REACTION OF FE-3(CO)(12) WITH TELLURIUM-NITROGEN HETEROCYCLES - A SOURCE OF NOVEL ORGANOIRON COMPOUNDS

Heterocyclic tellurium compounds containing both tellurium and nitroge n in the heterocyclic ring are shown to be useful precursors far the s ynthesis of novel organoiron compounds. Thus, reaction of Fe-3(CO)(12) with benzoisotellurazole yields (C6H4CHNTe)(2)Fe-3(CO)(7), 5. The str ucture of 5 was established by X-ray crystallography; it is based an a nonlinear chain of three iron atoms, Fe1-Fe2-Fe3 133.4(1)degrees, wit h Fe1-Fe2, 2.472(2) Angstrom doubly-bridged by nitrogen and Fe2-Fe3, 2 .683(2) Angstrom, doubly-bridged by tellurium. The reaction of Fe-3(CO )(12) with 2-methylbenzotellurazole results in two new crystalline pro ducts C18H7NFe3O10, 6, and C14H7NFe2O6, 7, involving detelluration of the heterocycle. X-ray crystallography shows that 6 contains a triangu lar arrangement of iron atoms, two edges of which are bridged respecti vely by the nitrogen and carbon atoms of the NC formal double bond and the latter edge is also bridged by a carbonyl in an almost symmetrica l manner. The third edge of the iron triangle is not directly bridged, and at 2.647(1) Angstrom, it is the longest edge of the triangle. In 7, one iron atom forms part of a benzoferrazole system, and the second iron is pi-bonded to the C-C-N=C residue of the ferrazole with a rela tively short Fe-Fe contact of 2.498(1) Angstrom.