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The Aluminum–Nitrogen Bond in Monomeric Bis(amino)alanes: A Systematic Experimental Study of Bis(tetramethylpiperidino)alanes and Quantum Mechanical Calculations on the Model System (H 2 N) 2 AlY
Author(s) -
Knabel Klaus,
Krossing Ingo,
Nöth Heinrich,
SchwenkKircher Holger,
SchmidtAmelunxen Martin,
Seifert Thomas
Publication year - 1998
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/(sici)1099-0682(199808)1998:8<1095::aid-ejic1095>3.0.co;2-d
Subject(s) - chemistry , nucleophile , monomer , halide , crystallography , crystal structure , bond length , computational chemistry , inorganic chemistry , organic chemistry , catalysis , polymer
Reactions of metallated nucleophiles M I Y [Y = OR, SR, NR 2 , PR 2 , AsR 2 , CR 3 , Si(SiMe 3 ) 3 , R = organyl, H] with bis(2,2,6,6‐tetramethylpiperidino)aluminum halides [tmp 2 AlX, (X = Cl, Br, I)] offer facile access to a variety of bis(amino)alanes of the type tmp 2 AlY. As indicated by 27 Al‐NMR spectroscopy, mass spectrometry and X‐ray crystal structure determina‐tions, all of these compounds are monomeric in the solid state, in solution, and in the gas phase. Even Al–E single bonds (E = Si, P, As etc.) that are not commonly encountered are stabilized by the supporting tmp fragments. The results of a systematic analysis of the bonding parameters determined for the tmp 2 AlY compounds, combined with a quantum mechanical study on model compounds (H 2 N) 2 AlY, not only reveal the presence of a highly polar Al–N bond, but at the same time rule out AlN‐pp(π) bonding, in contrast to the situation in the analogous tmp 2 BY compounds. It is shown that the Al–N bond length depends on the acidic character of the protic species HY: the shorter d (Al–N), the less basic is Y.