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

A decanuclear silver chalcogenide cluster, [Ag(10)(Se){Se(2)P(O(i)Pr)(2)}(8)] (2) was isolated from a hydride-encapsulated silver diisopropyl diselenophosphates, [Ag(7)(H){Se(2)P(O(i)Pr)(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, [Cu(x)Ag(10-x)(Se){Se(2)P(O(i)Pr)(2)}(8)] (x = 0–7, 3), via heating [Cu(x)Ag(7−x)(H){Se(2)P(O(i)Pr)(2)}(6)] (x = 1–6) at 60 °C. Compositions of 3 were accurately confirmed by the ESI mass spectrometry. While the crystal 2 revealed two un-identical [Ag(10)(Se){Se(2)P(O(i)Pr)(2)}(8)] structures in the asymmetric unit, a co-crystal of [Cu(3)Ag(7)(Se){Se(2)P(O(i)Pr)(2)}(8)](0.6)[Cu(4)Ag(6)(Se){Se(2)P(O(i)Pr)(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){Se(2)P(OEt)(2)}(8)] (1) are quite similar (10 metals, 1 Se(2−), 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.