Abstract: Polymers having photoreactive metal-metal bonds along the backbone of the polymer are disclosed, which bonds rendering the polymers photo-labile. Metals participating in such metal-metal bonds are from Groups VIB and VIIB (first column) of the Periodic Table as well as nickel. Each metal-metal bond is present in a cord group present in at least one monomer incorporated into the polymer. The core group also comprises carbonyl groups and an aromatic cyclopentadienyl (Cp) group bonded to each metal atom. Various organic and organosiloxane linker groups bonded to the Cp groups render the core group-containing monomer polymerizable into a composition of matter having physical properties determined in part by the chemical composition and conformation of the linkers. Reactions for synthesizing core groups, monomers, and various polymers therefrom are disclosed, including copolymerization reactions.