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Cationic Polyhedral Chalcogenaboranes: Activation without breaking Wade's Rules.

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This study introduces novel cationic chalcogenaboranes that challenge established Wade

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Area of Science:

  • Inorganic Chemistry
  • Cluster Chemistry
  • Organometallic Chemistry

Background:

  • Wade's rules correlate cluster charge with skeletal electron pairs (SEPs).
  • Traditional understanding dictates charge changes alter SEP counts in inorganic clusters.
  • Chalcogenaboranes are a class of inorganic clusters containing boron and chalcogen elements.

Purpose of the Study:

  • To synthesize and characterize the first cationic chalcogenaboranes.
  • To investigate the electronic properties and reactivity of these novel cationic clusters.
  • To challenge the conventional understanding of Wade's rules regarding charge and SEPs.

Main Methods:

  • Synthesis of closo-[12-X-2-IPr-1-EB11H10]BF4 compounds (X=H, I; E=S, Se).
  • Spectroscopic and experimental techniques to confirm charge localization.
  • Theoretical calculations to support experimental findings.

Main Results:

  • Successful synthesis of cationic chalcogenaboranes with a positive charge but conserved SEP count.
  • Enhanced reactivity towards electrophiles compared to neutral precursors.
  • Demonstrated control over regioselectivity with hard/soft bases via LUMO modulation.
  • Experimental and theoretical confirmation of positive charge localization within the borane cluster.

Conclusions:

  • Cationic chalcogenaboranes can exist with the same SEP count as neutral precursors, contradicting strict interpretations of Wade's rules.
  • The positive charge enhances reactivity and allows for tunable selectivity.
  • These findings open new avenues in cluster chemistry and reactivity.