Antiaromatic ruthenacyclopentatriene complexes

Area of Science:

• Organometallic Chemistry
• Aromaticity Studies
• Ruthenium Complexes

Background:

• Previous reports on ruthenacyclopentatrienes were limited to half-sandwich compounds.
• The aromaticity or antiaromaticity of these complexes remained unverified.
• Understanding the electronic properties of novel organometallic structures is crucial.

Purpose of the Study:

• To synthesize and characterize new ruthenacyclopentatrienes with a distinct geometry.
• To investigate the antiaromatic nature of these novel compounds.
• To explore the reactivity of these complexes with alkynes and reducing agents.

Main Methods:

• Synthesis of novel ruthenacyclopentatrienes with octahedral geometry.
• Characterization using spectroscopic and analytical techniques.
• Reactivity studies involving 1-hexyne and reducing agents like sodium borohydride (NaBH4).

Main Results:

• Successful synthesis and characterization of octahedral ruthenacyclopentatrienes.
• Confirmation of their antiaromatic character.
• Investigation of reactions with 1-hexyne and reductants.
• Formation of a dihydridoborate-ruthenacyclopentatrienyl radical upon one-electron reduction.
• Observation of near-infrared-I/near-infrared-II (NIR-I/NIR-II) absorption in the radical species.

Conclusions:

• Novel octahedral ruthenacyclopentatrienes have been synthesized and confirmed to be antiaromatic.
• These complexes exhibit unique reactivity, including reduction to a radical with NIR absorption.
• This work expands the understanding of ruthenacyclopentatriene chemistry and their electronic properties.