Cumulated double bond systems as ligands : XI. Di- an tri-nuclear iron complexes resulting from the reaction of [Fe 2(CO) 9] with RNSNR (R = t-C 4H 9, 4-MeC 6H 4); crystal and molecular structure of (Fe 2(CO) 6{RNC(O)S}] [Fe 3(CO) 9(RNS)S] and [Fe 3(CO) 9(RN)S

Abstract

Reaction of RNSNR (R = t-C 4H 9, 4-MeC 6H 4) with (Fe 2(CO) 9[leads to the rupture of one or two NS double bonds as evidenced by the formation of a number of complexes containing RNS, RN and S fragments. In the case of R = t-C 4H 9 and 4-MeC 6H 4 the RNS fragment behaves as a four-electron donor ligand, with the NS bond still double, and as a six-electron donor ligand with the NS bond single, bridging two iron atoms in [Fe 2(CO) 7(RNS)] and [Fe 2(CO) 6(RNS)], respectively. Insertion of CO into the NS bond of [Fe 2(CO) 6(RNS)] yields [Fe 2(CO) 6{RNC(O)S}]; a crystal structure determination has been carried out for the product with R = 4-MeC 6H 4. Heating of the solid complex affords azotoluene, which is also isolated from the reaction mixtures. In the case of R = t-C 4H 9[Fe 2(CO) 6S 2], [Fe 3(CO) 9S 2] and [Fe 3(CO) 9(RNS)S] are also formed. A crystal structure determination of the last compound reveals a prismane type structure, in which both a six-electron donor RNS fragment and a four-electron donor S atom are linked to the three iron atoms. For R = 4-MeC 4H 4 a different trinuclear iron complex [Fe 3(CO) 9(RN)S] was isolated, and the structure was established by a crystal structure determination; a nitrene fragment (RN) as well as a S atom are both triply bridging to a non linear array of three iron atoms of the Fe 3(CO) 9 skeleton.