To Rearrange or not to Rearrange: Reactivity of NHCs towards Chloro- and Hydrostannanes R2SnCl2(R = Me, Ph) and Ph3SnH

Article abstract of DOI:10.1002/zaac.201600271

The reaction of 1,3-diisopropylimidazolin-2-ylidene (iPr₂Im) with diphenyldichlorostannane and dimethyldichlorostannane, respectively, leads to the formation of the adducts (iPr₂Im)·SnPh₂Cl₂(1) and (iPr₂Im)·SnMe₂Cl₂(2). These compounds are stable in solution to temperatures up to 80 °C for several days and rearrangement to backbone-tethered bis(imidazolium) salts or ring expansion reaction to six membered heterocyclic rings was not observed. The reaction of iPr₂Im with triphenylstannane Ph₃SnH leads to reductive dehydrocoupling of the stannane to yield distannane Sn₂Ph₆and iPr₂ImH₂. Thus, the reactivity of these tin compounds is completely different compared to those of the lighter congener silicon, for which rearrangement (chlorides) and NHC ring expansion (hydrides) was reported earlier.