Thermolysis of tris(silyl) tin hydride 2 at 70 °C for 3 hours results in elimination of tBu2MeSiH and generation of bis(silyl) stannylene 3 which dimerizes instantaneously yielding distannene 4. Compound 3 can be trapped by NHCMe yielding stannylene‐NHCMe complex 5. Upon heating (70 °C, 24 h) 4 yields stannyl radical 8 along with pentastannatricyclo[2.1.0.02, 5]pentane 10 (ca. 30 %) and traces (ca. 5 %) of the novel octastannacubane 9. Remarkably, octastannacubane 9 is produced in 70 % yield by mild heating (50 °C) of 1,1,2,2‐tetrasilyldistannane 11, along with tBu2MeSiH. Octastannacubane 9 was characterized by X‐ray crystallography, NMR and UV/Vis spectroscopy. Based on DFT quantum‐mechanical calculations the 11 → 9 transformation occurs via reductive elimination of two tBu2MeSiH molecules from 11 yielding a distannyne, (or its bis‐stannylene isomer), followed by its tetramerization.

Thermolysis of tris(silyl) tin hydride 2 at 70 °C for 3 hours results in elimination of tBu2MeSiH and generation of bis(silyl) stannylene 3 which dimerizes instantaneously yielding distannene 4. Compound 3 can be trapped by NHCMe yielding stannylene‐NHCMe complex 5. Upon heating (70 °C, 24 h) 4 yields stannyl radical 8 along with pentastannatricyclo[2.1.0.02, 5]pentane 10 (ca. 30 %) and traces (ca. 5 %) of the novel octastannacubane 9. Remarkably, octastannacubane 9 is produced in 70 % yield by mild heating (50 °C) of 1,1,2,2‐tetrasilyldistannane 11, along with tBu2MeSiH. Octastannacubane 9 was characterized by X‐ray crystallography, NMR and UV/Vis spectroscopy. Based on DFT quantum‐mechanical calculations the 11 → 9 transformation occurs via reductive elimination of two tBu2MeSiH molecules from 11 yielding a distannyne, (or its bis‐stannylene isomer), followed by its tetramerization.

Thermolysis of a 1 : 1 mixture of tris(di‐tert‐butylmethylsilyl)germane 9 and bis(di‐tert‐butylmethylsilyl)germane 17 at 100 °C produces unexpectedly octagermacubane 18, having two 3‐coordinate Ge0 atoms (40 % yield). 18 was characterized by X‐ray crystallography and it is a singlet biradical (according to DFT quantum mechanical calculations and the absence of an EPR signal). Reactions of 18 with CH2Cl2 and H2O yield the novel dichloro‐octagermacubane 24 and hydroxy‐octagermacubane 25, respectively. Reduction of 18 with tBuMe2SiNa in THF produces an isolable octagermacubane radical anion 26‐Na. Based on X‐ray crystallography, EPR spectroscopy and DFT quantum mechanical calculations, 26‐Na is classified as a Ge‐centered radical anion.

Thermolysis of a 1 : 1 mixture of tris(di-tertbutylmethylsilyl)germane 9 and bis(di-tert-butylmethylsilyl)germane 17 at 100 °C produces unexpectedly octagermacubane 18, having two 3-coordinate Ge 0 atoms (40 % yield). 18 was characterized by X-ray crystallography and it is a singlet biradical (according to DFT quantum mechanical calculations and the absence of an EPR signal). Reactions of 18 with CH 2 Cl 2 and H 2 O yield the novel dichloro-octagermacubane 24 and hydroxyoctagermacubane 25, respectively. Reduction of 18 with tBuMe 2 SiNa in THF produces an isolable octagermacubane radical anion 26-Na. Based on X-ray crystallography, EPR spectroscopy and DFT quantum mechanical calculations, 26-Na is classified as a Ge-centered radical anion.

A stable lithium stannenolate 7 was synthesized and isolated by the reaction of acylstannane 6 with LDA or tBu2MeSiLi in THF. 7 was characterized by X-ray crystallography and by NMR...