Abstract:1,2-Di(silyl)benzene (3), has been prepared in a three-step process starting with the reaction of 1,2-dibromobenzene and p-tolyl(chloro)silane with magnesium in tetrahydrofuran. which affords 1,2-bis(p-tolylsilyl)benzene (1) as a stable high-yield intermediate. Compound 1 has been converted into 1,2-bis(trifluoromethanesulfonatosilyl)benzene (2) with trifluoro- methanesulfonic acid, and finally into 3 by reduction with lithiumaluminiumhydride, both again in high yields. - In an attempt to prepare 1,2,4,5-tetr… Show more
“…The 1 H coupled 29 Si NMR spectrum shows all expected 1 H couplings (Figure b) and proves unequivocally the structure of 4 . The quartet structure of the 29 Si resonance stems from the large 1 J (Si - H) coupling (199 Hz) and each line is further split into a doublet of a doublet by 2 J (Si - CH) (13.2 Hz) and 3 J (Si - C CH) couplings (10.6 Hz). , The vinyl protons in the polymer P3 are not resolved and only one broad signal is observed at 6.8 ppm ( w 1/2 ≈ 60 Hz). 1 a and b.…”
The synthesis of Si-B-N-C ceramic materials can be accomplished via two different routes using B-tris(trichlorosilylvinyl)borazine (2) as starting material. This silyl-functionalized ethinylborazine is obtained by Pt-catalyzed hydrosilylation of B, B′, B′′-tri-ethynylborazine (1) with HSiCl 3 in quantitative yield with a selectivity of 80% β-substituted product. Amminolysis of 2 with methylamine leads to the soluble silazane polymer P3 which contains intact borazine rings connected by sCHdCHsSisNMe linkages. In a second approach, the trichlorosilyl groups of 2 are hydrogenated to yield the B-tris(hydrosilylvinyl)borazine (4). With polymer P3 or 4, a highly durable Si-B-N-C ceramic is obtained after pyrolysis under inert atmosphere. The composition SiBN 1+x C 2 of the ceramic material corresponds exactly to the backbone of the precursor molecules 2 or 4, and very compact materials are obtained in each case. The ceramic yield of approximately 94% starting from the silane precursor 4 sets a new standard for this type of ceramics using the pyrolysis of a single site molecular precursor. Conductivity measurements show a semiconductor behavior of the ceramic at about 10 2 (Ωm) -1 at room temperature. The composition of the ceramic was characterized by laser-ablation ICP-MS, which was used for that purpose for the first time. The very satisfying results demonstrate the high potential of this direct solid sampling technique.
“…The 1 H coupled 29 Si NMR spectrum shows all expected 1 H couplings (Figure b) and proves unequivocally the structure of 4 . The quartet structure of the 29 Si resonance stems from the large 1 J (Si - H) coupling (199 Hz) and each line is further split into a doublet of a doublet by 2 J (Si - CH) (13.2 Hz) and 3 J (Si - C CH) couplings (10.6 Hz). , The vinyl protons in the polymer P3 are not resolved and only one broad signal is observed at 6.8 ppm ( w 1/2 ≈ 60 Hz). 1 a and b.…”
The synthesis of Si-B-N-C ceramic materials can be accomplished via two different routes using B-tris(trichlorosilylvinyl)borazine (2) as starting material. This silyl-functionalized ethinylborazine is obtained by Pt-catalyzed hydrosilylation of B, B′, B′′-tri-ethynylborazine (1) with HSiCl 3 in quantitative yield with a selectivity of 80% β-substituted product. Amminolysis of 2 with methylamine leads to the soluble silazane polymer P3 which contains intact borazine rings connected by sCHdCHsSisNMe linkages. In a second approach, the trichlorosilyl groups of 2 are hydrogenated to yield the B-tris(hydrosilylvinyl)borazine (4). With polymer P3 or 4, a highly durable Si-B-N-C ceramic is obtained after pyrolysis under inert atmosphere. The composition SiBN 1+x C 2 of the ceramic material corresponds exactly to the backbone of the precursor molecules 2 or 4, and very compact materials are obtained in each case. The ceramic yield of approximately 94% starting from the silane precursor 4 sets a new standard for this type of ceramics using the pyrolysis of a single site molecular precursor. Conductivity measurements show a semiconductor behavior of the ceramic at about 10 2 (Ωm) -1 at room temperature. The composition of the ceramic was characterized by laser-ablation ICP-MS, which was used for that purpose for the first time. The very satisfying results demonstrate the high potential of this direct solid sampling technique.
“…Silicon hydrides have also attracted considerable interest as precursors for optoelectronic and nonlinear optical materials, which can be generated through new techniques including, e.g., dehydrogenative or desilanative coupling of arylsilanes. − These silicon-based polymers feature conjugated di/polysilane and arene units with enhanced absorption in the UV−Vis region, which has advantages for the production of photoresist and related materials . This synthetic potential has led to increasing interest in tailored arylsilane molecules with various specific photochemical properties associated with the substitution pattern …”
Arylgermanes of the types ArGeH 3 , Ar 2 GeH 2 , and Ar 3 GeH are important precursors for the preparation of oligo-and polygermanes. These precursors are readily prepared in good yields via an in situ Grignard reaction employing tetra(ethoxy)germane, an aryl halide, and magnesium metal in tetrahydrofuran as the reaction medium. The aryl-tri(ethoxy)germanes obtained were reduced to the germane hydrides with LiAlH 4 . This method is also applicable for aryl groups with sensitive substituents, as demonstrated for (4-methoxyphenyl)germane (p-anisylgermane, MeOC 6 H 4 GeH 3 ). With modified stoichiometry, bis(p-anisyl)germane is also available. The insertion of GeCl 2 into the C-Br bond of arylbromides using catalytic amounts of anhydrous AlCl 3 proved to be an efficient alternative if the reaction was carried out in the absence of a solvent. After LiAlH 4 reduction of the aryltrihalogermanes, phenyl-, p-tolyl-, and mesitylgermane were obtained in good yields. The arylgermanes have been identified by their analytical and spectroscopic data, including 73 Ge (s ) 9/2) NMR spectroscopy. Very surprisingly, sharp multiplet signals were observed with well-resolved 1 J(Ge,H) couplings. The molecular structure of p-MeOC 6 H 4 GeH 3 was determined from low-temperature X-ray diffraction data collected from a single-crystal grown "in situ" from the melt (mp: 15°C). The significant distortions observed in the anisyl part of the structure and the conformation of the molecule are in excellent agreement with results of ab initio quantum chemical calculations (MP2/6-31G*) of this compound.
“…Related nickel(IV) species with organyl ligands have only recently been isolated . Here we report the reaction of 1,2-disilylbenzene ( 1 ) 4d, with Ni(dmpe) 2 ( 2 ) (dmpe = 1,2-bis(dimethylphophino) ethane), which resulted in the isolation of a dimeric silylnickel(II) complex and the first silylnickel(IV) complex. …”
The first silylnickel(IV) complex was isolated
from the reaction of 1,2-disilylbenzene with a nickel(0)
complex and characterized by multinuclear NMR and
X-ray structure analysis. Bis(silyl)nickel(II) complexes,
intermediates in the formation of the silylnickel(IV)
complex, were also characterized by NMR and/or X-ray
analysis.
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