pi-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.