- Diorganostannide dianions (R2Sn2-) as reaction intermediates revisited: In situ 119Sn NMR studies in liquid ammonia
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It has frequently been proposed that diorganostannide dianions, SnR 22-, form during reactions of dihalodiorganostannanes or dihydrodiorganostannanes with sodium in liquid ammonia. The formation of this intermediate has been advanced to be an important step in the synthesis of a wide range of organostannanes. Here we report 119Sn NMR investigations in liquid NH3 of reaction intermediates that formed in situ during the conversions of dichlorodiphenylstannane, dihydrodiphenylstannane (diphenylstannane), dideuterodiphenylstannane, and dichlorodibutylstannane, respectively. This study revealed that the proposed SnR22- dianion was not present, but tetraorganodistannides, (R2Sn-SnR2)2-, and hydrodiorganostannides (tin hydrides), R2SnH- (or R 2SnD-, respectively), were detected instead.
- Trummer, Markus,Caseri, Walter
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p. 3862 - 3867
(2010/12/24)
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- Preparation of ethylene-bridged Group 14 metal-zirconocene complexes
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The reactions of the zirconocene-ethylene complex Cp2Zr(CH2=CH2)(PMe3) with Group 14 metal chlorides or alkoxides give ethylene-bridged group 14 metal-zirconocene complexes. A reaction mechanism via a five-membered intermediate which involves direct coupling of ethylene and single bonding is proposed.
- Ura, Yasuyuki,Hara, Ryuichiro,Takahashi, Tamotsu
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p. 299 - 303
(2007/10/03)
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- Wurtz-type reductive coupling reaction of primary alkyl iodides and haloorganotins in cosolvent/H2O(NH4Cl)/Zn media as a route to mixed alkylstannanes and hexaalkyldistannanes
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Mixed tetra-alkylstannanes R3SnR′ (R = Et, n-Pr, n-Bu and R′= Me, Et, n-Pr, n-Bu, n-Pent) and R2SnR′2 (R = n-Bu and R′ = Me, Et, n-Pr, n-Bu) can be easily prepared in a one-pot synthesis via coupling reaction of alkyl iodides R′I with R3SnX (X = Cl, I) and R2SnCl2 compounds in cosolvent-H2O(NH4Cl) medium mediated by zinc dust. Coupling also occurs with (Bu3Sn)2O. It has been verified that reactions are possible only with primary alkyl iodides; with secondary alkyl iodides the coupling reaction fails. When alkyl chlorides and bromides are used ditin compounds are obtained instead of the unsymmetrical tetra-alkylstannanes. This represents a route to hexaalkyldistannanes.
- Marton, Daniele,Tari, Massimo
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- Preparation of benzylstannanes by zinc-mediated coupling of benzyl bromides with organotin derivatives. Physicochemical characterization and crystal structures
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Benzyltrialkyl- (1-13) and benzyltriphenylstannanes (16-22) have been easily prepared in a one-pot synthesis via coupling reaction of benzyl bromide derivatives (C6H5CH2Br and XYC6H3CH2Br, X = H, Y = o-, m-, p-CH3, o-, m-, p-F, o-, m-Cl, and p-Br; X = o-F, Y = p-Br) with R3SnCl compounds (R = Et, Pr, Bu, and Ph) in THF/H2O (NH4Cl) medium mediated by zinc powder. Such coupling also occurs with (Bu3Sn)2O. Dibenzyldibutylstannane (15) is prepared by reaction of benzyl bromide with Bu2SnCl2 or (Bu2SnCl)2O, and (2-naphthylmethyl)tributylstannane (14) by reaction of 2-(bromomethyl)naphthalene with Bu3SnCl. 13C-and 119Sn-NMR data are reported for all compounds, and M?ssbauer data for benzyltributylstannanes 10 and 11 and benzyltriphenylstannanes 16-18 and 20-22. The crystal structures of Ph3SnBn, with Bn = o- (17) and m-ClC6H4CH2 (18) and o- (20) and m-FC6H4-CH2 (21) have been determined.
- Marton, Daniele,Russo, Umberto,Stivanello, Diego,Tagliavini, Giuseppe,Ganis, Paolo,Valle, Giovanni Carlo
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p. 1645 - 1650
(2008/10/08)
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