Ultrashort Beryllium−Beryllium Distances Rivalling Those of Metal−Metal Quintuple Bonds Between Transition Metals

A Neutral Beryllium(I) Radical

The reduction of a cyclic alkyl(amino)carbene (CAAC)-stabilized organoberyllium chloride yields the first neutral beryllium radical, which was characterized by EPR, IR, and UV/Vis spectroscopy, X-ray crystallography, and DFT calculations.

Computational Study of spx (x=1-3)-Hybridized Be-Be Bonds Stabilized by Amidinate Ligands

Complexes containing odd-electron Be-Be bonds are still rare until now. Hereby, a series of neutral di-beryllium amidinate complexes containing a Be-Be bond were explored theoretically. The complexes with direct chelation with the Be₂ dimer by the bidentate amidinate (AMD) ligands are always corresponding to their global minimum structures. The detailed bonding analyses reveal that the localized electrons of the Be-Be fragment can be adjusted by the amount of AMD ligands because each AMD ligand only takes one electron from the Be₂ fragment. Meanwhile, the hybridization of the central Be atom also changes as the number of AMD ligands increases. In particular, the sp³ -hybridized single-electron Be-Be bond is firstly identified in the tri-AMD-ligands-chelated neutral D_3h -Be₂ (AMD)₃ complex, which also possesses the higher stability compared to its monoanionic D_3h -Be₂ (AMD)₃ ^- and monocationic C₃ -Be₂ (AMD)₃ ⁺ analogues. Importantly, our study provides a new approach to obtain a neutral odd-electron Be-Be bond, namely by the use of radical ligands through side-on chelation.

Theoretical Designs for Organoaluminum C2Al4R4 with Well-Separated Al(I) and Al(III)

It is well-known that the chemistry of aluminum is dominated by Al(III) in the +3 oxidation state. Only during the past 2 decades has the chemistry of Al(I) and Al(II) been rapidly developed. However, if Al(I) and Al(III) are combined, the inherently high reactivities of Al(I) and Al(III) mostly result in their coupling with each other or interacting with surrounding elements, which easily results in significant deactivation or quenching of the desired oxidation states, as in the case of reported mixed valent Al-compounds. In this article, we report an unprecedented type of organoaluminum system, C₂Al₄R₄ (R = H, SiH₃, Si(C₆H₅)₃, SiiPrDis₂, SiMe(SitBu₃)₂), whose lowest-energy structure, C₂Al₄R₄-01, contains two Al(I) and two Al(III) atoms. The global nature and bonding motif of the parent C₂Al₄R₄-01 (R = H) were supported by an extensive global isomeric search, CBS-QB3 energy calculations, adaptive natural density partitioning, and bond order analysis. Interestingly and in sharp contrast to most organoaluminum species, C₂Al₄R₄-01 is associated with little multicenter bonding. C₂Al₄R₄-01 has a high feasibility of being observed either in the gas or condensed phases (with suitable substitutents). With well-separated Al(I) and Al(III), C₂Al₄R₄-01 (with suitable substitutents) could serve as the first Al/Al frustrated Lewis pair.