Selective syntheses of FeTe and FeTe sub 2 from organometallic precursors. The synthesis and pyrolysis of [Cp(Et sub 3 P) (CO)Fe] sub 2 (Te) sub n.

We have devised selective syntheses of the solid state compounds FeTe and FeTe sub 2 using organometallic reagents. Bis(dicarbonylcyclopentad ienyliron) reacts with either one and two equivalent(s) of triethylphosphine telluride in the presence of excess phosphine to give (Cp(Et sub 3 P)(CO)Fe sub 2 Te, 1, and (Cp(Et sub 3 P)(CO)FeTe sub 2), 2, respectively. Each compound is stable, crystalline and easily purified. Each is a mixture of diastereomers as shown by sup 1 H, sup (31) P and sup (125) Te NMR spectroscopy. That 1 is an intermediate in the synthesis of 2 is shown by independent reaction of 1 with Et sub 3 PTe to yield 2. That this reaction is reversible is shown by removal of Te from 2 with Et sub 3 P to give 1. Low temperature pyrolysis of 1 gives FeTe and of 2 gives FeTe sub 2, and each of these is specific with respect to solid state product. Along with CO and Et sub 3 P, ferrocene is produced quantitatively in these pyrolyses.