Synthesis of a terminal Ce(iv) oxo complex by photolysis of a Ce(iii) nitrate complex.

Reaction of [Ce(NR)] (R = SiMe) with LiNO in THF, in the presence of 2,2,2-cryptand, results in the formation of the Ce(iii) "ate" complex, [Li(2,2,2-cryptand)][Ce(-ONO)(NR)] () in 38% yield. Photolysis of at 380 nm affords [Li(2,2,2-cryptand)][Ce(O)(NR)] (), in 33% isolated yield after reaction work-up. Complex is the first reported example of a Ce(iv) oxo complex where the oxo ligand is not supported by hydrogen bonding or alkali metal coordination. Also formed during photolysis are [Li(2,2,2-cryptand)][(μ-O){Ce(μ-O)(NR)}] () and [Li(2,2,2-cryptand)][Ce(OSiMe)(NR)] (). Their identities were confirmed by X-ray crystallography. Complex can also be prepared reaction of [Ce(NR)] with LiOSiMe in THF, in the presence of 2,2,2-cryptand. When synthesized in this fashion, can be isolated in 47% yield. To rationalize the presence of , , and in the reaction mixture, we propose that photolysis of first generates and NO, homolytic cleavage of the N-O bond in its nitrate co-ligand. Complex then undergoes decomposition two separate routes: (1) ligand scrambling and oligomerization to form ; and, (2) abstraction of a trimethylsilyl cation to form a transient Ce(iv) silyloxide, [Ce(OSiMe)(NR)], followed by 1e reduction to form . Alternatively, complex could form directly ·SiMe abstraction by .