Chapter SevenSYNTHETIC ROUTES TO PHOSPHIDO AND ARSENIDO DERIVATIVES OF THE GROUP 13 METALS ALUMINUM, GALLIUM, AND INDIUM, TRIS(TERT‐BUTYL)GALLIUM AND ITS REACTIONS WITH AMMONIA, AND THE ALUMINUM(I) SPECIES PENTAMETHYLCYCLOPENTADIENYL ALUMINUM TETRAMER

1. INTRODUCTION

This chapter features the preparation of group 13–15 complexes of the organo‐substituted group 13 metals aluminum, gallium, and indium, as well as two different routes to the organoaluminum species {Al(η5‐C5Me5)}4.1

An important synthesis is that of the sterically crowded gallium trialkyl Ga(But)3 which was obtained in good yield by a very similar route to that originally reported in the literature.2 The structure of GaBut33 involves isolated GaBut3 units with planar coordinated gallium atoms in which the metal has no intermolecular contacts within the sums of the relevant van der Waals radii. This is in contrast to the corresponding structures of AlBut33, 4 and InBut3,3, 5 where nonplanar MC3 geometries are observed that are believed to be due to M·β‐CH3 intramolecular interactions. This observation is consistent with the usually lower Lewis acidity of Ga3+ in comparison with Al3+ or In3+.6 The treatment of GaBut3 with ammonia results in the formation of the 1 : 1 complex But2GaNH3 in virtually quantitative yield. Thermolysis of this complex under an ammonia atmosphere results in 2‐methylpropane elimination to give the amido‐bridged trimer {t‐Bu3Ga(μ‐NH2)}3. The ammonia and parent amido complexes represent stages ...

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