Synthesis of Cobalt-Centered Inorganic Sandwich Complexes.

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Materials Science

Background:

• Inorganic sandwich complexes with group 15 element rings at a single metal center have been sought for over 30 years.
• The synthesis of such complexes presents significant challenges in achieving stable structures.

Purpose of the Study:

• To report the synthesis of the first single-centered cobalt inorganic sandwiches.
• To explore the extension of inorganic sandwiching from phosphorus to arsenic analogues.
• To investigate the reaction mechanisms and metal-dependent reactivity in these systems.

Main Methods:

• Reaction of Zintl ion E73- (E = P, As) with Cobalt(II) sources.
• Mechanistic studies using spectroscopic and crystallographic techniques.
• Comparative studies with Titanium and Iron analogues.

Main Results:

• Successful synthesis of [(η3-E3)Co(η4-E4)]2- complexes, the first single-centered cobalt inorganic sandwiches.
• Demonstration of inorganic sandwiching with arsenic analogues for the first time.
• Elucidation of a two-step reaction pathway for the cobalt-phosphorus system involving a [Co(P7)2]4- intermediate.
• Observation of distinct metal-dependent reactivity for Titanium and Iron analogues.
• Improved synthesis of [Ti(η5-P5)2]2- and [Fe(η4-P4)2]2- using the P73- precursor.

Conclusions:

• The Zintl ion P73- is a versatile precursor for inorganic sandwich synthesis.
• Cobalt systems offer tunable product distribution based on solvent and reaction conditions.
• This work opens new avenues for designing and synthesizing novel inorganic cluster compounds.