Shimada Shigeru, Li Yong-Hua, Choe Yoong-Kee, Tanaka Masato, Bao Ming, Uchimaru Tadafumi
Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
Proc Natl Acad Sci U S A. 2007 May 8;104(19):7758-63. doi: 10.1073/pnas.0700450104. Epub 2007 Apr 30.
Palladium (Pd) generally prefers low oxidation states. So far, no stable Pd compound with a +5 oxidation state is known. Here, we report two multinuclear Pd compounds containing Pd centers ligated by five silicon (Si) atoms. A thermal condensation reaction of [{1,2-C(6)H(4)(SiMe(2))(SiH(2))}Pd(II)(Me(2)PCH(2)CH(2)PMe(2))] (Me = methyl) afforded two stereoisomers of dinuclear Pd(II) compounds and a trinuclear Pd compound as major products and a tetranuclear Pd compound as a minor product. The structures of the four Pd compounds were confirmed by single-crystal x-ray structure analysis. The dinuclear Pd compounds have a dimeric structure of [{1,2-C(6)H(4)(SiMe(2))(SiH)}Pd(II)(Me(2)PCH(2)CH(2)PMe(2))] connected through a Si-Si single bond formed by dehydrogenation of two molecules of the starting compound. The trinuclear and tetranuclear Pd compounds proved to have Pd centers bonded to five Si atoms with normal Pd-Si single-bond distances. Theoretical calculations of the trinuclear and tetranuclear Pd compounds accurately reproduced their x-ray structures and suggested that all of the Pd-Si bonds of the central Pd atoms have a relatively high single-bond character.
钯（Pd）通常倾向于低氧化态。到目前为止，尚未发现具有 +5 氧化态的稳定钯化合物。在此，我们报道了两种多核钯化合物，其中钯中心由五个硅（Si）原子配位。[{1,2-C(6)H(4)(SiMe(2))(SiH(2))}Pd(II)(Me(2)PCH(2)CH(2)PMe(2))]（Me = 甲基）的热缩合反应产生了两种双核 Pd(II) 化合物的立体异构体和一种三核钯化合物作为主要产物，以及一种四核钯化合物作为次要产物。这四种钯化合物的结构通过单晶 X 射线结构分析得以确认。双核钯化合物具有[{1,2-C(6)H(4)(SiMe(2))(SiH)}Pd(II)(Me(2)PCH(2)CH(2)PMe(2))]的二聚体结构，通过起始化合物的两个分子脱氢形成的 Si-Si 单键相连。三核和四核钯化合物被证明具有钯中心与五个硅原子键合，且钯 - 硅单键距离正常。对三核和四核钯化合物的理论计算准确地再现了它们的 X 射线结构，并表明中心钯原子的所有钯 - 硅键都具有相对较高的单键特征。
