Reactions of amidinate-stabilized germylene chlorides R1Ge­(:)Cl (R1 = PhC­(NtBu)2) and R2Ge­(:)Cl (R2 = PhC­(NCy)2, Cy = cyclohexanyl) with trimethylsilylethynyl lithium salt (LLi, L = −CCTMS) afforded alkynylgermyl-substituted germylenes R1(:)­Ge-GeL3 (1) and [R2GeL2]2Ge­(:) (2), respectively. Both of them may undergo the formation of Ge–Ge single bonds with a concomitant 1,2-shift of ethynyl groups. DFT calculations determined the reaction pathways where two possible intermediates (:)­GeL2 and RGe(:)­L (R = R1, R2) are proposed, which were consistent with the trapping reactions of (:)­GeL2 toward IAr–(:)­GeL2 (3, IAr = :C­{N­(Ar)­CH}2, Ar = 2,6-iPr2C6H3). The reaction of 1 with N3TMS gave a new aminogermylene R1(:)­Ge–N­(TMS)-GeL3 (4), indicating a reactive Ge–Ge bond.

The reaction of amidinatosilylene LSi(:)Cl [L = PhC­(NtBu)2] with N-heterocyclic carbene IAr [:C­{N­(Ar)­CH}2, where Ar = 2,6-iPr2C6H3] and NaOTf in tetrahydrofuran (THF) facilely afforded a silicon­(II) cation [LSi(:)-aIAr]+OTf– (1 + OTf – ), where IAr isomerizes to abnormal N-heterocyclic carbene aIAr, coordinating to the silicon­(II) center. Its Ge homologue, [LGe(:)-aIAr]+OTf– (2 + OTf – ), was also accessed via the same protocol. For the formation of 1 + , we propose that an in situ-generated Si­(II) cation [LSi(:)]+ under the treatment of LSi(:)Cl with NaOTf may isomerize IAr in THF. In contrast, the replacement of IAr with cyclic alkyl­(amino) carbene (cAAC) furnished a cAAC-silanyl radical ion [LSi­(H)-cAAC]•+(LiOTf2)− [3 •+ (LiOTf 2 ) – ], which may undergo an abstraction of the H radical from THF. All of the products were characterized by nuclear magnetic resonance spectroscopy, electron paramagnetic resonance, and X-ray crystallography, and their bonding scenarios were investigated by density functional theory calculations. These studies provide new perspective on carbene–silicon chemistry.