Synthesis and Reactivity of a Paramagnetic Iron Phosphaethynolate Complex

The
bulky iron(II) tris(carbene)borate complex PhB(AdIm)3FeCl
reacts with equimolar NaPCO to afford PhB(AdIm)3Fe(PCO)
as a rare example of a paramagnetic phosphaethynolate complex. Although
thermally and photochemically unstable, there is no evidence that
either of these conditions leads to the formation of an iron phosphido
complex. However, in the presence of excess NaPCO, thermolysis of
PhB(AdIm)3Fe(PCO) yields a dinuclear iron complex in which
a new side-bound diphosphene ligand is stabilized by N-heterocyclic carbene and borate groups. These results hint at the
utility of paramagnetic complexes for enlarging the scope of phosphaethynolate
chemistry.