π-ligands for generating transition metal-peptide complexes:: Coordination of amino acid derivatives to tungsten utilizing alkyne ligands

Amino acid derivatives bearing an alkyne (AA-CCH) at either the N- or C-terminus readily react with W(CO)(3)(S2CNMe2)(2) to replace the carbon monoxides and form the novel bis-alkyne complexes W(AA-CCH)(2)(S2CNMe2)(2); the solution behavior of these complexes shows that only the alkyne, and not the other functional groups on the amino acid, bonds to the tungsten.