Two-coordinate group 14 element(ii) hydrides as reagents for the facile, and sometimes reversible, hydrogermylation/hydrostannylation of unactivated alkenes and alkynes

Abstract

The ambient temperature hydrometallations of a variety of unactivated alkene and alkyne substrates using two-coordinate hydrido-tetrylenes, :E(H)(L†) (E = Ge or Sn; L† = extremely bulky amide), are reported.

Neutral, Cationic and Hydride‐substituted Siloxygermylenes

“…As summarized in Scheme , the formation of IPr⋅GeCl(OSiMe 3 )⋅BH 3 is less favorable (Δ r H =−98.7 kJ mol −1 ; Δ r G =−55.2 kJ mol −1 ) than its Ge II hydride analogue IPr⋅GeH(OSiMe 3 )⋅BH 3 (Δ r H =−123.4 kJ mol −1 ; Δ r G =−77.4 kJ mol −1 ), suggesting the more electronegative chloride ligand reduces the Lewis basicity of the germylene which affords a less thermodynamically stable adduct with BH 3 . This result is interesting as base‐free Ge II hydrides are often much less stable than their chloro counterparts, however the opposite stability trend is found within donor–acceptor complexes and partially explains the stability of the Ge II dihydride complex IPr⋅GeH 2 ⋅BH 3 …”

Redox‐Active N‐Heterocyclic Germylenes and Stannylenes with a Ferrocene‐1,1′‐diyl Backbone

“…We surmise that the target stannylene 1 Np Sn is not sufficiently stable for isolation and undergoes a decomposition reaction to the products described, possibly through an initial β‐hydrogen elimination step (see Scheme S1 in the Supporting Information) . Compounds 1 Mes Sn and 1 TMS Sn were structurally characterised by means of single‐crystal X‐ray diffraction studies.…”

Organosilicon and ‐germanium Hydrides in Catalyst‐Free Hydrometallation Reactions

“…Regiospecific hydrometallation of these unsaturated substrates was performed easily. The cycloalkene hydrometallation reactions ( n = 1, 2 or 4) are cleanly reversible (Scheme ) …”

“…β‐Hydride elimination processes were proposed to be of key importance in the reactions between {N(Ar)(Si i Pr 3 )}GeH and cycloocta‐1,5‐diene or 2‐methylbut‐2‐ene, leading to the isomerisation of the alkene skeletons. {N(Ar)(Si i Pr 3 )}Ge(cyclooct‐2‐enyl) and {N(Ar)(Si i Pr 3 )}Ge{C 2 H 4 C(H)Me 2 }, respectively (Scheme ), are thus the reaction products of the subsequent hydrogermylation …”