Reversible Reactions of Ethylene with Distannynes Under Ambient Conditions

Abstract

Ethylene's cycloadditions to unsaturated hydrocarbons occupy well-established ground in classical organic chemistry. In contrast, its reactivity toward alkene and alkyne analogs of carbon's heavier-element congeners silicon, germanium, tin, or lead has been little explored. We show here that treatment of the distannynes Ar(iPr4)SnSnAr(iPr4) [Ar(iPr4) = C6H3-2,6(C6H3-2,6-iPr2)2, 1] or Ar(iPr8)SnSnAr(iPr8) [Ar(iPr8) = C6H-2,6(C6H2-2,4,6-iPr3)2-3,5-iPr2, 2] with ethylene under ambient conditions affords the cycloadducts Ar(iPr4) Sn(mu2:nu1:n1-C2H4)2Sn Ar(iPr4 (3) or Ar(iPrs) Sn(mu2:nu1:nu1-C2H4)2Sn AriPrs (4) that were structurally and spectroscopically characterized. Ethylene incorporation in 3 and 4 involves tin-carbon sigma bonding and is shown to be fully reversible under ambient conditions; hydrocarbon solutions of 3 or 4 revert to the distannynes 1 or 2 with ethylene elimination under reduced pressure or upon standing at approximately 25 degrees C. Variable-temperature proton nuclear magnetic resonance studies showed that the enthalpies of reaction were near -48 (3) and -27 (4) kilojoules per mole.

Reversible Complexation of Ethylene by a Silylene under Ambient Conditions

“…These include disilynes, 12 digermynes, 3 frustrated Lewis-pair borane-phosphine molecules, 13 silylenes, 14 silylene precursors, 7k and digallenes, 15 but reversibility in ethylene binding, which is key for the development of possible catalysts, remains rare. 3,4 Further studies of the electronic factors that govern the reversibility of ethylene complexation by silylenes and their heavier group 14 element congeners are in hand. …”

Reversible Binding of Ethylene to Silylene–Phosphine Complexes at Room Temperature

“…[9] Remarkably, the stable distannyne reacts with two ethylene molecules, resulting in the formation of a bicyclic ethylene bis-adduct and the reactions are reversible. [10] The thermal lability of Sn À C s bond, a major factor for the reversibility, was elegantly demonstrated by the much higher thermal stability of the germanium analogue. In addition to these new systems, the concerted [2+1] cycloaddition is a typical reaction for divalent species.…”

Oxidation of Intramolecularly Coordinated Distannyne by S8: From Tin(I) to Tin(IV) Polysulfide Via Tin(II) Sulfide

“…[2] The studies dealing with the reactivity of the RE ER multiple bonds showed scission of the SiSi or GeGe triple bond by the addition of an olefin, [3] and most recently, Power and coworkers nicely outlined the cleavage of the Sn Sn multiple bond in the distannyne [ArSnSnAr] (Ar = C 6 H 3 -2,6-(C 6 H 3 -2,6-iPr 2 ) 2 ) by complexation with two molecules of either ethylene or norbornadiene. [4] Moreover, the latest study dealing with the reactivity of [ArSnSnAr] with cyclooctatetraene (cot) showed the powerful reducing character of the tin(I) compound towards neutral cot. [5] The reactivity studies of [ArSnSnAr] towards N 2 O also showed the reducing character of the Sn I species, yielding the organotin(II) oxide [ArSnOSnAr] as the final product.…”

“…The synthesis of compound 2 in the first step is followed by further oxidation of both Sn atoms to produce the respective Sn=S, which in situ dimerizes to afford [({2,6-(Me 2 NCH 2 ) 2 C 6 H 3 }Sn) 4 S 6 ] (4) due to the highly polar character of Sn=S. The proposed structure of compound 4 probably possesses double-decker arrangement (hereafter assigned as 4 a; Scheme 4) having two four-membered Sn 2 S 2 rings bridged by two sulfur atoms.…”