The effect of substitution of a thioether donor by a phosphine donor in thiacrown complexes of iron

Electrospray mass spectrometry and thermogravimetric analysis reveals that bis(1-phenyl-1-phospha-4,7-dithiacyclononane)iron(II) is more susceptible to ethene loss than bis(1,4,7-trithiacyclononane)iron(II). This is in accord with X-ray crystallographic studies, which show that the C–S bonds are longer in the former complex suggesting an increased population of the C–S σ* π-acceptor orbitals.