Optically active transition-metal complexes, 8 -: Transition-metal complexes of the optically active cyclopentadienyl ligand PinCp*:: Crystal structure of (SRe)-(η5-PinCp*)Re(NO)(PPh3)[CONHCH(CH3)C10H7]

The synthesis of (eta(5)-PinCp*)Re(CO)(3) [PinCp* = tetramethyl(pinanyl)cyclopentadienyl] is described. Successive substitution of two CO ligands by NO+ and PPh3 generates a 1:1 diastereomeric mixture of chiral-at-metal [(S-Re)/(R-Re)- (PinCp*)Re(CO)(NO)(PPh3)]BF4. The diastereomers are converted with sodium methoxide into the derivative "esters" (S-Re)/(R-Re)-(PinCP*)Re(COOCH3)(NO)(PPh3), and then with (+)-(R)-(1-naphthylethyl)amine to the "amides" (S-Re)/(R-Re)-(PinCp*)Re(NO)(PPh3)[CONHCH(CH3)C10H7] [(S-Re)/(R-Re) = 1:1] Fractional crystallisation separates the (S-Re) isomer with an optical purity of > 98%. The latter compound has been characterized by X-ray structure analysis. By treating the (S-Re)-amide with CF3CO2H and NaBF4, (S-Re)-(PinCp*)Re(CH3)(NO)(PPh3) can be generated. Protolysis of this compound with HBF4/Et2O in CD2Cl2 at -78 degrees C leads to the solvent-stabilized complex (S-Re)-[(PinCP*)Re(NO)(PPh3)(ClCD2Cl)]+BF4-. The thermal and configurational stability of this chiral Lewis acid is investigated at various temperatures. The syntheses of [PinCp*RhCl2](2), PinCp*TiCl3 and PinCp*M(CO)(2)(NO) (M = Mo, W) are also described. Starting with PinCp* M(CO)(2)(NO), the relatively stable 16-VE complexes PinCp*MCl2(NO) and PinCp*W(CH2SiMe3)(2)(NO) are synthesized.