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• 7784-23-8 aluminium(III) iodide 
• 211381-92-9 (2,2,6,6-tetramethylpiperidino)2Al(γ-picoline) tetraiodoaluminate 

Relevant academic research and scientific papers

Bis(tetramethylpiperidino)aluminum Halide Adducts tmp2AlX·Do and Tetrahaloaluminates of Tricoordinated Aluminum Cations [tmp2Al(Do)]AlX4

Upon treatment with Lewis bases Do (Do = pyridine bases or THF), the Lewis acids tmp2AlX (X = Cl, Br, I) are converted exclusively to the monoadducts tmp2AlX·Do (2-4). The AlX bonds of these addition compounds are considerably elongated, indicating a tendency towards the formation of ionic species [tmp2Al(Do)]X. Due to the steric requirements of the bulky tmp ligands, addition of an excess of the Lewis base does not force these compounds to form tetracoordinated aluminum cations [tmp2Al(Do)2]+ or pentacoordinated adducts tmp2AlX·Do2. Attempts to prepare ionic representatives by reaction of tmp2AlX·Do with "ate" complexes of comparatively low nucleophilicity [MY = NaBPh4, AgBPh4, LiB(C6F5)4, AgBF4, AgOtos] result in phenylation products [e.g. tmp2AlPh (5a) and BPh3·py (5b)] or tetracoordinated addition compounds tmp2AlY·Do (Y = anion). However, addition of one equivalent of AlX3 (X = Br, I) initiates halide abstraction with formation of the ionic [tmp2Al(Do)]AlX4 species 6a-f, as indicated by 27Al-NMR data and conductivity measurements. Solid [tmp2Al(Py)]AlI4 (6b) decomposes readily into tmpAlI2 and tmpAlI2·py (7c) Addition of non-polar aliphatic solvents to solutions of [tmp2Al(Do)]AlX4 (6) leads to slow decomposition into tmp2AlX and AlX3·Do (7a-b, d). This also occurs in polar donor solvents, where compounds AlX3·Do are favoured due to the formation of penta- or hexacoordinated species AlX3·Do·Solvn (n = 1, 2). Semiempirical AM1 calculations reveal the gas-phase stability of the tricoordinated bis(tmp)aluminum cation in the salt [tmP2AlPy]AlCl4 as the only representative in a series of calculated aluminum cations [(R2N)2AlPy]AlCl4 (R2N = Me2N, Et2N, iPr2N, tmp). According to these calculations, the stability of a given cation increases when tetrachloroalummate is replaced by tetraiodoaluminate. Ab initio calculations have been performed on two cations [(H2N)2Al(Do)]+ (Do = NH3, py) and indicate very short Al-N bond lengths owing to ionic bonding contributions.

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 (H2N)2AIY

Reactions of metallated nucleophiles M1Y [Y = OR, SR, NR2, PR2, AsR2, CR3, Si(SiMe3)3, R = organyl, H] with bis(2,2,6,6-tetramethylpiperidino)aluminum halides [tmp2AlX, (X = Cl, Br, I)] offer facile access to a variety of bis(amino)alanes of the type tmp2AlY. As indicated by 27Al-NMR spectroscopy, mass spectrometry and X-ray crystal structure determinations, 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 tmp2AlY compounds, combined with a quantum mechanical study on model compounds (H2N)2AlY, not only reveal the presence of a highly polar Al-N bond, but at the same time rule out AlN bonding, in contrast to the situation in the analogous tmp2BY 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.