The Parent GaH₂SbH₂ Monomer Stabilized by an N‐Heterocyclic Carbene

The synthesis and characterization of the stibanyltrielanes IDipp·GaH 2 Sb(SiMe 3 ) 2 ( 1a ) and IDipp·BH 2 Sb(SiMe 3 ) 2 ( 1b ) are presented. 1a represents the first example for the isolation of a molecular stibanylgallane monomer stabilized only by a Lewis base (LB). While methanolytic cleavage of the {SiMe 3 } residues in 1a cannot be achieved, the direct salt metathesis reactions of K(18c6)SbH 2 with LB·EH 2 X (LB = IDipp, NMe 3 ; E = B, Ga; X = I, OTf) afford the isolation of the parent compounds IDipp·BH 2 SbH 2 ( 2a ), Me 3 N·BH 2 SbH 2 ( 2b ), and IDipp·GaH 2 SbH 2 ( 3 ) for the first time in moderate yields. Specifically, the synthesis of 3 not only represents the first stabilization of the {GaH 2 SbH 2 } motif as the so far heaviest known ethylene‐like parent group 13/15 element combination but also validates its stabilization procedure by a LB to access a first sterically unhindered primary stibane. All compounds display drastic sensitivity toward air, light, and temperature. The products are characterized by NMR and infrared spectroscopy, as well as by single‐crystal X‐ray structure determination and mass spectrometry and the electronic structure is investigated by density functional theory calculations. Furthermore, the reaction of IDipp·GaCl 3 with K(18c6)SbH 2 yields a product mixture, in which 3 and the unprecedented IDipp·GaH(SbH 2 ) 2 ( 4 ) can be identified.