force of the dihydrides 1 and 3 towards the cyclic diazastannylene Me 2 Si(N t Bu) 2 Sn (7). In the course of this reaction Sn II in 7 was reduced to elementary tin whereas the hydrides were oxidized to hydrogene. Tin is obtained in its b-form as found by powder-X-ray diffraction. The shapes of the metal precipitates (porous, sponge-like pieces or nanoscaled powders) depend on the conditions of reactions. Besides the elements the spirocyclic aminoalkoxialane [Me 2 Si(N t Bu) 2 -AlO t Bu] 2 (8) or aminosiloxialane [Me 2 Si(N t Bu) 2 AlOSiMe 3 ] 2 (9) are formed. Structural details of the molecules 8 and 9 can be derived from single crystal X-ray analyses.
EinleitungAls selektive Reduktionsmittel werden Aluminiumhydrid-Komplexe seit vielen Jahren in der organischen Synthese verwendet [1]. Neben diesem ¹klassischenª Einsatzgebiet der Alane finden ihre leicht flu È chtigen 138
Eingerastet: Die Suzuki‐Miyaura‐Kupplung von β,β′‐diborylierten mit meso,meso′‐dibromierten Porphyrinblöcken wird für den Aufbau direkt doppelt meso‐β‐verknüpfter Porphyrinringe genutzt, darunter zweier Tetraporphyrinringe, Hexaporphyrinringe und eines verbrückten Heptaporphyrins (siehe Bild).
The siloxyalanes [(Et3SiOAlH2)2AlH3]
n
(1), [
t
BuMe2SiOAlH2]2 (2), [(
t
BuMe2SiO)2AlH]2 (3), and
[(
t
BuMe2SiO)5Al2H] (4) have been synthesized and characterized by IR and NMR spectroscopic means.
By X-ray diffraction studies on single crystals it was established that molecule 1 is a coordination polymer
in the solid state with tetrameric units [Et3SiOAlH2]4 (almost linear Al···Al···Al···Al arrangement)
interlinked by Al2H6 groups to form a one-dimensional chain (formal description with neutral building
blocks). Compound 3 is dimeric through Al−O contacts with a cis orientation of the hydride ligands
with respect to the central Al2O2 cycle. Compound 4 may be described as a double adduct between the
two Lewis acid−base compounds (
t
BuMe2SiO)2AlH and Al(OSiMe2
t
Bu)3. The bulkiness of the substituents
on the silicon atoms plays an important role in the aggregation of the compounds. Hydride bridging
between molecules or within the molecular entities is only observed in compound 1.
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