Alkyne-phosphinoalkyne coupling reactions on mixed-metal tungsten-cobalt centres; P-C(alkyne) bond cleavage versus P-C(alkyne) bond preservation

J. E. Davies, M. J. Mays, P. R. Raithby, K. Sarveswaran, G. A. Solan

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)

Abstract

Reactions of the alkyne-bridged tungsten-cobalt complexes [(η5-C5H5)(OC)2W(μ- R1CCR2)Co(CO)3](R1 = R2 = CO2Me 1a; R1 = H, R2 = But 1b) with Ph2PC≡CPh in refluxing toluene result in two different reaction pathways. On reaction with 1a three products are isolated namely, [(η5-C5H5)(OC)2W{μ- C2(CO2Me)2}Co(CO)3- (PPh2C≡CPh)] 2, the result of substitution of a cobalt carbonyl ligand by a phosphorus-bound molecule of Ph2PC≡CPh, [(η5-C5H5)(OC)2W{μ- PhCCC(CO2Me)=C(CO2Me)PPh2} Co(CO)2] 3 and [(η5-C5H5)(OC)W- {μ-C(CO2Me)=C(C=CPh)C(OMe)O}(μ-PPh2) Co(CO)2] 4, in which phosphorus-carbon(alkyne) bond cleavage of the phosphinoalkyne has ocurred along with phosphorus-carbon bond formation (3) and/or carbon-carbon bond formation (3 and 4). In contrast, reaction of 1b (with Ph2PC≡CPh affords two products, [(η5-C5H5)(OC)W-{μ-CBut CHCPhC(PPh2)}Co(CO)2] 5 and [(η5-C5H5)(OC)2W{μ- CButCHC(PPh2)CPh}Co(CO)2] 6, in which the bridging alkyne has coupled with an intact molecule of the phosphinoalkyne Ph2PCα≡CβPh at either its β- or α-carbon atoms, respectively. However, on reaction of 1b with the tert-butyl-substituted phosphinoalkyne, Ph2PC≡CBut, regiospecific coupling and oxidation of the phosphino moiety occur to give [(η5-C5H5)(OC)W-{μ-CBut= CHCBut=C(PPh2O)}Co(CO)2] 8, as the sole product. The reactivity of 6 towards diiron nonacarbonyl has been explored and found to afford the trimetallic complex [(η5-C5H5)(OC)2W{μ- CButCHC(PPh2Fe(CO)4)-CPh}Co(CO)2] 7 in good yield. Single crystal X-ray diffraction studies have been performed on 4, 6, 7 and 8 and possible reaction pathways for the formation of the new complexes are proposed and discussed.

Original languageEnglish
Pages (from-to)1269-1277
Number of pages9
JournalJournal of the Chemical Society, Dalton Transactions
Issue number8
DOIs
Publication statusPublished - 2001

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint Dive into the research topics of 'Alkyne-phosphinoalkyne coupling reactions on mixed-metal tungsten-cobalt centres; P-C(alkyne) bond cleavage versus P-C(alkyne) bond preservation'. Together they form a unique fingerprint.

Cite this