A New Class of Functionalized Polyoxometalates: Synthetic, Structural, Spectroscopic, and Electrochemical Studies of Organoimido Derivatives of [Mo6O19]2-

A convenient method for the systematic introduction of a variety of organoimido ligands at terminal oxo sites in the hexamolybdate cluster [Bu 4 N] 2 [Mo 6 O 19 ] is described, consisting of reaction with the appropriate organic isocyanate RNCO (R = n -butyl, cyclohexyl, 2,6-diisopropylphenyl) in pyridine solution. Singly functionalized imido-hexamolybdates [Mo 6 O 18 (NR)] 2 - incorporating each of the above substituents are described. In the case of the 2,6-(diisopropyl)phenylimido ligand (NAr), multiple functionalization has also been achieved: hexamolybdate derivatives [Mo 6 O (19 - x ) (NAr) x ] 2 - incorporating two, three, four, and five NAr ligands at terminal sites have been prepared. The complexes have been characterized by cyclic voltammetry, multinuclear ( 1 H, 14 N, 17 O, and 95 Mo) NMR and electronic spectroscopy, and single-crystal X-ray diffraction studies.