tert-Amyl Compounds of Aluminum and Gallium:  Halides, Hydroxides, and Chalcogenides

Abstract

The reaction of AlCl 3 with 3 equiv of the tert-amyl Grignard reagent (Me 2 EtC)MgCl yields the monomeric trialkyl compound Al(CMe 2 Et) 3 (1). Reaction of compound 1 with MeCN and [PPN]Cl yields the Lewis acid-base complexes Al(CMe 2 Et) 3 (MeCN) (2) and [PPN][AlCl-(CMe 2 Et) 3 ] (3), respectively. The hydrolysis of Al(CMe 2 Et) 3 in hexane results in the formation of the trimeric hydroxide [(Me 2 EtC) 2 Al(µ-OH)] 3 (4), which is converted to the dimer [(Me 2 EtC) 2 Al(µ-OH)] 2 (5) upon heating. The reaction of Al(CMe 2 Et) 3 with H 2 S at room temperature yields the cubane compound [(Me 2 EtC)Al(µ 3 -S)] 4 (6). If the reaction is carried out at 0 °C, then the hexamer [(Me 2 EtC)Al(µ 3 -S)] 6 (7) may be isolated along with compound 6. The selenide analog of 6, [(Me 2 EtC)Al(µ 3 -Se)] 4 (8), is prepared directly from the reaction of compound 1 with H 2 Se, while the telluride analog, [(Me 2 EtC)Al(µ 3 -Te)] 4 (9), is prepared by the direct reaction of compound 1 with tellurium metal. The gallium cubane compounds [(Me 2 EtC)Ga(µ 3 -E)] 4 , (E ) S (10), Se (11), Te ( 12)) have been prepared from the reaction of Ga(CMe 2 Et) 3 with the appropriate element. The tert-amyl compounds are compared to their tert-butyl analogs, and the isolation of compound 7 is used as a precedent to prepare [( t Bu)Al(µ 3 -S)] 6 (13). A structural analysis is made of the M 4 E 4 cubane cores (M ) Al, Ga, In; E ) S, Se, Te), and a new topological method is proposed to predict the intracage bond angles in group 13 cage compounds, [(R)M(µ 3 -X)] n . The molecular structures of compounds 3, 6, 8, and 10-12 have been determined by X-ray crystallography, and a discussion of the crystallographic problems associated with the tert-amyl group is presented.

Phosphane‐Catalyzed Reactions of LAlH2 with Elemental Chalcogens; Preparation of [LAl(μ‐E)2AlL] [E = S, Se, Te, L = HC{C(Me)N(Ar)}2, Ar = 2,6‐iPr2C6H3]

“…All Al 2 E 2 rings are, due to their symmetry, essentially planar, and the AlϪE bond lengths are analogous to those of similar Al 2 E 2 species (2.208Ϫ2.248 Å for S, 2.221Ϫ2.381 Å for Se, and 2.562Ϫ2.588 Å for Te), but the E(1)ϪAlϪE(1A) (E ϭ Se, [4Ϫ12] due to the steric bulk of the β-diketiminato ligand. The latter values are similar to those of Al 4 E 4 clusters (94.2Ϫ99.2°for Se and 94.1Ϫ96.3°for Te), [14,15] where the chalcogen atoms are always coordinated to three aluminum atoms. The S(1)ϪAlϪS(1A) angle fits within the range of similar compounds (95.9Ϫ101.9°).…”

“…Thus, the [AlE] n core can be either square planar (n ϭ 2), [4Ϫ13,17] cubic (n ϭ 4) [13Ϫ17] or adopt a hexagonal drum structure (n ϭ 6). [14] Other examples containing Al and E in a ratio that deviates from 1:1 have also been reported to exhibit a bent AlϪEϪAl moiety, adamantane-like Al 4 E 6 or more complex structures. [3,20Ϫ24] We have recently shown that [LAlH 2 ] (2), prepared from LH and AlH 3 ·NMe 3 , reacts with elemental selenium [3] and, in the presence of a phosphane as catalyst, also with elemental sulfur, [2] to give species of the general formula [LAl(EH) 2 ] (E ϭ Se, S).…”

A Polyhedral Aluminum Compound with an Al4C4N4 Framework

“…The X‐ray structure analysis of 1 reveals a remarkable Al 4 C 4 N 4 cage configuration in which the C atoms adopt exo positions and thus may be formally viewed as inserting into four Al−N bonds of an Al 4 N 4 cube (Figure 1 A). 9 It is surprising that a significant difference in the arrangement of the atoms within the cage skeleton of 1 is found in comparison with those of other known aluminum compounds with a 12‐membered core ((AlE) 6 , E=N,3d–3g O,10a S,10b P,10c As10d) which exclusively adopt the form of a hexagonal‐prismatic array. The core of 1 consists of six faces formed by two boat‐shaped six‐membered Al 2 C 2 N 2 rings and four puckered five‐membered Al 2 CN 2 rings.…”

Synthesis and X-ray Structures of Dilithium Complexes of the Phosphonate Anions [PhP(E)(NtBu)2]2- (E = O, S, Se, Te) and Dimethylaluminum Derivatives of [PhP(E)(NtBu)(NHtBu)]- (E = S, Se)

“…H NMR (THF-d 8 , 235 K, δ): 7.0-8.3 (m, 5 H, C 6 H 5 ), 3.62 (m, THF), 1.77 (m, THF), 1.12 [d, 4 J( 1 H-31 P) ) 1 Hz, 18 H, N t Bu] 31. P{ 1 H} NMR (THF-d 8 , 235K, δ): -14.4 [s, 1 J( 31 P-125 Te ) 1209 Hz)].…”