SYNTHESIS, CHARACTERIZATION, AND REACTIVITY OF NEW CLUSTERS THAT CONTAIN THE [MFE3S4]0 CORE, M = MO, W - A WEAKLY PERTURBED [MFE3S4]0 UNIT STRUCTURALLY AND ELECTRONICALLY ANALOGOUS TO THE REDUCED 3-IRON CENTERS IN FERREDOXINS
SYNTHESIS, CHARACTERIZATION, AND REACTIVITY OF NEW CLUSTERS THAT CONTAIN THE [MFE3S4]0 CORE, M = MO, W - A WEAKLY PERTURBED [MFE3S4]0 UNIT STRUCTURALLY AND ELECTRONICALLY ANALOGOUS TO THE REDUCED 3-IRON CENTERS IN FERREDOXINS
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DOI：
10.1021/ja00033a023
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发表时间：
1992-03-25
影响因子：
15
通讯作者：
SIMOPOULOS, A
中科院分区：
文献类型：
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作者：
COUCOUVANIS, D;ALAHMAD, SA;SIMOPOULOS, A
详细描述了新的“立方烷”型簇合物(Et4N)3[Fe3S4L3M(CO)3]，M=Mo，L=Ets-，BZS-，p-OMePhS-，PhO-，Cl-；M=W，L=p-OMePhS-的合成、表征和反应。通过[Fe_3S_4L_4]3-线性三聚体与M(CO)_3(MeCN)_3，M=Mo，W反应，以较好的产率得到(Et_4N)+盐。(Et_4N)_3[Fe_3S_4(Ets)_3Mo(CO)_3]为Pbcm空间群，晶胞尺寸为a=16.557埃，b=18.915埃，c=17.110埃；α=β=γ=90度，z=4。用四圈计算机控制的衍射仪采集了强度数据。对1290个数据的198个参数进行精化，(F(O)2>；3-sigma(F(O)1))，收敛到最终的R(W)值0.065。立方[Fe_3S_4Mo]_0核的结构表明，Mo(CO)_3碎片与Fe_3S_4配位体弱相互作用，Mo-S键长为2.63(1)埃，Fe-Mo距离为3.274(5)埃。在CH2Cl2中，对[Fe3S4L3M(CO)3]3-络合物的电化学测量表明，有两个可逆的还原波被分配给2-/3-和3-/4-氧化还原对。配合物的H-1核磁共振谱表现出各向同性位移的共振峰。络合物的Moessbauer谱表现出宽广的双峰。(Et4N)_3[Fe_3S_4(Ets)_3M(CO)_3]和(Et_4N)_3[Fe_3S_4(BZS)_3M(CO)_3]在4.2K下的零场谱均为结构，可与2：1或1：1：1的两组分或三组分双峰相匹配。在4.0T和6.0T的外场下记录的磁扰动谱可以用铁磁耦合(S1，2=9/2)Fe~(2+)/Fe~(3+)对与S=5/2 Fe~(3+)格位反铁磁耦合的模型来解释，得到S=2的基态.通过模拟Moessbauer谱获得的精细和超精细参数与先前报道的长硫弧菌Fd II和乌头酸酶中Fe3S4中心的参数非常相似。(Et4N)_3-[Fe_3S_4L_3Mo(CO)_3]与苯二酚的氧化脱羰反应，当铁的末端配体为Cl-时，生成溶剂化的单方烷(Et4N)_2[Fe_3S_4Cl3Mo(MeCN)(CAT)]；当末端配体为Ets-时，生成双桥双立方烷(Et4N)_4[Fe_3S_4(Ets)_3Mo(CAT)]_2。(Et4N)_3[Fe_3S_4(Ets)_3Mo(CO)_3]与二乙基二硫化物反应，以适中的产率合成了三桥双立方烷簇合物(Et_4N)_3[Fe_6S_8(Ets)_9Mo2]。在溶液中加热时，(Et4N)3[Fe3S4L3Mo(CO)3]簇合物(L=Cl-，p-COMePhO-)转化为相应的柱状加合物八核簇合物(Et4N)4[Fe6S6(L)9{Mo(CO)3}2]。在CH3CN溶液中，[Fe3S4(Ets)3Mo(CO)3]3-团簇中的Mo(CO)3碎片可被FeCl+取代。H-1核磁共振谱表明，在该反应中得到了[Fe4S4(Cl)x(Ets)4-x]2-团簇的统计混合物。
The synthesis, characterization, and reactions of the new "cubane"-type clusters (Et4N)3[Fe3S4L3M(CO)3], M = Mo, L = EtS-, BzS-, p-OMePhS-, PhO-, Cl-; M = W, L = p-OMePhS-, are described in detail. These clusters are obtained in a good yield as (Et4N)+ salts, by the reaction of the [Fe3S4L4]3- linear trimer with M(CO)3(MeCN)3, M = Mo, W. The (Et4N)3[Fe3S4(EtS)3Mo(CO)3].CH3CN cluster crystallizes in the Pbcm space group with cell dimension a = 16.557 angstrom, b = 18.915 angstrom, c = 17.110 angstrom; alpha = beta = gamma = 90-degrees, z = 4. Intensity data were collected using a four-circle computer-controlled diffractometer. Refinement of 198 parameters on 1290 data, (F(o)2 > 3-sigma(F(o)1), converged to a final R(w) value of 0.065. The structure of the cubic [Fe3S4Mo]0 core shows the Mo(CO)3 fragment interacting weakly with the Fe3S4 ligand with a Mo-S bond length of 2.63 (1) angstrom and a Fe-Mo distance of 3.274 (5) angstrom. Electrochemical measurements on the [Fe3S4L3M(CO)3]3-complexes in CH2Cl2 show two reversible reduction waves that are assigned for the 2-/3- and 3-/4- redox couples. The H-1 NMR spectra of the complexes exhibit isotropically shifted resonances. The Moessbauer spectra of the complexes show broad doublets. The zero field spectra of (Et4N)3[Fe3S4(EtS)3M(CO)3] and (Et4N)3[Fe3S4(BZS)3M(CO)3] at 4.2 K show structure and can be fit with two or three component doublets in a 2:1 or 1:1:1 ratios. The magnetically perturbed spectra, recorded in an applied field of 4.0 and 6.0 T, can be interpreted in terms of a model where a ferromagnetically coupled (S1,2 = 9/2) Fe2+/Fe3+ pair couples antiferromagnetically with the S = 5/2 Fe3+ Site to give an S = 2 ground state. The fine and hyperfine parameters, obtained by simulations of the Moessbauer spectra, are remarkably similar to parameters reported previously for the Fe3S4 centers in Desulfovibrio gigas Fd II and aconitase. The oxidative decarbonylation reactions of the (Et4N)3-[Fe3S4L3Mo(CO)3] with quinone afford the solvated single cubane (Et4N)2[Fe3S4Cl3Mo(MeCN)(cat)] when the terminal ligand on the iron site is Cl- and the doubly-bridged double-cubane (Et4N)4[Fe3S4(EtS)3Mo(cat)]2 when the terminal ligand is EtS-. The reaction of (Et4N)3[Fe3S4(EtS)3Mo(CO)3] with diethyl disulfide afforded the triply-bridged double-cubane cluster (Et4N)3[Fe6S8(EtS)9Mo2] in moderate yield. Upon heating in solution the (Et4N)3[Fe3S4L3Mo(CO)3] Clusters (L = Cl-, p-COMePhO-) are converted to the corresponding, prismane-adduct, octanuclear clusters (Et4N)4[Fe6S6(L)9{Mo(CO)3}2]. In CH3CN solution the Mo(CO)3 fragment in the [Fe3S4(EtS)3Mo(CO)3]3- cluster can be replaced by FeCl+. In this reaction a statistical mixture of [Fe4S4(Cl)x(EtS)4-x]2- clusters is obtained, as indicated by H-1 NMR spectroscopy.