Reactivity of electron donor-acceptor complexes. Part 10.—Hydrogen exchange reaction between acetylene, or molecular hydrogen, and various metallocene-quinone electron donor-acceptor complexes

Abstract

Various metallocenes were employed as electron donors and the activity of their electron donor acceptor (EDA) complexes with various quinones, nitro- and cyano- substituted compounds were studied. The hydrogen exchange reaction between acetylene, or molecular hydrogen, and various EDA complexes of metallocenes proceeded rapidly at room temperature but did not take place over either the metallocenes or quinones alone under the same reaction conditions. The exchange reaction proceeded over the EDA complexes via bonded hydrogen in the complexes, and the exchange rates were in the following decreasing order; nickelocene, cobaltocene and ferrocene. The cis-trans isomerization of butene was also studied over the EDA complexes. “Double-exchange” of hydrogen takes place reversibly between acetylene and the EDA complexes of 2,-6-dichloroquinone with nickelocene or cobaltocene in the following manner; C₂D₂+H₂Z = C₂H₂+D₂Z, where H₂Z denotes the EDA complexes. The EDA complexes of metallocenes sorbed a considerable amount of ammonia at room temperature.