Synthesis, structure, and reactivity of stable alkyl and aryl iodide complexes of the formula [(.eta.5-C5H5(Re(NO)(PPh3)(IR)]+BF4-
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Reaction of methyl complex (5-C5H5)Re(NO)(PPh3)(CH3) with HBF4*Et2O (CH2Cl2, 78 C) and then alkyl and aryl iodides RI gives adducts [(5-C5H5)Re(NO)(PPh3)(IR)]+BF4(3: R = a, CH3; b, CH2CH3; c, CH2CH2CH3; d, CH2CH2CH2CH3; e, CH2Si(CH3)3; f, CH2CH2CH2C1; g, CH2C1; h, C6H5; i, p-C6H4OCH3; 63-87%). The structure of 3e.(CH2Cl2)0.5 is confirmed by X-ray crystallography and compared to that of iodide complex (5-C5H4CH3)Re(NO)(PPh3)(I) [Re-I, 2.678 (1), 2.7210 (9) ]. The CI bond [2.18 (1) ] is not significantly longer than those in free alkyl iodides. Complexes 3a-c decompose (4860 h, CD2Cl2, 25 C) to bridging halide complexes (SS,RR)-[(5-C5H5)Re(NO)(PPh3)]2X+BF4[X = I (46-65%), Cl (29-48%)] and react with CH3CN to give acetonitrile complex [(5-C5H5)Re(NO)(PPh3)(NCCH3)]+BF4~(82-87%) and RI (72-82%). Complexes 3a-c rapidly alkylate PPh3 (<15 min, CDC13) to give phosphonium salts Ph3PR+BF4(93-86%) and iodide complex (5-C5H5)Re(NO)(PPh3)(I) (>99-92%). The reaction of 3b and PPh3 is second order (H* = 12.9 0.6 kcal/mol, S* = 12.0 0.9 eu) and (3.3 1.3) X 105 faster (298 K) than that of ICH2CH3 and PPh3 to give Ph3PCH2CH3+I(H* = 16.3 0.4 kcal/mol, S* = 25.9 1.5 eu). Complex 3b reacts similarly with Br, but 3h yields IC6H5 and (5-C5H5)Re(NO)(PPh3)(Br). Ethyl bromide and chloride complexes analogous to 3b are less stable but can be prepared in situ. 1989, American Chemical Society. All rights reserved.
Journal of the American Chemical Society
author list (cited authors)
Winter, C. H., Veal, W. R., Garner, C. M., Arif, A. M., & Gladysz, J. A.
complete list of authors
Winter, Charles H||Veal, William R||Garner, Charles M||Arif, Atta M||Gladysz, JA