Wheel-Like Icosanuclear Peroxotitanate—A Stable Water-Soluble Catalyst for Oxygen Transfer Reactions

Abstract

Water-soluble wheel-like icosanuclear peroxotitanate K 16 1) chelated by tartrate has been successfully isolated. As the largest peroxotitanate reported, {Ti 20 } features 20 (hydro)peroxo groups with three kinds of coordination modes in μ-η 1 :η 2 , μ-η 2 :η 2 , and η 2 fashions. The cluster is stable in solution and solid states. It has been tested for the catalytic oxidations of methyl phenyl sulfide and pyridine with hydrogen peroxide, respectively, which shows reversible elimination and the addition of peroxo groups. This provides a rare example of wellcharacterized titanium peroxide for homogeneous catalysis and mechanism research.

Water-Soluble Lanthanide–Titanium–Oxo Cluster, a Precursor for Biocompatible Nanomaterial

“…Titanium–oxo clusters (TOCs), the analogues of nano-titanium-oxide but with uniform scale and precise structures, are attractive as a rapidly growing class of molecular materials. − The TOCs can be used not only as molecular models, − but also as precursors for nano-TiO 2 . − They have a variety of applications in photocatalysis, − photocurrent sensors, and photovoltaic materials. − However, most TOCs are synthesized in organic solvents by solvothermal methods and can only dissolve in nonaqueous solvents, because most of them are neutral molecules and their surfaces are covered with the hydrophobic organic ligands, which largely limits their potential applications in biosystems and environmental situations. Water-soluble TOCs, which can be easily dissolved in water, are very rare. − Kakihana previously isolated a water-soluble Ti 4 O 2 TOC using a hydrophilic glycolate ligand . The Wang group reported a series of cationic TOCs isolated in water system, a [Ti 8 O 12 ­(OH 2 ) 24 ] 8+ cluster, a [Ti 18 O 27 (OH 2 ) 30 ­(SO 4 ) 6 ] 6+ cluster, and [Cs/RbTi 12 O 18 ­(OH 2 ) 24 Ser 6 ] 13+ clusters .…”

Countercation-Controlled Nuclearity of Zr/Hf Peroxo Oxalates

“…In addition, cluster formation with bridging peroxo groups is well-known for uranyl nanocages but less common for transition metals . There is one unique example of a high-nuclearity wheel-shaped peroxotitanate with bridging peroxo ligands . On the other hand, peroxide can also cap Nb/Ta 5+ in cluster forms. − …”

“…54 There is one unique example of a high-nuclearity wheel-shaped peroxotitanate with bridging peroxo ligands. 55 On the other hand, peroxide can also cap Nb/Ta 5+ in cluster forms. 56−58 It is interesting that identical reaction conditions for Zr and Hf lead to Zr peroxo oxalate species vs Hf oxalate species.…”

Synthesis, Structure, and Light Absorption Behaviors of Prismatic Titanium-Oxo Clusters Containing Lacunary Lindqvist-like Species

“…As a pioneer of photocatalytic materials, titanium dioxide (TiO 2 ) has drawn plenty of research attention because of its inherent physicochemical properties. − Due to the important applications of TiO 2 in catalysis and energy areas, atomically precise polyoxotitanium clusters (PTCs) have been studied with the goal of understanding the structure–property relationships of titanium oxide materials at the molecular level. In the past decade, PTCs have achieved speedy growth in their structural library through the joint efforts of worldwide researchers. − However, the rational design of PTCs is challenging, as their formation mechanism is affected by various parameters, including the synthetic method, temperature, reactant ratio, and solvent, as well as functional ligands. − Meanwhile, numerous structural types of PTCs such as spherical, cyclic, rectangular, tubal, and prismatic clusters have been prepared and characterized by X-ray diffraction. − Representative examples of prismatic PTCs are Ti 12 and Ti 18 , documented in 2018 and 2016, respectively. , In view of their alluring architectures and unexplored functions, the development of such prismatic crystalline complexes could be quite attractive.…”