Issue 4, 1994

The influence of the ring substituent, R, on the substitution of carbonyl groups by phosphine ligands in [Co2{µ-PPh2CHCRC(O)}(µ-PPh2)(CO)4](R = H, Ph or SiMe3)

Abstract

The room-temperature reaction of the complexes [Co2{µ-PPh2CHCRC(O)}(µ-PPh2)(CO)4](R = H 1a, Ph 1b or SiMe31c) with 1 equivalent of PPhMe2 gave a combination of phosphine substituted products which depends on the nature of R. When R = H 1a, two isomeric monosubstituted complexes of formula [Co2{µ-PPh2CHCHC(O)}(µ-PPh2)(CO)3(PPhMe2)]2a and 3a are afforded in a ratio of approximately 1 : 1 in which the phosphine co-ordinates either at the cobalt atom π-co-ordinated by the carbon–carbon double bond (2a) or at the cobalt to which the PPh2 and CO groups of the metallacyclic ligand are σ bonded (3a). When R = Ph 1b, the corresponding monosubstituted derivatives, [Co2{µ-PPh2CHCPhC(O)}(µ-PPh2)(CO)3(PPhMe2)]2b and 3b are formed together with traces of the disubstituted complex [Co2{µ-PPh2CHCPhC(O)}(µ-PPh2)(CO)2(PPhMe2)2]4b. In the case of R = SiMe31c, only the monosubstituted isomer [Co2{µ-PPh2CHC(SiMe3)C(O)}(µ-PPh2)(CO)3(PPhMe2)]3c is obtained. Conversion of the monosubstituted complexes 2a, 2b and 3a, 3b to the disubstituted complexes [Co2{µ-PPh2CHCRC(O)}(µ-PPh2)(CO)2(PPhMe2)2](R = H 4a or Ph 4b) takes place on thermal reaction of respectively 2a, 3a and 2b, 3b with a further equivalent of PPhMe2. An X-ray crystal structural determination has been performed on complex 4a and reveals a pseudo-axial/cis arrangement of the phosphine groups which are located one on each cobalt atom. The complex [Co2{µ-PPh2CHCPhC(O)}(µ-PPh2)(CO)4]1b reacted with the secondary phosphine PPh2H initially in the same way as with PPhMe2 to give isomeric species of formula [Co2{µ-PPh2CHCPhC(O)}(µ-PPh2)(CO)3(PPh2H)]2d and 3d. Thermolysis of complex 2d resulted in 42% conversion to the isomeric 3d along with traces of 1b and [Co2{µ-PPh2CHCPhC(O)}(µ-PPh2)(CO)2(PPh2H)2]4d.

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1994, 609-617

The influence of the ring substituent, R, on the substitution of carbonyl groups by phosphine ligands in [Co2{µ-PPh2CHCRC(O)}(µ-PPh2)(CO)4](R = H, Ph or SiMe3)

A. J. M. Caffyn, A. Martín, M. J. Mays, P. R. Raithby and G. A. Solan, J. Chem. Soc., Dalton Trans., 1994, 609 DOI: 10.1039/DT9940000609

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements