Activation of Ge-H and Sn-H Bonds with N-Heterocyclic Carbenes and a Cyclic (Alkyl)(amino)carbene

A study of the reactivity of several N-heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene 1-(2,6-di-iso-propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene (cAAC(Me)) with the group 14 hydrides GeH(2)Mes(2) and SnH2Me2(Me =CH3, Mes = 1,3,5-(CH3)(3)C6H2) is presented. The reaction of GeH(2)Mes(2) with cAAC(Me) led to the insertion of cAAC(Me) into one Ge-H bond to give cAAC(Me)H-GeHMes(2) (1). If 1,3,4,5-tetra methyl-imidazolin-2-ylidene (Me(2)lm(Me)) was used as the carbene, NHC-mediated dehydrogenative coupling occurred, which led to the NHC-stabilized germylene Me(2)lm(Me).GeMes(2) (2). The reaction of SnH2Me2 with cAAC(Me) also afforded the insertion product cAAC(Me)H-SnHMe2 (3), and reaction of two equivalents Me(2)lm(Me) with SnH2Me2 gave the NHC-stabilized stannylene Me(2)lm(Me).SnMe2 (4). If the sterically more demanding NHCs Me(2)lm(Me), 1,3-di-isopropyl-4,5-dimethyl-imidazolin-2-ylidene (iPr(2)lm(Me)) and 1,3-bis-(2,6-di-isopropylphenyl)-imidazolin-2-ylidene (Dipp(2)lm) were employed, selective formation of cyclic oligomers (SnMe2)(n) (5; n=5-8) in high yield was observed. These cyclic oligomers were also obtained from the controlled decomposition of cAAC(Me)H-SnHMe2(3).

Automated summary

A study on the reactivity of various N-heterocyclic carbenes and cyclic carbenes with group 14 hydrides reveals the formation of different reaction products, some of which may have potential applications.