Copper(i) diselenocarbamate clusters: synthesis, structures and single-source precursors for Cu and Se composite materials

Abstract

Neutral tetrahedral [Cu₄(Se₂CNⁿPr₂)₄] (1), monocationic hydride-centered tetracapped tetrahedral [Cu₈(H){Se₂CNR₂}₆]⁺ (R = ⁿPr, 2_H; Et, 3_H) and neutral hydride-centered tricapped tetrahedral [Cu₇(H){Se₂CNR₂}₆] (R = ⁿPr, 4_H; Et, 5_H) clusters were formed. They are the first Cu(I) complexes supported by dialkyl diselenocarbamates. The as-synthesized complexes 2_H and 3_H, formed from a reaction mixture of Cu(I) salts, diselenocarbamates, and [BH₄]⁻ in an 8 : 6 : 1 ratio, can be further reduced to 4_H and 5_H, respectively, in the presence of one equiv. of [BH₄]⁻. Replacement of [BH₄]⁻ with [BD₄]⁻ afforded the deuteride analogues [Cu₈(D){Se₂CNR₂}₆]⁺ (R = ⁿPr, 2_D; Et, 3_D) and [Cu₇(D){Se₂CNR₂}₆] (R = ⁿPr, 4_D; Et, 5_D), which confirm the presence of hydride in the corresponding (2_H, 3_H, 4_H and 5_H) compounds. These complexes were fully characterized by elemental analysis, ESI-MS, and ¹H, ²H and ⁷⁷Se NMR spectroscopy, and their molecular structures were unequivocally established by single crystal X-ray crystallographic analyses (1, 2_H–5_H). The hydride-encapsulated copper frameworks of (2_H, 3_H) and (4_H, 5_H) reveal a tetracapped tetrahedral cage of Cu₈ and a tricapped tetrahedral cage of Cu₇, respectively, which are enclosed within a Se₁₂ icosahedron constituted by six dialkyl diselenocarbamate ligands. Compounds 2_H and 3_H display orange emission in both the solid and solution state under UV irradiation at 77 K. In addition, the thermolysis behaviors of 2_H were studied to demonstrate the potential of these compounds as single-source precursors for copper selenide nanocomposites, which were analyzed by XRD, EDX, and SEM techniques.