Aminodimethylalanes (R¹R²NAlMe₂) as Useful Synthetic Precursors of Aminoalane Difluorides Using Trimethyltin Fluoride:  Crystal Structures of (2,6-i-Pr₂C₆H₃)N(SiMe₃)AlMe₂ and (2,6-i-Pr₂C₆H₃)N(SiMe₃)AlF₂

Abstract

Aminodimethylalanes R1R2NAlMe2 (R1 = 2,6-i-Pr2C6H3, 2,6-Me2C6H3; R2 = SiMe3, Si(i-Pr)Me2, Si(t-Bu)Me2, Si(2,4,6-Me3C6H2)Me2) are prepared in high yield via reaction of the respective amine R1R2NH with trimethylaluminum in n-hexane. Further reaction of (2,6-i-Pr2C6H3)N(SiMe3)AlMe2 with 2 equiv of trimethyltin fluoride in toluene affords the aminoalane difluoride (2,6-i-Pr2C6H3)N(SiMe3)AlF2. An X-ray structural determination of (2,6-i-Pr2C6H3)N(SiMe3)AlMe2 shows it to be dimeric with bridging methyl and terminal amino groups. The aminoalane difluoride (2,6-i-Pr2C6H3)N(SiMe3)AlF2 is trimeric with a six-membered alternating aluminum−fluorine ring. Terminal fluorine atoms are located above and below the ring. Reactions of aminoalanes R1R2NAlMe2 with 2 equiv of trimethyltin fluoride in THF yield the monomeric THF adducts R1R2NAlF2·THF.

Neue Hypersilanide der Erdmetalle Aluminium, Gallium und Indium

“…Solche Assoziationen sind sehr selten zu beobachten; abgesehen vom Aluminiumtrimethyl [21] ist dieser Typ unseres Wissens nur noch bei der dimeren Amidoverbindung (Me 2 AlNR 1 R 2 ) 2 mit den sperrigen N-Substituenten R 1 = SiMe 3 und R 2 = 2,6-( i Pr) 2 C 6 H 3 ro È ntgenographisch nachgewiesen [22]. Einfache Al±Me±Al-Bru È cken sind bei den ¹Sesquiverbindun-genª Me 5 Al 2 OCMe 3 [23] sowie Me 5 Al 2 NPh 2 [24] (Assoziate aus AlMe 3 und Me 2 AlOCMe 3 bzw.…”

Homoleptische Amide von Zink, Cadmium und Quecksilber

“…Zinkamide neigen zur Dimerisierung und Oligomerisierung [4,5], was mit einer in der Epitaxie unerwu È nschten Erniedrigung des Dampfdruckes dieser Verbindungen verbunden ist. Die Bildung ho È hermolekularer Einheiten kann jedoch durch den Einsatz sterisch anspruchsvoller Liganden verhindert werden [6±9], ein Prinzip, das bei Aluminiumamiden bereits erfolgreich angewandt wurde [10]. Auch Cadmium bildet vornehmlich dimere Amide [11] aber auch durch intramolekulare Koordination stabilisierte Monomere [12,13].…”

Low‐Coordinate Aluminum Amides from Silylanilines and Alkylalanes

“…[11] Introduction of the bulky Me 3 Si group in {Me 2 AlN(Dipp)SiMe 3 } 2 prevented amide bridging, but methyl bridging via two-electron-threecenter bonds was observed. [8] The present observation that compounds 1-4 are most likely monomeric in solution may be explained by the lower bridge-forming tendency of alkyl groups other than methyl. [12] In order to obtain a crystalline species, the larger and crystalline aniline derivative MesN(H)SiPh 3 was prepared, lithiated and reacted with Et 2 AlCl to give the solid compound Et 2 AlN(Mes)SiPh 3 (5), see Equation (3).…”

“…The new aluminum amides 1-4 were synthesized according to a general method. [8] Melting Point Depression Experiment: 0.17 g of 1 was dissolved in benzene (5.0 g). The freezing point of the mixture was measured by slowly cooling the mixture, and the temperature was recorded once every 15 s. This procedure was repeated three times.…”

“…A series of dimethylaluminum silyl anilides Me 2 AlN(Ar)SiR 2 RЈ (Ar = Mes, Dipp; R = Me, RЈ = Me, iPr, tBu, Mes) has been prepared by the Roesky group, and {Me 2 AlN(Dipp)SiMe 3 } 2 was found to be dimeric with bridging methyl substituents. [8] Contrary to the majority of previously reported aluminum amides the aluminum precursors Et 3 Al, Et 2 AlCl and iBu 2 -AlH are commercially available and inexpensive, and the silyl anilines can be prepared in simple one-step procedures from the readily available anilines ArNH 2 (Ar = Mes, Dipp) and R 3 SiCl (R = Me, Ph). In addition, we report the synthesis and characterization of the dinuclear Ph 2 Si{N(Mes)-AlEt 2 } 2 and the hydride-bridged eight-membered-ring compound {MesN(SiMe 3 )Al(iBu)(μ-H)} 2 (μ-LiH)(μ-iBu 2 AlH).…”