Alessandro Bismuto

To get more information about the reactivity profile of the donor-stabilized guanidinatosilylene [ArNC(NMe₂)NAr]Si[N(SiMe₃)₂] (1; Ar = 2,6-diisopropylphenyl), a series of test reactions was studied. Thus, treatment of 1 with Me₃SiN₃, (PhO)₂P(O)N₃, PhC(O)Ph, Me–C≡C–C≡C–Me, Ph–C≡C–C≡C–Ph, CO₂, CS₂, ZnCl₂, or ZnEt₂ yielded the respective products 9–17, all of which were characterized by elemental analyses, NMR spectroscopic investigations in the solid state and in solution, and single-crystal X-ray diffraction studies. The formation of compounds 9–17 is based on oxidative addition reactions (for 9–15) or Lewis acid/base reactions (for 16 and 17). In most cases, these typical silylene reactions are coupled with additional reactivity facets, which are correlated with the guanidinato or bis(trimethylsilyl)amido ligand of 1. According to these studies, silylene 1 proved to be a very useful building block with high synthetic potential for the preparation of new silicon(IV) and silicon(II) compounds, with quite novel structural motifs.

The silylene [DippNC(NMe₂)NDipp]Si[N(SiMe₃)₂] (Dipp = 2,6-diidopropylphenyl) proved to be a very useful building block with a high synthetic potential for the preparation of new silicon(IV) and silicon(II) compounds (see examples 1–9).

Environmentally sustainable hydrogen-evolving electrocatalysts are key in a renewable fuel economy, and ligand-based proton and electron transfer could circumvent the need for precious metal ions in electrocatalytic H₂ production. Herein, we show that electrocatalytic generation of H₂ by a redox-active ligand complex of Al³⁺ occurs at −1.16 V vs. SCE (500 mV overpotential).

Two in one: Proton and electron transfer by a complex comprising Al³⁺ and a redox-active iminopyridine ligand promotes electrocatalytic H₂ evolution. The Al³⁺ center brings the reduction potential of the ligand into an accessible range for low-overpotential proton production. The proposed mechanism involves two protonation events at the ligand and a subsequent two-electron reduction to liberate hydrogen (see figure).

The first iminoboryl complex with a non-phosphine donor ligand has been isolated and fully characterized. The structural and spectroscopic parameters of the Pt^II complex, which bears one phosphine and one N-heterocyclic carbene ligand, suggest that the Pt center backdonates less to the iminoboryl ligand than in conventional (iminoboryl)bis(phosphine) complexes, despite the presence of a strongly σ-donating NHC ligand. This iminoboryl complex was found to undergo facile hydroboration with catecholborane, leading to an N-borylated hydroboryl complex.

The first iminoboryl complex with a non-phosphine donor ligand has been isolated and fully characterized. This iminoboryl complex was found to undergo facile hydroboration with catecholborane, leading to an N-borylated hydroboryl complex.

We present a direct cross-coupling reaction between arylaluminum compounds (ArAlMe₂⋅LiCl) and organic halides RX (R=aryl, alkenyl, alkynyl; X=I, Br, and Cl) without any external catalyst. The reaction takes place smoothly, simply upon heating, thereby enabling the efficient and chemo-/stereoselective formation of biaryl, alkene, and alkyne coupling products with broad functional group compatibility.

All in Al: Simply heating an arylaluminum (ArAlMe₂⋅LiCl) and an organic halide RX (R=aryl, alkenyl, alkynyl; X=I, Br, Cl) without any external catalyst results in a smooth and direct cross-coupling reaction taking place. This approach enables the efficient, chemo-/stereoselective formation of coupling products with broad functional group compatibility.

Monomeric N-heterocyclic carbene (NHC)-stabilized compounds (IMes)R₂MP(H)SitBuPh₂ (2: M = Al, R = Et; 3: M = Ga, R = Et; 4: M = Ga, R = iPr; 5: M = In, R = Et) have been prepared in moderate yields through the cleavage of four-membered metal phosphine rings like [iPr₂GaP(H)SitBuPh₂]₂ (1) described herein. These compounds were isolated and characterized by means of X-ray crystallographic analysis as well as NMR spectroscopy. On this basis the structural properties, specifically the M–P bond lengths and C_NHC–M–P angles, are discussed and compared to literature-known compounds insofar as possible. Proceeding from the cis setting between the phosphorus-bound hydrogen and the metal-bound organic substituent with very low torsion angles, which result in a nearly coplanar arrangement, the results of thermally induced elimination reactions are described. Further, the resulting heterocubane structures 6 and 7 are described.

A series of new N-heterocyclic carbene (NHC)-stabilized monomeric metal silylphosphanides of aluminium, gallium and indium were characterized through single-crystal X-ray diffraction and their structural and thermal properties are described.