡C-C≡C-Cu) and dicopper acetylide (Cu-C≡C-Cu)

Dicopper diacetylide Cu-C≡C-C≡C-Cu, prepared from butadiyne has been studied by FT-IR spectroscopy in comparison to dicopper acetylide Cu-C≡C-Cu. Upon ageing by exposure to air at room temperature, Cu-C≡C-Cu has been transformed into Cu-C≡C-C≡C-Cu as demonstrated by FT-IR spectroscopy and this compound is further transformed on standing in air. A special kind of solid state oxidative coupling reaction occurs so that polyynes chains are formed in these aged solids. It is shown that the FT-IR spectrum of copper acetylide prepared from ammonia solutions of Cu⁺ and Cu²⁺ ions is comparable to that of air oxidized Cu-C≡C-Cu (and Cu-C≡C-C≡C-Cu) prepared exclusively from Cu⁺ ions in presence of a reducing agent demonstrating that Cu²⁺ ions display the same oxidizing effect as oxygen causing coupling reactions in solution and producing Cu-C≡C-C≡C-Cu.Cu-C≡C-Cu oxidized at 60–70°C with CuCl₂ produces a product which could be formulated as Cu(C≡C)₂₀Cu; FT-IR absorption at 1950 cm⁻¹ could suggest the presence of cumulenic carbon chain although acetylenic carbon chains cannot be excluded completely.     

Reactivity of Fe_3(CO)_(12) with Alkynes R-C≡C-R': Syntheses and Crystal Structures of Substituted Cyclic Ketones and Carbonyl Iron Complexes

The reactivity of carbonyl iron cluster with alkynes has been studied by the thermal reaction of Fe_3(CO)_(12) with R-C≡C-R'(R = Fc(Ferrocenyl); R′ = Ph(Phenyl), Fc, H). The hexacarbonyldiiron cluster with ferracyclopentadiene ring(μ_2, η~4-C_4Ph_4)Fe_2(CO)_6(1) and one tetraphenyl substituted cyclopentadienone(Ph_4C_4CO)(2) were simultaneously obtained by the reaction of Fe_3(CO)_(12) with alkyne(Ph-C≡C-Ph). Only one ferrole cluster(μ_2, η~4-C_4Fc_2H_2)Fe_2(CO)_6(3) was separated by using Fc-C≡C-H as alkyne. One tri-carbonyl iron complex(η~4-C_4Fc_4CO)Fe(CO)_3(4) and an unexpected new cyclic ketone compound 2,2,4,5-tetraferrocenylcyclopenta-4-en-1,3-di-one [Fc_4C_3(CO)_2](5) were obtained by using Fc-C≡C-Fc as alkyne. A new complex(η4-2,4-diphenyl-3,5-diferrocenylcyclopenta-2,4-dien-1-one)-tricarbonyl iron(η~4-C_4Ph_2Fc_2CO)Fe(CO)_3(6) was synthesized by the reaction of Fe_3(CO)_(12) with Fc-C≡C-Ph. The structures of compounds 1~6 were determined by X-ray single-crystal diffraction and spectroscopic characterization. The crystal structures of two new compounds 5 and 6 were analyzed. Our experimental results reveal the structural models of the reaction products are affected by the kinds of substituents from alkynes R-C≡C-R′.     

Reaction of [VO(OPr)3] with hexamethyldisylthiane in the presence of β-diketones

The reaction of [VO(OPr)₃] (Pr is n-propyl) with hexamethyldisylthiane Me₃SiSSiMe₃ in the presence of β-diketones (acetylacetone (HAcac), hexafluoroacetylacetone (Hfac), and dipivaloylmethane (Dpm)), is studied. In all cases, vanadium(IV) and vanadium(III) β-diketonate complexes of different types are formed. New crystalline modification [V(Acac)₃] is obtained in the reaction with HAcac. The mixedligand vanadium(III) complex of the composition [V₂(Hfac)₂(μ-OPr)]₂ is formed with Hfac. In the presence of Dpm, the known vanadium(IV) complex [V₂O₂(Dpm)₂(μ-OPr)₂] is obtained in which two vanadyl groups VO²⁺ are linked by two bridging propoxy groups. The structures of all products are determined by X-ray diffraction analysis.     

Vibrational overtone spectroscopy, energy levels, and intensities of (CH3)3C-C≡C-H

The vibrational overtone spectra of the acetylenic (Δυ = 4, 5) and methyl (Δυ = 5, 6) C-H stretch transitions of tert-butyl acetylene [(CH(3))(3)C-C≡C-H] were obtained using the phase shift cavity ring down (PS-CRD) technique at 295 K. The C-H stretch fundamental and overtone absorptions of the acetylenic (Δυ = 2 and 3) and methyl (Δυ = 2-4) C-H bonds have been obtained using a Fourier transform infrared and near-infrared spectrophotometer. Harmonic frequency ω(ν(1)) and anharmonicities x(ν(1)) and x(ν(1), ν(24)) are reported for the acetylenic C-H bond. Molecular orbital calculations of geometry and vibrational frequencies were performed. A harmonically coupled anharmonic oscillator (HCAO) model was used to determine the overtone energy levels and assign the absorption bands to vibrational transitions of methyl C-H bonds. Band strength values were obtained experimentally and compared with intensities calculated in terms of the HCAO model where only the C-H modes are considered. No adjustable parameters were used to get order of magnitude agreement with experimental intensities for all pure local mode C-H transitions.     

Spectroscopy of the excited-state complex of zinc(II) with 3,3′-bis(dipyrrolylmethene)

Spectra of nonstationary transient absorption of metal bis(dipyrrolylmethene) complexes in cyclohexane and ethanol, which exhibit different photophysical and photochemical properties in these solvents, have been measured and the yields of excited triplet states have been evaluated. It has been shown that the yield of triplets is determined by the intramolecular structure and the difference in fluorescence and phototransformation yields is due to intermolecular interaction of the excited molecules with the solvation shell.     

Effect of the Grignard Reagent on the X→Csp Migration of the MR3 Group in HC≡CCH2XMR3 Compounds

The effect of the Grignard compounds (EtMgBr, PhMgBr, t-BuMgCl, cyclo-C₆H_{1 1}MgBr, and PhCÍÄCMgBr) on the isomerization of HCÍÄCCH₂XMR₃ into R₃MCÍÄCCH₂XH (M = Si, Ge; X = O, S) was studied. The efficiency of the 1,4-(Xarr;Csp)-migration of the R₃M group was shown to depend on the nucleophilicity of the Grignard compound and nature of the MÄX bond.     

Theoretical study on the reaction mechanism of (CH_3)_3CO~· radical with NO

Alkoxy radicals RO? form an important class of hydrocarbon oxidation intermediates in combustion processes, interstellar and atmospheric chemistry[1—8]. The number of NO to NO2 conversions can take place during the oxidation of the parent hydrocarbon in the atmosphere and hence affecting tropospheric ozone production. The experimental and theoretical investi-gations of the reactions of alkoxy radicals will be ad-vantageous for safeguarding the environment. Despite the importance of alkoxy r…     

Reactions of the Ru3(CO)10(μ-Ph2PCH2PPh2) cluster with enynes RCH=CHC≡CR (R is phenyl or ferrocenyl). Formation of indenone derivatives of triruthenium clusters

The thermal reaction of Ru₃(CO)₁₀(-Ph₂PCH₂PPh₂) (1) with enyne PhCH=CHCCPh afforded the trinuclear ruthenium clusters Ru₃(CO)₆{₃-P(Ph)CH₂PPh₂}{₃-C(Ph)=CHCC(Ph)(1,2-C₆H₄)C(=0)} (2), Ru₃(-H)(CO)₅{₃-P(Ph)CH₂PPh₂}{₃-C(Ph)=CHCC(Ph)(1,2-C₆H₄)C(—0)} (3), and Ru₃(CO)₆(-CO){₃-P(Ph)CH₂PPh₂}{₃-C(C=CPh₂)CH=C(H)Ph} (4) and also two isomers of Ru₃(CO)₅(-CO)(-Ph₂PCH₂PPh₂){₃-C₄Ph₂(CH=CHPh)₂} (5a and 5b). Clusters 2, 3, and 4 were characterized by IR spectroscopy, ¹H and ³¹P NMR spectroscopy, and X-ray diffraction analysis. The reaction of complex 1 with enyne FcCH=CHCCFc gave rise to the Ru₃(CO)₆{₃-P(Ph)CH₂PPh₂}{₃-C(Fc)=CHCC(Fc)(1,2-C₆H₄)C(=0)} (6) and Ru₃(-H)(CO)₅{₃-P(Ph)CH₂PPh₂}{₃-C(Fc)=CHCC(Fc)(1,2-C₆H₄)C(—0)} (7) clusters. According to the spectral data, the latter compounds are isostructural to complexes 2 and 3, respectively.     

Reaction of HRu3(CO)10(μ-COMe) with bma: NMR and X-ray structural evidence for the formation of the Ph2PH-substituted cluster HRu3(CO)8(Ph2PH)[μ-PPh2C=CC(O)OC(O)]

Me₃NO activation of the methylidyne-bridged cluster HRu₃(CO)₁₀(μ-COMe) (1) in the presence of the unsaturated diphosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma) furnishes the bma-substituted cluster HRu₃(CO)₈(bma)(μ-COMe) (2) and the diphenylphosphine-substituted cluster HRu₃(CO)₈(Ph₂PH)[μ-PPh₂C=CC(O)OC(O)] (3) as the major and minor products, respectively. The ¹H and ³¹P NMR data indicate that the bma ligand in cluster 2 is chelated to one of the ruthenium atoms that is bridged by the hydride and methylidyne ligands. Cluster 3 has been fully characterized in solution by IR and NMR spectroscopies, and the solid-state structure determined by X-ray crystallography. 3 crystallizes in the monoclinic space P2₁, a?=?12.1467(7)?Å, b?=?19.284(1)?Å, c?=?16.867(1)?Å, β?=?109.639(6)°, V?=?3721.0(4)?ų, Z?=?4, and d_calcd?=?1.774?g?cm^?3; R?=?0.0325, R _w?=?0.0383 for 3518 reflections with I?>?3σ(I). The X-ray data confirm that one of the P–C(maleic anhydride) bonds of the bma ligand has been cleaved and that cluster 3 contains Ph₂PH and μ-PPh₂C=CC(O)OC(O) ligands, the latter which functions as a face-capping ligand to all three ruthenium atoms. Control experiments indicate that cluster 2 does not function as a precursor to cluster 3 under the employed reaction conditions.     

Complexation of Indole-3-acetic Acid with Iron(III): Influence of Coordination on the π-Electronic System of the Ligand

 The iron(III) complex of indole-3-acetic acid (1) was prepared, and its physicochemical properties, mode of iron(III) coordination, and electronic structure were studied using UV/Vis, diffuse reflectance infrared Fourier transform (DRIFT), and transmission ⁵⁷Fe M?ssbauer spectroscopic techniques. The data obtained provide evidence that iron(III) is not only coordinated by the carboxylic O-donor atom, but also via the conjugated π-electronic system of the pyrrole moiety involving both the non-shared electronic pair of the heteroatom and the C(2)*C(3) double bond. Considering the well-known increased sensitivity of the pyrrole residue in indole derivatives to oxidation as compared to the benzene ring, as well as the formation of a triple complex (peroxidase-1-O₂) proposed for the enzymatic 1 oxidative degradation mechanism involving as a key step the Fe³⁺ → Fe²⁺ transition in the enzyme form as discussed in literature, it is concluded that iron(III) coordination with 1 can influence the redox properties of the pyrrole ring by affecting its π-electronic system.     

From dicopper diacetylide (Cu-C≡C-C≡C-Cu) to carbyne

Hydrolysis of dicopper diacetylide Cu-C≡C-C≡C-Cu in HCl solution yields diacetylene as major product together with a mixture of polyynes and minor amounts of carbonaceous matter. After I month ageing the main hydrolysis product from dicopper diacetylide is insoluble carbonaceous matter (23.47% by weight) together with diacetylene and its superior homologues (polyynes formed from solid state oxidative coupling reaction) which have been qualitatively and quantitatively identified by electronic spectroscopy. Similar behaviour and results are observed on dicoppper acetylide Cu-C≡C-Cu. In the carbonaceous insoluble matter recovered after hydrolysis, the presence of carbyne was detected by FT-IR spectroscopy.Dicopper acetylide Cu-C≡C-C≡C-Cu and dicopper acetylide, irrespective for the degree of oxidation reached in air, undergo a controlled thermal decomposition by heating under reduced pressure yielding in few seconds carbyne and copper(I) oxide, both identified by FT-IR spectroscopy.