Department of Physical Chemistry, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
Phys Chem Chem Phys. 2013 Oct 14;15(38):15816-20. doi: 10.1039/c3cp52634h. Epub 2013 Aug 20.
The ligand exchange reaction between monodisperse Au25(2-PET)18 (2-PET: 2-phenylethylthiolate) clusters and 1,1'-binaphthyl-2,2'-dithiol (BINAS) was long thought to induce decomposition of the cluster (Si et al., J. Phys. Chem. C, 2009). We repeated the experiment and analyzed the reaction products using MALDI-TOF mass spectrometry. The spectra clearly indicate successful ligand exchange, bidentate binding of the BINAS ligand and intact Au25 clusters. The reaction products are identified as Au25(2-PET)18-2x(BINAS)x (x = 1-4) for a 24 h reaction with a 50-fold molar excess of BINAS. Two likely binding motifs are discussed. Analysis of atomic distances in both the cluster and the free ligand indicates interstaple binding connecting the central sulfur atom of the protecting (SRAu)2SR with the outer sulfur atom of a second unit. The results presented have implications on the binding position of BINAS in Au38(SR)24-2x(BINAS)x clusters.
人们曾长期认为，单分散 Au25(2-PET)18（2-PET：2-苯乙基硫醇盐）簇与 1,1'-联萘-2,2'-二硫醇（BINAS）之间的配体交换反应会导致簇的分解（Si 等人，J. Phys. Chem. C，2009）。我们重复了该实验，并使用 MALDI-TOF 质谱法分析了反应产物。光谱清楚地表明配体交换成功，BINAS 配体的双齿结合和完整的 Au25 簇。反应产物被鉴定为 Au25(2-PET)18-2x(BINAS)x（x = 1-4），反应时间为 24 小时，BINAS 的摩尔过量为 50 倍。讨论了两种可能的结合模式。对簇和游离配体中原子距离的分析表明，连接保护基（SRAu）2SR 中心硫原子和第二个单元外硫原子的是连接基（staple）之间的结合。所呈现的结果对 Au38(SR)24-2x(BINAS)x 簇中 BINAS 的结合位置具有启示意义。
