**Ryoya Sato and Masaki Matsuda \***

Department of Chemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan; 207d1308@st.kumamoto-u.ac.jp

**\*** Correspondence: masaki@kumamoto-u.ac.jp

Received: 3 August 2020; Accepted: 21 August 2020; Published: 24 August 2020

**Abstract:** Organic π-radical crystals are potential single-component molecular conductors, as they involve charge carriers. We fabricated new organic π-radical crystals using axially ligated metal phthalocyanine anions ([MIII(Pc)L2] <sup>−</sup>) as starting materials. Electrochemical oxidation of [MIII(Pc)L2] − afforded single crystals of organic <sup>π</sup>-radicals of the type MIII(Pc)Cl2·THF (M = Co or Fe, THF = tetrahydrofuran), where the π-conjugated macrocyclic phthalocyanine ligand is one-electron oxidized. The X-ray crystal structure analysis revealed that MIII(Pc)Cl2 formed three-dimensional networks with <sup>π</sup>-<sup>π</sup> overlaps. The electrical resistivities of CoIII(Pc)Cl2·THF and FeIII(Pc)Cl2·THF at room temperature along the *a*-axis were 6 <sup>×</sup> 102 and 6 <sup>×</sup> 103 <sup>Ω</sup> cm, respectively, and were almost isotropic, meaning that MIII(Pc)Cl2·THF had three-dimensional electronic systems.

**Keywords:** organic π-radical; molecular conductor; phthalocyanine; three-dimensional network; three-dimensional electronic system
