ore carbon atoms are joined together to form a part of a substituted or unsubstituted ring or ring system having 4 to 30 carbon atoms, (R???GeR???)x is a cyclic bridging group, where Ge is germanium, where the one or more Ge atoms bridge the two (C5H4???dRd) rings, and the two R???'s form a cyclic ring or ring system with Ge; more particularly, non-limiting examples of cyclic bridging group Ge may