Shen Wei-Zheng, Schnebeck Ralf-Dieter, Freisinger Eva, Lippert Bernhard
Fakultät Chemie, Technische Universität Dortmund, 44221 Dortmund, Germany.
Dalton Trans. 2008 Aug 14(30):4044-9. doi: 10.1039/b802924e. Epub 2008 Jun 26.
[(en)Pt(mu-OH)2Pt(en)]2+, a dinuclear mu-hydroxo bridged complex (with en = ethylenediamine) crystallizes with excess AgNO3 in high yield as the trinuclear complex ((en)Pt(mu-OH)2Pt(en))Ag3 (Pt2Ag, 1) from water. The two halves of the complex are significantly bent (dihedral angle 42.2 degrees ) and the three metals form a triangle with the following distances: Pt1...Pt2, 2.9729(9) angstroms, Pt1...Ag1, 2.818(1) angstroms and Pt2...Ag1, 2.809(1) angstroms. The shortness of the Pt...Ag distances and the dispositions of the three metal ions strongly suggest that dative bonds from Pt to Ag are responsible for the bending of the two halves of the edge-sharing dinuclear [(en)Pt(mu-OH)2Pt(en)]2+ complex. This scenario appears to be yet another cause of bending of edge-sharing dinuclear mu-OH bridged metal complexes of d8 metal ions, adding to those involving Pt...Pt bonding, or anion binding, among others. Comparison with related mu-OH dimers of cis-(NH3)2PtII or (tmeda)PtII (tmeda = N,N,N',N'-tetramethylethylenediamine), which do not display Ag+ binding, suggests that the feature of Ag+ binding is not common to all cis-bis(am(m)ine) complexes of PtII. Interestingly the complete removal of Ag+ from 1 does not lead to the mu-OH dimer but rather to the known mu-OH tetramer [((en)Pt(mu-OH))4]4+.
[(en)Pt(μ-OH)₂Pt(en)]²⁺，一种双核μ-羟基桥联配合物（en = 乙二胺），与过量的AgNO₃一起从水中高产率结晶形成三核配合物((en)Pt(μ-OH)₂Pt(en))Ag₃（Pt₂Ag，1）。该配合物的两半显著弯曲（二面角为42.2度），三种金属形成一个三角形，其距离如下：Pt1...Pt2为2.9729(9)埃，Pt1...Ag1为2.818(1)埃，Pt2...Ag1为2.809(1)埃。Pt...Ag距离较短以及三种金属离子的排列强烈表明，从Pt到Ag的配位键是导致边缘共享双核[(en)Pt(μ-OH)₂Pt(en)]²⁺配合物两半弯曲的原因。这种情况似乎是d⁸金属离子的边缘共享双核μ-OH桥联金属配合物弯曲的又一个原因，除此之外还有涉及Pt...Pt键合或阴离子结合等原因。与不显示Ag⁺结合的顺式-(NH₃)₂PtII或(tmeda)PtII（tmeda = N,N,N',N'-四甲基乙二胺）的相关μ-OH二聚体相比，表明Ag⁺结合的特征并非所有PtII的顺式双(胺)配合物所共有。有趣的是，从1中完全去除Ag⁺并不会导致μ-OH二聚体，而是导致已知的μ-OH四聚体[((en)Pt(μ-OH))₄]⁴⁺。
