ISSN:
0009-2940
Schlagwort(e):
Rhenium complexes
;
Alkylidene complexes
;
Diazo compounds
;
Alkene complexes
;
Chemistry
;
Inorganic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The methylidene complex [(η5-C5H5)Re(NO)(PPh3)(=CH2)]+ PF-6 or the Re—CD2 analog react with diazo compounds N2CHR [R — H, Si(CH3)3, COPh, CO2C2H5] in CH2Cl2 at -80°C to give alkene complexes [(η5-C5H5)Re(NO)(PPh3)(η2-H2C=CHR)]+ PF-6 or D2C=CHR analogs. The two Re=C geometric isomers of benzylidene complex [(η5-C5H5)Re-(NO)(PPh3)(=CHPh)]+ PF-6 and CH2N2 react to give opposite configurational diastereomers of styrene complex [(η5-C5H5)Re(NO)(PPh3)(η2-H2C=CHPh)]+ PF-6. Stereochemical features of these reactions are analyzed in detail, and are interpreted in terms of models involving (a) attack of the diazo compound upon the Re=C face opposite to the bulky PPh3 ligand, (b) an antiperiplanar disposition of the Re=C and C—N2 bonds in the transition state, utilizing the diazo carbon face that minimizes interactions of the substitutent (R) and cyclopentadienyl ligand, and (c) N2 loss from the resulting intermediate [(η5-C5H5)Re(NO)(PPh3)(CHR′CHRN2)]+ PF-6 via a conformer with antiperiplanar P—Re—CHR′—C and Re—CHR′—CHR—N linkages, with anchimeric assistance of the rhenium fragment d orbital HOMO from the backside.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/cber.19951280303
