COORDINATIVELY UNSATURATED IRON CHALCOGENOLATE COMPLEXES WITH TRIGONAL PLANAR LIGAND SPHERES - SYNTHESIS, PROPERTIES, AND REACTIONS WITH NITROGEN AND OXYGEN DONOR MOLECULES

The new bulky organo-selenium compound 2,4,6-triphenylbenzeneselenole (1A) was synthesized by a multistep-reaction from 1,3,5-triphenylbenze ne. 1A was converted by oxidation into the air-stable bis(2,4,6-triphe nylphenyl)diselenide (1B), which was characterized by X-ray diffractio n. The stepwise reaction of [Fe-2{N(SiMe3)(2)}(4)] with 1A leads to th e complexes [Fe-2(SeC6H2-2,4,6-Ph-3)(2){N(SiMe3)(2)}(2)] (2) and [Fe2( SeC6H2-2,4,6-Ph3)4] (3), controlled by their molar ratios. The convers ion of 2 to 3 is also described. In addition, the coordinatively unsat urated thiolate complexes [Fe-2{SC6H3-2,6-(SiMe3)(2)}(2){N(SiMe3)(2)}( 2)] (4) and [Fe-2{SC6H3- 2,6-(SiMe3)(2)}(4)] (5) were synthesized by s tepwise reaction of [Fe-2{N(SiMe3)(2)}(4)] with 2,6-bis(trimethylsilyl )benzenethiole. It is also possible to convert the heteroleptic compou nd 4 into the homoleptic thiolate complex 5. During our investigations of the reactivity of 5 towards small electroneutral molecules, the co mpounds [Fez(SC6H3-2,6-(SiMe3)2)4. (MeCN)(2)] (6) and [Fe{SC6H3-2,6-(S iMe3)(2)}(2)(OPEt3)] (7) were obtained. 6 is the product of the additi on of two molecules of acetonitrile to 5. The iron atoms of 6 are coor dinated by three sulfur and one nitrogen atom in a distorted tetrahedr al manner. When 5 is treated with triethylphosphine oxide instead of a cetonitrile, the mononuclear complex 7 with the coordination number th ree is formed. The iron atom is surrounded by two sulfur and one oxyge n donor functions.