Studies of the Ligand Effect on the Synthesis of Dialuminoxanes by Various β-Diketiminato Ligands

Abstract

Reactions of LH (L = HC[C(Me)N(2,6-Me(2)C(6)H(3))](2)) with Me(n)AlCl(3-n) in diethyl ether afforded the adducts LH·AlMe(n)(Cl)(3-n) (n = 2, 3; 1, 4; 0, 5) in good yields. Treatment of 3 at elevated temperatures in toluene resulted in LAlMeCl (2) by intramolecular elimination of methane. The controlled hydrolysis of LAlMeCl (2) with equimolar amounts of water in the presence of N-heterocyclic carbene (NHC) gave a mixture of [LAl(Me)](2)(μ-O) (7) and dimeric [LAlMe(μ-OH)](2) (8). A convenient route for the preparation of [LAlMe(μ-OH)](2) (8) was the NHC-assisted controlled hydrolysis of LAlMeI (9). Stepwise hydrolysis of LAlH(2) (11) gave dialuminoxane hydride [LAl(H)](2)(μ-O) (12) and dialuminoxane hydroxide [LAl(OH)](2)(μ-O) (13), respectively. Anhydrous treatment of LAlCl(2) (1) or LAlMeCl (2) with Ag(2)O afforded chlorinated dialuminoxane [LAl(Cl)](2)(μ-O) (14) and [LAl(Me)](2)(μ-O) (7), respectively.

Characterization and Photophysical Properties of a Luminescent Aluminum Hydride Complex Supported by a β-Diketiminate Ligand

“…Secondly, the aluminum atom is displaced from the C 3 N 2 plane, and a dihedral angle between the C 3 N 2 and AlN 2 planes is 23.95 • , probably because of the steric hindrance of the diisopropylphenyl and the phenyl groups. Such a distorted structure was not observed in the previously reported structures of β-diketiminate aluminum dihydrides [41,46,47], while similar distortion has frequently been observed in the sterically encumbered dihalogen, dialkyl, and other metal complexes [48]. On the other hand, the Al-N lengths and the N-Al-N coordination angles are within the natural values of the reported dihydride complexes [41,46,47].…”

“…Such peak broadening should be due to the quadrupolar feature of 27 Al (I = 5/2). In the 27 Al{ 1 H} NMR, the broad peak was observed at around 65 ppm, which is the characteristic value for four-coordinated aluminum nuclei [44] and is similar to that of the related β-diketiminate aluminum hydride complex [41]. The complex is storable under an inert atmosphere in both C 6 D 6 solution and crystalline states at room temperature without any decomposition.…”

“…According to the earlier study [41], with a minor modification, the aluminum dihydride complex LAlH was prepared by the reaction of the β-diketiminate ligand [42] and an excess amount of lithium aluminum hydride in toluene at 90 • C (Scheme 1). From the results of the 1 H NMR measurements, the ligand was completely consumed in 16 h. After recrystallization, compound LAlH was fully characterized by 1 H, 13 C{ 1 H} and 27 Al{ 1 H} NMR spectroscopy and high-resolution mass spectrometry with the DART (Direct Analysis in Real-Time) method.…”

Synthesis, characterization and reactivity of an imidazolin-2-iminato aluminium dihydride

“…The β-diketimino group, in particular, has been a key ligand to a rich chemistry of respective aluminium dihydrides. [9][10][11][12] A prominent example is II (Fig. 1), which can The guanidinate IV, the phosphinimide V, as well as the troponimide VI (Dipp = 2,6-diisopropylphenyl).…”

Ein stabiles neutrales Radikal in der Koordinationssphäre des Aluminiums

“…Die Al-Cl-Abstände in 2 betragen 2.1612(7) und 2.1638(7) ,bzw.2.1315(5), 2.1355(5) und 2.1439(5) in der Vorstufe 1.D ie zwei Al-C-Abstände (1.967(2) und 2.097-(2) )u nterscheiden sich deutlich, wobei die kürzere Bindung einer kovalenten Al-C-Einfachbindung näherkommt, wie etwa im LHAlMe 2 Cl (1.950 und 1.980 )( L= HC[C-(Me)N(Ar)] 2 ,A r = 2,6-iPr 2 C 6 H 3 ), [17] Al 2 [CH(SiMe 3 ) 2 ] 4 (1.982-1.985 )], [10] während die andere Bindung länger ist als eine Al-C-Bindung in NHC-Addukten wie [[(NHC:)-(H) 2 Al] 2 ](2.086 ), [13] und (bisNHC)(Br) Al[Fe(CO) 4 ](2.048 und 2.045 ). 2 kristallisiert in der monoklinen Raumgruppe C2/c.E in zentrales Aluminiumatom wird von zwei Chloratomen und zwei cAAC-Liganden verzerrt tetraedrisch koordiniert.…”