Gallium complexes pyridine

Complex Formation. B-Ttichlorobora2iQe was reported to readily form crystalline adducts of uncertain stmcture with pyridine (131). The Lewis acids aluminum tribromide or gallium trichloride form 1 1 adducts with hexamethylbota2iQe (eq. 36) ia which the metal atom coordinates with a nitrogen with loss of planarity of the ring (132,133). 

The formation of molecular complexes between aluminum trihalides and pyridine or alkylpyridines has been the subject of systematic studies.35,36 Calorimetric data yield bond dissociation energies D(X3Al—py) of 323, 308 and 264 kJ mol-1 for X = C1, Br and I, respectively, and this same order is found for alkylpyridine adducts, although the A1—N bond is weakened in the case of lutidine by the effects of steric hindrance. For gallium halides the values of D(X3M—py) are smaller 248, 237 and 195 kJ mol-1 for chloride, bromide and iodide adducts, respectively. 

Sodium tetraazidoahiminate complexed by pyridine and tetrahydrofuran and analog-uous indium and gallium derived materials were obtained, the last uncomplexed. They are explosive on rapid heating, sodium tetraazidogallate at 150 C, and shock... 

Cationic Compiexes. Apart from the aqua ions and partially substituted species such as [GaCl(H20)5] +, cationic complexes of gallium halides with pyridine, bipyridine, or phenanthroline are known, for example, [GaCl2(phen)2]+ and [Ga(phen)3] +. Furthermore, given the steric hindrance about the gallium center in complexes formulated as GaX3(NH3) (X = Cl, n = 1, 3, 5, 6, 7, 14 X = Br, n = 1, 5, 7, 9, 14 X = I, n = 1, 5, 6, 7, 9, 13, 20), it is likely that where n is greater than 3 these are also cationic solvates. 

---