METAL-CARBON AND CARBON-OXYGEN BELATED REACTIVITY IN TANTALUM P-TERT-BUTYLCALIX[4]ARENE COMPLEXES UNDERGOING ORGANIC FUNCTIONALIZATION

[(Calix[4]OMe)TaCl2] (2), formed from [calix[4](OMe)(2)] (1) and TaCl5 via a demethylation reaction, undergoes exhaustive alkylation to [(ca lix[4]OMe)TaR(2)] (3-5), which give photochemically or thermally induc ed concerted dealkylation at the metal and at the methoxy group, to gi ve [calix[4]TaR] (6-8). Double migration air alkyl groups has been obs erved in the reaction of 3-5 with CO and Bu(t)NC to form the correspon ding eta(2)-ketones [(calix[4]OMe)Ta(eta(2)-COR(2))] (9-11) and eta(2) -imines [(calix[4]OMe)Ta{eta(2)-N(Bu(t))CR(2)}] (12-14).