Disulfide Versus Diselenide Complexes of Copper: Air-Free and Air-Exposed Syntheses Result in Variable Ligands and Coordination

Reactions of bis (1-methylimidazole-2)disulfide (MMI DS ) or bis (1-methylimidazole-2)diselenide (MMI DSe ) with Cu(I) result in a variety of products depending on conditions. Under air-free conditions, dinuclear complexes [Cu 2 (µ, κ S - MMI) 2 ( κ N,N’ - MMI DS ) 2 ][BF 4 ] 2 and [Cu 2 (µ, κ Se -MMI Se ) 2 ( κ N,N’ - MMI DSe ) 2 ][BF 4 ] 2 were obtained and structurally characterized. Both complexes show reduction of the MMI DS or MMI DSe and subsequent bridging of the thione or selone between the dinuclear Cu(I) centers. Combining MMI DSe with Cu(I) in air resulted in crystallization of three different complexes from the same reaction mixture, as confirmed by X-ray crystallography. The various products, [Cu( κ N,N’ - MMI MSe )( κ N,N’ - MMI TSe )(CH 3 CN)][BF 4 ] 2 , [Cu( κ N,N’ - MMI Se -CH 2 -MMI Se ) 2 [BF 4 ] 2 , and the co-crystallized [[Cu( κ N,N’ - MMI DSe ) 2 ][Cu( κ N,N’ - MMI Se -CH 2 -MMI Se )][BF 4 ] 4 , indicate that significant reactivity occurs with the availability of air and CH 2 Cl 2 solvent. In addition to oxidation of Cu(I) to Cu(II), the MMI DSe ligands also react to form monoselenide, triselenide, and Se-CH 2 -Se bridged selenide ligands. Graphical Abstract Although Cu(I) reactions with bis (1-methylimidazole-2)disulfide (MMI DS ) or bis (1-methylimidazole-2)diselenide (MMI DSe ) under air-free conditions result in formation of [Cu 2 (µ, κ S - MMI) 2 ( κ N,N’ - MMI DS ) 2 ][BF 4 ] 2 and [Cu 2 (µ, κ Se - MMI Se ) 2 ( κ N,N’ - MMI DSe ) 2 ][BF 4 ] 2 , respectively, treating MMI DSe with Cu(I) in air results in crystallization of three different complexes from the same reaction mixture: [Cu( κ N,N’ - MMI MSe )( κ N,N’ - MMI TSe )(CH 3 CN)][BF 4 ] 2 , [Cu( κ N,N’ - MMI Se -CH 2 -MMI Se ) 2 [BF 4 ] 2 , and the co-crystallized [[Cu( κ N,N’ - MMI DSe ) 2 ][Cu( κ N,N’ - MMI Se -CH 2 -MMI Se )][BF 4 ] 4 , indicating that significant reactivity occurs with the availability of air and CH 2 Cl 2 solvent.