Aluminiumhydrazide. Bildung eines dimeren Di(tert-butyl)aluminiumhydrazids mit viergliedrigem Al2N2-Heterozyklus und Umsetzung eines Dialkylaluminiumchlorids mit Dilithium-bis(trimethylsilyl)hydrazid

Abstract

Inhaltsu È bersicht. Die Umsetzung von Di(tert-butyl)aluminiumchlorid mit tert-Butylhydrazin ergibt ein Addukt (1), das in reiner Form isoliert und durch Kristallstrukturbestimmung charakterisiert wurde. 1 reagiert mit n-Butyllithium unter Deprotonierung und Salzeliminierung zu dem Di(tert-butyl)aluminiumhydrazid (2), das in Lo È sung und im Festko È rper dimer vorliegt und einen viergliedrigen Al 2 N 2 -Heterozyklus mit zwei exozyklischen N±N-Bindungen aufweist. 2 steht damit im Gegensatz zu anderen Di(tert-butyl)aluminiumhydraziden, in denen fu È nf-oder sechsgliedrige Heterozyklen vorliegen. Werden Proben von 1, die nicht durch Umkristallisieren gereinigt wurden, mit n-Butyllithium behandelt, bildet sich unter Úffnung der N±N-Bindungen neben einem unu È bersichtlichen Produktgemisch das dimere, zentrosymmetrische Aluminiumamid [(Me 3 C) 2 AlN(H)CMe 3 ] 2 (3). Ein a È hnliches Amid (4) entsteht in geringer Ausbeute aus (Me 3 SiCH 2 ) 2 AlCl und Dilithiumhydrazid Li 2 N 2 (SiMe 3 ) 2 . Auch im zweiten aus dieser Reaktion isolierten Produkt (5) bleibt die N±N-Bindung des Hydrazids nicht erhalten; vielmehr bildet sich unter C±H-Aktivierung eine tricyclische Verbindung, in der zwei fu È nfgliedrige AlNSiC 2 -Heterocyclen u È ber Al±N-Bru È cken miteinander verbunden sind.Abstract. The reaction of di(tert-butyl)aluminium chloride with tert-butylhydrazine yielded an adduct (1) which was isolated in a pure form and characterized by crystal structure determination. 1 reacted with n-butyllithium by deprotonation and salt elimination to give the corresponding di(tertbutyl)aluminium hydrazide (2), which is a dimer in solution and in the solid state and possesses a four-membered Al 2 N 2 heterocycle with two exocyclic N±N bonds. The structure of 2 differs from that of other di(tert-butyl)aluminium hydrazides which have four-or five-membered heterocycles. Treatment of impure samples of 1 with n-butyllithium yielded by the cleavage of the N±N bonds a mixture of several un-known products, from which the dimeric, centrosymmetric aluminium amide [(Me 3 C) 2 AlN(H)CMe 3 ] 2 (3) was isolated. A similar product (4) was obtained in a low yield by the reaction of (Me 3 SiCH 2 ) 2 AlCl with the dilithium hydrazide Li 2 N 2 (SiMe 3 ) 2 . An intact N±N bond was neither found in the second product isolated from this reaction. Instead a tricyclic compound was formed by C±H activation which has two five-membered AlNSiC 2 heterocycles bridged by Al±N bonds.

Dimethylindium hydrazides [Me2In-NH-NHR]2 (R=CMe3, C6H5)

“…1). With only one exception, similar structures were observed for dimeric organoelement hydrazides of gallium [2,5,6,11,12,14], while a broader variability of structural motifs was determined for the corresponding aluminum derivatives [2,4,10,16]. The only neutral indium hydrazide published so far, In{N(SiMe 3 )-NMe 2 } 3 , formed a monomer in the solid state [23].…”

“…However, more systematic experiments are required to get a concise impression of the principal applicability of these precursors. Secondly, these hydrazides showed a nice coordination behaviour owing to their bidentate character with lone electron pairs at two neighbouring nitrogen atoms [2], and many different structural motifs were detected with the formation of adducts [3][4][5][6], of monomers containing ''side-on'' coordinated hydrazide groups [7][8][9], of dimers possessing heterocycles [5,8,[10][11][12][13][14][15][16], and of oligomeric compounds with a cage-like arrangement of metal and nitrogen atoms [5,13,14,[17][18][19][20]. In the past, most work has been done with respect to the synthesis and structural characterization of dialkylelementhydrazides of the elements aluminum and gallium.…”

Adducts of organogallium chlorides with hydrazines and the formation of dimeric dialkylgallium hydrazides possessing different ring sizes

“…As was shown in preceding investigations of our group [11,12], the treatment of hydrazine adducts of the type R 2 AlCl NH 2 -N(H)R 0 with n-butyllithium afforded the corresponding dialkylaluminum hydrazides by deprotonation and salt elimination in quite reasonable yields. We hoped to employ this procedure for the synthesis of gallium hydrazides, too.…”

“…All remaining dialkylgallium hydrazides published so far contain the same structural motif in their molecular centres consisting of a four-membered Ga 2 N 2 heterocycle and two exocyclic N-N bonds. In contrast, the homologous dialkylaluminum hydrazides show a broader variability of structures with four- [2,3,11], five- [12] and six-membered heterocycles [12][13][14] and none, one, or two endocyclic N-N groups, respectively (Scheme 1). The respective structural motif seems to be determined by the steric demand of the substituents 0022-328X/$ -see front matter Ó 2005 Elsevier B.V. All rights reserved.…”

Unusual reaction pathways of gallium(III) silylamide complexes

“…Only one more Al(III) compound is known in which the formation of the N-H moiety of the -N(H)SiMe 3 bridge stems from ligand decomposition. Reaction of two equivalents of (Me 3 SiCH 2 ) 2 AlCl with the hydrazide Li 2 N 2 (SiMe 3 ) 2 yielded two compounds simultaneously, namely, {(Me 3 SiCH 2 ) 2 Al[μ-N(H)(SiMe 3 )]} 2 and {(Me 3 SiCH 2 )Al[N(SiMe 3 )(CH 2 SiMe 2 CH 2 )]} 2 (Scheme 3, Uhl et al, 2000). This reaction clearly shows that the methyl groups undergo C-H activation, causing the formation of the N-H moiety.…”