COMPARATIVE ELECTRONIC-PROPERTIES OF VANADIUM-IRON-SULFUR AND MOLYBDENUM-IRON-SULFUR CLUSTERS CONTAINING ISOELECTRONIC CUBANE-TYPE [VFE3S4]2+ AND [MOFE3S4]3+ CORES
COMPARATIVE ELECTRONIC-PROPERTIES OF VANADIUM-IRON-SULFUR AND MOLYBDENUM-IRON-SULFUR CLUSTERS CONTAINING ISOELECTRONIC CUBANE-TYPE [VFE3S4]2+ AND [MOFE3S4]3+ CORES
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DOI：
10.1021/ic00252a016
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发表时间：
1987-03-11
影响因子：
4.6
通讯作者：
HOLM, RH
中科院分区：
文献类型：
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作者：
CARNEY, MJ;KOVACS, JA;HOLM, RH
立方烷型簇合物[VFe_3S_4]的电子性质（Sp-C6H4Me）3（DMF）3]-（1），[VFe3S4Cl3（dmpe）-（MeCN）]-（2），和[VFe3S4Cl3（DMF）3]-（3）和[MoFe3S4（SEt）4（dmpe）]-（5），[MoFe3S4Cl3（Al2cat）（THF）] 2-（6），和[MoFe_3S_4Cl_4（dmpe）]~（7）作为季铵盐在固态下进行了研究。这些集合允许对包含等电子和基本上同构的[VFe 3S 4] 2+和[MoFe 3S 4] 3+核心的簇进行比较性质评估。比较中还包括先前研究的簇[MoFe 3S 4（Sp-C6 H4 Cl）4（al 2cat）] 3”（4）。在4.2-300 K和H 0/T至28 kOe/K下对所有团簇的磁化率和磁化强度测定分别建立了S= 3/2基态，|Z）|53cm-1。Curie-Weiss定律如下。100 K，µ= 3.86-3.94 µ，韦斯常数较小（-< 2 K）。在μ= g <$uBS= 3 μ的大HJT值处接近饱和磁化强度。四重基态也保持在溶液中。零场穆斯堡尔谱与一个（C3 n：1，3）或两个（Cs：2，4-7）四极偶线拟合，具体取决于理想化的簇对称性。1-7的同分异构体位移表明，在Fe末端配体的奇偶性下，V团簇中的Fe原子比Mo团簇中的Fe原子略微减少。位移和结构数据表明，V的氧化态不超过3+和Fe的平均氧化态是非常接近2.5+。磁穆斯堡尔谱1-5和7在外地高达80 kOe揭示了两个铁的子网站的比例为2：1。它们的特点是观察到的磁性超精细领域相反的符号，demonstrating S= 3/2基态来自反平行自旋耦合。在相应的属性的差异自旋状态，电子离域的程度，和磁超精细领域的反平行自旋耦合是次要的。同样，结构（其他地方报道）在核心尺寸上高度相似。两个等电子核在电子和结构上实际上是可互换的。实验数据进行了比较，最近SCF理论模型的集群[MoFe 3S 4（SH）6] 3”，与预测的性能一般是好的。
The electronic properties of the sets of new cubane-type clusters [VFe3S4 (Sp-C6H4Me) 3 (DMF) 3]“(1),[VFe3S4Cl3 (dmpe)-(MeCN)]-(2), and [VFe3S4Cl3 (DMF) 3]"(3) and [MoFe3S4 (SEt) 4 (dmpe)]"(5),[MoFe3S4Cl3 (al2cat)(THF)] 2"(6), and [MoFe3S4Cl4 (dmpe)]~(7) as quaternary ammonium salts were investigated in the solid state. The sets allow comparative properties to be assessed for clusters that contain the isoelectronic and essentially isostructural [VFe3S4] 2+ and [MoFe3S4] 3+ cores. Also included in the comparison is the previously studied cluster [MoFe3S4 (Sp-C6H4Cl) 4 (al2cat)] 3"(4). Magnetic susceptibility and magnetization determinations for all clusters at 4.2-300 K and H0/T up to 28 kOe/K, respectively, establish a S= 3/2 ground state with| Z)| 5 3 cm" 1. The Curie-Weiss law is followed below ca. 100 K with µ= 3.86-3.94 µ and small values of the Weiss constant (-< 2 K). Saturation magnetization is approached at large HJT values with µ= g¿ uBS= 3 µ. The quartet ground state is also maintained in solution. Zero-field Móssbauer spectra were fit with one (C3 „: 1, 3) or two (Cs: 2, 4-7) quadrupole doublets depending on the idealized cluster symmetry. Isomer shifts of 1-7 indicate that the Fe atoms in the V clusters are slightly more reduced than those in the Mo clusters at parity of Fe terminal ligands. Shifts and structural data imply that the V oxidation state does not exceed 3+ and the Fe mean oxidation state is very near 2.5+. Magnetic Móssbauer spectra of 1-5 and 7 at fields up to 80 kOe revealed two Fe subsites in the ratio 2: 1. These are characterized by observed magnetic hyperfine fields of opposite sign, demonstratingthat the S= 3/2 ground state arises from antiparallel spin coupling. Differences in corresponding properties—spin state, extent of electron delocalization, and magnetic hyperfine fields in antiparallel spin coupling—are minor. Likewise, structures (reported elsewhere) are highly similar in core dimensions. The two isoelectronic cores are electronically and structurally practically interchangeable. Experimental data are compared with a recent SCF-theoretical model of the cluster [MoFe3S4 (SH) 6] 3"; agreement with predicted properties is generally good.