The many ways to have a quintuple bond

Area of Science:

• Inorganic Chemistry
• Theoretical Chemistry
• Computational Chemistry

Background:

• Investigating multiple bonding in transition metal compounds is crucial for understanding chemical reactivity.
• Previous studies have explored quadruple bonds, but quintuple bonds remain less understood.

Purpose of the Study:

• To theoretically examine the existence and persistence of quintuple (five-fold) bonding in RMMR molecule isomers.
• To elucidate the structural preferences and electronic factors governing these molecules.

Main Methods:

• Computational chemistry methods were employed to study the potential energy surfaces of RMMR molecules.
• Analysis included identifying local minima, structural preferences, and electronic interactions.

Main Results:

• The study identified complex potential energy surfaces with multiple local minima for RMMR molecules.
• A preference for trans-bent conformations or bridging R groups was observed, rather than linear geometry.
• A low-symmetry C(s) structure was found to be a common global minimum alongside the trans-bent isomer.

Conclusions:

• The metal-metal (MM) quintuple bond is robust and persists across various isomers and geometries of RMMR molecules.
• Structural preferences are dictated by a balance between maximizing MM bonding and minimizing MR antibonding interactions.