A theoretical study of the Al–(SiO)1,2 compounds

Abstract

Density-functional theory and ab initio methods have been applied to characterize the structural features of Al–(SiO)1,2 compounds. According with previous work [Schnöckel et al., J. Chem. Phys. 112, 1444 (2000)], it has been shown that an Al atom spontaneously reacts with SiO forming a linear O-bonded molecule, AlOSi (2Π). Three minima have been found in the potential-energy surface of Al–(SiO)2: two local minima corresponding to cis–cis and to trans–trans forms with two equivalent SiO fragments arising from addition of a second SiO to AlOSi, and the third one corresponding to the global minimum with a chain structure. It has been shown that the chain structure could be obtained either spontaneously from the reaction between an aluminum atom and a cyclic (SiO)2 dimer or from the isomerization reaction of the cis–cis Al–(SiO)2 structure but requiring, in this case, an activation energy about 10 kcal/mol. Bonding characterization performed within topological frameworks reveals that the interaction in all the (SiO)n and Al–(SiO)n (n=1 and 2) compounds should be considered as a highly polar interaction. Structural comparisons have been made between Al–dicarbonyl and Al–disilonyl on the ground of the topological analysis.