title: Thorium 2-pyridylamidinates: synthesis, structure and catalytic activity towards the cyclo-oligomerization of epsilon-caprolactone.
abstract: Salt metathesis of ThCl(4).3THF with N,N'-bis(trimethylsilyl)-2-pyridyl-lithium-TMEDA (1) yields bis(N,N'-bis(trimethylsilyl)-2-pyridylamidinate) thorium-chloride (mu-Cl)(2)Li(TMEDA) (2) (60% isolated yield) and tris(N,N'-bis(trimethylsilyl)-2-pyridylamidinate) thorium monochloride (3) (10% isolated yield). The latter compound is the first crystallographically characterized tris(amidinate) thorium complex. The bis pyridyl amidinate thorium (2) displays a unique reactivity towards the dual-site cyclo-oligomerization of epsilon-caprolactone, which produces two fractions of macrocyclic oligo-esters with extremely narrow (1.01-1.06) polydispersity. A mechanism for the dual-site oligomerization reaction is proposed based on kinetic, poisoning, and (1)H NMR studies.
authors.affiliation: Schulich Faculty of Chemistry and Institute of Catalysis Science and Technology, Kyriat Hatechnion, Haifa 32000, Israel.
authors.forename: Elena
authors.initials: E
authors.lastname: Rabinovich
authors.forename: Sinai
authors.initials: S
authors.lastname: Aharonovich
authors.forename: Mark
authors.initials: M
authors.lastname: Botoshansky
authors.forename: Moris S
authors.initials: MS
authors.lastname: Eisen