Simple and Selective Synthesis of Copper-Containing Metal Nanoclusters Using (PPh₃ )₂ CuBH₄ as Reducing Agent

A simple and selective synthetic protocol, using (PPh₃ )₂ CuBH₄ as reducing agent, for Cu-containing mixed metal nanoclusters (NCs) is reported. Representative NCs include alkynyl-protected [Ag₂₅ Cu₄ (PhCC)₁₂ (PPh₃ )₁₂ Cl₆ H₈ ]³⁺ (1), thiolate-capped [AuCu₁₄ (SR)₁₂ (PPh₃ )₆ ]⁺ (R = 4-flurothiophenol) (2), and phosphine-stabilized [Au₉ Cu₂ (PPh₃ )₈ Cl₂ ]⁺ (3), which are fully characterized by single-crystal X-ray diffraction analysis, electrospray ionization mass, nuclear magnetic resonance (¹ H, ² H, ¹³ C, and ³¹ P NMR), and optical measurements, respectively. This work demonstrates the advantages of using (PPh₃ )₂ CuBH₄ as a reducing agent in the synthesis of Cu-containing heterometallic NCs in terms of versatility as well as high yield and high purity of the products. This work may open the door to utilizing functional metal borohydride, as a new generation of reducing agent for the simple and selective synthesis of metal NCs.