A Monomeric Aluminum Imide (Iminoalane) with Al–N Triple-Bonding: Bonding Analysis and Dispersion Energy Stabilization

Abstract

The reaction of :AlAr i Pr8 (Ar i Pr8 = C 6 H-2,6-(C 6 H 2 -2,4,6- i Pr 3 ) 2 -3,5- i Pr 2 ) with Ar Me6 N 3 (Ar Me6 = C 6 H 3 -2,6-(C 6 H 2 -2,4,6-Me 3 ) 2 ) in hexanes at ambient temperature gave the aluminum imide Ar i Pr8 AlNAr Me6 ( 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 :AlAr i Pr8 and Ar Me6 N̈:. 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 :AlAr i Pr8 with 1-AdN 3 or Me 3 SiN 3 gave transient imides that immediately reacted with a second equivalent of the azide to give Ar i Pr8 Al[(NAd) 2 N 2 ] ( 2 ) or Ar i Pr8 Al(N 3 ){N(SiMe 3 ) 2 } ( 3 ).

Carbon–chalcogen bond formation initiated by [Al(NONDipp)(E)]−anions containing Al–E{16} (E{16} = S, Se) multiple bonds

“… 27 The first iminoalane was isolated in 2001, 28 although it was not until 2012 that the first structurally characterized example of an Al–N multiple bond was reported. 29 This general class of compound containing Al–E{15} multiple bonds has recently been extended to include a formal Al–N triple bond, 30 and the first examples of phospha- and arsa-alumenes, with multiple Al–P and Al–As bonds, respectively. 31 …”

Contrasting E−H Bond Activation Pathways of a Phosphanyl‐Phosphagallene

“…[ 9 , 10 ] A similar strategy was recently used to allow access to aluminium‐imides starting from organic azides aluminium(I) reagents. [ 10d , 10e , 10f ]…”

A Free Aluminylene with Diverse σ‐Donating and Doubly σ/π‐Accepting Ligand Features for Transition Metals**

“…[13] Taking advantage of sterically demanding terphenyl ligands, [14] Power,T uononen et al very recently disclosed the first and sole example of ar oom-temperature-stable monomeric aluminylene (alanediyl) :AlAr iPr8 (Ar iPr8 = C 6 H-2,6-(C 6 H 2 -2,4,6-i Pr 3 ) 2 -3,5-i Pr 2 )(E)(Figure 1b)via areduction reaction of AlI 2 Ar iPr8 with 5% w/w Na/NaCl. [15] This breakthrough allowed further explorations into unusual/unprecedented patterns of reactivity of E toward hydrogen [15] and organic azides, [16] in which the latter led to the first stable iminoalane with an AlNtriple bond. In the present work, we report the synthesis,c haracterization and coordination chemistry of af ree one-coordinate N-aluminylene (Figure 1c).…”