This experiment will investigate three related systems which contain copper deficient anti-fluorite-type copper sulfide layers. The overall aim is to correlate magnetic and structural properties with composition in these systems. We will probe: 1. Whether there is a magnetically driven structural distortion in Sr2CoO2Cu2S2; 2. The nature of the superstructure and magnetic ordering in the highly copper deficient mixed-valent manganese compound Sr2MnO2Cu1.2S2; 3. The correlation of structures and composition and the possible occurrence of superstructures in the mixed-valent Ce compounds CeCu1-xOS.