摘要
Reaction of Fe(CO) 2 (NO) 2 and sparteine/ tetramethylethylenediamine (TMEDA) in tetrahydrofuran afforded the electron paramagnetic resonance (EPR)-silent, neutral {Fe(NO) 2 } 10 dinitrosyliron complexes (DNICs) [(sparteine)Fe(NO) 2 ] (1) and [(TMEDA)Fe(NO) 2 ] (2), respectively. The stable and isolable anionic {Fe(NO) 2 } 9 DNIC [(S(CH 2 ) 3 S)Fe(NO) 2 ] - (4), with a bidentate alkylthiolate coordinated to a {Fe(NO) 2 } motif, was prepared by the reaction of [S(CH 2 ) 3 S] 2- and the cationic {Fe(NO) 2 } 9 [(sparteine)Fe(NO) 2 ] + (3) obtained from the reaction of complex 1 and [NO][BF 4 ] in CH 3 CN. Transformation from the neutral complex 1 to the anionic complex 4 was verified via the cationic complex 3. Here complex 3 acts as an {Fe(NO) 2 }-donor reagent in the presence of thiolates. The EPR spectra of complexes 3 and 4 exhibit an isotropic signal with g = 2.032 and 2.031 at 298 K, respectively, the characteristic g value of {Fe(NO) 2 } 9 DNICs. On the basis of N-O/Fe-N(O) bond lengths of the single-crystal X-ray structures of the {Fe-(NO) 2 } 9 /{Fe(NO) 2 } 10 DNICs, the oxidation level of the {Fe(NO) 2 } core of DNICs can be unambiguously assigned. The mean N-O distances falling in the range of 1.214(6)-1.189(4) Å and the Fe-N(O) bond distances in the range of 1.650(7)-1.638(3) Å are assigned as the neutral {Fe(NO) 2 } 10 DNICs. In contrast, the mean N-O bond distances ranging from 1.178(3) to 1.160(6) Å and the mean Fe-N(O) bond distances ranging from 1.695(3) to 1.661(4) Å are assigned as the anionic/neutral/cationic {Fe(NO) 2 } 9 DNICs. In addition, an EPR spectrum in combination with the IR ν NO (the relative position of the ν NO stretching frequencies and their difference Δν NO ) spectrum may serve as an efficient tool for discrimination of the existence of the anionic/cationic/neutral {Fe-(NO) 2 } 9 DNICs and the neutral {Fe(NO) 2 } 10 DNICs. © 2006 American Chemical Society.