The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Georgii I. Nikonov - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and structural studies of Germyl and Germyl/stannyl substituted tungstenocenes.
Dalton Transactions, 2007Co-Authors: Andrey Y Khalimon, Konstantin Yu Dorogov, Andrei V Churakov, L G Kuzmina, D A Lemenovskii, Judith A K Howard, Georgii I. NikonovAbstract:One-pot reactions of [WCp2(H)2] and [WCp2(H)(SnMe3)] with nBuLi followed by an equivalent of GeMe2Cl2 afford mono(Germyl) substituted tungstenocenes [WCp2(H)(GeMe2Cl)] (1) and [WCp2(SnMe3)(GeMe2Cl)] (7). Reactions of the products with tin halides in the presence NEt3 afford the mixed complexes [WCp2(SnR2X)(GeMe2Y)] (X, Y = Cl, Br, RMe, Et), which were further converted to moderately stable compounds [WCp2(SnR2H)(GeMe2H)] (R = Me (10), Et (11)). A number of asymmetric mono(halo)-substituted Germyl/stannyl tungstenocenes [WCp2(SnMe2X)(GeMe2H)] (X = Cl (12), Br (13)) and [WCp2(SnEt2Y)(GeMe2H)] (Y = Br (14), I (15)) were prepared by selective halogenation of the Sn–H bond in 10 and 11. X-Ray studies of [WCp2(H)(GeMe2Cl)] (1), [WCp2(SnEt2Br)(GeMe2Cl)] (4), and [WCp2(SnEt2Br)(GeMe2H)] (14) established classical structures of these compounds. X-Ray study of complex [WCp2(SnMe2Cl)(GeMe2Cl)] (3) revealed the presence of interligand Ge–Cl⋯Sn–Cl interactions in a highly Ge/Sn disordered structure. Analyses of molecular parameters of 1, 4, and 14 suggest the presence of a negative hyperconjugation between metal lone pairs and the σ*-orbital of the E–X bond, which is stronger in bromo substituted complexes in comparison with chloro substituted ones.
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synthesis and structural studies of Germyl and Germyl stannyl substituted tungstenocenes
Dalton Transactions, 2007Co-Authors: Georgii I. Nikonov, Andrey Y Khalimon, Konstantin Yu Dorogov, Andrei V Churakov, L G Kuzmina, D A Lemenovskii, Judith A K HowardAbstract:One-pot reactions of [WCp2(H)2] and [WCp2(H)(SnMe3)] with nBuLi followed by an equivalent of GeMe2Cl2 afford mono(Germyl) substituted tungstenocenes [WCp2(H)(GeMe2Cl)] (1) and [WCp2(SnMe3)(GeMe2Cl)] (7). Reactions of the products with tin halides in the presence NEt3 afford the mixed complexes [WCp2(SnR2X)(GeMe2Y)] (X, Y = Cl, Br, RMe, Et), which were further converted to moderately stable compounds [WCp2(SnR2H)(GeMe2H)] (R = Me (10), Et (11)). A number of asymmetric mono(halo)-substituted Germyl/stannyl tungstenocenes [WCp2(SnMe2X)(GeMe2H)] (X = Cl (12), Br (13)) and [WCp2(SnEt2Y)(GeMe2H)] (Y = Br (14), I (15)) were prepared by selective halogenation of the Sn–H bond in 10 and 11. X-Ray studies of [WCp2(H)(GeMe2Cl)] (1), [WCp2(SnEt2Br)(GeMe2Cl)] (4), and [WCp2(SnEt2Br)(GeMe2H)] (14) established classical structures of these compounds. X-Ray study of complex [WCp2(SnMe2Cl)(GeMe2Cl)] (3) revealed the presence of interligand Ge–Cl⋯Sn–Cl interactions in a highly Ge/Sn disordered structure. Analyses of molecular parameters of 1, 4, and 14 suggest the presence of a negative hyperconjugation between metal lone pairs and the σ*-orbital of the E–X bond, which is stronger in bromo substituted complexes in comparison with chloro substituted ones.
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Bis(Germyl)-Substituted Niobocenes
Organometallics, 2003Co-Authors: Georgii I. Nikonov, And Andrei V. Churakov, Mikhail Yu. AntipinAbstract:Reactions of niobocene hydrides with halo-germanes present a new effective method for the synthesis of mono(Germyl)- and bis(Germyl)niobocenes. Chloro-demethylation of Cp 2 NbH(GeMe 3 ) 2 under the action of Cl 2 SnMe 2 is very facile and leads to the first asymmetric niobocene having two different germanium centers.
Jose M Riveros - One of the best experts on this subject based on the ideXlab platform.
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ligand exchange ion molecule reactions of simple silyl and Germyl cations
International Journal of Mass Spectrometry, 2003Co-Authors: Luciano A Xavier, Josefredo R Pliego, Jose M RiverosAbstract:Abstract The gas-phase reaction of Me 3 Si + with Si(OMe) 4 , studied under FT-ICR conditions, reveals that aside from the expected silyl ion– n -donor base association an exchange mechanism exists that gives rise to Me 2 SiOMe + . Further reaction of this ion was observed to result in a second exchange of a methyl group by a methoxy group in the silyl ion. The similar reaction between Me 3 Si + and Ge(OMe) 4 yields not only the silyl ions with progressive exchange of methyl by methoxy but the different Germyl ions, Me n Ge(OMe) 3− n + ( n =0–3). Ab initio calculations for the simple model system MeSiH 2 + +MeOGeH 3 reveal that these reactions proceed by initial formation of a very strong Lewis acid–base complex where migration of the Germyl or silyl group can result in a moiety held together by an alkyl bridge. Methide abstraction in this intermediate can then give rise to silyl and Germyl cations. The present results suggest that other Si and Ge systems may display this very same kind of rich chemistry.
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Ligand exchange ion–molecule reactions of simple silyl and Germyl cations
International Journal of Mass Spectrometry, 2003Co-Authors: Luciano A Xavier, Josefredo R Pliego, Jose M RiverosAbstract:Abstract The gas-phase reaction of Me 3 Si + with Si(OMe) 4 , studied under FT-ICR conditions, reveals that aside from the expected silyl ion– n -donor base association an exchange mechanism exists that gives rise to Me 2 SiOMe + . Further reaction of this ion was observed to result in a second exchange of a methyl group by a methoxy group in the silyl ion. The similar reaction between Me 3 Si + and Ge(OMe) 4 yields not only the silyl ions with progressive exchange of methyl by methoxy but the different Germyl ions, Me n Ge(OMe) 3− n + ( n =0–3). Ab initio calculations for the simple model system MeSiH 2 + +MeOGeH 3 reveal that these reactions proceed by initial formation of a very strong Lewis acid–base complex where migration of the Germyl or silyl group can result in a moiety held together by an alkyl bridge. Methide abstraction in this intermediate can then give rise to silyl and Germyl cations. The present results suggest that other Si and Ge systems may display this very same kind of rich chemistry.
Taichi Nakano - One of the best experts on this subject based on the ideXlab platform.
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the first stereospecific arylation of z Germyl stannyl ethenes with an aryl halide or heteroaryl halide under palladium catalysis
Applied Organometallic Chemistry, 2008Co-Authors: Takumi Kataishi, Yutaka Takahashi, Kotaro Kato, Yoshiaki Makihara, Yuichi Kitashima, Sigeru Ohara, Fumiaki Anzai, Seiich Inokuma, Masaaki Ubukata, Taichi NakanoAbstract:A combination catalyst of Pd(dba)2-PPh3-CuI-LiCl or Pd(dba)2-P(2-furyl)3-CuI-LiCl effectively catalyzed the cross-coupling of (Z)-Germyl(stannyl)ethenes with aryl halides, providing novel triethyl(2,2-diarylethenyl)germanes in good to high yields. The reaction proceeds with retention of configuration. Cross-coupling results in the formation of phenylene or phenyleneethynylene derivatives with terminal stereochemically defined vinylgermane unit(s). Copyright © 2008 John Wiley & Sons, Ltd.
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Acid‐dependent selective formation of trans‐aryl(Germyl)ethenes or 1‐aryl‐1‐Germylethenes by the protodestannylation of (Z)‐Germyl(stannyl)ethenes
Applied Organometallic Chemistry, 2005Co-Authors: Taichi Nakano, Yoshiya Senda, Kayo Fukaya, Naoyuki Sugiuchi, Yutaka Takahashi, Hiroyuki KuriharaAbstract:Protodemetallation of (Z)-1-aryl-2-Germyl-1-stannylethenes using hydrochloric acid in the presence of tetraethylammonium chloride (TEACl) proceeds at 0 °C with retention of configuration to afford trans-1-aryl-2-Germylethenes with high yields. In contrast, the reaction using hydroiodic acid in the presence of tetrabutylammonium iodide (TBAI) brings about a novel 1,2-Germyl migration accompanying the destannylation to form 1-aryl-1-Germylethenes. These 1,2-Germyl migration products result with especially high selectivity from adducts bearing a substituent at the ortho- or para-position on the aromatic ring in the adduct. However, the Germyl(stannyl)ethenes bearing a substituent at the meta position on the ring produce a regioisomeric mixture of a trans-Germylethene and a 1-aryl-1-Germylethene. Copyright © 2005 John Wiley & Sons, Ltd.
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synthesis of z 1 aryl 2 Germyl 1 stannyl ethenes and the related ethenes precursors to stereodefined Germylethenes via pd dba 2 p och2 3cet catalyzed germastannation of acetylenes in thf
Journal of Organometallic Chemistry, 2001Co-Authors: Yoshiya Senda, Taichi Nakano, Yohichi Oguchi, Michihiro Terayama, Taijyu Asai, Toshihiko MigitaAbstract:(Z)-1-Aryl-2-(Germyl)-1-(stannyl)ethenes are synthesized in high yields by the addition of tributyl(triethylGermyl)stannane to arylacetylenes catalyzed by a specific combination catalyst, Pd(dba)2 and 4-ethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, in tetrahydrofuran. Ethynylthiophene and 2-methyl-3-butyn-2-ol are also subject to the germastannation to afford the respective adducts in high yields. In addition, the JSn–H and 13C-NMR data for their adducts are presented.
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alternative synthesis of z 1 aryl 1 tributylstannyl 2 triethylGermyl ethenes and the unprecedented Germyl 1 2 migration during the destannylation of the adducts
Chemistry Letters, 2000Co-Authors: Taichi Nakano, Yoshiya Senda, Takashi MiyamotoAbstract:A specific combination catalyst, Pd(dba)2 and 4-ethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, effectively catalyzed the addition of tributyl(triethylGermyl)stannane to arylacetylenes in tetrahydrofuran to give (Z)-1-aryl-2-(Germyl)-1-(stannyl)ethenes in high yields. The (Z)-1-aryl-2-(Germyl)-1-(stannyl)ethenes were subject to the unprecedented Germyl 1,2-migration during the destannylation using HI / TBAI in toluene to produce 1-aryl-1-(Germyl)ethenes in high yields.
Luciano A Xavier - One of the best experts on this subject based on the ideXlab platform.
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ligand exchange ion molecule reactions of simple silyl and Germyl cations
International Journal of Mass Spectrometry, 2003Co-Authors: Luciano A Xavier, Josefredo R Pliego, Jose M RiverosAbstract:Abstract The gas-phase reaction of Me 3 Si + with Si(OMe) 4 , studied under FT-ICR conditions, reveals that aside from the expected silyl ion– n -donor base association an exchange mechanism exists that gives rise to Me 2 SiOMe + . Further reaction of this ion was observed to result in a second exchange of a methyl group by a methoxy group in the silyl ion. The similar reaction between Me 3 Si + and Ge(OMe) 4 yields not only the silyl ions with progressive exchange of methyl by methoxy but the different Germyl ions, Me n Ge(OMe) 3− n + ( n =0–3). Ab initio calculations for the simple model system MeSiH 2 + +MeOGeH 3 reveal that these reactions proceed by initial formation of a very strong Lewis acid–base complex where migration of the Germyl or silyl group can result in a moiety held together by an alkyl bridge. Methide abstraction in this intermediate can then give rise to silyl and Germyl cations. The present results suggest that other Si and Ge systems may display this very same kind of rich chemistry.
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Ligand exchange ion–molecule reactions of simple silyl and Germyl cations
International Journal of Mass Spectrometry, 2003Co-Authors: Luciano A Xavier, Josefredo R Pliego, Jose M RiverosAbstract:Abstract The gas-phase reaction of Me 3 Si + with Si(OMe) 4 , studied under FT-ICR conditions, reveals that aside from the expected silyl ion– n -donor base association an exchange mechanism exists that gives rise to Me 2 SiOMe + . Further reaction of this ion was observed to result in a second exchange of a methyl group by a methoxy group in the silyl ion. The similar reaction between Me 3 Si + and Ge(OMe) 4 yields not only the silyl ions with progressive exchange of methyl by methoxy but the different Germyl ions, Me n Ge(OMe) 3− n + ( n =0–3). Ab initio calculations for the simple model system MeSiH 2 + +MeOGeH 3 reveal that these reactions proceed by initial formation of a very strong Lewis acid–base complex where migration of the Germyl or silyl group can result in a moiety held together by an alkyl bridge. Methide abstraction in this intermediate can then give rise to silyl and Germyl cations. The present results suggest that other Si and Ge systems may display this very same kind of rich chemistry.
Andrey Y Khalimon - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and structural studies of Germyl and Germyl/stannyl substituted tungstenocenes.
Dalton Transactions, 2007Co-Authors: Andrey Y Khalimon, Konstantin Yu Dorogov, Andrei V Churakov, L G Kuzmina, D A Lemenovskii, Judith A K Howard, Georgii I. NikonovAbstract:One-pot reactions of [WCp2(H)2] and [WCp2(H)(SnMe3)] with nBuLi followed by an equivalent of GeMe2Cl2 afford mono(Germyl) substituted tungstenocenes [WCp2(H)(GeMe2Cl)] (1) and [WCp2(SnMe3)(GeMe2Cl)] (7). Reactions of the products with tin halides in the presence NEt3 afford the mixed complexes [WCp2(SnR2X)(GeMe2Y)] (X, Y = Cl, Br, RMe, Et), which were further converted to moderately stable compounds [WCp2(SnR2H)(GeMe2H)] (R = Me (10), Et (11)). A number of asymmetric mono(halo)-substituted Germyl/stannyl tungstenocenes [WCp2(SnMe2X)(GeMe2H)] (X = Cl (12), Br (13)) and [WCp2(SnEt2Y)(GeMe2H)] (Y = Br (14), I (15)) were prepared by selective halogenation of the Sn–H bond in 10 and 11. X-Ray studies of [WCp2(H)(GeMe2Cl)] (1), [WCp2(SnEt2Br)(GeMe2Cl)] (4), and [WCp2(SnEt2Br)(GeMe2H)] (14) established classical structures of these compounds. X-Ray study of complex [WCp2(SnMe2Cl)(GeMe2Cl)] (3) revealed the presence of interligand Ge–Cl⋯Sn–Cl interactions in a highly Ge/Sn disordered structure. Analyses of molecular parameters of 1, 4, and 14 suggest the presence of a negative hyperconjugation between metal lone pairs and the σ*-orbital of the E–X bond, which is stronger in bromo substituted complexes in comparison with chloro substituted ones.
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synthesis and structural studies of Germyl and Germyl stannyl substituted tungstenocenes
Dalton Transactions, 2007Co-Authors: Georgii I. Nikonov, Andrey Y Khalimon, Konstantin Yu Dorogov, Andrei V Churakov, L G Kuzmina, D A Lemenovskii, Judith A K HowardAbstract:One-pot reactions of [WCp2(H)2] and [WCp2(H)(SnMe3)] with nBuLi followed by an equivalent of GeMe2Cl2 afford mono(Germyl) substituted tungstenocenes [WCp2(H)(GeMe2Cl)] (1) and [WCp2(SnMe3)(GeMe2Cl)] (7). Reactions of the products with tin halides in the presence NEt3 afford the mixed complexes [WCp2(SnR2X)(GeMe2Y)] (X, Y = Cl, Br, RMe, Et), which were further converted to moderately stable compounds [WCp2(SnR2H)(GeMe2H)] (R = Me (10), Et (11)). A number of asymmetric mono(halo)-substituted Germyl/stannyl tungstenocenes [WCp2(SnMe2X)(GeMe2H)] (X = Cl (12), Br (13)) and [WCp2(SnEt2Y)(GeMe2H)] (Y = Br (14), I (15)) were prepared by selective halogenation of the Sn–H bond in 10 and 11. X-Ray studies of [WCp2(H)(GeMe2Cl)] (1), [WCp2(SnEt2Br)(GeMe2Cl)] (4), and [WCp2(SnEt2Br)(GeMe2H)] (14) established classical structures of these compounds. X-Ray study of complex [WCp2(SnMe2Cl)(GeMe2Cl)] (3) revealed the presence of interligand Ge–Cl⋯Sn–Cl interactions in a highly Ge/Sn disordered structure. Analyses of molecular parameters of 1, 4, and 14 suggest the presence of a negative hyperconjugation between metal lone pairs and the σ*-orbital of the E–X bond, which is stronger in bromo substituted complexes in comparison with chloro substituted ones.