Min Jeong Go

Synthesis, X-ray structures, and controlled ring opening polymerization behavior of L-lactide using titanium complexes chelated by tetradentate diamine-diethanolate ligand.

The synthesis and characterization of LTi(O-i-Pr)(2) (1) and LTiCl(2) (2) complexes containing a new [ONNO]-type tetradentate diamine-diethanolate ligand such as (HOCMe(2)CH(2)NMeCH(2)CH(2)NMeCH(2)CMe(2)OH) (LH(2)) was achieved. Single-crystal X-ray analyses revealed that monomeric complexes 1 and 2 had pseudo-C(2) and pseudo-C(1) symmetric distorted octahedral geometry, respectively. Interestingly, complex 1 has fac-fac geometry for tetradentate L around a Ti centre in both solid and solution, whereas complex 2 has different geometry in solid (mer-fac, C(1)) and solution (fac-fac, C(2)). They are effective catalysts for the controlled ring opening polymerization of L-lactide, as shown by the linearity of the number average of the molecular weight of polylactides versus conversion, as well as narrow PDI values.

New class of scorpionate: tris(tetrazolyl)-iron complex and its different coordination modes for alkali metal ions.

We report formation of a new metallascorpionate ligand, [FeL3](3-) (IPtz), containing a Fe core and three 5-(2-hydroxyphenyl)-1H-tetrazole (LH2) ligands. It features two different binding sites, oxygen and nitrogen triangles, which consist of three oxygen or nitrogen donors from tetrazole. The binding affinities of the complex for three alkali metal ions were studied using UV spectrophotometry titrations. All three alkali metal ions show high affinities and binding constants (>3 × 10(6) M(-1)), based on the 1:1 binding isotherms to IPtz. The coordination modes of the alkali metals and IPtz in the solid were studied using X-ray crystallography; two different electron-donor sites show different coordination numbers for Li(+), Na(+), and K(+) ions. The oxygen triangles have the κ(2) coordination mode with Li(+) and κ(3) coordination mode with Na(+) and K(+) ions, whereas the nitrogen triangles show κ(3) coordination with K(+) only. The different binding affinities of IPtz in the solid were manipulated using multiple metal precursors. A Fe-K-Zn trimetallic complex was constructed by assembly of an IPtz ligand, K, and Zn precursors and characterized using X-ray crystallography. Oxygen donors are coordinated with the K ion via the κ(3) coordination mode, and nitrogen donors are coordinated with Zn metal by κ(3) coordination. The solid-state structure was confirmed to be a honeycomb coordination polymer with a one-dimensional infinite metallic array, i.e., -(K-K-Fe-Zn-Fe-K)n-.

Bis(μ-trimethyl-silanolato-κO:O)bis-{[2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentyl-phenolato-κN,O]zinc}.

The binuclear title complex, [Zn2(C22H28N3O)2(C3H9OSi)2], has a crystallographic imposed centre of symmetry. The ZnII atom is coordinated by three O and one N atom from one 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenolate ligand and two bridging trimethylsilanolate anions in a distorted tetrahedral geometry. The dihedral angle between the benzotriazole ring system and the benzene ring is 19.83 (5)°. The tert-pentyl groups are disordered over two orientations with refined site-occupancy ratios of 0.858 (4):0.142 (4) and 0.665 (6):0.335 (6).

4-{[(1S,2R)-2-Hy-droxy-indan-1-yl]amino}-pent-3-en-2-one.

In the molecule of the title compound, C14H17NO2, the dihedral angle formed by the mean planes through the indan ring system and the aminopentenone fragment is 83.26 (13)°. An intramolecular N—H⋯O hydrogen bond is observed. In the crystal, molecules are linked into one-dimensional chains extending along the [010] direction via O—H⋯O and C—H⋯O hydrogen bonds.

(1S,2R)-1-[(E)-(Thio­phen-2-yl­methyl­idene)amino]­indan-2-ol

In the title compound, C14H13NOS, the dihedral angle formed by the mean planes through the indane ring system and the thiophene ring is 85.04 (11)°. The imine bond is located in the thiophene plane [the S—C—C—N torsion angle is 0.00 (3)°] and an intramolecular O—H⋯N hydrogen bond is observed.