Übergangsmetall-komplexe miet schwefelliganden: XXI. Thiolato-amin-komplexe von eisen(II) und molybdän(II) mit [M(SNNS)]-einheiten und CO-, PMe 3-, NO- sowie N 2H 4-koliganden (SNNS = (SC 6H 4N(R)C 2H 4N(R)C 6H 4S) 2−, R = H, CH 3)

Abstract

Iron(II) and molybdenum(II) complexes with the tetradentate thiolate amine ligands bmae 2− and bmab 2− respectively have been synthesized in order to compare their properties with the isoelectronic complexes containing the tetradentate thiolate-thioether ligand dttd 2− [bmae 2− = 1,2-bis(2-mercaptoanilino)ethane(−2); bmab 2− = 2,3-bis(2-mercaptoanilino)butane(−2); dttd 2− = 2,3;8,9-dibenzo-1,4,7,10-tetrathiadecane(−2)]. The reaction of FeCl 2 · 4H 2O with bmae-Na 2 and CO in MeOH at ambient temperatures yields [Fe(CO) 2bmae]; by analogous procedures [Fe(PMe 3) 2bmae], [Fe(CO) 2bmab] and [Fe(PMe 3) 2bmab] are obtained. Heating as well as UV irradiation of [Fe(CO) 2bmae] in solution lead to reversible CO elimination and the formation of [Fe(bmae)] respectively; in the presence of PMe 3, the complex [Fe(CO)(PMe 3)bmae] forms. The same reactions are observed with the [Fe(bmab)] complexes. The coordinatively unsaturated [Fe(bmae)] is accessible by several methods, for example by the facile NaBH 4 reduction of the Schiff base complex [Fe(gma)], [gma 2− = glyoxal-bis(2-mercaptoanile)(−2)]; from [Fe(bmae)] the free ligand bmae-H 2 is obtained by hydrolysis with NaOH/DMF or HCl/THF. Although [Fe(bmae)] is only poorly soluble in all common solvents, suspensions of it react rapidly with CO and PMe 3 yielding the corresponding complexes. With N 2H 4 and NO respectively [Fe(N 2H 4)bmae] and the paramagnetic [Fe(NO)bmae] (μ eff 1.71 B.M.) are obtained. In contrast to the reduction labile [Fe(dttd)] fragment the [Fe(bmae)] unit is stable even against strongly reducing agents e.g. Na in liquid ammonia. Until now only [Mo(NO) 2bmae] was obtained as an example of a low oxidation state [Mo(bmae)] complex, from the reaction of [Mo(NO) 2Cl 2] with bmae-Na 2. All compounds were characterized spectroscopically as well as by elemental analysis.