Reactions of nucleophiles with bis(µ-thiosulphato-S)-bis(dinitrosylferrate)(2–), [Fe2(S2O3)2(NO)4]2–, and of electrophiles with heptanitrosyltri-µ3-thio-tetraferrate(1–), [Fe4S3(NO)7]–: new routes to bis(µ-organothiolato)-bis(dinitrosyliron) complexes [Fe2(SR)2(NO)4] and the crystal and molecular structure of trimethylsulphonium heptanitrosyltri-µ3-thio-tetraferrate(1–), SMe3[Fe4S3(NO)7]

Abstract

Sodium bis(µ-thiosulphato-S)-bis(dinitrosylferrate)(2–), Na₂[Fe₂(S₂O₃)₂(NO)₄], reacts rapidly in aqueous solution with a range of thiols RSH [R = alkyl (C₁–C₅), CH₂CO₂Me, CH₂CH₂OH, or 2-pyrimidinyl] in the presence of sodium thiosulphate to give the neutral complexes [Fe₂(SR)₂(NO)₄] generally in yields of 50–65%. With sodium sulphide a mixture of the Roussin red and black salts, Na₂[Fe₂S₂(NO)₄] and Na[Fe₄S₃(NO)₇] respectively, is formed, readily separable by solvent extraction with diethyl ether. The latter salt reacts with arenediazonium tetrafluoroborates RN₂⁺BF₄^– to yield the corresponding bis(µ-arenethiolato)-bis(dinitrosyliron) complexes [Fe₂(SR)₂(NO)₄]. Alkylation of Na[Fe₄S₃(NO)₇] with R₃O⁺BF₄^–(R = Me or Et) yields [Fe₂(SR)₂(NO)₄] but with Me₃S⁺BF₄^– or Me₃SO⁺ BF₄^– metathesis, rather than alkylation, occurs to provide Me₃S⁺(or Me₃SO⁺)[Fe₄S₃(NO)₇]^–. Crystals of [SMe₃][Fe₄S₃(NO)₇] are triclinic, with space group P, a= 9.655(2), b= 11.707(3), c= 8.968(1)Å, α= 106.11(2), β= 91.78(3), γ= 84.92(2)°, and Z= 2: The compound is a salt with no close contacts between cation and anion. Reduction of the anion in [SMe₃][Fe₄S₃(NO)₇] to the more nucleophilic dianion causes alkylation and formation of [Fe₂(SMe)₂(NO)₄].