Pendulum-like hemilability in a Ti-based frustrated Lewis Trio

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Lewis Acid-Base Chemistry

Background:

• Frustrated Lewis Pairs (FLPs) are reactive species formed between Lewis acids and bases that do not fully associate.
• Theoretical predictions suggested the existence of Frustrated Lewis Trios (FLTs) with potential for novel reactivity.
• Stabilizing highly electrophilic metal fragments is crucial for developing new catalytic systems.

Purpose of the Study:

• To provide the first experimental realization of a theoretically predicted Frustrated Lewis Trio (FLT).
• To investigate the unique bonding and reactivity of a titanium complex stabilized by a tetradentate PNNP ligand.
• To elucidate the mechanism of heterolytic bond activation mediated by the FLT system.

Main Methods:

• Synthesis and characterization of a novel titanium complex featuring a tetradentate PNNP ligand.
• Experimental studies including X-ray crystallography and spectroscopy.
• Computational analysis (e.g., DFT calculations) to understand electronic structure and bonding.

Main Results:

• Successful synthesis and structural characterization of the FLT complex, showcasing two equally long, frustrated Ti-P bonds.
• Experimental and computational evidence for the distinct roles of the Lewis basic phosphine groups in bond activation.
• Observation of pendulum-like hemilability of one phosphine ligand, dynamically tuning the electronic properties at the titanium center.

Conclusions:

• The study presents the first experimental example of an FLT, validating theoretical predictions.
• The FLT system demonstrates a novel mechanism for heterolytic bond activation via dual phosphine cooperation and hemilability.
• This work opens new avenues for designing advanced catalysts based on frustrated Lewis acid-base interactions.