Synthesis, structure, and reactivity of chiral rhenium carboxylic and carbonic acid ester complexes of the formula [(.eta.5-C5H5)Re(NO)(PPh3)(.eta.1-O:C(X)X')]+ X''-
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Reactions of chlorocarbon complexes [(η5-C5H5)Re(NO)(PPh3)(ClX)]+BF4- (X = CH2Cl, C6H5) with (a) methyl formate, (b) methyl acetate, (c) ethyl acetate, (d) phenyl acetate, (e) propiolactone, (f) γ-butyrolactone, (g) 2H-pyran-2-one, (h) 4H-pyran-4-one, (i) dimethyl carbonate, (j) ethylene carbonate, and (k) imidazolidone give the corresponding σ complexes [(η5-C6H5)Re(NO)(PPh3)(η1-O=C(X)X′)]+BF4- (1a-k+BF4-; 87-42% after workup). Reactions of (η5-C5H5)Re(NO)(PPh3)(H), Ph3C+PF6-, and esters b,f give 1b,f+PF6- (83-88%). Crystal structures of 1b,f+PF6- show similar ON-Re-O=C torsion angles (27.6 (9)°, 12.1 (6)°) and C=O bond lengths (1.23 (1), 1.236 (7) Å), but the ester oxygen is E to the rhenium in the former and Z in the latter. Spectroscopic, structural, and dynamic properties of 1a-k+X- are analyzed in detail. The ester ligands in 1c,f,i+BF4- are readily displaced by acetone and propionaldehyde at room temperature (Lewis basicity order: propionaldehyde > acetone > c,f,i). Analogous substitutions occur with alcohols. © 1992, American Chemical Society. All rights reserved.
author list (cited authors)
Saura-Llamas, I., Dalton, D. M., Arif, A. M., & Gladysz, J. A.