Bis(pentamethylcyclopentadienyl) U(III) oxide and U(IV) oxide carbene complexes

Oxidation of the sterically crowded complex (C5Me5)(3)U provides access to two classes of uranium compounds that previously were unknown, a U(III) oxide and a U(IV) carbene, [(C5Me5)(2)U](2)(mu-O) (1) and (C5Me5)(2)U(O)[C(NMeCMe)(2)] (2), respectively. The structure of 1 allows a direct actinide versus lanthanide comparison within the [(C5Me5)(2)M](2)(mu-O) class. The uranium carbene complex (2), represents a rare example of a monometallic uranium mono-oxo-compound. Complex 1 has a 2.094(14) Angstrom U(1)-O(1) bond distance and a 171.5(6)degrees U(1)-O(1)-U(2) bond angle while the U(1)-O(1) and U(1)-C(21)[C(NMeCMe)(2)] bond distances in complex 2 are 1.917(6) and 2.673(7) Angstrom, respectively, (C) 2004 Published by Elsevier Ltd.