# Synthesis and Structure of Diphosphene-Bridged Dicarborane Dianions with [2n+3] Skeletal Electrons

## TL;DR

Scientists synthesized new carborane compounds with an unusual electron count using a diphosphene bridge and confirmed their structure through experiments and theory.

## Contribution

The synthesis of diphosphene-bridged dicarborane dianions with [2n+3] skeletal electrons is demonstrated for the first time.

## Key findings

- Dicarborane dianions with [2n+3] skeletal electrons were successfully synthesized using a diphosphene bridge.
- Unpaired electrons are delocalized across the carborane cages and diphosphene bridge, confirmed by experimental and theoretical evidence.

## Abstract

In contrast to the extensively studied carboranes with
even skeletal
electron counts ([2n+2], [2n+4]),
systems with odd electron counts ([2n+3]) are rare
(n = number of skeletal atoms). With the assistance
of a diphosphene-bridge, dicarborane dianions {[(Ar)­NC­(tBu)­C2B10H10]­P}2
2– [Ar = Dipp (2) or Dmp (4); Dipp = 2,6-iPr2C6H3, Dmp = 2,6-Me2C6H3] with formal [2n+3] skeletal electrons in each carborane cage were obtained via single
electron reduction of imine-stabilized carboranyl-phosphinidene or
-diphosphene with potassium graphite (KC8) or cobaltocene
(CoCp2), respectively. The delocalization of the two unpaired
electrons across the carborane cages and diphosphene-bridge was evidenced
by experimental and theoretical results.