Synthesis, Structure, and Bonding Analysis of Lewis Base and Lewis Acid/Base‐Stabilized Phosphanylgallanes

Phosphanylgallane with hydrogen and halogen substituents (RXGa PHR, R=organic substituent, X=halogen/hydrogen) are regarded as putative suitable precursors for accessing Ga=P doubly bonded species. Herein, we report on the synthesis, structure, and bonding analysis of a series of Lewis base- and Lewis acid/base-stabilized phosphanylgallane bearing P H and Ga Cl/H substitution. To avoid oligomerization, the treatment of IDip.GaCl3 and (IDip)GaH2Cl (IDip=1,3-bis(2,6-diisopropylphenyl) imidazole-2-ylidene) with LiPHR or LiPHR(BH3) (R=Ph, Tip, Mes, NiPr2, NCy2) affords the corresponding Lewis base and Lewis acid/base coordinated H,Cl-functionalized monomeric phosphanylgallane, respectively. The structure of these derivatives were determined by spectroscopic and X-ray crystallographic analyses. The observed Ga P bond lengths are comparable to those previously reported phosphanylgallane analogues. The nature of the CIDip-Ga coordination bond was assessed with Energy Decomposition Analysis, suggesting a relatively stable adduct. Reactions of the phosphanylgallane with Brønsted bases were investigated

Evidence of AlII Radical Addition to Benzene

Electrophilic AlIII species have long dominated the aluminum reactivity towards arenes. Recently, nucleophilic low-valent AlI aluminyl anions have showcased oxidative additions towards arenes C-C and/or C-H bonds. Herein, we communicate compelling evidence of an AlII radical addition reaction to the benzene ring. The electron reduction of a ligand stabilized precursor with KC8 in benzene furnishes a double addition to the benzene ring instead of a C-H bond activation, producing the corresponding cyclohexa-1,3(orl,4)-dienes as Birch-type reduction product. X-ray crystallographic analysis, EPR spectroscopy, and DFT results suggest this reactivity proceeds through a stable AlII radical intermediate, whose stability is a consequence of a rigid scaffold in combination with strong steric protection

Evidence of AlII Radical Addition to Benzene

Electrophilic AlIII species have long dominated the aluminum reactivity towards arenes. Recently, nucleophilic low-valent AlI aluminyl anions have showcased oxidative additions towards arenes C−C and/or C−H bonds. Herein, we communicate compelling evidence of an AlII radical addition reaction to the benzene ring. The electron reduction of a ligand stabilized precursor with KC8 in benzene furnishes a double addition to the benzene ring instead of a C−H bond activation, producing the corresponding cyclohexa-1,3(orl,4)-dienes as Birch-type reduction product. X-ray crystallographic analysis, EPR spectroscopy, and DFT results suggest this reactivity proceeds through a stable AlII radical intermediate, whose stability is a consequence of a rigid scaffold in combination with strong steric protection

Evidence of AlII Radical Addition to Benzene

Electrophilic AlIII species have long dominated the aluminum reactivity towards arenes. Recently, nucleophilic low-valent AlI aluminyl anions have showcased oxidative additions towards arenes C C and/or C H bonds. Herein, we communicate compelling evidence of an AlII radical addition reaction to the benzene ring. The electron reduction of a ligand stabilized precursor with KC8 in benzene furnishes a double addition to the benzene ring instead of a C H bond activation, producing the corresponding cyclohexa-1,3 (orl,4)-dienes as Birch-type reduction product. X-ray crystallographic analysis, EPR spectroscopy, and DFT results suggest this reactivity proceeds through a stable AlII radical intermediate, whose stability is a consequence of a rigid scaffold in combination with strong steric protection

Revisiting the origin of the bending in group 2 metallocenes AeCp2 (Ae = Be–Ba)

Metallocenes are well-established compounds in organometallic chemistry, and can exhibit either a coplanar structure or a bent structure according to the nature of the metal center (E) and the cyclopentadienyl ligands (Cp). Herein, we re-examine the chemical bonding to underline the origins of the geometry and stability observed experimentally. To this end, we have analysed a series of group 2 metallocenes [Ae(C5R5)2] (Ae = Be–Ba and R = H, Me, F, Cl, Br, and I) with a combination of computational methods, namely energy decomposition analysis (EDA), polarizability model (PM), and dispersion interaction densities (DIDs). Although the metal–ligand bonding nature is mainly an electrostatic interaction (65–78%), the covalent character is not negligible (33–22%). Notably, the heavier the metal center, the stronger the d-orbital interaction with a 50% contribution to the total covalent interaction. The dispersion interaction between the Cp ligands counts only for 1% of the interaction. Despite that orbital contributions become stronger for heavier metals, they never represent the energy main term. Instead, given the electrostatic nature of the metallocene bonds, we propose a model based on polarizability, which faithfully predicts the bending angle. Although dispersion interactions have a fair contribution to strengthen the bending angle, the polarizability plays a major role

Kristalline Anionen auf Basis klassischer N-Heterocyclischer Carbene

Merschel A, Rottschäfer D, Neumann B, et al. Kristalline Anionen auf Basis klassischer N-Heterocyclischer Carbene. Angewandte Chemie. 2022: e202215244

Crystalline Anions Based on Classical N‐Heterocyclic Carbenes

Merschel A, Rottschäfer D, Neumann B, et al. Crystalline Anions Based on Classical N‐Heterocyclic Carbenes. Angewandte Chemie International Edition. 2022: e202215244

Cover Picture: Crystalline Anions Based on Classical N‐Heterocyclic Carbenes

Merschel A, Rottschäfer D, Neumann B, et al. Cover Picture: Crystalline Anions Based on Classical N‐Heterocyclic Carbenes. Angewandte Chemie International Edition. 2023