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From tert ‐Butylhydrazine Adducts of AlR 3 (R = Me, CMe 3 ) to Oligonuclear AlN Cage Compounds – Evidence for a Hydrazine Twist Across an Al 3 Triangle
Author(s) -
Uhl Werner,
Hagemeier Elke,
Layh Marcus,
Rezaeirad Babak,
Kösters Jutta,
Würthwein ErnstUlrich,
Ghavtadze Nugzar,
Massa Werner
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201001308
Subject(s) - chemistry , adduct , crystallography , thermal decomposition , steric effects , amide , stereochemistry , medicinal chemistry , organic chemistry
The thermal decomposition of the hydrazine adducts R 3 Al←NH 2 –N(H)CMe 3 ( 1a , R = CMe 3 ; 1b , R = Me) was investigated. Compound 1a afforded the hydrazide [(Me 3 C) 2 Al–N(H)–N(H)–CMe 3 ] 2 ( 2 ) upon heating to 155 °C. Compound 2 is dimeric in the solid state with a four‐membered Al 2 N 2 heterocycle in its molecular core. Heating of 2 to 190 °C gave the drum‐like imidoalane [Me 3 CAlNH] 6 ( 4 ) in which the Al and N atoms occupy the vertices of a hexagonal prism. This reaction is believed to proceed via the dimeric amide [(Me 3 C) 2 Al–NH 2 ] 2 ( 3 ) that was isolated in small quantities from a mixture obtained at a slightly lower temperature. Adduct 1b , which is sterically less shielded than 1a , decomposes readily at room temperature to yield an unprecedented Al–N cage compound, [Me 2 Al–N(H)–N(H)CMe 3 ] 2 [MeAl–N(CMe 3 )–NH] ( 5 ), with a norbornane‐like arrangement of three Al and four N atoms, and a hydrazinediido group in the bridging position. Heating of 5 gave, with the release of methane, the tetraaluminum compound [MeAlN(H)–NCMe 3 ] 4 ( 6 ) in which four hydrazinediide moieties are bridged by AlMe groups. Heating of 6 resulted in the gradual degradation of the N–N bonds and the formal release of 1 or 3 equiv. of nitrene, N–H, to give the unique cage compounds (MeAl) 4 [N(H)–NCMe 3 ] 3 (NCMe 3 ) ( 7 ) and (MeAl) 4 [N(H)–NCMe 3 ](NCMe 3 ) 3 ( 8 ). The structures of compounds 6 – 8 may be derived from Al 4 N 4 cubes in which a number of edges (four, three or one) are bridged by nitrogen atoms of hydrazinediido groups.