posted on 2021-04-21, 22:13authored byJoshua
D. Queen, Sini Irvankoski, James C. Fettinger, Heikki M. Tuononen, Philip P. Power
The reaction of :AlAriPr8 (AriPr8 =
C6H-2,6-(C6H2-2,4,6-iPr3)2-3,5-iPr2) with ArMe6N3 (ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2) in hexanes at ambient temperature
gave the aluminum imide AriPr8AlNArMe6 (1). Its crystal structure displayed short
Al–N distances of 1.625(4) and 1.628(3) Å with linear
(C–Al–N–C = 180°) or almost linear (C–Al–N
= 172.4(2)°; Al–N–C = 172.5(3)°) geometries.
DFT calculations confirm linear geometry with an Al–N distance
of 1.635 Å. According to energy decomposition analysis, the Al–N
bond has three orbital components totaling −1350 kJ mol–1 and instantaneous interaction energy of −551
kJ mol–1 with respect to :AlAriPr8 and ArMe6N̈:. Dispersion accounts for
−89 kJ mol–1, which is similar in strength
to one Al–N π-interaction. The electronic spectrum has
an intense transition at 290 nm which tails into the visible region.
In the IR spectrum, the Al–N stretching band is calculated
to appear at ca. 1100 cm–1. In contrast, reaction
of :AlAriPr8 with 1-AdN3 or
Me3SiN3 gave transient imides that immediately
reacted with a second equivalent of the azide to give AriPr8Al[(NAd)2N2] (2) or AriPr8Al(N3){N(SiMe3)2} (3).