Praseodymium alkoxide chemistry: Synthesis and molecular structure of [Pr-4(mu(4)-O)(2)(mu(3)eta(2)-OR)(2)(mu,eta(2)-OR)(4)(mu,eta(l)-OR)(OR)(OPMe(3))](2) (R=C(2)H(4)OMe) and [Y4Pr(mu(5)-O)(mu(3)-OR)(4)(mu-OR)(4)(OR)(5)] (R=Pr-i)

Various routes to praseodymium alkoxide shave been investigated. Compounds such as Pr5O(OR)(13) [R = Pr-i (1), Am-1], [Pr4O2(ONp)(8)](m) (Np = neopentyl), [Pr(OC(2)H(4)NMe(2))(3)](3) were obtained by reaction of praseodymium turnings with the corresponding alcohols. Alcoholysis reactions of the bis-trimethylsilylamide afford [Pr4O(ONp)(10)](m), [Pr4O2(ONp)(8)](m), Pr-3(OR)(9)(ROH)(2) [R = Bu(t), Am-t] and [Pr4O2(OC(2)H(4)OMe)(8)](m) (2a), the latter derivatives illustrating the trend for the formation of oxo species. The compounds were characterized by elemental analysis, FT-IR and NMR. Their reactivity has been investigated, the mixed-metal species Pr4TiO(OPri)(14) and Y4PrO(OPri)(13) were obtained. Ligand exchange reactions afforded [Pr4O2(OR)(3)(OR')(5)](m) species (R = Pr-i, R' = C(2)H(4)NMe(2)' R = SiMe(3), R' = Pr-i) and [Pr(OC(2)H(4)NMe(2))(thd)(2)](2). X-ray structure analysis of the adduct obtained by reaction of [Pr4O2(OC(2)H(4)OMe)(8)](m) with trimethylphosphine oxide reveals a centrosymmetric framework [Pr-4(mu(4)-O)(2)(mu(3),eta(2)-OR)(2)(mu,eta(2)-OR)(4)(mu,eta(1)-OR)(OR)(OPMe(3))](2) (2b) of eight octa-coordinated praseodymium atoms, assembled by tetrahedral and square-planar oxo ligands. The M-O bond lengths spread over the range 2.246(6)-2.762(6) Angstrom and to follow the order Pr-OR (terminal) < mu,eta(2)-Pr-OR < mu(3),eta(2)-Pr-OR < Pr-O(ether). The Y4PrO(OPri)(13) species corresponds to a pentanuclear oxo aggregate similar to that of the parent homometallic species. Copyright (C) 1997 Elsevier Science Ltd.