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.     

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.     

Radio-gas-chromatographische Analyse der 11C-markierten isotopen ?thylene und Acetylene

Zusammenfassung Die radio-gas-chromatographische Trennung der isotopen Äthylene C₂H₄, C₂H₃D und C₂H₂D₂ mit Hilfe einer kontinuierlichen Umlaufmethode unter Benutzung hochwirksamer Silbernitrat-Äthylenglykol-Kolonnen wird beschrieben. Durch Vorschaltung eines (diskontinuierlichen) Reduktionsprozesses mit Chrom(II)-chlorid, der ohne nachweisbaren Isotopenaustausch verläuft, läßt sich diese Methode auch auf die Analyse der isotopen Acetylene: HCCH, DCCH und DCCD anwenden. Der bedeutsamste Vorteil der hier beschriebenen Apparatur ist der gegenüber der konventionellen Einsäulen-Gas-Chromatographie erzielte Zeitgewinn, der besonders bei der Analyse mit kurzlebigen Radioisotopen markierter Verbindungen von ausschlaggebender Bedeutung ist.

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Summary The gas-chromatographic separation of the isotopic ethylenes: C₂H₄, C₂H₃D and C₂H₂D₂ is achieved by using highly efficient silver nitrate/ethyleneglycol columns in combination with a recycling method. The analysis of the three isotopic acetylenes: HCCH, HCCD and DCCD is accomplished by reducing these compounds with chromous chloride solution to the corresponding ethylenes prior to the gas-chromatographic separation. (No isotopic exchange occurs during the reduction process.)One of the advantages of the described method is that separations of the isotopic compounds are obtained in a much shorter time than with the conventional one-column technique, which is of great importance in the radio-gas-chromatography of isotopic molecules labeled with short-lived radioisotopes.

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Nach Arbeiten, die mit Mitteln der U.S. Atomenergie-Kommission ausgeführt wurden.

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Die Autoren danken Dr. D. R. Christman, der freundlicherweise die Reduktionen der Acetylene durchführte und Standardproben der benötigten deuterierten Verbindungen herstellte.     

Triethynylsilane and some of its Si-substituted derivatives

Conclusions Triethynylsilane and some of its Si-substituted derivatives, corresponding to the general formula (HCC)₃SiX, where X=H, OCH₃, OCOCH₃, OSi(CH₃)₃, OSi(CCH)₃, were synthesized.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2147–2148, September, 1978.     

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.     

Some new organoxy (alkyl) ethynylsilanes

Conclusions Some ethynyl(organoxy)silanes were obtained by the transetherification of CH₃O(CH₃)₂SiC CH with 1,3 dichloroisopropanol, 4-iodophenol, and 3, 5-xylenol, of CH₃O(CH₃)Si(C CH)₂ with ethanol, of CH₃O(CH₃)Si(CH = CH₂) (C CH) with ethanol and propanol, and of CH₃(CH₃O)₂SiC CH with butanol.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 450–451, February, 1977.     

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.     

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.     

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.     

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.     

Organometallic chemistry and homogeneous catalysis of Rh and Rh-Co mixed metal carbonyl clusters

The reactions of hydrosilane and/or alkyne as well as isonitriles with rhodium and rhodium cobalt mixed metal carbonyl clusters, e.g., Rh₄(CO)₁₂ and Co₂Rh₂(CO)₁₂, are studied. Novel mixed metal complexes, e.g., CoRh(CO)₅ (HCCBu ⁿ ), (R₃Si)₂Rh(CO) _n Co(CO)₄, Rh(R–NC)₄Co(CO)₄, Co₂Rh₂(CO)₁₀(HCCR), and Co₂Rh₂(CO)₉(HCCBu ⁿ ), are synthesized and identified. The catalytic activities of these rhodium and rhodium-cobalt mixed metal complexes are examined in hydrosilyation, silylformylation, and novel silylcarbocyclization reactions. Possible mechanisms for these reactions are proposed and discussed.     

Reactivity and flexibility in platinum metal clusters

The synthesis, structural properties, and fluxional behaviour of platinum-triosmium and platinum-triruthenium clusters derived from Os₃Pt(-H)₂ (CO)₁₀(PR₃) and Ru₃Pt(-H)(-CC ^t Bu)(CO)₉ (dppe) and related species are described.     

Rhenium complexes with π-acetylenic ligands that contain silicon,germanium, and tin

Conclusions A study was made of the reaction of CpRe(CO)₂·THF with acetylenes of type Ph₃MCCPh, where M=Si, Ge, Sn. The previously unknown acetylenic complexes of rhenium CpRe(CO)₂(-Ph₃MCCPh), where M=Si and Ge, were isolated and studied, and it was shown that these complexes can undergo partial rearrangement to compounds with phenylvinylidene ligands.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1124–1126, May, 1979.     

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.     

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).     

The importance of nonconventional structures in the binding of Ni<Superscript>+</Superscript> to ethynylsilanes and ethynylgermanes

The influence of the nature of the heteroatom on the Ni⁺ gas-phase binding energies of HCC–XH₃ (X is C, Si, or Ge) compounds has been investigated through the use of high-level density functional theory methods. The structures of the corresponding Ni⁺ complexes were optimized at the B3LYP/6-311G(d,p) level of theory. Final energies were obtained in single-point B3LYP/6-311+G(2df,2p) calculations. Nonconventional complexes, in which the metal cation interacts simultaneously with the CC system and with one of the X–H bonds of the substituent XH₃ group, play a significant role in the binding of Ni⁺ to HCC–XH₃ (X is Si or Ge) derivatives. Conversely, such nonconventional complexes are not local minima of the propyne–Ni⁺ potential-energy surface. This establishes a clear distinction between unsaturated carbon derivatives and the Si- and Ge-containing analogues as far as bonding to transition-metal monocations is concerned. Actually, the attachment of Ni⁺ to HCC–XH₃ (X is Si or Ge) compounds in the gas phase yields a mixture of conventional and nonconventional complexes. These agostic-type interactions can be viewed as a dative bond from the X–H bonding orbital toward the empty s orbital of the metal, and a back-donation from the valence electron pairs of the metal into the X–H antibonding orbital of the neutral species.Proceedings of the 11th International Congress of Quantum Chemistry satellite meeting in honor of Jean-Louis Rivail