Cleavage of the rhenium-methyl bond of (.eta.-C5H5)Re(NO)(PPh3)(CH3) by protic and halogen electrophiles: stereochemistry at rhenium

Diastereomeric Halfsandwich Rhenium Complexes Containing Hemilabile Phosphane Ligands

“…This is in line with earlier observations that substitution reactions at half-sandwich complexes of rhenium proceed with retention of configuration. [33,34] …”

Synthesis and Structure of σ-Complexes of the Chiral Rhenium Lewis Acid [(η5-C5H5)Re(NO)(PPh3)]+ and Aromatic Nitrogen Heterocycles

“…The triflate complex (^5-C5H 5)Re(N O )(PPh3)-(OTf) (1) has been previously shown to react with primary, secondary, and tertiary amines to give the corresponding adducts [(^5-C5H 5)Re(NO)-(PPh3)(N R R 'R ")]+TfO -in high yields [10], Thus, 1 was generated in toluene as described earlier [13] and treated with 5 equivalents of pyridine (Scheme I). After 2 h, w orkup gave the cr-pyridine complex [(/75-C5H 5)Re(N O )(PPh3)(N C 5H 5)]+TfCT (2) as an analytically pure orange powder in 95% yield.…”

“…Hence, the optically ac tive triflate complex (+)-(/? )-1 [13] and isoquino line were reacted (Scheme II). W orkup gave the optically active isoquinoline complex (+ )-(S)-4 in 74% yield, [a^f9 111 ± 2° [15].…”

“…W orkup gave the optically active isoquinoline complex (+ )-(S)-4 in 74% yield, [a^f9 111 ± 2° [15]. The configuration at rhenium, which corresponds to retention, was as- signed by analogy to the results of closely related substitution reactions [13,16], and the commonly observed correlation with the sign of [ a ]^ in this series o f com pounds [7 -9 , 13, 16]. Complex (+)-(S)-4 was subsequently treated with the cyanide salt (CH 3CH 2)4N +CN~ (Scheme II).…”

“…Then H O Tf (0.0389 ml, 0.439 mmol) was added with stirring to generate (>75-C5H 5)Re(NO)(PPh3)(OTf) (1) [13]. After 5 min, pyridine (0.178 ml, 2.20 mmol) was added with stirring.…”