SYNTHESIS AND REACTIVITY OF CHIRAL RHENIUM INDENYL COMPLEXES OF THE FORMULA [(ETA(5)-C9H7)RE(NO)(PPH3)(X)]N+
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Reaction of (5-C9H7)Re(CO)3 and NO+BF4- yields [(6-C9H7)Re(NO)(CO)2]+BF4- (2, 94%), which with PPh3 (C1CH2CH2C1, reflux) gives [(5-C9H7)Re(NO)(PPh3)(CO)]+BF4- (3, 94%). When 2 is dissolved in acetone, addition products of the formula (1-C9H7)Re(NO)(CO)2(1-OC(CH3)2)2 form. Attempted reduction of the CO ligand in 3 yields hydride complexes. However, reaction of 2 and NaBH4 gives (5-C9H7)Re(NO)(CO)(CH3) (6, 45%), which with PPh3 (C1CH2CH2C1, reflux) yields (5-C9H7)Re(NO)(PPh3)(CH3) (5, 18%) and (5-C9H7)Re(NO)-(PPh3)(COCH3) (7, 54%). Reaction of 5 and HBF4OEt2 in CH2C12 at 80 C gives the unstable, substitution-labile dichloromethane complex [(5-C9H7)Re(NO)(PPh3)(ClCH2Cl)]+BF4- (8), which is characterized by NMR. Subsequent addition of acetone or cyclohexanone yields -ketone complexes [(5-C9H7)Re(NO)(PPh3)(1-0CR2)]+BF4- (8276%), and addition of CO (250 psi) gives 3 (92%). In another approach to 5 and 8, 3 and NaOCH3 are combined to give (5-C9H7)Re(NO)(PPh3)(CO2CH3) (11, 92%). Sequential reactions with CH3MgBr and BH3THF produce 7 (53%) and (5-C9H7)Re(NO)(PPh3)(CH2CH3) (12, 95%). The latter could not be converted to 8 in high yield. However, reaction of 12 and HI affords (6-C9H7)Re(NO)(PPh3)(I) (88%), which with CuCH3 gives 5 (62%). 1993, American Chemical Society. All rights reserved.
