- Compounds of Group 14 Elements with an Element-Element (E = Si, Ge, Sn) Bond: Effect of the Nature of the Element Atom
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Two series of germanium compounds, (p-Tol)3Ge-MMe3 (M = Si (1), Ge (2), Sn (3)) and (Me3Si)3Ge-MPh3 (M = Ge (4), Sn (5)), were prepared using lithium or potassium intermediates. The changing of the reaction conditions results in trigermane Ph3Ge-Ge(SiMe3)2-GePh3 (6). The molecular structures of 1, 2, and 6 were investigated by X-ray analysis. By UV/visible spectroscopy it is established that introduction of a tin atom results in a significant bathochromic absorption shift. Furthermore, according to cyclic voltammetry, oxidation potentials decrease in the order 1 > 2 > 3. The electronic structures of 1-4 and related (Me3Si)3Ge-SiPh3 were investigated by DFT calculations. Fluorescence properties of 1-3 were studied in the solid state and in solution; for compound 3 phosphorescence (lifetime is 4.58 ms) is observed in the solid state. (Graph Presented).
- Zaitsev, Kirill V.,Lermontova, Elmira Kh.,Churakov, Andrei V.,Tafeenko, Viktor A.,Tarasevich, Boris N.,Poleshchuk, Oleg Kh.,Kharcheva, Anastasia V.,Magdesieva, Tatiana V.,Nikitin, Oleg M.,Zaitseva, Galina S.,Karlov, Sergey S.
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p. 2765 - 2774
(2015/06/30)
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- Formation of silicon-carbon bonds by photochemical irradiation of (η5-C5H5)Fe(CO)2SiR3 and (η5-C5H5)Fe(CO)2Me to Obtain R3SiMe
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Photochemical irradiation of an equimolar mixture of (η5 -C5H5)Fe(CO)2SiR3, FpSiR 3, and FpMe leads to the efficient formation of the silicon-carbon-coupled product R3SiMe, R3 = Me 3, Me2Ph, MePh2, Ph3, ClMe 2, Cl2Me, Cl3, Me2Ar (Ar = C 6H4-p-X, X = F, OMe, CF3, NMe2). Similar chemistry occurs with related germyl and stannyl complexes at slower rates, Si > Ge Sn. Substitution of an aryl hydrogen to form FpSiMe2C6H4-p-X has little effect on the rate of the reaction, whereas progressive substitution of methyl groups on silicon by Cl slows the process. Also, changing FpMe to FpCH2SiMe3 dramatically slows the reaction as does the use of (η5-C 5Me5)Fe(CO)2 derivatives. A mechanism involving the initial formation of the 16e intermediate (η5-C 5H5)Fe(CO)Me followed by oxidative addition of the Fe-Si bond accounts for the experimental results obtained.
- Fortier, Skye,Zhang, Yongqiang,Sharma, Hemant K.,Pannell, Keith H.
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p. 1041 - 1044
(2010/04/25)
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- Method of preparing organometallic compounds
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A method of preparing an ultra-pure organometallic compound comprising using a microchannel device for synthesis in reacting a metal halide with an alkylating agent to produce an ultra-pure alkylmetal compound for processes such as chemical vapor deposition.
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Page/Page column 7-8
(2009/02/11)
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- Process for the preparation of group IVA and group VIA compounds
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Methods of preparing Group IVA and Group VIA organometallic compounds, particularly Group IVA organometallic compounds, are provided. Such manufacturing methods employ an amine and/or phosphine catalyst in a transalkylation step and may be performed in a batch, semi-continuous or continuous manner.
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- Thermal decomposition of platinum(IV)-silicon, -germanium, and -tin complexes
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The thermal decomposition of a number of complexes of the type [PtMe2(Me3E)X(diimine)] (E = Si, Ge, Sn; X = Cl, Br, I) has been studied. The thermal stability of complexes, as determined by thermogravimetric analysis (TGA), varies depending on the diimine ligand in the order 2,2′-bipyridyl (bpy) > 4,4′-di-tert-butyl-2,2′-bipyridyl (bpy-tbu2) > N-(2-(dimethylamino)ethyl)pyridine-2-aldimine (paen-me2) > (2-imino-n-propyl)pyridine (py-n-pr). Stability also varies according to the trends E = Sn ≈ Ge > Si and X = I > Br > Cl. The products of thermal decomposition have also been determined by 1H NMR and three distinct modes of decomposition are evident: reductive elimination of Me3EX, reductive elimination of Me4E, and α-elimination of Me2E. The competition between reductive elimination of Me3EX and Me4E depends primarily on the halide, X, with the ratio Me3EX:Me4E highest for X = Cl and lowest for X = I. The competition between reductive elimination and α-elimination depends primarily on E, with the tendency to α-elimination of Me2E increasing as E = Si 2(Me3Si)(bpy)] as 233 ± 14 kJ mol-1.
- Levy, Christopher J.,Puddephatt, Richard J.
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p. 4115 - 4120
(2008/10/08)
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Sterically overloaded digermylsilylmethanes tBu2SiX-CY(GeMe3)2 (X = H, Me, F, Br; Y = H, Br, Li) 7-16 are accessible via tBu2SiH-CH(GeMe3)2 7 (from tBu2SiHF and LiCH(GeMe3)2). The compounds are distinguished by hindered rotation about the SiC single bond shown. 7-16 enter into many reactions: (i) electrophilic substitution of Y = H by Li started with MeLi/THF, or of Y = Li by Br, EMe3, R started with Br2, Me3SnCl, Me3GeCl, Me3SiO(CH2)4Cl, or of X - H by Br started with Br2; (ii) homophilic substitution of Y = Br by H started with tBu3SiNa; (iii) nucleophilic substitution of X = F, Br by R started with MeLi, nBuLi. The latter reactions are possible only when Y = Li, and probably proceed over the silaethen tBu2Si=C(GeMe3)2 as reaction intermediate. tBu2SiF-CLi(GeMe3)2, a potential precursor of the hitherto unknown germaethene Me2Ge=C(GeMe3)(SiMetBu2), forms an adduct Li(THF)+4 [tBu2SiF-C(GeMe3)2] in THF and an adduct tBu2SiF-CLi(GeMe3)2·2THF after evaporation of THF. The structure of the latter compound shows a distorted tetrahedral geometry of the central Si and C atom with the Li atom being bonded to the latter. In addition, Li is coordinated by two molecules of THF in a slightly distorted trigonal-planar geometry. A short F ··· Li contact is not observed. (Crystals of tBu2SiF-CLi(GeMe3)2·2THF are orthorhombic, space group Pca21, with a = 20.739(3), b = 16.185(5), c = 17.642(4) A, V = 5921.4 A3, Z= 8, Dcalc = 1.256 g cm-3. R = 0.057 for 527 refined parameters and 4144 observed data.) tBu2SiF-CLi(GeMe3)2·TMEDA is supposed to have a similar structure. tBu2SiH-CLi(GeMe3)2·OP(NMe2)3 and tBu2SiMe-CLi(GeMe3)2·OEt2 have different strutures.
- Wiberg, Nils,Hwang-Park, Hae-Sook,Mikulcik, Patrizia,Mueller, Gerhard
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p. 239 - 253
(2007/10/03)
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- Reactivity of dianionic hexacoordinate germanium complexes toward organometallic reagents. A new route to organogermanes
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Lithium and potassium tris(benzene-1,2-diolato)germanates (2a and 2b, respectively) and potassium tris(butane-2,3-diolato)germanate (3) are easily prepared from GeO2 in quantitative yields. They are very reactive toward organometallic reagents, the reactivity depending on the ligands on the germanium. Complexes 2 react with an excess of Grignard reagent to give the corresponding tetraorganogermanes R4Ge while the less reactive complex 3 leads to the functional triorganogermanes R3GeX. Tetraorganogermanes can also be prepared from complex 2b by reaction with organic bromides in the presence of Mg (Barbier reaction). The influence of Cp2TiCl2 and MgBr2 on the reactivity of Grignard reagents with these complexes was also investigated: in both cases formation of triorganogermanes was favored.
- Cerveau,Chuit,Corriu,Reyé
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p. 1510 - 1515
(2008/10/08)
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- Bis(dimethylgermyl)alkane-iron tetracarbonyls: Synthesis, photolysis, and reactivity
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This work concerns the synthesis, spectroscopic analysis, and reactivity of tetracarbonyliron bis(dimethylgermyl)alkanes Me2Ge(CH2)nGe(Me2)Fe(CO)4 (n = 1, 2). These heterocycles are obtained by cyclization of bis(dimethylgermyl)alkanes Me2HGe(CH2)nGeHMe2 (n = 1, 2) with Fe(CO)5 under UV irradiation. They are stable at room temperature, but the heterocycle with n = 1 decomposes under prolonged UV irradiation with formation of the heterocycle with n = 2, perhydrotetragermin, and (CO)3Fe(μ-GeMe2)3Fe(CO)3. Various CO substitution reactions with phosphines and cleavage reactions with organic and organometallic halides are described; they provide a convenient procedure for the generation of germanium or tin-carbonyl iron clusters. Reactions of tetracarbonyliron bis(dimethylgermyl)methane with sulfur and with oxygen presumably lead first to the dithia- (or dioxa-) digermolane Me2GeCH2Ge(Me2)Y-Y (Y = S or O) and after, by sulfur (or oxygen) loss, to thia- (or oxa-) digermetane Me2GeCH2GeMe2Y (Y = S or O), which are unstable, giving products suggestive of Me2GeY (Y = O or S) and Me2Ge=CH2 intermediates.
- Barrau, Jacques,Hamida, Najib Ben,Agrebi, Abdelhamid,Satge, Jacques
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p. 1585 - 1593
(2008/10/08)
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- Chemistry of heavy carbene analogues R2M (M = Si, Ge, Sn). 12. Concerted and nonconcerted insertion reactions of the germylene Me2Ge into the carbon-halogen bond
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During the reaction of Me2Ge with CCl3X (X = Cl, Br), PhCH2X (X = Br, I), and Ph2CHCl, 1H CIDNP is observed in the products of net insertion of Me2Ge into the carbon-halogen bond and in Me2GeX2 (X = Cl, Br). It is concluded that a two-step radical reaction takes place by an abstraction-recombination mechanism. No reaction takes place with alkyl halides that have a C-X bond dissociation energy of more than about 70 kcal/mol. Me2Ge is generated thermally at 70-95°C or photochemically from the 7-germabenzonorbornadiene 1 and reacts in both cases in the singlet state. The activation energy for forming Me2Ge from 1 is 19 kcal/mol for the reaction with CCl4. Insertion products are also formed with the alkenyl halides CH2=CHCH2X, PhCH=CHX (X = Cl, Br), and 2-bromobut-2-ene, but without showing CIDNP effects. Since Me2GeX2 was not found either, Me2Ge reacts in these cases in a nonradical manner. It does not react with 1-chlorocyclohexene, but it does react with Me2GeX2 under formation of digermanes and/or oligogermanes without CIDNP.
- K?cher, Jürgen,Lehnig, Manfred,Neumann, Wilhelm P.
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p. 1201 - 1207
(2008/10/08)
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- Thermolyse, pyrolyse et photolyse d'heterocycles germanies et soufres a 4 et 5 chainons: especes intermediaires a germanium doublement lie
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The thermolysis, pyrolysis and photolysis of thiagermetane , dithiagermolane and thiagermetane dioxide have been studied.Thiagermetane and dithiagermolane decompose leading to various new germylated heterocycles: , and probably proceed by two competitive mechanisms which involve the transient species germaethene , germathione , thiagermirane and thiadigermetane .Pyrolysis of thiagermetane dioxide also involves germaethene and probably a new doubly-bonded germanium species, the germasulfene (by mass spectroscopy), which finally gives germoxanes (Me2GeO)n (n = 3,4).
- Barrau, J.,Rima, G.,El-Amine, M.,Satge, J.
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- Electrophilic cleavages in (CH3)3SnCH2M(CH3)3 (M = Sn, Ge, Si, C). 1. Product distribution
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The extent to which Sn-CH2 and/or Sn-CH3 cleavage occurs in (CH3)3SnCH2M(CH3)3 (M = Sn, Ge, Si) in reactions with several electrophiles has been determined. With iodine and with
- Hawker, Darryl W.,Wells, Peter R.
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p. 821 - 825
(2008/10/08)
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- Tetramethylsilane in synthesis: Selective mono- and polymethylations of germanium tetrachloride
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In the presence of catalytic amounts of aluminum bromide (or chloride), selective mono-, di-, tri-, or tetramethylation of germanium tetrachloride was effected in high yield with tetramethylsilane (Me4Si) as the methylating reagent. According to the Me4Si/GeCl4 ratio, MeGeCl3, Me2GeCl2, Me3GeCl, and Me4Ge were prepared in 66, 86, 100, and 91% maximum yields, respectively. In these reactions, Me4Si was converted into Me3SiCl and subsequently Me2SiCl2. A mechanism for methylation is proposed, involving the initial formation of Me4Ge (observed regardless of the proportions of starting reagents) followed by disproportionation reactions, with methylchlorosilanes or -germanes present when the initial molecular ratio Me4Si/GeCl4 was lower than 4/1.
- Bordeau, Michel,Djamei, S. Mohammad,Dunoguès, Jacques
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p. 1087 - 1089
(2008/10/08)
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