Alkynylphosphanes as supports for mixed-metal Co4M (M = Ru, Os) fluoride complexes: Syntheses, structures and thermolysis studies |
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| Authors: | Duncan AJ Harding |
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| Institution: | Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK |
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| Abstract: | Treatment of the tetrameric group eight fluoride complexes MF(μ-F)(CO)3]4 M = Ru (1a), Os (1b)] with the alkynylphosphane, Ph2PC CPh, results in fluoride-bridge cleavage and the formation of the air-sensitive monomeric octahedral complexes MF2(CO)2(PPh2CCPh)2] M = Ru (2a), Os (2b)] in high yield. The molecular structure of 2b reveals a cis, cis, trans configuration for each pair of ligands, respectively. The free alkyne moieties in 2 can be readily complexed to hexacarbonyldicobalt fragments by treatment with dicobalt octacarbonyl to afford MF2(CO)2(μ-η1:η2-PPh2CCPh)2{Co2(CO)6}2] M = Ru (3a), Os (3b)]. Evidence for an intramolecular non-bonded contact between a bound fluoride and a cobalt carbonyl carbon atom is seen in the molecular structure of 3a. Thermolysis of 3a at 50 °C results in fluoride dissociation to give RuF(CO)2(μ-η1:η2-PPh2CCPh)2{Co2(CO)6}2]+ (4), while no reaction occurred with the osmium analogue. Prolonged thermolysis at 120 °C in a sealed vessel of both 3a and 3b gave only insoluble decomposition products. |
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| Keywords: | Alkynylphosphanes Hexacarbonyldicobalt Ruthenium Osmium Fluoride Thermolysis |
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