Synthesis, structure, and reactivity of the formaldehyde complex [(.eta.5-C5H5)Re(NO)(PPh3)(.eta.2-H2C:O)]+ PF6- Academic Article uri icon

abstract

  • Reaction of [(η5-C5H5)Re(NO)(PPh3)(=CH2)]+PF6- with C6H5I+-O- gives formaldehyde complex [(η5-C5H5)Re(NO)(PPh3 )(η2-H2C=O)] +PF6- (1, 83%), which is characterized by X-ray crystallography. The η2-H2C=O ligand adopts a conformation such that overlap of its π* orbital with the rhenium fragment HOMO is maximized, and its oxygen terminus is syn to the PPh3. Extended Huckel MO calculations on model compound [(η5-C5H5)Re(NO)(PH3)(η2-H2C=O)]+ predict a similar conformational energy minimum. Complex 1 slowly reacts with CD3CN (18 days, 25 °C) to give [(η5-C5H5)Re(NO)(PPh3)(CI)3CN)]+PF6- (2-d3, 67-92%) and rapidly reacts with Nal (acetone, 25 °C) to precipitate [(η5-C5H5)Re(NO)(PPh3)(η2-H2C=O)]+I- (3, 68%). Addition of 3 to CH3OH rapidly gives (η5-C5H5)Re(NO)(PPh3)(I) (4, 65%). Unlike previously synthesized (neutral) η2-H2C=O complexes, 1 undergoes nucleophilic additions but not well-defined electrophilic additions. Thus, addition of PR3 to 1 gives [(η5-C5H5)Re(NO)(PPh3)(OCH2PR3)]+PF6- (5, R = Ph, 89%; 6, R = Me, 85%). Reaction of 1 with formyl complex (η5-C5H5)Re(NO)(PPh3)(CHO) gives methoxide complex (η5-C5H5)Re(NO)(PPh3)(OCH3) (7, 52%) and [(η5-C5H5)Re(NO)(PPh3)(CO)]+PF6-. Attempted addition of (η5-C5H5)Co(CO)(PMe3) to 1 in acetone-d6 gives [(η5-C5H5)Re(NO)(PPh3)(η1-(CD3)2C-O)]+PF6- (8-d6). The relationship of this chemistry to metal-catalyzed reactions involving formaldehyde is discussed. © 1986, American Chemical Society. All rights reserved.

author list (cited authors)

  • Buhro, W. E., Georgiou, S., Fernandez, J. M., Patton, A. T., Strouse, C. E., & Gladysz, J. A.

citation count

  • 30

publication date

  • May 1986