Addition of Ethylene or Hydrogen to a Main‐Group Metal Cluster under Mild Conditions

Abstract

Reaction of the tin cluster Sn8(Ar(Me6))4(Ar(Me6)=C6H2-2,6-(C6H3-2,4,6-Me3)2) with excess ethylene or dihydrogen at 25 °C/1 atmosphere yielded two new clusters that incorporated ethylene or hydrogen. The reaction with ethylene yielded Sn4(Ar(Me6))4(C2H2)5 that contained five ethylene moieties bridging four aryl substituted tin atoms and one tin-tin bond. Reaction with H2 produced a cyclic tin species of formula (Sn(H)Ar(Me6))4, which could also be synthesized by the reaction of {(Ar(Me6))Sn(μ-Cl)}2 with DIBAL-H. These reactions represent the first instances of direct reactions of isolable main-group clusters with ethylene or hydrogen under mild conditions. The products were characterized in the solid state by X-ray diffraction and IR spectroscopy and in solution by multinuclear NMR and UV/Vis spectroscopies. Density functional theory calculations were performed to explain the reactivity of the cluster.

Access to Base Adducts of Low‐Valent Organotin‐Hydride Compounds by Controlled, Stepwise Hydrogen Abstraction from a Tetravalent Organotin Trihydride

“…The resulting mixtures contained distannane 7 alongw ith considerable amountso ft he tetrameric (ArSnH) 4 .T he latter reproducibly precipitated from the reaction mixturea sapaleyellow solid, which allowed straightforward isolationo ft he compound in ay ield of approximately 40 %. Although we have no confirmation of the structure, the spectroscopicdata are essentially identical to those reportedb yP ower and co-workers, [8] which strongly indicates the tetrameric nature of the isolated solid rather than aggregates of differing order.W erationalise this finding by the rapid generation of the monomeric [ArSnH] through amine base-induced dehydrogenation and weak coordinatives tabilisation of the intermediate [ArSnH] by the amine, which generates as ufficiently high concentration of [ArSnH] and only moderately donor-stabilised intermediates to allow the formation of the tetramer.Weconsider this approach to be av aluable alternative route to the tetrastannacyclobutane derivative originally presented by Power and co-workers. [8] …”

“…Hydrogen atoms, except for H1 and H2, and latticeb enzene have been omittedf or the sake of clarity. SnÀHb ond lengths are likely underestimated.S elected bondlengths [] and angles [8] are summarised in Ta ble 1. of chirality.T his fact becomes evident in the signal patterns of the 1 …”

“…In addition to the broad signal sets of 6,f urthers harp resonances in trace amountsc an be observed that correspond well with the shifts www.chemeurj.org of the stannacyclobutane (Ar'SnH) 4 recently reported by Power and co-workers. [8] Assuming the dissolved crystalst ob ep ure, this observation mayb er ationalised by the decomposition of small amountso f4 or 6 by NHC dissociation to form aggregates of [Ar'SnH] and free NHC or Ar'SnH(NHC), respectively (Scheme 4). Free NHC or Ar'SnH(NHC)m ay prevent full decompositiono ft he samples.…”

“…Although we cannot provide structural evidence, solution 1 Ha nd especially 119 Sn NMR spectroscopy in [D 1 ]chloroform, as well as IR spectroscopy,r evealed signal sets essentially in agreement with (Ar'SnH) 4 reported previously by Power and co-workers and thus strongly indicate the formation of the tetramer. [8] …”

“…[7] In the case of at erphenyl moiety with considerably reduced steric bulk, such as Ar' (Ar' = 2,6-dimesitylphenyl, mesityl = 2,4,6-trimethylphenyl), Ar'SnH was found to form the tetrameric tetrahydrostannacyclobutane. [8] Likely monomeric two-coordinatea midotin(II) hydrides have been studied by Jones and co-workers, [9] Rivard and co-workers described [SnH 2 ]a nd [SnH 2 SiH 2 ]t rapped in donor-acceptor complexes [10] and intramolecular base adducts formed from tin(II) hydrides have been presented by Roeskya nd co-workers. [11] Among other synthetic routes, organotin(IV) and -tin(II) hydrides can be accessedb ym etathesis of the respective halides with suitable hydride sources.…”