778642-65-2Relevant academic research and scientific papers
Mononuclear, five-coordinate lanthanide amido and aryloxide complexes bearing tetradentate (N2O2) Schiff bases
Schuetz, Steven A.,Silvernail, Carter M.,Incarvito, Christopher D.,Rheingold, Arnold L.,Clark, Joanna L.,Day, Victor W.,Belot, John A.
, p. 6203 - 6214 (2004)
Two monomeric, five-coordinate lanthanide complexes, [bis-5,5′-(1,3- propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato]samarium[2,6-bis(tert-butyl) -4-methylphenoxide] and [bis-5,5′-(1,3-propanediyldiimino)-2,2-dimethyl-4- hexene-3-onato]erbium[2,6-bis(tert-butyl)-4-methylphenoxide], were isolated from the reactions of 2,6-bis(tert-butyl)-4-methylphenol with [bis-5,5′-(1,3- propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato]lanthanide[bis(trimethylsilyl) amido] (lanthanide = Er3+ and Sm3+). The purified phenoxides were recovered in excellent yields and analytical purity, and the reactions proceeded cleanly without Schiff-base degradation or cluster formation. Analogously, [bis-3,3′-(1,3-propanediyldiimino)-1-phenyl-2- butene-1-onato]erbium[bis(trimethylsilyl)amido] was also directly converted to [bis-3,3′-(1,3-propanediyldiimino)-1-phenyl-2-butene-1-onato]erbium[2, 6-bis(tert-butyl)-4-methylphenoxide]; however, a less sterically demanding alcohol (i.e., ethanol) yielded a neutral trinuclear oxo alkoxide species with each dianionic Schiff base asymmetrically bridging through μ-oxo interactions. In this polynuclear cluster, each symmetry-related, seven-coordinate erbium(III) ion exhibits monocapped trigonal prismatic geometry, which assembles by sharing triangular capped faces. Single-crystal X-ray diffraction revealed square-pyramidal metal coordination in each five-coordinate lanthanide ion with varied S4 ruffling of the square base donor atoms and the six-membered propylene diamine chelate ring adopting the boat conformation. To contrast the effect of subtle ligand changes, we also report the synthesis and characterization of [bis-5,5′-(2,2-dimethyl-1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3- onato]samarium[bis(trimethylsilyl)amido], having gem-dimethyl substituents appended to the propylene bridge central carbon. The six-membered diamine chelate ring in this compound adopts the chair conformation without metal-hydrocarbon interaction. Also presented are qualitative activity observations and polymerization data for the polymerization of rac-lactide and ε-caprolactone using the five-coordinate lanthanide amidos and phenoxides.
