Three‐Spin System with a Twist: A Bis(semiquinonato)copper Complex with a Nonplanar Configuration at the Copper(<scp>II</scp>) Center

Abstract

A new twist: Structural twisting by about 32° between the semiquinoneiminecopper(II) entities in 2 caused by weak Cu–S interaction results in a different spin arrangement (↑,↓,↑) than for planar 1 (↑,↑,↓). Most revealingly, 2 has an EPR spectrum typical for a radical whereas 1 displays a signal for a CuII center. Oxidation state distributions for the 22+,+,0,−,2− forms are assigned on the basis of UV/Vis/NIR spectroelectrochemistry.