The design motif in ferrocene-based architectures plays an important role to secure the targeted chemical, electronic, opto-electronic, redox properties. One of such architectures includes motifs bearing an unsaturated backbone attached to one or both the cyclopentadienyl ring. This review focuses on the synthesis and properties of these special classes of ferrocenes having olefinic, and acetylenic and cumulenic backbones. (c) 2006 Elsevier B.V. All rights reserved.