The reactions of tricobalt alkylidyne complexes

Gillian A. Acum, Martin J. Mays, Paul R. Raithby, Gregory A. Solan

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Abstract

The alkylidyne-capped complexes [Co33-CR)(CO)9] (R = Me 1a, CO2Me 1b) react with PPh2CH=CH2 in heptane at 308 K to give the phosphine-substituted complexes [Co33-CR)(CO)8(PPh2CH=CH2)] (R = Me 2a, CO2Me 2b), [Co33-CR)-(CO)7(PPh2CH=CH2)2] (R = Me 3a, CO2Me 3b) and, in the case of R = CO2Me, the tris-substituted complex [Co33-CCO2Me)(CO)6(PPh2CH=CH2)3] 4. Heating of complexes 2a and 2b at 343 K results in loss of a CO group and coordination of the vinyl moiety of the PPh2CH=CH2 ligand to afford [Co33-CR)(μ-PPh2CH=CH2)(CO)7] (R = Me 5a, CO2Me 5b). In contrast, reaction of [Co33-CR)(CO)9] (R = Me 1a, CO2Me 1b) with cis-Ph2PCH=CHPPh2 (dppee) gives [Co33-CR)(μ-Ph2PCH=CHPPh2)(CO)7] (R = Me 6a, CO2Me 6b) in which the dppee ligand bridges two adjacent cobalt atoms via both phosphino moieties. Nuclear magnetic resonance studies on 5a and 5b indicate that two isomeric structures in a ratio of 7:3 are present in solution at 293 K. Conversion of [Co33-CR)(μ-PPh2CH=CH2)(CO)7] 5a and 5b back to [Co33-CR)(CO)8(PPh2CH=CH2)] 2a and 2b can be achieved by purging with CO at 293 K while further purging at 343 K results in conversion to [Co33-CR)(CO)9] 1a and 1b. The structure of [Co33-CCO2Me)(μ-Ph2PCH=CHPPh2)(CO)7] 6b was determined by single-crystal X-ray diffraction. All the complexes have been characterized spectroscopically and by elemental analysis.

Original languageEnglish
Pages (from-to)137-145
Number of pages9
JournalJournal of Organometallic Chemistry
Volume508
Issue number1-2
DOIs
Publication statusPublished - 8 Feb 1996

Keywords

  • Alkylidyne
  • Carbonyl
  • Crystal structure
  • Tricobalt
  • Vinyl
  • Vinylphosphine

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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