NMR Spectra and structures of organotin compounds

The reactions of 1,3-dichloro-1,1,3,3-tetrabutyldistannoxane and dialkyltin dihalides with silver perfluorooctanesulfonate provided the corresponding sulfonates as hydrates. The number of water molecules (n) of hydration was dependent on the conditions. The distannoxane derivative was identified as n from 0.5 to 6, while in the hydrated mononuclear species and DMSO complexes n varied widely from 4 to 13. 119Sn NMR spectroscopy and conductivity measurements indicated the ionic dissociation of these compounds in solution. These compounds exhibited unusually high solubility in polar organic solvents. The ionic dissociation together with facile hydration probably causes the unusual solubility. The Lewis acidity of these compounds was found to be high among organotin derivatives on the basis of ESR spectra of superoxide/metal-ion complexes. In contrast to well-known organotin triflates, these compounds suffered no hydrolysis upon storage in open air. The high catalytic activity of the distannoxane 1 was exemplified for various carbon-carbon bond-forming reactions, such as Mukaiyama-aldol as well as -Michael reactions and allylation of aldehydes.

Organotin perfluorooctanesulfonates as air-stable Lewis acid catalysts: synthesis, characterization, and catalysis.

Dialkynyltin compds. alkynyltin of the type Me2Sn(C.tplbond.CL)2 [1; L = 2-pyridyl (a), Me2NCH2 (b), MeOCH2 (c), MeOCH:CH (d), EtSCH2 (e)] were prep. and the 1,1-organoboration of 1 with triethyl- (2a) and triisopropylborane (2b) has been studied. The first detectable intermediates were in all cases zwitterionic compds. 3 (I, R2 = Et) (from Et3B) and 4 (I, R2 = Me2CH) [from (Me2CH)3B] with a cationic triorganotin fragment, stabilized by coordinative s L-Sn bonds and by side-on coordination to the C.tplbond.C bond of an alkynylborate moiety. The nature of this stabilization has been established by three x-ray analyses (3b, 4b, and 4d) in the solid state and by multinuclear NMR (1H, 11B, 13C, 15N, 119Sn NMR) in soln. The comparison of the mol. structure of 3b, 4b, and 4d with that of intermediates without functional groups shows that the distance of the tin atom to the C.tplbond.C bond is elongated. However, the planar arrangement of all relevant atoms proves that the side-on coordination of the tin atom to the C.tplbond.C bond is still present. These intermediates 3 and 4 rearrange to stannoles 5, 6 (II) and/or to 1-stanna-4-bora-2,5-cyclohexadienes 9, 10 (III). In the case of 3b and 3e, 119Sn NMR indicates that dialkenyltin compds. 7b and 7e are also formed as minor products. In the case of 3e, the 3-stannolene 8e is one of the final products. In the stannoles 5 and 6 a coordinative L-B bond is evident, and there is NMR spectroscopic evidence of a weak coordinative L-Sn bond.

Stabilization of Triorganotin Cations — Competition between Intramolecular Coordinative O, S or NSn Bonds and Side‐on π Coordination to CC Bonds

Phosphine, arsine and amine oxide complexes of some organotin and organolead halides

V.G.Kumar Das

Papers

New sulfoxide and amide complexes of methyltin cations

Acetolysis of hexaaryldileads

New bis- and tetrakis-complexes of trimethyl- and dimethyltin(IV) cations: Me3SnL2BPh4 and Me2SnL4(BPh4)2

Cleavage of hexaphenyldilead by mercuric salts