Übergangsmetall-Komplexe mit Schwefelliganden, V. Synthese, Reaktivität und Struktur von Carbonyl-, Phosphin-und Hydrazin- Eisen(II)-Komplexen mit zwei- und vierzähnigen Schwefelliganden / Transition Metal Complexes with Sulfur Ligands, V. Synthesis, Reactivity and Structure of Carbonyl-, Phosphine-, and Hvdrazin-Iron(II). Complexes with Two-and Fourdentate Sulfur Ligands

Abstract

Reaction of FeCl3 · 4 H2O with dttd2-, the dianion of 2,3,8,9-dibenzo-1.4,7,10-tetru-thiadecane, leads to the solvated [Fe(dttd)], which coordinates CO, PMe3 and N3H4 yielding [Fe(CO)2dttd], [Fe(PMe3)2dttd], [Fe(CO)PMe3(dttd)], [Fe(N2H4)2dttd] and [Fe(N2H4)CO(dttd), respectively. With H2S and [Fe(dttd)] the Fe(III) complex (PPN)2[Fe2(S)2(dttd)2] is obtained. PPh3 cannot be coordinated to [Fe(dttd)], whereas the reaction between [Fe(PPh3)(CO)3I2] and LiSC6H4SCH3yields [Fe(PPh3)CO(CH3SCeH4S)2] besides the major product [Fe(CO)2(CH3SCeH4S)2]. A PPh3 complex can be obtained also with o-benzenedithiolate, C6H4S2 2-: Reacting [Fe(PPh3)(CO)3I3] with Li2S2C6H4 yields the binuclear [Fe(PPh3)(CO)2C6H4S2]2. Oxidation of [Fe(N3H4)CO(dttd)] by various agents leads to [Fo(CO)dttd]2 without evidence of formation of a N2 complex intermediate. Nucleophilic attack of [Fe(CO)2(CH3SC6H4S)2] by lithium organyls as e.g. LiPh leads to the benzoylato complex [Li(THF)3][Fe(CO)(PhCO)(CH3SC6H4S)2]; the structures of the starting complex as well as of the adduct have been elucidated by X-ray structure determination. Nucleophilic attack of the corresponding [Fe(CO)2dttd] by LiPh occurs reversibly at the Fe center; by cleavage of a Fe-S bond [Fe(Ph)(CO)2dttd′]- is formed, where dttd′ is acting as a tridentate ligand. This result shows how the reactions of formally equivalent complexes like [Fe(CO)2(CH3SC6H4S)2] and [Fe(CO)2dttd] depend strongly upon the denticity of the sulfur ligands. The dependence upon the character of the nucleophilic agent is shown by the reaction of [Fe(CO)2dttd] with Li[BEt3H]; in this case again a CO ligand is attacked reversibly yielding the formyl complex [LiBEt3][Fe(HCO)CO(dttd)], the structure of which could be elucidated so far only spectroscopically as well as by elemental analysis. [Fe(Ph)(CO)gdttd′]- forms salts like e.g. (AsPh4)[Fe(Ph)(CO)2dttd]; in solution they slowly loose CO yielding e.g. binuclear (AsPh4)2[Fe(Ph)dttd]3. Attempts to isolate the anion as [Li(TMED)3]+ salt load to the loss of CO as well as of phenyl ligands yielding the paramagnetic [Fe(TMED)dttd], which is also obtained directly from [Fe(dttd)] and TMED. The phenyl complex [Fe(Ph)dttd]2 2- is also formed by reaction of [Fe(dttd)] with LiPh; on reaction with dimethyl-formamide it yields [Fe(DMF)dttd]2. A series of the above described compounds has been investigated by Mößbauer spectroscopy.