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N ‐Methyl‐Piperidine Stabilised Halogen Alanes
Author(s) -
Veith Michael,
Kirs Tatjana,
Huch Volker
Publication year - 2013
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201200459
Subject(s) - chemistry , crystallography , adduct , halogen , bipyramid , pentagonal bipyramidal molecular geometry , hydrogen bond , crystal structure , ligand (biochemistry) , coordination sphere , trigonal bipyramidal molecular geometry , halogen bond , halide , stereochemistry , molecule , inorganic chemistry , biochemistry , alkyl , receptor , organic chemistry
Alanes of the formula H x Al X 3– x ( x = 0, 1, 2, 3; X = Cl, Br, I) and the mixed halogen species HAlClBr were synthesized as N ‐methyl‐piperidin (nmp) adducts H x AlX 3– x · z nmp ( z = 1, 2) and HAlClBr · 2nmp by different routes. The crystal and molecular structures of (H 3 Al · nmp) 2 , H 2 AlBr · 2nmp, H 2 AlI · 2nmp, the isotypic and isomorphous HAlBr 2 · 2nmp, HAlI 2 · 2nmp, as well as ACl 3 · nmp, ABr 3 · nmp, AI 3 · nmp, and HAlClBr · 2nmp are described. The aluminum atoms in these molecular structures either form a pentagonal bipyramid as coordination sphere with the amine bases in apical positions or are in the center of a distorted tetrahedron (AlCl 3 · nmp, ABr 3 · nmp, AI 3 · nmp). In the nmp adduct of alane, a central Al 2 H 2 ring is formed by dimerisation of AlH 3 , each aluminum atom displaying a further nmp ligand together with two terminal hydrogen atoms. The influence of the halogen atoms on the hydrogen bonds in the iso‐structural compounds were studied by IR spectroscopy, showing in both series H 2 Al X · 2nmp and HAl X 2 · 2nmp ( X = Cl, Br, I) a dependence of ν(Al–H) on the substitution pattern: 1770.2–1775.2–(not measured) cm –1 (H 2 Al X ) and 1785.0–1788.0–1791.0 cm –1 (HAl X 2 ). The δ values of the 27 Al‐NMR spectra in solution show dependences on the halide numbers bonded to aluminum and display a regular growth with heavier element in the H 2 Al X · 2nmp series δ ( 27 Al): 121.2 (Cl), 126.0 (Br), 131.5 (I)], whereas they have an unsteady evolution in the HAl X 2 · 2nmp series [δ ( 27 Al): 118.0 (Cl), 122.0 (Br), 108.0 (I)] and the Al X 3 · nmp series [δ ( 27 Al): 102.1 (Cl), 104.8 (Br), 61.9 (I)].