Reactivity of diiron nonacarbonyl in tetrahydrofuran. : IV. The synthesis and crystal and molecular structure of 1,3-dithianeirontetracarbonyl, ( cyclo-l,3-C 4H 8S 2)Fe(CO) 4

Abstract

Diiron nonacarbonyl and 1,3-dithiacyclohexane (l,3- dithiane) react at room temperature in THF to yield the new compound (cyclo-l,3-C 4H 8-S 2)Fe(CO) 4, The synthesis and corresponding X-ray structural analysis of the rnononuclear iron species are presented here. The compound (cyclo-l,3-C 4H 8SI 2)Fe(CO) 4 is the first example of a zerovalent transition metal complex of the synthetically important sulfur heterocycle. X.-ray analysis shows a trigonal bipyramidal geometry about the central iron atom. One sulfur atom of the l,3-dithiane ligand occupies an axial site in the substituted trigonal bipyramid and the ring adopts a chair conformation. The Fe-C axial bond length is 0.02 Å shorter than that in Fe(CO) 5 but is longer than those in (pyridine) Fe(CO) 4 and (pyrazine)Fe(CO) 4 by an equal amount. The mean Fe-C equatorial bond distance of 1.764 Å is significantly shorter (0.04 to 0.073 Å) than any of the distances in the three aforementioned compounds. Crystallographic data are: space group Pn2 1a; a = 13.488(3) Å; b = 9.058(2) Å; c = 9.771(2) Å; Z =4; V = 1193.8(4) Å 3. The structure was refined anisotropically to R 1 = 0.056 and R 2 = 0.075. 857 reflections for which F 0 23σ(F 0 2) were collected.