Electron paramagnetic resonance study of the reactions of roussin esters Fe 2(SR) 2(NO) 4 with a range of nucleophilic anions

Abstract

The Roussin methyl ester Fe 2(SMe 2)(NO) 4 reacted with bromide or iodide to yield the known paramagnetic mononuclear complexes [Fe(NO) 2X 2] − (X = Br or I). With thiocyanate the reactions of Fe 2(SR) 2(NO) 4 (R = Me or Bu t ) proceeded via the S-bonded intermediates [Fe(NO) 2(SR)(SCN)] − to the N-bonded product [Fe(NO) 2(NCS) 2] −: azide and cyanate gave a similar product [Fe(NO) 2(NXY) 2] −, with no detectable intermediates. Nitrite yielded the known [Fe(NO) 2(NO 2) 2] − with a range of Fe 2(SR) 2(NO) 4 (R = Me, Et, Pr i or Ph) in a range of solvents (CH 2Cl 2, acetone or DMF): Fe 4S 4(NO) 4 with nitrite in CH 2Cl 2 gave a mixture of [Fe(NO) 2(NO 2) 2] − and [Fe(NO) 2(SH) 2] −. With Fe 2(SMe) 2(NO) 4, sulphate and chromate yielded complexes of the type, [Fe(NO) 2(SMe)(OR)] 2− (R = CrO 3 or SO 3). The bis-chelating ligand piperazinobis(dithiocarbamate) with Fe 2(SMe) 2(NO) 4 gave both a five-coordinate square pyramidal mononitrosyl and a tetrahedral dinitrosyl complex, based on Fe(NO)S 4 and Fe(NO) 2S 2 chromophores, respectively. The two complexes [Fe(NO) 2(S 2MoS 2)] − and [Fe(NO)(S 2MoS 2) 2] 2− which are formed by reaction of tetrathiomolybdate with a range of esters Fe 2(SR) 2(NO) 4 have been synthesized also by redox reactions from the known complexes [Fe(NO) 2(S 2MoS 2)] 2− and [Fe(S 2MoS 2) 2] 3−, respectively.