Metastable Aluminum(I) Compounds: Experimental and Quantum Chemical Investigations on Aluminum(I) Phosphanides—An Alternative Channel to the Disproportionation Reaction?

Abstract

The well known thermodynamic instability of Al and Ga monohalides is caused by the favored disproportionation process to the bulk metal and the trihalides. During this highly complex process, a number of metalloid clusters that are intermediates on the way to the metal have been trapped. Therefore, all observations in the field of metalloid Al/Ga clusters have been traced to this favored disproportionation process. The failure to form phosphanide-substituted Al clusters, in contrast to the generation of similar Ga clusters and analogous Al amide clusters, was the starting point of this contribution. For aluminum(I) phosphanides, there exists a different decomposition route in which the salt-like bulk material AlP and not Al metal is the final product. The synthesis of two molecular "AlP" intermediate species, together with supporting DFT calculations, provide plausible arguments for this decomposition route, which is thermodynamically favored for many AlR/GaR species and which, surprisingly, has not been discussed before.

K[Al4(PPh2)7PPh]: An AlII Phosphanide / Phosphinidene Intermediate on the Path to AlP Formation

“…[9][10][11] The latter complex contains a naked P 3-ion that presumably results from a successive ligand-based decomposition process leading to the Al 3 P moiety. DFT studies showed how the ligand redox vs. disproportionation pathways followed different routes from the Al I precursors to give markedly different products.…”

Growth of metalloid aluminum clusters on graphene vacancies

“…[19][20][21][22][23][24][25] Here we consider the use of graphene as a template for growing small metalloid aluminum clusters. The pioneering work of Schnöckel and co-workers has led to the development of many striking group 13 metalloid systems, [29][30][31][32][33][34][35] including the large Al 77 [N(SiMe 3 )] 2 20 , Al 50 Cp 1 2 ⇤ , and Si@Al 56 [N(2, 6-iPr 2 C 6 H 3 )SiMe 3 ] 12 . Metalloid clusters are often conceptualized as metastable intermediates on the way to formation of a bulk metal, and have been a) Author to whom correspondence should be addressed.…”

Modeling the stability and growth of metalloid clusters for energetic materials

“…All these systems are synthesized from AlX (X=Cl, Br, or I) monovalent aluminum halide precursors formed in a specialized cocondensation apparatus. [14,15,16,17,18] 12 . These clusters crystallize into low-symmetry molecular crystals that are very airsensitive; in this report we focus on isolated clusters for comparison with recent gas-phase cluster studies in ultra-high vacuum.…”