A lean synthesis of copper nanoparticles (Cu NP) from CuCl₂ in dodecane via formation of Cu(I)–dodecanethiolate (Cu(I)-DDT) and their decomposition paths including spontaneous C–S bond cleavage of the alkanethiol on the surface of Cu NP is presented. The reduction of Cu(I)-DDT by the tert-butylamine–borane complex (TBAB) in dodecane under N₂ at elevated temperatures leads to the formation of thiol-protected Cu NP with narrow size distribution in the size range of 3–10 nm depending on the reaction conditions. The Cu NP in the presence of excess dodecanethiol reacts further to Cu₂S NP under decomposition of the ligand on the particle surface. The Cu₂S formation occurs after a short time at T > 175 °C or within ∼12 h at room temperature. If excess thiol is removed immediately after the synthesis, the resulting colloid shows irreversible aggregation within days or hours. Our results suggest that alkanethiols are not long-term stable on nanocopper surfaces and that the formation of copper(I) sulfide under the cleavage of the C–S bond occurs even at room temperature.

中文翻译：

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铜纳米粒子的合成：硫代烷烃分解的稳定性和转化为Cu ₂ S纳米粒子

通过形成Cu（I）-十二烷硫醇盐（Cu（I）-DDT）并从十二烷中的CuCl ₂精益合成铜纳米颗粒（Cu NP）及其分解途径，包括在烷烃表面自发地进行烷硫醇的C-S键裂解。提出了铜NP。在高温下，N ₂下十二烷中的叔丁胺-硼烷络合物（TBAB）还原Cu（I）-DDT导致形成巯基保护的Cu NP，在3-10的尺寸范围内具有狭窄的尺寸分布取决于反应条件。在过量十二烷硫醇的存在下，Cu NP在颗粒表面上的配体分解下进一步与Cu ₂ S NP反应。Cu ₂ S的形成在T短时间后发生> 175°C或在室温下约12小时内。如果在合成后立即除去过量的硫醇，则所得的胶体会在数天或数小时内显示出不可逆的聚集。我们的结果表明，烷硫醇在纳米铜表面上不是长期稳定的，即使在室温下，在C–S键断裂下硫化铜（I）的形成也会发生。