Synthesis, structure, and reactivity of functionalized germyl complexes of the formula (.eta.5-C5H5)Re(NO)(PPh3)(GePh2X): equilibria involving the germylene complex [(.eta.5-C5H5)Re(NO)(PPh3)(:GePh2)]+ TfO-
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Reactions of Li+[(η5-C5H5)Re(NO)(PPh3)]− with Ph3GeCl and Ph2GeCl2 (THF, −78 °C) give germyl complexes (η5-C5H5)Re(NOHPPh3HGePh3) (3, 84%) and (η5-CsHs)Re(NO)(PPh3)(GePh2Cl) (4, 82%). Reactions of 4 with LiAlH and Me3SiOTf give (η5-C5H6)Re(NO)(PPh3)(GePh2H) (5, 88%) and (η5-C5Hs)Re(NO)(PPh3)(GePh2OTf) (6, 82%). The triflate substituent in 6 is very labile, as evidenced by rapid reactions with halide ion sources to give (η5-C5H5)Re(NO)(PPh3)(GePh2X) (X = F, Br, I; 92–94%) and with pyridine and 4-methylpyridine to give [(η5-C5H5) Re(NO) (PPh3) (GePh2(4-NC5H4R))]TfO− (83–76%). The , 3C NMR resonances of the diastereotopic germanium phenyl groups in 6 coalesce at low temperatures (ΔG*(268 K, CD2Cl2) = 12.6 kcal mol−1). The most likely mechanisms for this dynamic behavior entail initial triflate dissociation to give the germylene complex [(η5-C5H5)Re(NO)(PPh3)(=GePh2)]+TfO− (12). The crystal structure of 6 (monocliπic, P21/n (No. 14); α = 16.908 (3) Å, b = 20.160 (3) Å, c = 10.437 (2) Å, β = 93.82 (2)°, Z = 4) exhibits features suggestive of a substantial resonance contribution by 12. Addition of HBF4OEt2 to 3 gives the hydride complex [(η5-C5H5)Re(NO)(PPh3)(GePh.i)(H)]+BF4− (43%), and reaction of 5 with n-BuLi and then HBF4•OEt2 gives the germylcyclopentadienyl complex (η5-C5H4GePh2H)Re(NO)(PPh3)(H) (46%). © 1991, American Chemical Society. All rights reserved.
author list (cited authors)
Lee, K. E., Arif, A. M., & Gladysz, J. A.