# Prediction of One‐Dimensional Metallicity and π‐Band Superconductivity in Rhodizonate Radical Pancakes

## TL;DR

Scientists predict a new class of organic conductors and potential superconductors using potassium and carbon monoxide compounds.

## Contribution

The paper introduces a novel stabilization mechanism for radical stacking via multicentered bonding and Coulombic repulsion.

## Key findings

- K3C6O6 exhibits equidistant radical stacking stabilized by pancake bonding and ionic repulsion.
- The material shows predicted metallicity and π-band superconductivity.
- Design principles for new organic conductors using environmentally benign elements are proposed.

## Abstract

Computational exploration of condensed phases made of potassium and carbon monoxide leads to predictions of stable salts composed of cyclic six‐membered oxocarbon anions and K+ cations, K
n
(C6O6)
m
. The states of reduction in these systems are wide‐ranging, with C6O6 molecules formally reduced by −2, −3, −3.5, and −6 in semiconducting and metallic phases. Special attention is paid to K3C6O6, in which triply charged radical anions stack closely and equidistantly in one dimension. Equidistant interactions of radicals are exceedingly rare and typically unstable due to spontaneous symmetry breaking, Peierls or Jahn–Teller distortion. The predicted exception of K3C6O6 is explained by inter‐ring multicenter bonding, also known as pancake bonding, in combination with large ionic repulsion. This fascinating interplay of interactions facilitates an exceptionally high density of states at the Fermi level and leads us to predictions of metallicity, a negative temperature coefficient of resistivity, and rare π‐band superconductivity. These predictions reinvigorate the search for new organic conductors and superconductors using molecular design of metallic salts.

Equidistant stacking of radicals is typically unstable due to symmetry‐lowering distortions. We predict that such arrangements can be stabilized by multicentered covalent (“pancake”) bonding and Coulombic repulsion between negatively charged radicals. This leads to design principles for a new class of organic conductors—potentially superconductors—based on abundant, environmentally benign elements.