Tang Zhen, Nomura Yasuo, Kuwata Shigeki, Ishii Youichi, Mizobe Yasushi, Hidai Masanobu
Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan, and Institute of Industrial Science, The University of Tokyo, Roppongi, Minato-ku, Tokyo 106-8558, Japan.
Inorg Chem. 1998 Sep 21;37(19):4909-4920. doi: 10.1021/ic9806885.
Reactions of [CpMCl(&mgr;(2)-SH)(2)MCpCl] (1, M = Ir; 2, M = Rh; Cp = eta(5)-C(5)Me(5)) with excess FeCl(2).4H(2)O in THF gave the paramagnetic trinuclear clusters [(CpM)(2)(&mgr;(3)-S)(2)FeCl(2)] (3, M = Ir; 4, M = Rh), which were further converted into the dicationic 78e(-) pentanuclear bow-tie cluster (CpIr)(2)(&mgr;(3)-S)(2)Fe(&mgr;(3)-S)(2)(IrCp)(2) (5) by treatment with NaBPh(4). When complex 1 was allowed to react with CoCl(2) and NiCl(2).6H(2)O or Ni(cod)(2) (cod = cyclooctadiene), the related pentanuclear 79e(-) and 80e(-) bow-tie clusters (CpIr)(2)(&mgr;(3)-S)(2)M(&mgr;(3)-S)(2)(IrCp)(2) (6, M = Co; 7, M = Ni) were obtained directly, respectively. Cyclic voltammograms of 5BPh(4), 6BPh(4), and 7BPh(4) showed two reversible reduction waves at -0.25 to -0.43 V and -1.04 to -1.34 V. In both redox couples, the redox potential was in the order Fe < Co < Ni. One-electron reduction of clusters 5BPh(4), 6BPh(4), and 7BPh(4) with Co(eta(5)-C(5)H(5))(2) gave the corresponding monocationic pentanuclear 79-81e(-) bow-tie clusters (CpIr)(2)(&mgr;(3)-S)(2)M(&mgr;(3)-S)(2)(IrCp)(2) (8, M = Fe; 9, M = Co; 10, M = Ni). The molecular structures of 3, 4, 5BPh(4).CH(2)Cl(2), 6CoCl(3)(NCMe), 7[NiCl(4)].CH(2)Cl(2), 8[BPh(4)], 9[BPh(4)], and 10[BPh(4)] were unambiguously determined by X-ray diffraction study. The structures of the pentanuclear bow-tie cluster cores remarkably changed stepwise as the core electrons increased from 78 to 81. Two of the M-Ir (M = Fe, Co) bonds in the 79e(-) clusters 6 and 8 show significant elongation in comparison with the Fe-Ir bonds in the 78e(-) cluster 5. Two different types of the bow-tie structures were observed for the 80e(-) clusters 7 and 9. Cluster 7 has a Z-shaped metal core with only two Ni-Ir bonds, while in cluster 9, the six metal-metal bonds in the bow-tie structure are retained with slight elongation of the Co-Ir bonds in comparison with the corresponding dication 6. The 81e(-) cluster 10 has two normal Ni-Ir bonds and one long Ni-Ir bonding interaction with the fourth nonbonding Ni-Ir contact. This structural variation is interpreted in terms of the total electron counts and molecular orbital calculations of the clusters.
[CpMCl(μ(2)-SH)(2)MCpCl]（1，M = Ir；2，M = Rh；Cp = η(5)-C(5)Me(5)）与过量的FeCl(2)·4H(2)O在四氢呋喃中反应生成顺磁性三核簇[(CpM)(2)(μ(3)-S)(2)FeCl(2)]（3，M = Ir；4，M = Rh），用NaBPh(4)处理后进一步转化为二价阳离子78e(-)五核领结簇(CpIr)(2)(μ(3)-S)(2)Fe(μ(3)-S)(2)(IrCp)(2)（5）。当配合物1与CoCl(2)以及NiCl(2)·6H(2)O或Ni(cod)(2)（cod = 环辛二烯）反应时，分别直接得到相关的五核79e(-)和80e(-)领结簇(CpIr)(2)(μ(3)-S)(2)M(μ(3)-S)(2)(IrCp)(2)（6，M = Co；7，M = Ni）。5BPh(4)、6BPh(4)和7BPh(4)的循环伏安图在-0.25至-0.43 V和-1.04至-1.34 V处显示出两个可逆还原波。在这两个氧化还原对中，氧化还原电位顺序为Fe < Co < Ni。用Co(η(5)-C(5)H(5))(2)对簇5BPh(4)、6BPh(4)和7BPh(4)进行单电子还原得到相应的单价阳离子五核79 - 81e(-)领结簇(CpIr)(2)(μ(3)-S)(2)M(μ(3)-S)(2)(IrCp)(2)（8，M = Fe；9，M = Co；10，M = Ni）。通过X射线衍射研究明确确定了3、4、5BPh(4)·CH(2)Cl(2)、6CoCl(3)(NCMe)、7[NiCl(4)]·CH(2)Cl(2)、8[BPh(4)]、9[BPh(4)]和10[BPh(4)]的分子结构。随着核心电子数从78增加到81，五核领结簇核心的结构显著逐步变化。与78e(-)簇5中的Fe - Ir键相比，79e(-)簇6和8中的两个M - Ir（M = Fe，Co）键明显伸长。对于80e(-)簇7和9观察到两种不同类型的领结结构。簇7具有Z形金属核心，只有两个Ni - Ir键，而在簇9中，领结结构中的六个金属 - 金属键得以保留，与相应的二价阳离子6相比，Co - Ir键略有伸长。81e(-)簇10有两个正常的Ni - Ir键和一个长的Ni - Ir键合相互作用以及第四个非键合的Ni - Ir接触。这种结构变化根据簇的总电子数和分子轨道计算来解释。
