Reaction of the Hexa-1,3,5-triyne Me3SiC≡CC≡CC≡CSiMe3 with Ru4(CO)13(μ 3-PPh): Parallels with the Chemistry of Alkynes and Diynes

Reaction of Ru₄(CO)₁₃(₃-PPh) (1) with the 1,3,5-hexatriyne Me₃SiCCCCC CSiMe₃ under mild thermal conditions affords initially Ru₄(CO)₁₀(-CO)₂{₄-¹,¹,²-P(Ph)C(CCSiMe₃)C(CCSiMe₃) (2), via the facile formation of a P–C bond in a manner similar to that demonstrated previously with alkynes and diynes. The 62-CVE cluster 2 readily decarbonylates to give crystallographically characterised Ru₄(CO)₁₀(-CO)(₄-PPh){₄-¹,¹,²,²-Me₃SiCCC₂CCSiMe₃} (3). Attempts to further incorporate the pendant alkyne moieties in 3 into the Ru₄ coordination environment were partially successful with Ru₄(CO)₁₀(₄-PPh)(₄-¹,¹,³,³-RC₄R') (4, R/R'=SiMe₃/CCSiMe₃) being formed as a minor product together with the unusual toluene coordinated species Ru₄(CO)₇(⁶-C₆H₅Me)(₄-PPh)(₄-¹,¹,³,³-Me₃SiC₄CCSiMe₄) (5). Cluster 3 reacts with an excess of Me₃SiCCCCCCSiMe₃ to give the open chain cluster Ru₄(CO)₉(₃-PPh){₄-²,²,⁴,⁴,-C₄(CCSiMe₃)(SiMe₃)C₄(CCSiMe₃)₃} (6).     

Synthesis of novel symmetrical and nonsymmetrical 6-membered heterocycles with pendant electron-rich organoiron substituents

The functionalized complexes [(dppe)Cp^*Fe(CC)]₂-(Py) (Py=2,6-C₅H₃N and 3,5-C₅H₃N (dppe=1,2-bis(diphenylphosphino)ethane) were isolated in good yields from reaction of the chloro complex (dppe)Cp^*FeCl with the protected bis-acetylenic heterocyclic precursor. These electron-rich pyridyl ligands constitute interesting examples of organometallic heterocycles bearing redox-active substituents. Attempts to find an alternative route starting from the alkynyl complex [(dppe)Cp^*Fe(CCH)] and the corresponding dibromopyridines using a Sonogashira cross-coupling reaction are also described. By this route, the monofunctionalized products [(dppe)Cp^*Fe(CC)]-2,6-Py-Br and [(dppe)Cp^*Fe(CC)]-3,5-Py-Br could be cleanly isolated. These compounds open the way to the generation of heteroaromatics featuring nonequivalent alkyne substituents such as [(dppe)Cp^*Fe(CC)]-2,6-Py-[(CC)SiMe₃] or [(dppe)Cp^*Fe(CC)]-3,5-Py-[(CC)SiMe₃] by further coupling.In commemoriation of the centenary of Academician A. N. Nesmeyanov.UMR CNRS 6509 Organométalliques et catalyse: Chimie et Electrochimie Moléculaires, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1207–1218, September, 1999.     

Cyclosilethynes containing exocyclic cyclopentyl and cyclohexyl groups

The reaction of BrMgCCSiMe₂CCSiMe₂CCSiMe₂CCSiMe₂CCMgBr with chloro(cyclopentyl)(methyl)silane in a large excess of THF gave 1-cyclopentyl-1,4,4,7,7,10,10,13,13-nonamethyl-1,4,7,10, 13-pentasilacyclopentadeca-2,5,8,11,14-pentayne. Similarly, 1,10-di(cyclopentyl)- or 1,6-di(cyclopentylmethyl)-1,4,4,7,7,10,13,13,16,16-decamethyl-1,4,7,10,13,16-hexasilacyclooctadeca-2,5,8,11,14,17-hexaynes were synthesized from BrMgCCSiMe₂CCSiMe₂CCMgBr and dichloro(cyclopentyl)methylsilane or dichloro(cyclopentylmethyl)(methyl)silane. Condensation of Me₂Si(CCMgBr)₂ with dichloro(cyclohexyl)-methylsilane afforded 1,7-di(cyclohexyl)-1,4,4,7,10,10-hexamethyl-1,4,7,10-tetrasilacyclododeca-2,5,8,11-tetrayne.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1282–1284.Original Russian Text Copyright © 2004 by O. Yarosh, Zhilitskaya, N. Yarosh, Albanov, Klyba, Voronkov.This revised version was published online in April 2005 with a corrected cover date.     

Mechanisms of Reactions of H2O and NH3 Molecules with (≡Si–O)3Si⋅and (≡ Si–O)3Si–⋅ Radicals on the Silica Surface

Spin traps, which are diamagnetic centers (SiO)₂Si, are used to register low-molecular radicals OH, NH₂, and H formed by the reactions of H₂O and NH₃ molecules with the radicals (Si–O)₃Si and (Si–O)₃Si–O stabilized on the silica surface. The experimental data and the results of quantum-chemical calculations for model systems are used to determine the mechanism and thermochemical characteristics of these reactions. A new paramagnetic center (Si–O)₂SiNH₂ was identified on the silica surface, and its radiospectroscopic characteristics are determined.     

Diacetylenic Derivatives of Fe2(CO)6(μ-EE′): Spectroscopic Investigations of Fe2(CO)6{μ-EC(H) = C(C≡ CMe)E′} (E = E′, E ≠ E′; E, E′ = S, Se, Te)

The diacetylenic adducts, Fe₂(CO)₆{-EC(H) = C(C CMe)E} (E = E, E E; E, E = S, Se, Te) (1–8) have been obtained from the room temperature stirring of Fe₂(CO)₆(-EE) with HC CC CMe in methanol solvent containing sodium acetate. Compounds 1–8 have been characterized by IR and multinuclear NMR (¹H, ¹³C, ⁷⁷Se, and ^l25Te) spectroscopy. Trends in the chemical shifts of ⁷⁷Se and ¹²⁵Te NMR spectra of Fe₂(CO)₆{-EC(H) = C(C CMe)E} with a variation of EE are discussed.     

Structure and charge distribution of some alkynoyl cations

We have performedab initio calculations to determine the structure and charge distribution of some alkynoyl cations and their parent alkynoyl fluorides. We have used Mulliken population analysis and a new technique developed by Yáñez, Stewart and Pople. Our results indicate that the mesomeric form O⁺C–CC–R is one of the most important contributors to the structure of these cations, in agreement with experimental conclusions. We have also found that the participation of mesomeric form O=C=C=C⁺ -R is not negligible and increases with -substitution. In the 3-phenylpropynoyl cation substantial delocalization of charge into the phenyl group occurs. Calculations from YSP population analysis are in good agreement with experimental evidence.     

Ethynylisopropylgermanes and Their Trimethylsilyl Derivatives

The reaction of ethynylmagnesium bromide with chloroisopropylgermanes (i-Pr_{4 - n} GeCl_{/sub> n} , n = 1-3) was used to prepare previously unknown ethynylisopropylgermanes i-Pr_{4 - n} Ge(CCH) _n (n = 1-3). The reaction of Me₃SiCCMgBr with i-PrGeCl₃ afforded i-Pr(Me₃SiCC)_{3 - n} GeCl _n (n = 1, 2). The reaction of the monochloride with BrMdCCH gave i-Pr(HCC)₂GeCCSiMe₃, while with the dichloride, i-Pr(HCC)·Ge(CSiMe₃)₂ formed. The latter compounds were obtained by independent synthesis from i-PrGe(CCH)₃, EtMgBr, and ClSiMe₃. The reaction of (bromomagnesioethynyl)triisopropylgermane with Me₃SiCl gave i-Pr₃GeCSiMe₃.     

Synthesis and structures of silicon-, germanium-, and tin-containing tungsten carbyne complexes (ButO)3W≡C—EPh3 and [(ButO)3W≡C]2EPh2 (E = Si,Ge, Sn)

New tungsten carbyne complexes (Bu^tO)₃WC—SiPh₃, [(Bu^tO)₃WC]₂SiPh₂, [(Bu^tO)₃WC]₂GePh₂, and [(Bu^tO)₃WC]₂SnPh₂ were prepared by the reactions of (Bu^t)₆W₂ with Ph₃SiCC—Pr or Ph₂E(CC—Pr)₂ (E = Si, Ge, Sn) in individual crystalline form in 48—80% yields. The structures of both the (Bu^tO)₃WC—GePh₃ and (Bu^tO)₃WC—SnPh₃ compounds synthesized earlier and the new complexes were established by X-ray diffraction analysis.     

DFT study of the mechanism of alkane hydrogenolysis by transition metal hydrides. 1. Interaction of silica-supported zirconium hydrides with methane

Model reactions of silica-supported zirconium hydrides (Si—O—)₃ZrH and (Si—O—)₂ZrH₂ with methane, resulting in cleavage of a C—H bond in the methane molecule and the formation of (Si—O—)₃ZrCH₃ and (Si—O—)₂Zr(H)CH₃ as products were studied using the DFT approach with the PBE density functional. The processes proceed as bimolecular reactions without preliminary formation of agostic complexes. According to calculations, zirconium dihydrides (Si—O—)₂ZrH₂ are more reactive toward the methane C—H bonds than zirconium monohydrides (Si—O—)₃ZrH. The calculated activation energies of the reactions with participation of zirconium dihydrides (Si—O—)₂ZrH₂ are in better agreement with the known experimental data for the Yermakov—Basset catalytic system.     

Mass spectrometric study of high-temperature dehydroxylation of disperse silicas and the interpretation of their IR spectra in the region of Si-O stretching vibrations

Field-desorption mass spectrometry has been used to determine the lower boundary of the temperature interval for the removal of surface hydroxyl groups ofaerosil. Both in the regime of cation desorption and in the regime of anion desorption, at temperatures above 900°K, OH ions of the corresponding sign are registered. It is concluded that the thermal decomposition of the surface bonds Si-OH is homolytic in character. A mechanism is proposed for the dehydroxylation of SiO₂, according to which the initially formed radical centers Si and SiO^. change into ions: Si⁺ (I) and SiO^– (II). The bands at 888 and 908 cm^–1 in the IR spectra of silicas obtained at high temperatures are assigned to vibrations of Si-O bonds in I and II, respectively.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 61–66, January–February, 1985.     

Disproportionation of the alkynyl derivatives of alkali metal aluminum hydrides in electron-donor solvents

Conclusions The reaction of disproportionation of mixed hydride alkynyl complexes of aluminum in ether, THF, and hexametapol was studied by²⁷Al NMR, and it was shown that the stability of MAlH(3–n)) (CCR)_n, where M=Li, Na, K, and R=Ph, n-Bu decreases in the order: MAlH(CCR)₃ < MAlH₂(CCR)₂ < MAlH₃(CCR). The tendency of these complexes to disproportionate increases with an increase in the solvation of the cation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 343–349, February, 1984.We would like to thank A. V. Kisin for recording the²⁷Al NMR spectra.     

Zwitterionic [(H3NCH2C≡CC≡CCH2NH3)]Cu2Cl4 π-Complex: Template Synthesis and Crystal Structure

Crystals of the [(H₃NCH₂CCCCCH₂NH₃)]Cu₂Cl₄ -complex, formed in the oxidative dimerization of propargylammonium cations, were obtained by ac electrochemical synthesis from CuCl₂ · 2H₂O and propargylammonium chloride ([CCCH₂NH₃]Cl) and studied by X-ray diffraction analysis (DARCh automated diffractometer, MoK radiation, /2 scan mode; 2275 reflections with F 4(F), R = 0.048). Crystals are monoclinic: space group B2/b, a = 19.591(6) Å, b = 7.299(3) Å, c = 8.636(3) Å, = 106.83(3)°, Z = 4. The structure consists of individual [(H₃NCH₂CCCCCH₂NH₃)]Cu₂Cl₄ moietes united through the elongated Cu···Cl contacts (2.827(5) Å) into chains oriented along the [010] direction. The bond of the centrosymmetric propargylammonium dimer is -coordintated by copper(I) atom and is elongated to 1.227(6) Å.     

Thermal studies on metal complexes of 5-nitroso-pyrimidine derivatives

Four Hg(II) complexes, containing as ligands 6-amino-5-nitrosouracil (AH), 6-amino-3-methyl-5-nitrosouracil (BH) or 6-amino-1-methyl-5-nitrosouracil (CH), have been synthesized and their thermal behaviour studied by TG and DSC techniques: Hg₃Cl₆(AH)₄, HgCl₂(BH)₂· 2 H₂O, HgCl₂(BH)₂ · H₂O and HgC₂· 2 H₂O.The dehydration processes take place in only one step, with enthalpies in the range 40.2–60.0 kJ · mole^–1 H₂O.Pyrolytic processes start between 200 and 250°, in all cases the thermal stability of the corresponding pyrimidine derivative being lower than that of the free ligand. These processes finish between 600 and 750°, with no residue.

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Zusammenfassung Vier 6-Amino-5-nitrosouracil (AH), 6-Amino-3-methyl-nitrosouracil (BH) oder 6-Amino-1-methyl-5-nitrosouracil (CH) als Liganden enthaltende Hg(II)-Komplexe wurden synthetisiert: Hg₃Cl₆(AH)₄, HgCl₂(BH)₂ · 2 H₂O, HgCl₂(BH)₂ · H₂O und HgC₂ · 2 H₂O. Die Dehydratisierungsprozesse verlaufen in nur einem Schritt mit Enthalpien im Bereich von 40.2–60.0 kJ pro mol H₂O. Pyrolitische Prozesse setzen zwischen 200 und 250° ein. In allen Fällen ist die thermische Stabilität der entsprechenden Pyrimidin-Derivate geringer als die der freien Liganden. Diese Prozesse sind zwischen 600 und 750° beendet, wobei kein Rückstand zurückbleibt.

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g₃l₆()₄, gl₂( )₂ · 2 ₂O, gl₂()₂ · ₂O, g₂ · 2 ₂, — 6- -5-, — 6--3- — 6---5- . , 40.2–60.0 · ^–1 ₂. 200 250° 600–750° - . , .

     

Copper(I) Acetylenide π-Complexes. Synthesis and Structure of Cluster Compound HAmp[Cu9Cl8(C≡CCH2OH)2] (HAmp is 4-Aminopyridinium Cation)

Crystals of the HAmp[Cu₉Cl₈(CCCH₂OH)₂] cluster compound (HAmp is the 4-aminopyridinium cation (NH₂–C₅H₄NH)⁺) were obtained through ac electrochemical synthesis and their structure was determined using X-ray diffraction analysis (DARCh autodiffractometer, /2 scan mode, 3435 independent reflections with F 4(F), R = 0.047). The crystals are triclinic: space group P , a = 12.547(5) Å, b = 12.502(4) Å, c = 8.201(2) Å, = 75.93(2)°, = 82.21(3)°, = 76.05(3)°, V = 1207(2) ų, Z = 2. Two crystallographically independent moieties ^–(CCCH₂OH) were detected in the complex structure. Each moiety acts as a double bridging ,-ligand and binds four or five Cu(I) atoms, thus forming the [Cu₄(CCCH₂OH)] and [Cu₈(CCCH₂OH)₂] clusters. The shortest Cu···Cu distance is equal to 2.337(4) Å.     

Free Radical Reactions of N2O Molecules

Experimental data are presented on the spectral (ESR, IR, and optical) and thermochemical characteristics of a complex between the (Si–O)₃Si^.radical and an N₂O molecule. The rate constants of separate reactions in the systems (Si–O)₃Si^.+ N₂O and (Ge–O)₃Ge^.+ N₂O are found. The results of quantum chemical calculations of potential energy surfaces and spectral characteristics are presented for the following systems: H^.+ N₂O, H₃C^.+ N₂O, H₃Si^.+ N₂O, F₂HSi^.+ N₂O, F₃Si^.+ N₂O, and F₃Ge^.+ N₂O. The latter three systems served as molecular models for experimentally found systems. Based on experimental and theoretical data, the product of N₂O addition to (Si–O)₃Si^.has the structure Si–N=N–O^.. The reactions of free radicals H^., H₃C^., H₃Si^., F₂HSi^., F₃Si^., (Si–O)₃Si^., and (Ge–O)₃Ge^.with N₂O are compared. The spectrum of optical absorbance of the (Si–O)₃Si–O^.radical is recorded and qualitatively characterized.     

3-Phenoxy- and 3-phenylthio-1-propynyl substituted derivatives of silicon and germanium

Reactions of bromomagnesiopropargyl phenyl ethers and their isostmctural sulfides BrMgCCCH₂XPh (X = O, S) with MeVinSiCl₂, Me(CH₂Cl)SiCl₂, EtSiHCl₂, and Me₂SiHCl afforded the corresponding 3-phenoxy- and 3-phenylthio-1-propynyl substituted derivatives of silicon (PhXCH₂CC)₂SiRR¹ and PhXCH₂CCSiHMe₂ (X = O, S). Reactions of the above-mentioned Iotsitch reagents with GeCl₄ led to the corresponding germanium derivatives (PhXCH₂CC)₄Ge (X = O, S).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 511–513, March, 1994.     

Triterpene glycosides and their genins fromThalictrum foetidum. V. Structure of cyclofoetoside B

A new glycoside (cyclofoetoside B) (I) has been isolated from the epigeal part of the plantThalictrum foetidum L. (Ranunculaceae). On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that cyclofoetoside B is 24S-cycloartane-3, 16, 24, 25, 29-pentaol 3-O--L-arabinopyranoside 16-O-[O--L-rhamnopyranoside-(1 6)--D-glucopyranoside], C₄₇-H₈₀O₁₇, mp 194–197°C (methanol); [] _D ²⁴ +15.7 ± 2° (c 0.88; pyridine). The enzymatic hydrolysis of (I) has yielded cyclofoetigenin B (III), 24S-cycloartane-3,16,24,25,29-pentaol 16-O--D-glucopyranoside, (IV), C₃₆H₆₂O₁₀, mp 223–225°C (acetone), [] _D ²⁴ +37 ± 2° (c 0.97; methanol) and 24S-cycloartane-3,16,24,25,29-pentaol 16-O-[O--L-rhamnopyranosyl-(1 6)--D-glucopyranoside, C₄₂H₇₂O₁₄, mp 229–231°C (methanol), [] _D ³⁰ +41 ± 2° (c 0.7; methanol). Details of the IR and¹H and¹³C NMR spectra of the compounds are given.Irkutsk Institute of Organic Chemistry, Academy of Sciences of the USSR. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Trashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 341–345, May–June, 1986.     

Synthesis, Characterization and Luminescence Studies of Trinuclear Rhenium–Cobalt Mixed-Metal Alkynyl Complexes Containing a Tetrahedral Co2C2 Cluster Unit

The reaction of rhenium(I) diynyl complexes [Re(CO)₃(N–N)(CC--CCH)] [N–N = ^tBu₂bpy (1), bpy (2)] with Co₂(CO)₈ in THF yielded a new class of luminescent trinuclear rhenium–cobalt mixed-metal alkynyl complexes, [Co₂{-HC₂CC[Re(CO)₃(N–N)]}(CO)₆] [N–N = ^tBu₂bpy (3), bpy (4)]. Their luminescence and electrochemical properties have also been studied.     

Intensity of the η(C≡C) Bands in the IR Spectra of Acetylene Derivatives and σR 0 Constants of Organosilicon,Organogermanium, and Organotin Substituents

The integral absorptivities of shape-characteristic (CC) bands in the IR spectra of 66 acetylene derivatives RCCX (R = H, Me₃M; X are inorganic and organic substituents) are related by a common linear equation to the _R ⁰ constants of the R and X substituents. The _R R⁰ constants of 10 Alk₃M substituents were calculated. The _R ⁰, _R , and _R ⁺ constants of Me₃M substituents were analyzed. The positive _R ⁰ values (0.12, 0.06, and 0.04 for R = Si, Ge, and Sn, respectively) suggest that in the ground electronic state of Me₃MCCX molecules the resonance acceptor effect of the Me₃M substituents (d, conjugation) prevails over donor (, conjugation). The first effect attenuates and the second enhances as the atomic number of M increases.     

Study of Redox-induced Reactions of Vinylidene and bis-Vinylidene Complexes of Manganese

Oxidative dehydrodimerization of some phenylvinylidene complexes of manganese is studied by cyclic voltammetry. In the case of (⁵-C₅H₅)(CO)₂Mn=C=C(H)Ph, the process occurs as the homolysis of the C–H bond in the radical cation of {(⁵-C₅H₅)(CO)₂Mn=C=C(H)Ph}^+· and the dimerization of intermediate -phenylethinyl cation [(⁵-C₅H₅)(CO)₂Mn–CC–Ph]⁺ to a binuclear dication of bis-carbine type (⁵-C₅H₅)(CO)₂Mn⁺C– C(Ph)=C(Ph)–CMn⁺(CO)₂(⁵-C₅H₅). The reduction of the latter leads to binuclear bis-vinylidene complex (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)₂(⁵-C₅H₅). Oxidative dehydrodimerization of complexes (⁵-C₅R₅)(CO)(L)Mn=C=C(H)Ph (R = H, L = PPh₃; R = Me, L = CO) occurs through the immediate C–C coupling of radical cations {(⁵-C₅R₅)(CO)(L)Mn=C=C(H)Ph}^+· and yields binuclear dication bis-carbine complexes (⁵-C₅R₅)(CO)(L)Mn⁺C–C(H)(Ph)–C(H)(Ph)–CMn⁺(CO)(L)(⁵-C₅R₅), whose reduction leads to neutral compounds (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)(L)(⁵-C₅H₅). Complex (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)₂(⁵-C₅H₅) undergoes the oxidation-induced nucleophilic addition of water, forming cyclic bis-carbene product with a bridge heterocyclic ligand (-3,4-diphenyl-2,5-dihydro-2,5-diylidene)-bis-(⁵-cyclopentadienyldicarbonyl manganese).