Organogallium-phosphorus, -arsenic and -antimony compounds

Extensive studies have been performed on self-assembled dimeric and trimeric or-ganogallium phosphides, 86 and 87, and arsenides, 88 and 89, in relation to their use as precursors for gallium phosphide and gallium arsenide semiconductors [237-240]. Their association in solution was observed some time ago as a result of molecular weight determinations in solution [158, 160] and many of the compounds have been structurally characterized. As already shown, the degree of association depends upon the steric bulkiness of the organic groups. 

A list of dimeric and trimeric supermolecules is given in Table 3.6, with their Ga-P bond lengths [241-251]. 

The sum of the covalent bond radii are 2.338 A for Ga P and 2.446 A for Ga-As. These values can be compared with the Ga-P interatomic distance in monomeric PhsGa — P(SiMe3)3 (2.539 A) and Ph2ClGa — P(SiMe3)3 (2.459 A) which contain pure dative P — Ga bonds [252], with monomeric (Me3Si)3- 

As— Ga(Cl)(CH2Bu )2 (2.626 A) [253] which contain dative Ga — As bonds, and with monomeric Bu 2GaAsBuS (2.466 A) [254] and (C5Me5)2GaAs(SiMe3)2 (2.433 A) [255], containing normal covalent As-Ga bonds. In structurally characterized [ClPr GaAsBu 2]2 the Ga-As bonds are basically identical (2.529 and 2.520 A) [256], 

Data relating to gallium-arsenic dimeric supermolecules are collected in Table 3.7. 

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