Reaction of Ru (η4-1, 5-COD)(η6-1, 3, 5-COT)(1) with CNtBu causes initial substitution of 1, 3, 5-COT to produce Ru (η4-1, 5-COD)(CNtBu) 3, which slowly reacts with the liberated 1, 3, 5-COT to give Ru (η1: η3-COT)(CNtBu) 3, whereas reactions with alkyl phosphites, alkylphosphonites, and alkylphosphinites cause selective displacement of 1, 5-COD.