Lactide as the Playmaker of the ROP Game: Theoretical and Experimental Investigation of Ring-Opening Polymerization of Lactide Initiated by Aminonaphtholate Zinc Complexes

A family of homo- and heteroleptic zinc complexes bearing aminonaphtholate ligands was synthesized and fully characterized. Using NMR spectroscopy and DFT calculation, bis-alkoxy-bridged complexes [LZn­(μ-OR)]₂ were confirmed to have dimeric structures in solution, analogous to those obtained via X-ray crystallography. Surprisingly, a detailed experimental and theoretical study of the catalytic activity of [LZn­(μ-OR)]₂ in the ring-opening polymerization (ROP) of lactides showed that although well-defined alkoxy dimers possess a single-site structural motif, the most active initiator is obtained during in situ alcoholysis of the alkylzinc precursor. These results indicate that rational ancillary and alkoxy ligand design that takes into account its mutual interaction on monomer coordination may be key to the synthesis of new high-performance ROP catalysts

Lactide as the Playmaker of the ROP Game: Theoretical and Experimental Investigation of Ring-Opening Polymerization of Lactide Initiated by Aminonaphtholate Zinc Complexes

A family of homo- and heteroleptic zinc complexes bearing aminonaphtholate ligands was synthesized and fully characterized. Using NMR spectroscopy and DFT calculation, bis-alkoxy-bridged complexes [LZn­(μ-OR)]₂ were confirmed to have dimeric structures in solution, analogous to those obtained via X-ray crystallography. Surprisingly, a detailed experimental and theoretical study of the catalytic activity of [LZn­(μ-OR)]₂ in the ring-opening polymerization (ROP) of lactides showed that although well-defined alkoxy dimers possess a single-site structural motif, the most active initiator is obtained during in situ alcoholysis of the alkylzinc precursor. These results indicate that rational ancillary and alkoxy ligand design that takes into account its mutual interaction on monomer coordination may be key to the synthesis of new high-performance ROP catalysts

Synthesis of Functionalized Materials Using Aryloxo-Organometallic Compounds toward Spinel-like MM′₂O₄ (M = Ba²⁺, Sr²⁺; M′ = In³⁺, Al³⁺) Double Oxides

The predesigned single-source precursors [Ba­{(μ-ddbfo)₂InMe₂}₂] (<b>1</b>), [Me₂In­(μ-ddbfo)]₂ (<b>2</b>), [Sr­{(μ-ddbfo)₂AlMe₂}₂] (<b>4</b>), and [Me₂Al­(μ-ddbfo)]₂ (<b>5</b>) (ddbfoH = 2,3-dihydro-2,2-dimethylbenzofuran-7-ol) for spinel-like double oxides and group 13 oxide materials were prepared via the direct reaction of the homoleptic aryloxide [M­(ddbfoH)₄]­(ddbfo)₂·ddbfoH (M = Ba²⁺, Sr²⁺ (<b>3</b>)) and InMe₃ or AlMe₃ in toluene. In all of the reactions, there was an organometallic-driven abstraction of the OH protons from the 7-benzofuranols in the Ba²⁺ and Sr²⁺ cation sphere. All compounds were characterized by elemental analysis, ¹H NMR, and FT-IR spectroscopy. In addition, the molecular structures of <b>1</b>, <b>2</b>, and <b>3</b> were determined by single-crystal X-ray diffraction. The oxide products derived from the compounds mentioned above were studied using elemental analysis, Raman spectroscopy, X-ray powder diffraction, and scanning and transmission electron microscopy equipped with an energy-dispersive spectrometer. Moreover, their specific surface area and mesopore size distribution were evaluated using nitrogen porosimetry. Preliminary investigations of the Eu-doped SrAl₂O₄ and In₂O₃ phosphors revealed that the oxides obtained could be considered as matrices for lanthanide ions

Synthesis, Crystal Structures, and Optical and Magnetic Properties of Samarium, Terbium, and Erbium Coordination Entities Containing Mono-Substituted Imine Silsesquioxane Ligands

Mono-substituted cage-like silsesquioxanes of the T8-type can play the role of potential ligands in the coordination chemistry. In this paper, we report on imine derivatives as ligands for samarium, terbium, and erbium cations and discuss their efficient synthesis, crystal structures, and magnetic and optical properties. X-ray analysis of the lanthanide coordination entities [MCl3(POSS)3]·2THF [M = Er3+ (3), Tb3+ (4), Sm3+ (5)] showed that all three compounds crystallize in the same space group with similar lattice parameters. All compounds contain an octahedrally coordinated metal atom, and additionally, 3 and 5 structures are strictly isomorphous. However, surprisingly, there are two different molecules in the crystal structure of the terbium coordination entity 4, monomer (sof 65%) and dimer (sof 35%), with one and two metal centers. Absorption measurements of the investigated materials recorded at 300 K showed that regardless of the lanthanide involved, their energy band gap equals 2.7 eV. Moreover, the analogues containing Tb3+ and Sm3+ exhibit luminescence typical of these rare earth ions in the visible and infrared spectral range, while the compound with Er3+ does not generate any emission. Direct current variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3–5 were performed between 1.8 and 300 K. The magnetic properties of 3 and 4 are dominated by the crystal field effect on the Er3+ and Tb3+ ions, respectively, hiding the magnetic influence between the magnetic cations of adjacent molecules. Complex 5 exhibits a nature typical for the paramagnetism of the samarium(III) cation

Synthesis of Functionalized Materials Using Aryloxo-Organometallic Compounds toward Spinel-like MM′₂O₄ (M = Ba²⁺, Sr²⁺; M′ = In³⁺, Al³⁺) Double Oxides

The predesigned single-source precursors [Ba­{(μ-ddbfo)₂InMe₂}₂] (<b>1</b>), [Me₂In­(μ-ddbfo)]₂ (<b>2</b>), [Sr­{(μ-ddbfo)₂AlMe₂}₂] (<b>4</b>), and [Me₂Al­(μ-ddbfo)]₂ (<b>5</b>) (ddbfoH = 2,3-dihydro-2,2-dimethylbenzofuran-7-ol) for spinel-like double oxides and group 13 oxide materials were prepared via the direct reaction of the homoleptic aryloxide [M­(ddbfoH)₄]­(ddbfo)₂·ddbfoH (M = Ba²⁺, Sr²⁺ (<b>3</b>)) and InMe₃ or AlMe₃ in toluene. In all of the reactions, there was an organometallic-driven abstraction of the OH protons from the 7-benzofuranols in the Ba²⁺ and Sr²⁺ cation sphere. All compounds were characterized by elemental analysis, ¹H NMR, and FT-IR spectroscopy. In addition, the molecular structures of <b>1</b>, <b>2</b>, and <b>3</b> were determined by single-crystal X-ray diffraction. The oxide products derived from the compounds mentioned above were studied using elemental analysis, Raman spectroscopy, X-ray powder diffraction, and scanning and transmission electron microscopy equipped with an energy-dispersive spectrometer. Moreover, their specific surface area and mesopore size distribution were evaluated using nitrogen porosimetry. Preliminary investigations of the Eu-doped SrAl₂O₄ and In₂O₃ phosphors revealed that the oxides obtained could be considered as matrices for lanthanide ions

Unexpected Reactions between Ziegler–Natta Catalyst Components and Structural Characterization of Resulting Intermediates

In this work, we investigated precursors and procatalysts with well-defined crystal structures and morphologies in Ziegler–Natta systems to improve our understanding of the nature of the active metal sites. Molecular cluster precursors such as [Mg₄Ti₃(μ₆-O)­(μ₃-OH)₃(μ-OEt)₉(OEt)₃(EtOH)₃Cl₃], [Mg₄Ti₃(μ₆-O)­(μ₃-OH)­(μ₃-OEt)₂(μ-OEt)₉(OEt)₃(EtOH)₃Cl₃], and [Mg₆Ti₄(μ₆-O)₂(μ₃-OH)₄(μ-OEt)₁₄(OEt)₄(EtOH)₂Cl₂] were prepared via simple elimination of the cyclopentadienyl ring from Cp₂TiCl₂ as CpH in the presence of magnesium metal and ethanol. Titanocene dichloride acts as both a source of titanium and a magnesium-chlorinating agent. The resulting novel complexes were characterized using single-crystal X-ray diffraction. In these compounds, Ti­(OEt)₄ molecules are grafted onto Mg₄ and Mg₆ ethoxide cubane-like surfaces; this strongly affects the procatalyst morphology, which is transferred to the polymer. Mg₄(OR)₈ units act as carriers for the AlR₃ co-catalyst, resulting in return of alkyl functions to the Ti center

Transformation of Barium–Titanium Chloro–Alkoxide Compound to BaTiO₃ Nanoparticles by BaCl₂ Elimination

In this Article, we present how the molecular precursor of binary oxide material having an excess of alkali earth metal can be transformed to the highly phase pure BaTiO₃ perovskite. Here, we synthesized and compared two barium–titanium complexes with and without chloride ligands to determine the influences of different ligands on the phase purity of binary oxide nanoparticles. We prepared two barium–titanium complexes, i.e., [Ba₄Ti₂(μ₆-O)­(OCH₂CH₂OCH₃)₁₀­(HOCH₂CH₂OCH₃)₂­(HOOCCPh₃)₄] (<b>1</b>) and [Ba₄Ti₂(μ₆-O)­(μ₃,η₂-OCH₂CH₂OCH₃)₈­(μ-OCH₂CH₂OCH₃)₂­(μ-HOCH₂CH₂OCH₃)₄Cl₄] (<b>2</b>). The barium–titanium precursors were characterized using elemental analysis, infrared and nuclear magnetic resonance spectroscopies, and single-crystal X-ray structural analysis, and their thermal decomposition products were compared. The complex <b>1</b> decomposed at 800 °C to give a mixture of BaTiO₃ and Ba₂TiO₄, whereas <b>2</b> gave a BaCl₂/BaTiO₃ mixture. Particles of submicrometer size (30–50 nm) were obtained after leaching of BaCl₂ from the raw powder using deionized water. Preliminary studies of barium titanate doped with Eu³⁺ sintered at 900 °C showed that the dominant luminescence band arose from the strong electric dipole transition, ⁵D₀–⁷F₂

Transformation of Barium–Titanium Chloro–Alkoxide Compound to BaTiO₃ Nanoparticles by BaCl₂ Elimination

In this Article, we present how the molecular precursor of binary oxide material having an excess of alkali earth metal can be transformed to the highly phase pure BaTiO₃ perovskite. Here, we synthesized and compared two barium–titanium complexes with and without chloride ligands to determine the influences of different ligands on the phase purity of binary oxide nanoparticles. We prepared two barium–titanium complexes, i.e., [Ba₄Ti₂(μ₆-O)­(OCH₂CH₂OCH₃)₁₀­(HOCH₂CH₂OCH₃)₂­(HOOCCPh₃)₄] (<b>1</b>) and [Ba₄Ti₂(μ₆-O)­(μ₃,η₂-OCH₂CH₂OCH₃)₈­(μ-OCH₂CH₂OCH₃)₂­(μ-HOCH₂CH₂OCH₃)₄Cl₄] (<b>2</b>). The barium–titanium precursors were characterized using elemental analysis, infrared and nuclear magnetic resonance spectroscopies, and single-crystal X-ray structural analysis, and their thermal decomposition products were compared. The complex <b>1</b> decomposed at 800 °C to give a mixture of BaTiO₃ and Ba₂TiO₄, whereas <b>2</b> gave a BaCl₂/BaTiO₃ mixture. Particles of submicrometer size (30–50 nm) were obtained after leaching of BaCl₂ from the raw powder using deionized water. Preliminary studies of barium titanate doped with Eu³⁺ sintered at 900 °C showed that the dominant luminescence band arose from the strong electric dipole transition, ⁵D₀–⁷F₂

Transformation of Barium–Titanium Chloro–Alkoxide Compound to BaTiO₃ Nanoparticles by BaCl₂ Elimination

In this Article, we present how the molecular precursor of binary oxide material having an excess of alkali earth metal can be transformed to the highly phase pure BaTiO₃ perovskite. Here, we synthesized and compared two barium–titanium complexes with and without chloride ligands to determine the influences of different ligands on the phase purity of binary oxide nanoparticles. We prepared two barium–titanium complexes, i.e., [Ba₄Ti₂(μ₆-O)­(OCH₂CH₂OCH₃)₁₀­(HOCH₂CH₂OCH₃)₂­(HOOCCPh₃)₄] (<b>1</b>) and [Ba₄Ti₂(μ₆-O)­(μ₃,η₂-OCH₂CH₂OCH₃)₈­(μ-OCH₂CH₂OCH₃)₂­(μ-HOCH₂CH₂OCH₃)₄Cl₄] (<b>2</b>). The barium–titanium precursors were characterized using elemental analysis, infrared and nuclear magnetic resonance spectroscopies, and single-crystal X-ray structural analysis, and their thermal decomposition products were compared. The complex <b>1</b> decomposed at 800 °C to give a mixture of BaTiO₃ and Ba₂TiO₄, whereas <b>2</b> gave a BaCl₂/BaTiO₃ mixture. Particles of submicrometer size (30–50 nm) were obtained after leaching of BaCl₂ from the raw powder using deionized water. Preliminary studies of barium titanate doped with Eu³⁺ sintered at 900 °C showed that the dominant luminescence band arose from the strong electric dipole transition, ⁵D₀–⁷F₂