The characteristic features of bulk silicon surfaces are echoed in the related partially substituted—and thus unsaturated—neutral silicon clusters (siliconoids). The incorporation of siliconoids into more‐extended frameworks is promising owing to their unique electronic features, but further developments in this regard are limited by the notable absence of functionalized siliconoid derivatives until now. Herein we report the isolation and full characterization of the lithium salt of an anionic R5Si6‐siliconoid, thus providing the missing link between silicon‐based Zintl anions and siliconoid clusters. Proof‐of‐principle for the high potential of this species for the efficient transfer of the intact unsaturated R5Si6 moiety is demonstrated by clean reactions with representative electrophiles of Groups 13, 14, and 15.

The recent progress in the synthesis of partially substituted neutral silicon clusters (siliconoids) revealed unique structures and electronic anisotropies that are reminiscent of bulk and nano surfaces of silicon.

The generation of heavier double-bond systems without by- or side-product formation is of considerable importance for their application in synthesis. Peripheral functional groups in such alkene homologues are promising in this regard owing to their inherent mobility. Depending on the steric demand of the N-alkyl substituent R, the reaction of disilenide Ar2Si=Si(Ar)Li (Ar = 2,4,6-iPr3C6H2) with ClP(NR2)2 either affords the phosphinodisilene Ar2 Si=Si(Ar)P(NR2)2 (for R = iPr) or P-amino functionalized phosphasilenes Ar2(R2N)Si=Si(Ar)=P(NR2) (for R = Et, Me) by 1,3-migration of one of the amino groups. In case of R = Me, upon addition of one equivalent of tert-butylisonitrile a second amino group shift occurs to yield the 1-aza-3-phosphaallene Ar2(R2N)Si=Si(NR2)(Ar)-P=C=NtBu with pronounced ylidic character. All new compounds were fully characterized by multinuclear NMR spectroscopy as well as single-crystal X-ray diffraction and DFT calculations in selected cases.

Unsaturated silicon clusters (siliconoids) are short-lived intermediates during the transition from molecules to the elemental bulk; stable representatives reiterate surface features of silicon materials. The incorporation of suitable heteroatoms into the cluster scaffold of stable siliconoids extends this analogy to the technological process of silicon doping. Here, we report boron-and phosphorus-containing heterosiliconoids with BSi 5 and PSi 5 core based on the global minimum Si 6 R 6 platform (dubbed benzpolarene for its relationship to benzene). The reductive cleavage of an SiR 2 moiety (R = 2,4,6-iPr 3 C 6 H 2 ) from Si 6 R 6 selectively yields a dianionic Si 5 R 4 2− cluster as its lithium salt. Treatment with Me 3 SiCl affords the corresponding trimethylsilyl-substituted (Me 3 Si) 2 Si 5 R 4 . Reaction of Si 5 R 4 2− with iPr 2 NECl 2 (E = B, P) yields the unprecedented p-and n-doped heterosiliconoids iPr 2 NESi 5 R 4 . Their peculiar electronic features are compared to those of the hexasilabenzpolarene starting material on grounds of NMR spectroscopy, X-ray diffraction, and DFT calculations.