Microwave-assisted synthesis of dimolybdenum tetracarboxylates and a decanuclear osmium cluster

An improved method for the synthesis of dimolybdenum tetracarboxylates has been developed. The standard procedure for the preparation of these compounds involves extended reflux (up to 20 h) of a mixture of Mo(CO)6 and the appropriate carboxylic acid, along with its anhydride, under an inert atmosphere. Using a microwave reactor and a closed vessel, Mo2(acetate)4, Mo2(propionate)4 and Mo2(benzoate)4 have been prepared in superior yields in less than 1 h. Furthermore, this new method does not require the use of the acid anhydride or the use of an inert gas. An improved method for the preparation of [N(PPh3)2]2[Os10C(CO)24] directly from Os3(CO)12 has also been developed. The published synthesis of this osmium cluster calls for the pyrolysis of Os3(CO)11(py) for 64 h. Microwave irradiation of a mixture of Os3(CO)12 and diglyme in a closed vessel yields the desired product in just over 1 h.