Reaction of Fe-3(CO)(12) with tellurium-nitrogen heterocycles: A source of novel organoiron compounds.

Heterocyclic tellurium compounds containing both tellurium and nitrogen in the heterocyclic ring are shown to be useful precursors far the synthesis of novel organoiron compounds. Thus, reaction of Fe-3(CO)(12) with benzoisotellurazole yields (C6H4CHNTe)(2)Fe-3(CO)(7), 5. The structure 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, with 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 products C18H7NFe3O10, 6, and C14H7NFe2O6, 7, involving detelluration of the heterocycle. X-ray crystallography shows that 6 contains a triangular arrangement of iron atoms, two edges of which are bridged respectively 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 symmetrical 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 relatively short Fe-Fe contact of 2.498(1) Angstrom.