The scandium terminal imido complex supported by a monoanionic tetradentate NNNN ligand, [LSc=N(DIPP)](L = [MeC(N(DIPP))CHC(Me)(NCH2CH2N(Me)CH2CH2NMe2]-, DIPP = 2,6-(iPr)2C6H3)(1), undergoes a C–N bond cleavage at elevated temperature to give a mononuclear scandium anilido intermediate 2a, which subsequently aggregates into a binuclear scandium anilido complex 2. The mononuclear intermediate 2a reacts with alkyne or imine to provide two scandium anilido complexes 3 and 4, which contain a dianionic tetradentate NNNC ligand or a dianionic tetradentate NNNN ligand. DFT calculations on the reaction mechanism of C–N bond cleavage in 1 were also performed.
Four lanthanum alkoxides stabilized by a carbon-bridged bis(phenolate) ligand were synthesized and their catalytic behavior for the ring-opening polymerization of L-lactide was explored. Reactions of [(MBMP)LaCp(THF) 2 ] (MBMP 2 = 2,2′-methylene-bis(6-tert-butyl-4-methyl phenoxo)) with HOCH 2 Ph, HOCH 2 CF 3 , HOCH(CH 3 ) 2 , and HOCH 2 CH 2 N(CH 3 ) 2 , respectively, in a 1:1 molar ratio in THF gave the dimeric lanthanum alkoxo complexes [(MBMP)Ln(μ-OR)(THF) 2 ] 2 (OR = OCH 2 Ph(1), OCH 2 CF 3 (2), OCH(CH 3 ) 2 (3), OCH 2 CH 2 N(CH 3 ) 2 (4)]. These complexes were well characterized, and the definitive molecular structure of complex 1 was determined. It was found that complexes 1 to 4 are efficient initiators for the ring-opening polymerization of L-lactide. The structure of the alkoxo groups has a significant effect on the catalytic behavior, and complex 2 can initiate L-lactide polymerization in a controlled manner.
Two ytterbium complexes stabilized by phenoxy（quinolinyl）amide ligand 3,5-But2-2-OC6H2CH2N-8-C9H6N （L） were synthesized and characterized. Reaction of anhydrous YbC13 with 1 equiv, of LLi2 in THF gave the ytterbium chloride [LYbCI（THF）]2 （1） in 73% yield. A further reaction of complex 1 with equimolar of NaN（SiMe3）2 in THF afforded the unexpected heterobimetallic ＂ate＂-complex L2YbNa（THF）2 （2） via a ligand redistribution reaction. Complex 2 could also be prepared in high isolated yield by the reaction of anhydrous YbC13 with 2 equiv, of LNa2 generated in situ. Both complexes 1 and 2 were characterized by IR spectroscopy, elemental analysis, and sin- gle-crystal X-ray diffraction analysis. It was found that complex 2 was an effective catalyst for the addition reaction of aromatic amines to carbodiimides.
Three homoleptic lanthanide complexes, [C6H5COCHC（CH3）N（p-CIC6H4）]3Ln（THF）n （n = 0, Ln = Yb （1）; n = 0, Ln = Y （2）; n = 1, Ln = Nd （3））, were synthesized by amine elimination reaction of Ln[N（SiMe3）2]3 with 1-phenyl-3-N-（p-chlorophenylimino）-1-butanone. These com- plexes crystallize in triclinic, space group PI with a = 9.805（3）, b = 14.831（6）, c = 16.075（6） A, a = 111.996（9）, β = 91.570（7）, y = 93.744（6）° V= 2159.4（13） A3, Z= 2, Dc = 1.515 g/cm3, F（000） = 986, μ（MoKa） = 2.396 mm-1, R = 0.0360 and wR = 0.0850 for 9548 observed reflections with I 〉 20（I） for complex 1; a = 9.861（5）, b = 14.852（9）, c = 16.111（9） A, a = 112.362（13）,β = 91.949（11）, y = 93.678（14）°, V= 2173（2） A3, Z= 2, Dc = 1.377 g/cm3, F（000） = 924,μ（MoKa） = 1.570 mm-1, R = 0.0735 and wR = 0.1389 for 8015 observed reflections with I 〉 20（I） for complex 2; and a = 9.308（3）, b = 15.357（3）, c = 17.419（4） A, a = 66.493（13）, β = 88.61（2）, y = 86.664（19）°, V = 2279.4（9） A3, Z= 2, Dc = 1.499 g/cm3, F（000） = 1046,μ（MoKa） = 1.364 mm-1, R = 0.0843 and wR = 0.2280 for 8433 observed reflections with I 〉 20（I） for complex 3. Each central metal in complexes 1 and 2 is six-coordinated by three nitrogen and three oxygen atoms from three β-ketoiminate ligands to give a distorted octahedral geometry, while the central metal in 3 is seven-coordinated by three nitrogen and three oxygen atoms from three β-ketoiminate ligands and one oxygen atom from the solvated THF molecule to complete a distorted monocapped trigonal prism.
