Density functional theory study on (F2AlN3) n (n = 1–4) clusters

Abstract

Possible geometrical structures and relative stabilities of (F 2 AlN 3 ) n (n = 1-4) clusters were studied using density functional theory at the B3LYP/6-311?G* level. The optimized clusters (F 2 AlN 3 ) n (n = 2-4) possess cyclic structure containing Al-N a -Al linkages, and azido in azides has linear structure. The IR spectra of the optimized (F 2 AlN 3 ) n (n = 1-4) clusters have three vibrational sections, the whole strongest vibrational peaks lie in 2218-2246 cm -1 , and the vibrational modes are N 3 asymmetric stretching vibrations. Trends in thermodynamic properties with temperature and oligomerization degree n are discussed, respectively. A study of their thermodynamic properties suggests that monomer 1A forms the most stable clusters (2A, 3A, and 4B) can occur spontaneously in the gas phase at temperatures up to 800 K.

DFT Studies on Structure-Property Relationship of (I2AlN3)n (n = 1-4) Clusters

“…Table-1 The smaller value for Nα-Al-Nα is in agreement with the larger size and the lower valence density around Al (due to its positive partial charge) and the consequently arising smaller repulsion between the bonding electron densities. Furthermore, as the oligomerization degree n increases, the trends of average geometrical parameters appear to be similar to those reported previously for (X2AlN3)n (X = H, F; n = 1-4) clusters 10,11 .…”

“…The tetramers (I2AlN3)4 were produced by four I2AlN3 oligomerizing via the α-N atoms. They belong to C1 (4A), S4 (4B) and Ci (4C) symmetry, respectively, of which only the S4 symmetry structure with the N3 alternatively up and down has been suggested for the tetramers [(CH3)ClAlN3]4 and [(CH3)BrAlN3]4 5 of the aluminium azides and the other two structures have not been found except that our group have reported 10,11 . As shown in Fig.…”

“…All calculations were performed using the Gaussian 03 program 13 with the hybrid density-functional B3LYP method 14 . Moreover, the previous studies have shown that the B3LYP method is able to provide more reliable results 10,11,15,16 . Considering reasonable computational costs and accuracy, the 6-311 + G * basis set for N and Al atoms 17 , and LanL2DZ basis set for I atoms were employed 18 .…”

“…In this paper, motivated by and based on previously studies on the clusters (H 2 AlN 3 ) n (n = 1-4) 10 , (F 2 AlN 3 ) n (n = 1-4) 11 , and (MYH 2 ) 4 (M = B, Al, Ga; Y = N, P, As) 12 , we performed density functional theory (DFT) investigations the structural features, energies and IR spectra of (I 2 AlN 3 ) n (n = 1-4) clusters, as well as the contributions of temperature and oligomerization degree n to the thermodynamic properties were established. The results are expected to provide further insight on the properties of group III A azide clusters, on one hand and also to shed some light into the trends with respect to cluster size.…”