From Coordination to Noncoordination: Syntheses and Substitution Lability Studies of Titanium Triflato Complexes

• Published in: Inorganic chemistry 2024-08, Vol.63 (31), p.14392-14401
• Main Authors: Schwitalla, Kevin, Yusufzadeh, Zainab, Schmidtmann, Marc, Beckhaus, Rüdiger
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X; 1520-510X
• DOI: 10.1021/acs.inorgchem.4c01033

A new concept for obtaining cationic complexes with triflate counteranions from coordinating triflato ligands was developed. Various routes are leading to titanium­(IV) and titanium­(III) triflato complexes efficiently. The reactions of pentafulvene titanium complexes with either triflic acid or silver triflate give the corresponding titanium­(IV) triflato complexes in excellent yields. Hydrolysis of the titanium­(IV) bistriflato complexes leads to cationic aqua complexes via displacement of the triflato ligand, which consequently acts as a noncoordinating anion. A functionalized titanium­(IV) monotriflato complex was synthesized by insertion of a nitrile into the Ti–C bond and the triflato ligand was displaced by an NHC. While the titanium­(IV) complexes are mostly inert toward substrates, the donor-free titanium­(III) triflato complex is a strong Lewis acid and forms various adducts with monodentate Lewis bases. The titanium­(III) complex was oxidized by reaction with TEMPO, resulting in a diamagnetic titanium­(IV) complex. The reaction with bidentate ligands results in cationic titanium­(III) complexes due to displacement of the triflato ligand by the bidentate ligands. Treatment with acetone leads to an aldol reaction of two acetone molecules and the formation of a cationic diacetone alcohol complex.