Nucleophilic\nDisplacement Reactions of Silver-Based\nMetal–Organic Chalcogenolates

We\nreport nucleophilic displacement reactions that can increase\nthe dimensionality or coordination number of silver-based metal–organic\nchalcogenolates (MOChas). MOChas are crystalline ensembles containing\none-dimensional (1D) or two-dimensional (2D) inorganic topologies\nwith structures and properties defined by the choice of metal, chalcogen,\nand ligand. MOChas can be readily prepared from a variety of small-molecule\nligands and metals or metal ions. Although MOChas offer ligand diversity,\nmost reported examples use relatively small ligands, typically involving\nshort alkyl chains, aryl rings, or molecular cages. This is because\nlarger, more complex molecules often yield poor product morphologies\nwith indeterminate structures. In this study, we overcame this limitation\nby employing a ligand exchange strategy whereby a 1D MOCha, silver(I)\nmethyl 2-mercaptobenzoate (2MMB), is used as a silver source for preparing\n2D examples. The reaction proceeds generally toward products composed\nof the stronger nucleophile. We show that the reaction prefers displacing\n1D topologies to yield 2D ones and replacing thiolates with selenolates.\nWe performed a study to characterize the mechanism by which organic\nchalcogenols and dichalcogenides exchange with MOChas. The collected\ndata and product analysis support a proposed mechanism of nucleophilic\nsubstitution, explaining how both organic chalcogenols and dichalcogenides\ncan displace ligands in MOChas. This work provides a new synthetic\nroute that will enable the preparation of more elaborate MOChas and\nheterostructures thereof. This approach enabled the preparation of\npreviously inaccessible oligophenyl MOChas, which were successfully\nsolved via small-molecule serial femtosecond crystallography (smSFX)\nat the SPring-8 Ångström Compact Free Electron LAser (SACLA)\nfacility.