The range of antiferromagnetic coupling governs the conductivity: semiconducting behavior and ammonia gas sensing property of diamagnetic hexaradical-containing tetranuclear Co₄^III cluster and its nonradical congener

Long-range antiferromagnetic coupling impeded electron flow through the hexaradical-containing tetranuclear Co-4(III) complex (1), while the nonradical-containing tetranuclear Co-4(III) complex (2), with no paramagnetic centres, was a semiconductor and sensed NH3 efficiently at room temperature (25 degrees C).