Diarylpnictogenyldialkylalanes─Synthesis, Structures, Bonding Analysis, and CO₂ Capture

Abstract

Several new diphenylamino-and diphenylphosphanyldialkylalanes are reported, which were characterized in solution and in the solid state, assisted by in-depth bonding analysis within the DFT framework. In the case of bulky alkyl substituents on the aluminum atom, the species are stable in their monomeric form and were structurally characterized by single crystal X-ray diffraction, expanding the relatively small field of monomeric pnictogenylalanes. In the case of oligomeric diphenylpnictogenyldimethylalanes, their reactivity toward different σ-donor ligands was studied, and several examples of monomeric adducts could be structurally characterized, including the first cyclic(alkyl)(amino)carbene complexes. The reactivity of these CAAC complexes, their oligomeric precursors, and an unstabilized monomeric aminoalane toward CO 2 was probed, leading to different insertion products that could be characterized. Additionally, the mechanism was elucidated by DFT calculations.

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

“…[23] As a comparison, the aluminium analogues bear slightly more polarized bond i. e. 74 to 77 % contribution of the phosphorus atom. [7] Additionally, there is a lone pair (LP) on the phosphorus atom with p-character of around 50 %, which is in agreement with the pyramidalization observed in the crystal structures. Natural population analyses (NPAs) indicate a positive charge of ca.…”

“…[6] The oligomeric heterocycles have served as starting compounds for the generation of their monomeric forms (Scheme 1C). [3,7] Despite some Lewis base stabilized adducts have been reported in the past (Scheme 2, I), Schulz and coworkers have introduced a general straightforward synthetic route towards the monomeric species via E 13 -E 15 bond cleavage of the heterocycle with DMAP (4-dimethylamino-pyridine) as a Lewis base (Scheme 1C first reaction). [8] With many examples, monomeric species (II) containing AlÀ P and GaÀ P units have been isolated and characterized with this strategy, even involving a coordination transition metal on E 15 .…”

Diverse Cooperative Reactivity at a Square Planar Aluminium Complex and Catalytic Reduction of CO2

“…Whilst the insertion of CO 2 into AlÀ N bonds has been reported, [32][33][34] comparisons can be drawn between the reactivity of 3 towards CO 2 and that of transition metal pincer complexes featuring an amide donor. [35,36] The dimeric nature of 6 in the solid state highlights the greater oxophilicity of aluminium which drives dimerisation and bridging, rather than k 2 -N,Obound carbamate groups.…”

On the Reactivity of Mes*P(PMe3) towards Aluminum(I) Compounds – Evidence for the Intermediate Formation of Phosphaalumenes

“…The P−Al bond (2.3275(6) Å) is rather short for a single bond (Σ r cov (P−Al)=2.37 Å, [25] (cf. {(Me 3 Si) 2 CH} 2 Al−PPh 2 2.3367(16) Å) [26] . The central AlPC 4 six‐membered ring adopts a butterfly conformation, with a fold angle along the P1−C44 axis of 127.93(8)° and the Al atom is located above the Dip Nacnac plane (18.2(2)°).…”

“…{(Me 3 Si) 2 CH} 2 AlÀ PPh 2 2.3367(16) Å). [26] The central AlPC 4 six-membered ring adopts a butterfly conformation, with a fold angle along the P1À C44 axis of 127.93(8)°and the Al atom is located above the Dip Nacnac plane (18.2(2)°). The Al1À C47 distance of 1.9580(15) Å indicates a single bond, while the P1À C30 distance of 1.8587 (14) Å is in the typical range of PÀ C Ar distances (cf.…”