Photoinitiated reactions of allyltriorgano-silanes and -germanes with polyhaloidalkanes. Study of the mechanisms of the reactions by means of the 1H CIDNP method

The radical stages in the photolysis reactions of various allyltriorgano-silanes and -germanes (R₃MCH₂CHCH₂; M = Si, Ge) with polyhaloidalkanes have been studied using the ¹H CIDNP method. It has been shown that the mechanism of the photochemical reaction for M = Sn, Ge is different from the case when M = Sn. Some rather stable R₃MCH₂CH(Hal)CH₂R′ (M = Si, Ge) derivatives were isolated and characterized.     

Exchange reactions between oxygen and sulphur derivatives of silicon, germanium, tin and lead

The exchange of oxygen functional groups (--- OR, --- O --- and --- OCOMe) and sulphur functional groups (--- SR, --- S --- ) between R₃M (M = Si, Ge, Sn and Pb) and R₂M (M = Si, Sn) shows, in general, the heavier Group IV element to prefer sulphur. This supports the phenomenological rationalisation that the softness of the organometallic residue increase with the atomic weight of M, though germanium probably resembles silicon in its behaviour far more that it does tin.     

A spectroscopic study of atomic interactions in aryl derivatives of group iv elements

Spectroscopic features (quantitative IR, Raman, and UV spectra) are discussed for group IV (M=C, Si, Ge, Sn) aryls, mainly R₃MC₆H₅ and R₃MCH₂C₆H₅, in order to distinguish features of the intramolecular interactions. Confirmation is obtained for the existing view on the electron-acceptor behavior of heteroatoms joined to aromatic rings. The effect is seen in the IR and UV spectra, which implies that the ground and excited states are perturbed. The effect of M on the ring is shown to be an over-all one; the positive (induction) component follows the electronegativity of M in a scale close to Gordy's, while the negative one increases somewhat from Si to Ge and Sn.The effects in M aryls are analogous to those in M alkenyls, in particular the - conjugation in a phenyl radical attached to Si, which is already known for M allyls.     

Vibrational assignment of some X3MCo(CO)4 molecules (M = Si,Ge, Sn and X = Cl,Br, I)

The infrared and Raman vibrational spectra of X₃MCo(CO)₄ compounds (M = Si, Ge, Sn and X = Cl, Br, I) including depolarization measurements are presented. These spectra result in complete vibrational assignments which are different from those reported previously.     

Acyl iodides in organic synthesis: VII. Reactions with trialkyl(alkynyl)silanes,-germanes, and-stannanes

Reactions of acyl iodides R¹COI (R¹=Me, Ph) with trialkyl(alkynyl)silanes,-germanes, and stannanes (R²C≡CMR ₃ ³ ; M=Si, Ge, Sn) were studied. Acyl iodides reacted with the germanium and tin derivatives with cleavage of the M-C_sp bond and formation of the corresponding trialkyl(iodo)germanes and-stannanes R ₃ ³ MI (M=Ge, Sn) and alkynyl ketones R¹C(O)C≡CR² and R¹C(O)C≡CC(O)R¹. By contrast, the reaction of acetyl iodide with ethynyl(trimethyl)silane gave only a small amount of 1,2-diiodovinyl(trimethyl) silance as a result of iodine addition at the triple bond. Bis(trimethylsilyl)ethyne failed to react with acetyl iodide.     

Composés propargyliques et alléniques du Si,Ge, Sn chiraux possédant en α un carbone asymétrique mise en évidence des diastéréoisomères

The propargylic R¹R²R³MCH(CH₃)CCH and allenic R¹R²R³MCHCCHCH₃ compounds (M = Si, Ge, Sn) with two neighbouring asymmetric centres exist in two diastereotopic erythro and threo forms observable in NMR.     

Multinuclear NMR spectra of (CH3)3SnCH2M(CH3)3 (MSn,Ge, Si,C) and some halogenated derivatives

Chemical shift and scalar coupling constant information has been obtained from the ¹H, ¹³C, ²⁹Si and ¹¹⁹Sn NMR spectra of a series of compounds (CH₃)₃SnCH₂M(CH₃)₃, where M = Sn, Ge, Si or C and with one or two CH₃? (Sn) groups replaced by Cl, Br or I. The (CH₃)₃M and (CH₃)₃MCH₂ groups appear to have opposite substituent effects on chemical shifts.     

通过核独立化学位移(NICS)计算研究二价三、五、七元环C2H2M, C4H4M and C6H6M(M=C, Si, Ge, Sn and Pb)的芳香族特性

The aromatic character of divalent three, five and seven-membered rings C₂H₂M, C₄H₄M and C₆H₆M(M=C, Si, Ge, Sn and Pb) is investigated through magnetic and geometric criteria by Density Functional Theory (DFT)method using 6^-311++G(3df,2p) basis set of the GAUSSIAN 98 program. The result of Nucleus-independent Chemical Shifts (NICS)(0.5) calculations show an aromatic character for singlet state of C₂H₂M(M=C, Si, Ge, Sn and Sn) and nonaromatic character for triplet states of C₂H₂M(except M=Ge and Pb). NICS (0.5) calculations show nonaromatic character for the singlet state of C₄H₄C and antiaromatic character for C₄H₄M(M=Si, Ge, Sn and Pb). In contrast, NICS (0.5) calculations indicate antiaromatic character for the triplet state of C₄H₄C and nonaromatic character to C₄H₄M(M=Si, Ge, Sn and Pb). NICS (0.5) calculations show a slightly homoaromatic character for the singlet state of C₆H₆M and anti-aromatic character for triplet state of C₆H₆M.     

Atomic interactions in the hydrides and alkyls of C,Si, Ge,and Sn

The spectra of these group IV (M=C, Si, Ge, and Sn) compounds show that induction from M increases in a sequence that qualitatively agrees with the Pauli-Gordy-Mulliken scale; the induction constant o* for (CH₃)₃M is –0.3, –0.72, –0.76, and –0.9 in the four cases. M also acts as an electron acceptor, the effect increasing from Si via Ge to Sn; this and the induction determine the electron-density distribution in adjacent bonds. These concepts explain the anomalous behavior of the optical parameters and chemical shifts in the methyl derivatives of M. The analogy with the magnetic parameters indicates that the Olred-Rakhov electronegativity scale (X _C=2.6; X _Sl=1.9; X _Ge=2.0; X _Sn=1.93) does not reflect the induction effects of M in pure form but provides a good measure of the sum of the electronic effects. The present results do not confirm the view that silicon transmits induction less readily than carbon.     

Density functional study on the bromination of heteroelement-substituted acetylenes

The reactions of heteroelement-containing alkynes H₃SiC≡CH and R₃MC≡CPh [R₃M = H₃Si, Et₃Si, Et₃Ge, (MeO)₃Si, (EtO)₃Ge, N(CH₂CH₂O)₃Si, N(CH₂CH₂O)₃Ge, Bu₃Sn] with one and two bromine molecules were studied in terms of the density functional theory. Transition states along reaction channels leading to products of both addition at the triple bond (cis- and trans-dibromoalkenes and 1,1-dibromoalkenes) and cleavage of the M-C≡ bond were localized.     

Interaction between cobaltocenium and decamethylcobaltocenium salts and Ph3ELi (E = Si,Ge, Sn)

Reactions of cobaltocenium salts [(C₅R₅)₂Co]PF₆ (R = H, Me) with Ph3ELi (E = Si, Ge, Sn) and with Ph₂SbLi mainly follow two pathways (nucleophilic addition and one-electron reduction), yielding cobalt cyclopentadiene-cyclope ntadienyl complexes (⁴-Ph₃EC₅R₅)(⁵-C₅R₅)Co (R = H, E = Si, Ge, Sn; R = Me, E = Si) and cobaltocenes (C₅R₅)₂Co (R = H, Me), respectively. The contribution of nucleophilic addition of Ph₃ELi decreases in the order of elements Si > Ge > Sn and when hydrogen atoms are replaced by methyl groups in the initial cobaltocenium salt. Thermal decomposition of cobalt cyclopentadiene-cyclopentadienyl complexes results in substituted cobaltocenes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 10, pp. 2557–2560, October, 1996.     

Derives β-alcenyles des metaux de la colonne IVB : II. Action des halogenures organometalliques,de type R3MX,sur le magnesien du bromure de crotyle

The main Group IVB organometallic halides, R₃MX (M = Si, Ge, Sn, Pb; R = CH₃, C₆H₅) react with crotylmagnesium bromide in ether and THF, to give the corresponding organometallic allylic compounds. Generally, mixtures of the two primary (Z + E) and the secondary isomers are obtained.     

Bromination of silatranyl-, germatranyl-, silyl-, and germyl-phenylacetylenes

Reactions of element-substituted alkynes R₃MCCPh (R₃M = Me₃Si, Et₃Si, Ph₃Si, Et₃Ge, n-Bu₃Sn, N(CH₂CH₂O)₃Si, N(CH₂CH₂O)₃Ge, N(CH₂-CHMeO)₃Ge, and N(CH₂CH₂O)₂(CH₂CHPhO)Ge) with bromine, tetra-n-butylammonium tribromide (TBAT), and N-bromosuccinimide (NBS)/DMSO were investigated. The Z,E-ratio of isomeric dibromoalkenes formed in bromination reaction with Br₂ and TBAT are discussed. The crystal structures of N(CH₂CH₂O)₃SiCCPh and N(CH₂CHMeO)₃GeX (X = C CPh, C(Br)C(Br)Ph, C(Br₂)C(O)Ph), and Ph₃SiC(Br)C(Br)Ph are reported. © 2003 Wiley Periodicals, Inc. 15:43–56, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/.hc10211     

Darstellung und charakterisierung von verbindungen des typs (CH3)3ME(CF3)2 (M = Si,Ge, Sn; E = P,As)

Various preparative routes for the synthesis of (CH₃)₃SiP(CF₃)₂ are discussed. The most favourable method, reaction of (CH₃)₃MPH₂ with HE(CF₃)₂, provides a good yield of (CH₃)₃ME(CF₃)₂ compounds (M = Si, Ge, Sn; E = P, As). The reaction rate is dependent on M (Si < Ge <Sn) und E (P < As). The stability and reactivity of the (CH₃)₃ME(CF₃)₂ compounds are discussed. The new compounds were characterized by NMR and IR spectra and by cleavage reactions of the M-E bond. ¹H, ¹⁹F NMR and IR spectral data are reported.     

Experimental and theoretical investigation on binary semiconductor clusters of Bi/Si, Bi/Ge, and Bi/Sn

Bi(m)M(n)- (M = Si, Ge, Sn) binary cluster anions are generated by using laser ablation on mixtures of Bi and M (M = Si, Ge, Sn) samples and studied by reflectron time-of-flight mass spectrometer (RTOF-MS) in the gas phase. Some magic number clusters are present in the mass spectra which indicate that they are in stable structures. For small anions (m + n < or = 6), their structures are investigated with the DFT method and the energetically lowest lying structures are obtained. For the binary anionic clusters with the same composition containing Si, Ge, and Sn, they share similar geometric and electronic structure in the small size except that BiSi3-, BiSi5-, Bi2Si2-, Bi2Si3-, and Bi4Sn2- are different for the lowest energetic structures, and the ground states for all the anions are in their lowest spin states. The calculated VDE (vertical detachment energy) and binding energy confirm the obviously magic number cluster of BiM4- (M = Si, Ge, Sn), which agrees with the experimental results.     

Group IVB organometallic compounds of furan: 13C, 29Si and 119Sn n.m.r. Spectra

The ¹³C, ²⁹Si and ¹¹⁹Sn chemical shifts of 2- and 2,5-substituted organometallic (M=C, Si, Ge, Sn, Pb) derivatives of furan were measured. The most important factors, determining the specific features of the studied spectra, are d-orbital availability and atomic radius of the central atom M, as well as the relatively higher (as compared with benzene) energies of the π-electron energy levels of the furan ring.     

Synthèses photochimiques diastéréosélectives de complexes à liaison fer-métal du groupe 14

The diastereomeric Fe^*(MR₃(CO)(P^*R¹R²R³)Cp complexes (M  Si, Ge and Sn, R  aryl or methyl) are synthesized by photolysis of the prochiral Fe(MR₃(CO)₂Cp, precursors in the presence of the corresponding racemic phosphorus III ligands. Asymmetric induction at iron is observed if the phosphorus atom is bound to a group containing a specific heteroatom (nitrogen or oxygen).     

Infrarot-und Raman-Spektren von unvollständig und vollständig deuterierten Tetramethyl-Verbindungen (CH3) n M(CD3)4-n der ElementeM=Si,Ge, Sn und Pb

The infrared andRaman spectra of theM(CH₃)₄ andM(CD₃)₄ species,M=Si, Ge, Sn and Pb, have been reinvestigated. The spectra of the mixed tetramethyl compounds (CH₃)₃ MCD₃,M=Si, Ge, Sn and Pb, and of (CH₃)₂Si(CD₃)₂ and CH₃Si(CD₃)₃ have been recorded in the gaseous (i.r.) and liquid states (Raman). The proposed assignment is supported by a normal coordinate analysis.

     

Heteroorganic derivatives of sulfur-containing heterocycles. 28. Calculation and interpretation of vibrational spectra of thienyl derivatives of group IVB elements

The frequencies and forms of the normal vibrations were calculated for trimethyl(2-thienyl)-substituted silane, germane, and stannane molecules. An interpretation of the results of an experimental study of the IR spectra and Raman spectra of compounds with the general formula R_nMMe_4–n (R=2-thienyl, M=Si, Ge, Sn, n=1...4) is given.See [1] for communication 27.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1467–1482, November, 1989.     

Darstellung,Charakterisierung und Struktur funktionalisierter Fluorphosphaalkene des Typs R3E–P=C(F)NEt2 (R/E = Me/Si,Me/Ge,CF3/Ge,Me/Sn)

Preparation, Characterization, and Structure of Functionalized Fluorophosphaalkenes of the Type R₃E–P=C(F)NEt₂ (R/E = Me/Si, Me/Ge, CF₃/Ge, Me/Sn) P‐functionalized 1‐diethylamino‐1‐fluoro‐2‐phosphaalkenes of the type R₃E–P=C(F)NEt₂ [R/E = Me/Si ( 2 ), Me/Ge ( 3 ), CF₃/Ge ( 4 ), Me/Sn ( 5 )] are prepared by reaction of HP=C(F)NEt₂ ( 1 , E/Z = 18/82) with R₃EX (X = I, Cl) in the presence of triethylamine as base, exclusively as Z‐Isomers. 2–5 are thermolabile, so that only the more stable representatives 2 and 4 can be isolated in pure form and fully characterized. 3 and 5 decompose already at temperatures above –10 °C, but are clearly identified by ¹⁹F and ³¹P NMR‐measurements. The Z configuration is established on the basis of typical NMR data, an X‐ray diffraction analysis of 4 and ab initio calculations for E and Z configurations of the model compound Me₃Si–P=C(F)NMe₂. The relatively stable derivative 2 is used as an educt for reactions with pivaloyl‐, adamantoyl‐, and benzoylchloride, respectively, which by cleavage of the Si–P bond yield the push/pull phosphaalkenes RC(O)–P=C(F)NEt₂ [R = tBu ( 6 ), Ad ( 7 ), Ph ( 8 )], in which π‐delocalization with the P=C double bond occurs both with the lone pair on nitrogen and with the carbonyl group.