Structural, spectroscopic, and computational study of an octahedral, non-heme {Fe-NO}6-8 series:: [Fe(NO)(cyclam-ac)]2+/+/O
Structural, spectroscopic, and computational study of an octahedral, non-heme {Fe-NO}6-8 series:: [Fe(NO)(cyclam-ac)]2+/+/O
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DOI：
10.1021/ja030645
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发表时间：
2004-04-28
影响因子：
15
通讯作者：
Wieghardt, K
中科院分区：
文献类型：
--
作者：
Serres, RG;Grapperhaus, CA;Wieghardt, K
低自旋 [(FeCl)-Cl-II(cyclam-ac)] 与 CH3CN 中的 NO 反应生成八面体非血红素 (亚硝酰基) 铁络合物 (Fe(NO)(cyclam-ac)](PF6) (2), S = (1)/(2)，该络合物可被 (三(4-溴苯基)铵基)六氯锑酸盐单电子氧化成络合物[Fe(NO)(cyclam-ac)](PF6)(2) (1')，S = 0，或络合物[Fe(NO)(cyclam-ac)]Cl(ClO4)(H2O)-H-(1)；(cyclam-ac)(-)代表1,4,8,11-四氮杂环十四烷-1-乙酸的五齿单阴离子。同样，在CH3CN溶液2中可以电化学反应。或通过单电子化学还原成中性络合物[Fe(NO)(cyclam-ac)](0) (3)，S = 0。1-3分别代表{FeNO}(6-8)系列的成员。这三种物质的电子结构已通过EPR、UV-vis、Mossbauer和IR光谱法阐明。此外，1和2的晶体结构已通过X射线晶体学确定。考虑到 3 实际上是质子化 HNO 或 NOH 物质的可能性，对所有三种物质进行了详细的密度泛函计算。对于所有配合物的结构、能量、IR 参数以及 EPR 参数（g 值和超精细耦合），均使用最先进的 DFT 方法进行了计算，并与实验进行了比较，结果明确表明 3 确实是难以捉摸的 {FeNO}(8) 物质。已开发出低自旋非血红素亚硝酰基系列 {FeNO}(6)、{FeNO}(7) 和 {FeNO}(8) 中键合的详细图片，这允许将 1 描述为包含 N 配位 NO 的低自旋亚铁络合物，而 2 是具有 NO 配体的低自旋亚铁络合物，3 是具有配位 NO- 的低自旋亚铁络合物。通过描述，所有光谱和几何可观察到的现象都找到了令人满意的解释。
The reaction of low-spin [(FeCl)-Cl-II(cyclam-ac)] with NO in CH3CN yields the octahedral, non-heme (nitrosyl)iron complex (Fe(NO)(cyclam-ac)](PF6) (2), S = (1)/(2) which can be one-electron oxidized with (tris(4-bromophenyl)ammoniumyl)hexachloroantimonate to the complex [Fe(NO)(cyclam-ac)](PF6)(2) (1'), S = 0, or complex [Fe(NO)(cyclam-ac)]Cl(ClO4)(H2O)-H-. (1); (cyclam-ac)(-) represents the pentadentate monoanion of 1,4,8,11-tetraazacyclotetradecane-1-acetic acid. Similarly, in CH3CN solution 2 can be electrochemically or chemically reduced by one-electron to the neutral complex [Fe(NO)(cyclam-ac)](0) (3), S = 0. 1-3 represent members of the {FeNO}(6-8) series, respectively. The electronic structure of these three species have been spectroscopically elucidated by EPR, UV-vis, Mossbauer, and IR spectroscopy. The crystal structures of 1 and 2 have been determined by X-ray crystallography. In addition, detailed density functional calculations have been performed for all three species taking into account the possibility that 3 is actually a protonated HNO or NOH species. For all complexes structures, energetics, IR parameters, and Mossbauer parameters as well as EPR parameters (g-values and hyperfine couplings) have been calculated using state-of-the art DFT methods which are compared to experiment. The results establish unequivocally that 3 is indeed the elusive {FeNO}(8) species. Furthermore a detailed picture of the bonding in the low-spin non-heme iron nitrosyl series {FeNO}(6), {FeNO}(7), and {FeNO}(8) has been developed. This allows a description of 1 as a low-spin ferrous complex containing an N-coordinated NOdivided by, whereas 2 is a low-spin ferrous species with a NO. ligand and 3 is a low-spin ferrous complex with a coordinated NO-. On the basis of this description, all spectroscopic and geometric observables find a satisfactory interpretation.