Reactions of 1,2-catechol with tBu3M (M = Ga, In). Structures of intermediate products

Reactions of 1,2-catechol with tBu3M (M = Ga, In) have been studied. Trinuclear compounds [tBu5M3(OC6H4O)2] [M = Ga (1), M = In (2)] were synthesised in the reaction of 2 equiv. of C6H4(OH)2 with 3 equiv. of tBu3M in refluxing solvents. At room temperature the reaction of 1,2-catechol with tBu3In in Et2O leads to the formation of a binuclear complex [tBu4In2(OC6H4OH)2 · 2Et2O] (3) possessing a four-membered In2O2 core and two unreacted hydroxyl groups. The same reaction carried out in a non-coordinating solvent (CH2Cl2) results in formation a compound [tBu3In2(OC6H4O)(OC6H4OH)] (4), which undergoes a reaction with tBu3In to yield the product 2. Moreover two intermediate isomeric products 5 and 6 of formula [tBu3Ga2(OC6H4O)(OC6H4OH)] were isolated from the post-reaction mixture of 1,2-catechol with tBu3Ga. The compound 6 possessing a different coordination of gallium atoms than 5 is a result of the intramolecular rearrangement of the compound 5 to decrease the steric repultion between ligands. Compounds 3 and 6 were structurally characterised. According to the structure of intermediate products 3–6 a reaction pathway of 1,2-catechols with group 13 metal trialkyls was proposed.