Heterocumulenes SeCNR (R = C₆H₄OMe-2, C₆H₄Me-2) undergo facile cycloaddition to [(H-dpp-bian)Na(Et₂O)₂] (1) (H-dpp-bian = N-protonated 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) resulting in cycloadducts [(H-dpp-bian)Na(SeCNR)(DME)] (2, 3), which are the first cycloadducts derived from a sodium metallacycle reported so far. A comparative reaction of [(dpp-bian)Mg(THF)₃] (10) with SeCNR gives magnesium cycloadducts [(dpp-bian)Mg(SeCNR)(Solv)₂] (11, 12), which undergo fast decomposition at room temperature. New compounds are characterized by NMR, EPR, and IR spectroscopy, and elemental and X-ray diffraction analysis. Their electronic structures and reaction pathways were probed using DFT calculations.

Novel low-valent organotin imide complexes exhibit remarkable phosphorescent properties suitable for advanced luminescent applications.

The reactivity of the complex [(dpp-bian)GaNa(DME)₂] (1) (dpp-bian = 1,2-bis[(2,6-di-isopropylphenyl)imino]acenaphthene) towards isocyanates, benzophenone, diphenylketene, and 1,2-dibenzylidenehydrazine has been studied. Treatment of 1 with isocyanates led to derivatives of imidoformamide [(dpp-bian)Ga{C(=NPh)₂}₂–NPh][Na(DME)₃] (2), biuret [(dpp-bian)Ga(NCy)₂(CO)₂NCy][Na(DME)] (3), or carbamic acids [(dpp-bian)GaN(Cy)C(O)O]₂[Na(THF)(Et₂O)] (4), [(dpp-bian)GaC(=NCy)N(Cy)C(O)O][Na(Py)₃] (5). Treatment of 1 with 2 equiv. of Ph₂CO resulted in gallium pinacolate [(dpp-bian)GaO(CPh₂)₂O][Na(Py)₂] (9), while the reaction of 1 with 2 equiv. Ph₂CCO gave divinyl ether derivative [(dpp-bian)Ga{C(=CPh₂)O}₂][Na(DME)₃] (10). Complex 1 treated with 2 equiv. 1,2-dibenzylidenehydrazine underwent [1+2+2] cycloaddition to give C–C coupling product [(dpp-bian)Ga{N(NCHPh)}₂(CHPh)₂][Na(DME)₃] (11). When complex 1 was sequentially treated with 1 equiv. of 1,2-dibenzylidenehydrazine and 1 equiv. of pyridine or pyridine-d5; it gave [1+2+2] cycloaddition product [(dpp-bian)GaN(NCHPh)C(Ph)CN][Na(DME)₃] (12). Compounds 2–12 were characterized by NMR and IR spectroscopy, and their molecular structures were established by single-crystal X-ray diffraction analysis.

The silylene [(dpp-bian)Si:] (1), where dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene, exhibits remarkable reactivity with a variety of substrates. It reacts with chloroform and water via O–H and C–Cl bond activation to yield oxidative addition products 2 and 3, respectively. Reactions of 1 with dibenzylideneacetone and tolane involve exclusively the silicon atom and result in [4 + 1]- and [2 + 1]-cycloaddition products 4 and 6. Treatment with isoselenocyanate results in unprecedented cleavage of the CSe bond, leading to activation product 5. In contrast, treatment with acetylene and phenylacetylene leads to cooperative cycloaddition reactions, producing unique cycloadducts 7 and 8. These reactions represent a new type of cycloaddition to a tetravalent silicon atom, facilitated by a redox-active ligand. The new compounds were characterized by NMR and IR spectroscopy, elemental analysis, and X-ray diffraction studies. Their electronic structures and reaction pathways were investigated using DFT calculations.