Ring Opening versus Phenyl-Phosphorous Bond Clevage in incorporating a Phosphole into Triosmium Clusters

Article abstract of DOI:10.1039/DT9910003381

The five-membered heterocyclic compound 3,4-dimethyl-1-phenylphosphole (PhP<*>CH=CMeCMe=C<*>H) reacts with or to give the simple substitution products 12-x(PhPC4H2Me2)_x> (x = 1 or 2) in which the phospholes are co-ordinated as tertiary phosphines through the phosphorous atoms.Thermolysis of these compounds gives decarboxylation compounds containing modified phosphole ligands.Phosphorous-carbon bonds either to the phenyl group or within the five-membered ring have been cleaved.The X-ray structure of the main product 1 shows that the organic μ3 ligand is a six-electron donor which is co-ordinated differently from the corresponding eight-electron donating ligand derived from 1-phenylphosphole in the cluster .There is evidence for the reversible generation of this alternative form, 3, of the methylated compound 1 by photolysis.A minor product of the thermolysis is the hydrido cluster CH=CMeCMe=C<*>H)(μ3-C6H4)(CO)9> 2 which contains a five-membered phospholyl ring and an o-phenylene (benzyne) ligand which originated from the phenyl group.The X-ray structure shows that the phospholyl ligand bridges two osmium atoms as a phosphido ligand through the phosphorous atom.The major and minor products, 1 and 2, are both derived by C-P bond cleavage, either in the phosphole ring or to the phenyl substituent respectively.

Full text of DOI:10.1039/DT9910003381

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