Record Low Ionization Potentials of Alkali Metal Complexes with Crown Ethers and Cryptands

Electronic properties of series of alkali metals complexes with crown ethers and cryptands were studied via DFT hybrid functionals. For [M([2.2.2]crypt)] (M=Li, Na, K) extremely low (1.70-1.52 eV) adiabatic ionization potentials were found. Such low values of ionization energies are significantly lower than those of alkali metal atoms. Thus, the investigated complexes can be defined as superalkalis. As a result, our investigation opens up new directions in the designing of chemical species with record low ionization potentials and extends the explanation of the ability of the cryptates and alkali crown ether complexes to stabilize multiple charged Zintl ions.

Reduction of [Cp*Sb]4 with Subvalent Main-Group Metal Reductants: Syntheses and Structures of [(L1 Mg)4 (Sb4 )] and [(L2 Ga)2 (Sb4 )] Containing Edge-Missing Sb4 Units

[Cp*Sb]₄ (Cp*=C₅ Me₅ ) reacts with [L¹ Mg]₂ and L² Ga with formation of [(L¹ Mg)₄ (μ₄ ,η^1:2:2:2 -Sb₄ )] (L¹ =iPr₂ NC[N(2,6-iPr₂ C₆ H₃ )]₂ , 1) and [(L² Ga)₂ (μ,η^2:2 -Sb₄ )] (L² =HC[C(Me)N(2,6-iPr₂ C₆ H₃ )]₂ , 2). The cleavage of the Sb-Sb and Sb-C bonds in [Cp*Sb]₄ are the crucial steps in both reactions. The formation of 1 occurred by elimination of the Cp* anion and formation of Cp*MgL¹ , while 2 was formed by reductive elimination of Cp*₂ and oxidative addition of L² Ga to the Sb₄ unit. 1 and 2 were characterized by heteronuclear NMR spectroscopy and single-crystal X-ray diffraction, and their bonding situation was studied by quantum chemical calculations.

Homoatomic Polyhedra as Structural Modules in Chemistry: What Binds Fullerenes and Homonuclear Zintl Ions?

Ligand-free homoatomic polyhedra are fascinating, not only because of their aesthetic simplicity but also because of their physical and chemical properties. They serve as electron reservoirs, show structural changes that depend upon the electron count, and can be used as "superatomic" building blocks for the targeted assembly of complex structures. Herein, the increasingly pronounced relationship between the fullerides and the nine-atom Zintl ions, the terels, is considered, even though one class of the compounds can be described as large polyhedra with classical bonds and the other as small clusters with nonclassical bonds (Wade rules). In both classes soluble salts with isolated ions, polymer chains, and binary phases with strong interactions between the ions occur.