Isolable Pseudo-monocoordinate Group 14 to 16 Compounds Supported by Hydrindacenyl Ligands

Area of Science:

• Main-group chemistry
• Organometallic chemistry
• Materials science

Background:

• Monocoordinate main-group compounds are reactive intermediates with unique bonding.
• Neutral species like carbynes and nitrenes are of interest but difficult to isolate.
• Sterically encumbered ligands are crucial for stabilizing reactive species.

Purpose of the Study:

• To synthesize and characterize novel neutral pseudo-monocoordinate main-group compounds.
• To investigate the electronic structures and magnetic properties of these reactive species.
• To explore their potential as functional open-shell platforms in chemistry.

Main Methods:

• Dehalogenation of hydrindacenyl-tetrelene halides using potassium graphite.
• Photolysis of azide precursors to generate nitrenes.
• Reduction of dihalide precursors for heavier congeners.
• Electron paramagnetic resonance (EPR) spectroscopy and superconducting quantum interference device (SQUID) magnetometry.
• Ab initio multireference computational analyses.

Main Results:

• Isolation of the first structurally authenticated one-coordinate tetrel radicals (germylyne, stannylyne, plumbylyne).
• Characterization of a stable nitrene with a triplet ground state and defined zero-field splitting (ZFS).
• Synthesis of stibinidene and bismuthinidenes with large positive ZFS, rendering them nonmagnetic.
• Isolation of a telluryl radical with slow magnetic relaxation properties.
• A phosphanorcaradiene was isolated instead of a free phosphinidene, acting as a potential phosphinidene source.

Conclusions:

• Sterically encumbered ligands enable the isolation of previously elusive one-coordinate main-group compounds.
• These compounds exhibit diverse electronic and magnetic behaviors, including unquenched orbital angular momentum and significant ZFS.
• The synthesized species represent valuable functional open-shell platforms for fundamental studies and molecular design.
• This work expands the scope of low-valent main-group chemistry and opens new avenues for reactive species stabilization and utilization.