This NSF Young Investigator Award in the Inorganic, Bioinorganic, and Organometallic Program provides support for research in bioinorganic chemistry by Dr. Charles G. Riordan of the Chemistry Department, Kansas State University. Water-soluble organometallic complexes will be used as photolytic sources for carbon radicals which will be reacted with nucleic acids. A class of cobalt complexes has been found to cleave both single- and double-stranded DNA. Organometallic derivatives of these complexes will be prepared to deliver different kinds of alkyl radicals and the specificity of the attack of these radicals on DNA will be determined. The steric bulk of some of these alkyl radicals may result in sequence specificity because of recognition of DNA's tertiary structure. Also, methyl radicals produced in this manner will be used as footprinting probes to identify metalloprotein-DNA binding regions.