Tetranuclear MnII/ZnII and Novel Azido-Bridged Chair-Shaped Heptanuclear CdII Compounds: The Effect of Metal Ion and Coordination Mode of the Azide Group on the Structure of the Products: Tetranuclear MnII/ZnII and Novel Azido-Bridged Chair-Shaped Heptanuclear CdII Compounds: The Effect of Metal Ion and Coordination Mode of the Azide Gr