Spontaneous vs. Base‐Induced Dehydrochlorination of Group 14 ortho‐Carboranylamidinates

The reaction of the lithium ortho‐carboranylamidinate Li[HL] {HL = [o‐C2B10H10C(NiPr)(NHiPr)]} with ECl2R2 (E = Si, Ge, Sn, Pb; R = Cl, Me, Bu, Ph) leads to new ortho‐carboranylamidinates of the group 14 elements. In the case of the heavier elements, Ge, Sn, and Pb, compounds of the composition R2ECl[HL] were obtained in a straightforward manner, where the E atom adopts trigonal‐bipyramidal coordination. In the case of Si, disproportionation to R2Si[L] and H2L takes place immediately. The R2Si[L]‐type compounds, in which the Si atom exhibits a tetrahedral coordination, were obtained in a targeted synthesis protocol by reaction of the doubly lithiated ligand Li2L with R2SiCl2. The heavier homologues Cl2Ge[L] and Cl2Sn[L](THF) have been obtained accordingly. In contrast, it was found that deprotonation of R2ECl[HL] to R2E[L], employing triethylamine as a base, is not appropriate. All new compounds have been characterized by single‐crystal X‐ray diffraction, IR spectroscopy, and NMR spectroscopy, as well as mass spectrometry. Compounds of the types R2ECl[HL] and R2E[L] {E = Si, Ge, Sn, Pb; HL = [o‐C2B10H10C(NiPr)(NHiPr)]} are described. The stability of R2ECl[HL] increases on going from Si to Pb.