Synthesis and Characterization of Group 12 Metal(I) Complexes Bearing Extremely Bulky Boryl/Silyl Substituted Amide Ligands

Prediction of Covalent Metal-Metal Bonding in Cp-M-M'-Nacnac Complexes of Group 2 and 12 Metals (Be, Mg, Ca, Zn, Cd, Hg)

Bimetallic CpMM'Nacnac molecules with group 2 and 12 metals (M=Be, Mg, Ca, Zn, Cd, Hg) that contain novel metal-metal bonding have been investigated in a theoretical study of their molecular and electronic structure, thermodynamic stability, and metal-metal bonding. In all cases the metal-metal bonds are characterized as electron-sharing covalent single bonds from natural bond orbital (NBO) and energy-decomposition analysis with natural orbitals of chemical valence (EDA-NOCV) analysis. The sum of [MM'] charges is relatively constant, with all complexes exhibiting a [MM']2+ core. Quantum theory of atoms in molecules (QTAIM) analysis indicates the presence of non-nuclear attractors (NNA) in the metal-metal bonds of the BeBe, MgMg, and CaCa complexes. There is substantial electron density (0.75-1.33 e) associated with the NNAs, which indicates that these metal-metal bonds, while classified as covalent electron-sharing bonds, retain significant metallic character that can be associated with reducing reactivity of the complex. The predicted stability of these complexes, combined with their novel covalent metal-metal bonding and potential as reducing agents, make them appealing targets for the synthesis of new metal-metal bonds.

On the nature and limits of alkaline earth-triel bonding

The synthesis of a series of isostructural organometallic complexes featuring Ae-Tr bonds (Ae = Be, Mg; Tr = Al, Ga, In) has been investigated, and their electronic structures probed by quantum chemical calculations. This systematic study allows for comparison, not only of the metal-metal bonding chemistries of the two lightest alkaline earth (Ae) elements, beryllium and magnesium, but also of the three triel (Tr) elements, aluminium, gallium, and indium. Computational analyses (NBO, QTAIM, EDA-NOCV) reveal that Be-Tr bonding is more covalent than Mg-Tr bonding. More strikingly, these calculations predict that the beryllium-indyl complex - featuring the first structurally characterised Be-In bond - should act as a source of nucleophilic beryllium. This has been confirmed experimentally by its reactivity towards methyl iodide, which yields the Be-Me functionality. By extension, the electrophilic character of the beryllium centre in the beryllium-gallyl complex contrasts with the umpoled, nucleophilic behaviour of the beryllium centre in both the -indyl and -aluminyl complexes.

A Hg(i) corrugated sheet assembled by auxiliary dioxole groups and Hg⋯π interactions

Comproportionation between Hg0 and Hg2+ resulted in the formation of [Hg2(Pip)2] supported by Hg⋯Odioxole and Hg⋯π interactions. Structural and computational assessment determined the tendency of Hg(i) to partake in Hg⋯π interactions.

Synthesis and reactivity of heteroleptic zinc(I) complexes toward heteroallenes

Heteroleptic zinc(I) complexes L^1,2Zn-ZnCp* (L¹ = HC[C(CF₃)NC₆F₅]₂1; L² = HC[C(Me)NDipp]₂; Dipp = 2,6-i-Pr₂C₆H₃2) are synthesized by reactions of Cp*₂Zn₂ with L¹H and L²ZnH. 2 reacts with t-BuNCO to give unprecedented carbamate complex (4), while reactions with RN₃ gave bis-hexazene, triazenide, and trimeric azide complexes (5-7).