TY - JOUR
T1 - Formation of paramagnetic mononuclear iron nitrosyl complexes from diamagnetic di- and tetranuclear iron-sulphur nitrosyls
T2 - characterisation by EPR spectroscopy and study of thiolate and nitrosyl ligand exchange reactions
AU - Butler, Anthony R.
AU - Glidewell, Christopher
AU - Hyde, Andrew R.
AU - Walton, John C.
PY - 1985/1/1
Y1 - 1985/1/1
N2 - The diamagnetic Roussin esters Fe2(SR)2(NO)4 readily underwent exchange with thiols R′SH to yield Fe2(SR′)2(NO)4: the exchange was faster in polar, coordinating solvents where paramagnetic, mononuclear complexes of types [Fe(NO)2(solvent)2]+ and Fe(NO) 2(SR)(solvent) were formed. With the corresponding thiolate anions RS-, the esters Fe2(SR)2(NO)4 formed the mononuclear complexes [Fe(SR)2(NO)2]-, which were fully characterised by EPR spectroscopy for R = H, Me, Et, i-Pr, t-Bu and PhCH2: assignments of hyperfine couplings were confirmed by use of 15N. With Fe2(SR)2(NO)4 and a different set of thiolate anion, R′S -, in excess, thiol exchange occurred to give [Fe(SR′)2(NO)2]-. A mechanism for formation of Fe2(SR′)2(NO)4 from Fe2(SR)2(NO)4 has been proposed. The paramagnetic mononuclear complexes [Fe(SR)2(NO)2] were also readily formed from the diamagnetic clusters [Fe4S3(NO)7]- and Fe4S4(NO)4, together with [Fe(SR)3(NO)]-, and additionally from [Fe(CO)3NO]-. [Fe(SMe)2(NO)2]-. was found to be a precursor of isolable Fe2(SMe)2(NO)4, and [Fe(SH)2 (NO)2]- to be the common precursor of both Roussin′s red anion [Fe2S2(NO)4]- and Roussin's black anion [Fe4S3 (NO)7]- interconvertible by appropriate adjustment of pH. The nitrosyl groups in these complexes were freely labile, and mononitrosyliron and dinitrosyliron fragments were readily interconvertible: FE(NO) fragments were favoured by the dimethyldithiocarbamate ligand (Me2NCS 2) and Fe(NO)2 fragments by thiolate ligands, RS-, regardless of the origin of the Fe(NO)x(x = 1,2) fragment: both mono- and dinitrosyliron complexes persisted with [(i-PrO)2S2]- as ligand. Isotopic labelling showed the occurrence of rapid exchange of nitrogen between nitrosyl ligands and added nitrite in Fe(NO)(S2CNMe2)2 and [Fe(SR)2(NO)2]-.
AB - The diamagnetic Roussin esters Fe2(SR)2(NO)4 readily underwent exchange with thiols R′SH to yield Fe2(SR′)2(NO)4: the exchange was faster in polar, coordinating solvents where paramagnetic, mononuclear complexes of types [Fe(NO)2(solvent)2]+ and Fe(NO) 2(SR)(solvent) were formed. With the corresponding thiolate anions RS-, the esters Fe2(SR)2(NO)4 formed the mononuclear complexes [Fe(SR)2(NO)2]-, which were fully characterised by EPR spectroscopy for R = H, Me, Et, i-Pr, t-Bu and PhCH2: assignments of hyperfine couplings were confirmed by use of 15N. With Fe2(SR)2(NO)4 and a different set of thiolate anion, R′S -, in excess, thiol exchange occurred to give [Fe(SR′)2(NO)2]-. A mechanism for formation of Fe2(SR′)2(NO)4 from Fe2(SR)2(NO)4 has been proposed. The paramagnetic mononuclear complexes [Fe(SR)2(NO)2] were also readily formed from the diamagnetic clusters [Fe4S3(NO)7]- and Fe4S4(NO)4, together with [Fe(SR)3(NO)]-, and additionally from [Fe(CO)3NO]-. [Fe(SMe)2(NO)2]-. was found to be a precursor of isolable Fe2(SMe)2(NO)4, and [Fe(SH)2 (NO)2]- to be the common precursor of both Roussin′s red anion [Fe2S2(NO)4]- and Roussin's black anion [Fe4S3 (NO)7]- interconvertible by appropriate adjustment of pH. The nitrosyl groups in these complexes were freely labile, and mononitrosyliron and dinitrosyliron fragments were readily interconvertible: FE(NO) fragments were favoured by the dimethyldithiocarbamate ligand (Me2NCS 2) and Fe(NO)2 fragments by thiolate ligands, RS-, regardless of the origin of the Fe(NO)x(x = 1,2) fragment: both mono- and dinitrosyliron complexes persisted with [(i-PrO)2S2]- as ligand. Isotopic labelling showed the occurrence of rapid exchange of nitrogen between nitrosyl ligands and added nitrite in Fe(NO)(S2CNMe2)2 and [Fe(SR)2(NO)2]-.
UR - http://www.scopus.com/inward/record.url?scp=0001453357&partnerID=8YFLogxK
U2 - 10.1016/S0277-5387(00)87029-1
DO - 10.1016/S0277-5387(00)87029-1
M3 - Article
AN - SCOPUS:0001453357
SN - 0277-5387
VL - 4
SP - 797
EP - 809
JO - Polyhedron
JF - Polyhedron
IS - 5
ER -