SYNTHESIS AND REACTIVITY OF CHIRAL RHENIUM ALCOHOL COMPLEXES OF THE FORMULA [(ETA-5-C5H5)RE(NO)(PPH3)(ROH)]+BF4(-)
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Reactions of dichloromethane complex [(5C5H5)Re(NO)(PPh3)(ClCH2Cl)] BF4 (2 BF4 and alcohols ROH give the title compounds [(5C5H5)Re(NO)(PPh3)(ROH)] BF4; (3 BF4; a: R = Me, b: Et, c: CH2Ph, d: tBu) in 9195% yields as airstable powders after workup. Reactions of 3ac BF4 and Et3N produce alkoxide complexes (5C5H5)Re(NO)(PPh3)(OR) (4ac, 8090%), which in turn react with HBF4 OEt2 to give 3ac BF4. Reactions of 3ac BF4 and Ph3PX Br give the bromide complex (5C5H5)Re(NO)(PPh3)(Br) (8598%) and alcohols ROH. 3b,c BF4 and aldehydes react to give complexes [(5C5H5)Re(NO)(PPh3)(2OCHR)] BF4 (>94%). Reaction of 3b BF4 and HSi(OEt)3 generates the hydride complex (5C5H5)Re(O)(PPh3)(H) (5, 77%). Reaction of 5 with Ph3C PF6 and then ROH gives 3 PF6 (8891%). NMR experiments establish the order OCHR > ROH > ROR for ligand binding energies to the rhenium fragment [(5C5H5)Re(NO)(PPh3)]. Copyright 1990 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim