A New Synthetic Methodology in the Preparation of Bimetallic Chalcogenide Clusters via Cluster-to-Cluster Transformations

A decanuclear silver chalcogenide cluster, [Ag-10(Se){Se2P((OPr)-Pr-i)(2)}(8)] (2) was isolated from a hydride-encapsulated silver diisopropyl diselenophosphates, [Ag-7(H){Se2P((OPr)-Pr-i)(2)}(6)], under thermal condition. The time-dependent NMR spectroscopy showed that 2 was generated at the first three hours and the hydrido silver cluster was completely consumed after thirty-six hours. This method illustrated as cluster-to-cluster transformations can be applied to prepare selenide-centered decanuclear bimetallic clusters, [CuxAg10-x(Se){Se2P((OPr)-Pr-i)(2)}(8)] (x = 0-7, 3), via heating [CuxAg7-x(H){Se2P((OPr)-Pr-i)(2)}(6)] (x = 1-6) at 60 degrees C. Compositions of 3 were accurately confirmed by the ESI mass spectrometry. While the crystal 2 revealed two un-identical [Ag-10(Se){Se2P((OPr)-Pr-i)(2)}(8)] structures in the asymmetric unit, a co-crystal of [Cu3Ag7(Se){Se2P((OPr)-Pr-i)(2)}(8)](0.6)[Cu4Ag6(Se){Se2P((OPr)-Pr-i)(2)}(8)](0.4) ([3a](0.6)[3b](0.4)) was eventually characterized by single-crystal X-ray diffraction. Even though compositions of 2, [3a](0.6)[3b](0.4) and the previous published [Ag-10(Se){Se2P(OEt)(2)}(8)] (1) are quite similar (10 metals, 1 Se2-, 8 ligands), their metal core arrangements are completely different. These results show that different synthetic methods by using different starting reagents can affect the structure of the resulting products, leading to polymorphism.

Automated summary

A decanuclear silver chalcogenide cluster was isolated from a hydride-encapsulated silver diisopropyl diselenophosphates under thermal condition. This method can be used to prepare selenide-centered decanuclear bimetallic clusters, and different synthetic methods may result in polymorphism in the structure of the products.