The ring-opening and H/D exchange reactions of (C{sub 5}H{sub 4}Me){sub 2}Zr(H) (THF){sup +}. Evidence for hydrogenolysis of Zr-Cp bonds

The cationic hydride Cp{prime}{sub 2}Zr(H)(THF){sup +} (5; Cp{prime} = C{sub 5}H{sub 4}Me) reacts slowly in THF solution via THF ring opening to yield Cp{prime}{sub 2}Zr(O{sup n}Bu)(THF){sup +} (7). Hydride 5 undergoes rapid H/D exchange with D{sub 2} at the Zr-H site, and slow H/D exchange at the {beta} Cp{prime}-H sites. No H/D exchange at the {alpha} Cp{prime}-H or Cp{prime}-CH{sub 3} sites is detected. It is proposed that H/D exchange at the Zr-H site proceeds by a conventional {sigma}-bond methathesis process and that exchange at the {beta} Cp{prime}-H site involves an intermediate (Cp{prime})(methylcyclopentadiene)Zr species formed by D{sub 2} addition across a Zr-Cp{prime} bond. Exchange of H{sup -} and {sup n}BuO{sup -} ligands between Cp{prime}{sub 2}Zr centers also leads indirectly to H/D exchange at the {beta} Cp{prime}-H sites of 7. 20 refs.