528868-44-2Relevant academic research and scientific papers
Reactions of iridium and rhodium complexes containing η2-benzyne, η2-tetrafluorobenzyne, and η2-trifluorobenzyne ligands. Differential rates of arene elimination by protonation of isomeric fluoroaryl complexes and restricted rotation of PMe3 ligands in ortho-iodo and ortho-bromoaryl complexes
Hughes, Russell P.,Laritchev, Roman B.,Williamson, Alex,Incarvito, Christopher D.,Zakharov, Lev N.,Rheingold, Arnold L.
, p. 2134 - 2141 (2008/10/08)
Treatment of the tetrafluorobenzyne complex Cp*Ir(η2-C6F4)(PMe3) (1) with MeCO2H affords the tetrafluorophenyl complex Cp*Ir(2,3,4, 5,-C6F4H)(PMe3)(O2CMe) (2), which, on treatment with NaBH4, affords the hydride complex Cp*Ir(2,3,4,5,-C6F4H)(PMe3)H (3). Treatment of 3 with n-BuLi affords the trifluorobenzyne complex Cp*Ir(3,4,5-C6F3H)(PMe3) (4). Treatment of 4 with MeCO2H gives a mixture of two protonation products, Cp*Ir(2,3,4-C6F3H2)(PMe3) (O2CMe) (5) and Cp*Ir(3,4,5-C6F3 H2)(PMe3)(O2CMe) (6) in an 8:1 ratio. Treatment of the 5/6 mixture with CF3CO2H affords 1,2,3-C6F3H3 and Cp*Ir (O2CCF3)2(PMe3) but at dramatically different rates, with 5 reacting significantly faster than 6. Treatment of 1a with Br2, I2, or MeI gives the oxidative addition products Cp*Ir(2-C6BrF4)Br(PMe3) (7), Cp*Ir(2-C6IF4)I(PMe3) (8), or Cp*Ir(2-C6MeF4)I(PMe3) (9), respectively. The variable-temperature proton NMR spectra of complexes 7 and 8 reveal an unusual restricted rotation about the Ir-PMe3 bonds on the NMR time scale (7, ΔG? = 39 ± 2 kJ mol-1; 8, ΔG? = 38 ± 2 kJ mol-1). Similarly, treatment of Cp*Rh(η2-C6F4) (PMe3) (1b) with I2 leads to formation of Cp*Rh(2-C6IF4)I(PMe3) (10), which also exhibits restricted rotation about the metal-phosphorus bond (ΔG? = 44 ± 2 kJ mol-1). While the tetrafluorobenzyne complex (1a) is unreactive toward CO, the hydrocarbon analogue Cp*Ir(η2-C6H4) (PMe3) (1c) does react to give the CO monoinsertion product (11). Compound 1c also reacts with I2 to afford Cp*Ir(2-C6IH4)I(PMe3) (12), which also shows restricted rotation about the Ir-PMe3 bond (ΔG? = 43 ± 2 kJ mol-1). X-ray crystal structures of complexes 3, 4, 5, 7, 8, 10, and 11 are reported.
