Discovering complexes containing a metal-metal quintuple bond: from theory to practice

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Materials Science

Background:

• The field of metal-to-metal multiple bonding was considered mature until recent breakthroughs.
• Theoretical studies predicted, and experimental work confirmed, the existence of quintuple bonds in dinuclear complexes.
• The discovery of the first isolable quintuple bonded chromium phenyl dimer by Power and co-workers in 2005 marked a significant advancement.

Purpose of the Study:

• To review recent advances in the synthesis and characterization of metal-to-metal quintuple bonded complexes.
• To explore the bonding schemes and structural features of these low-coordinate dinuclear species.
• To highlight the interesting reaction chemistry of quintuple bonded complexes with unsaturated hydrocarbons and small inorganic molecules.

Main Methods:

• Synthesis of dinuclear group VI metal-to-metal quintuple bonded complexes stabilized by sterically hindered N-based bidentate ligands.
• Characterization of these complexes, focusing on structural determination and metal-metal bond lengths.
• Investigation of the reactivity of quintuple bonded complexes with various unsaturated substrates.

Main Results:

• Successful synthesis and characterization of numerous dinuclear group VI metal-to-metal quintuple bonded complexes.
• Observation of extremely short metal-metal bond lengths in these low-coordinate homo-univalent species.
• Demonstration of unique bonding schemes and interesting reactivity patterns with unsaturated hydrocarbons and small inorganic molecules.

Conclusions:

• The discovery of quintuple bonded dinuclear complexes has reinvigorated the field of metal-to-metal multiple bonding.
• These complexes exhibit remarkable structural and bonding properties due to their low coordination numbers.
• The unique reactivity of these compounds opens new avenues for synthetic and mechanistic studies in inorganic chemistry.