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 SnH 2 Me 2 (Me=CH 3 , Mes=1,3,5-(CH 3 ) 3 C 6 H 2 ) 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-tetramethyl-imidazolin-2-ylidene (Me 2 Im Me ) was used as the carbene, NHC-mediated dehydrogenative coupling occurred, which led to the NHC-stabilized germylene Me 2 Im Me ⋅GeMes 2 (2). The reaction of SnH 2 Me 2 with cAAC Me also afforded the insertion product cAAC Me H-SnHMe 2 (3), and reaction of two equivalents Me 2 Im Me with SnH 2 Me 2 gave the NHC-stabilized stannylene Me 2 Im Me ⋅SnMe 2 (4). If the sterically more demanding NHCs Me 2 Im Me , 1,3-di-isopropyl-4,5-dimethyl-imidazolin-2-ylidene (iPr 2 Im Me ) and 1,3-bis-(2,6-di-isopropylphenyl)-imidazolin-2-ylidene (Dipp 2 Im) were employed, selective formation of cyclic oligomers (SnMe 2 ) n (5; n=5-8) in high yield was observed. These cyclic oligomers were also obtained from the controlled decomposition of cAAC Me H-SnHMe 2 (3).