Iron(III) Bound by Hydrosulfide Anion Ligands: NO-Promoted Stabilization of the [FeIII鈥揝H] Motif
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- 作者：Chih-Chin Tsou ; Wei-Chun Chiu ; Chun-Hung Ke ; Jia-Chun Tsai ; Yun-Ming Wang ; Ming-Hsi Chiang ; Wen-Feng Liaw
- 刊名：Journal of the American Chemical Society
- 出版年：2014
- 出版时间：July 2, 2014
- 年：2014
- 卷：136
- 期：26
- 页码：9424-9433
- 全文大小：463K
- ISSN：1520-5126
文摘
Spontaneous transformation of the thermally stable [HS]鈭?/sup>-bound {Fe(NO)2}9 dinitrosyl iron complex (DNIC) [(HS)2Fe(NO)2]鈭?/sup> (1) into [(NO)2Fe(渭-S)]22鈥?/sup> (Roussin鈥檚 red salt (RRS)) along with release of H2S, probed by NBD-SCN (NBD = nitrobenzofurazan), was observed when DNIC 1 was dissolved in water at ambient temperature. The reversible transformation of RRS into DNIC 1 (RRS 鈫?DNIC 1) in the presence of H2S was demonstrated. In contrast, the thermally unstable hydrosulfide-containing mononitrosyl iron complex (MNIC) [(HS)3FeIII(NO)]鈭?/sup> (3) and [FeIII(SH)4]鈭?/sup> (5) in THF/DMF spontaneously dimerized into the first structurally characterized FeIII鈥揾ydrosulfide complexes [(NO)(SH)Fe(渭-S)]22鈥?/sup> (4) with two {Fe(NO)}7 motifs antiferromagnetically coupled and [(SH)2Fe(渭-S)]22鈥?/sup> (6) resulting from two FeIII (S = 5/2) centers antiferromagnetically coupled to yield an S = 0 ground state with thermal occupancy of higher spin states, respectively. That is, the greater the number of NO ligands bound to [2Fe2S], the larger the antiferromagnetic coupling constant. On the basis of DFT computation and the experimental (and calculated) reduction potential (E1/2) of complexes 1, 3, and 5, the NO-coordinate ligand(s) of complexes 1 and 3 serves as the stronger electron-donating ligand, compared to thiolate, to reduce the effective nuclear charge (Zeff) of the iron center and prevent DNIC 1 from dimerization in an organic solvent (MeCN).
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