Carbonyl insertion into metal-boron based clusters: pathway to a rhodathiacarborane

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Boron Chemistry

Background:

• Rhodathiaboranes are complex inorganic clusters with potential applications in catalysis.
• Understanding the reactivity of these metallaboranes with small molecules like carbon monoxide is crucial for developing new synthetic methodologies.

Purpose of the Study:

• To investigate the reaction of a ten-vertex hydridorhodathiaborane with carbon monoxide.
• To characterize the novel products formed, including a hydroxy-functionalized carborane.
• To elucidate the mechanism of carbon monoxide incorporation into the polyhedral cage.

Main Methods:

• Reaction of hydridorhodathiaborane with excess carbon monoxide.
• Characterization of products using multielement NMR spectroscopy and mass spectrometry.
• Single-crystal X-ray diffraction analysis of key compounds.
• Density Functional Theory (DFT) calculations and variable temperature NMR studies.

Main Results:

• Formation of a novel eleven-vertex rhodathiacarborane with a hydroxy-functionalized carbon vertex via CO insertion.
• Synthesis of CO-ligated ten-vertex arachno-rhodathiaborane adducts.
• Identification of a specific CO-Rh/PPh3 intermediate mediating the CO to C-OH transformation.
• Observation of fluxional behavior in the new rhodathiacarborane involving rotation of the {Rh(CO)(PPh3)} unit.

Conclusions:

• Rhodathiaborane platforms exhibit versatility in activating and incorporating small molecules through metal-polyhedron cooperation.
• The reaction pathway involves ligand substitution and cage insertion of CO, leading to functionalization.
• The study provides insights into the complex reactivity and dynamic behavior of metallaborane clusters.