Atomically precise copper chalcogenide nanoclusters are an exceptionally diverse class of nanomaterials with potential applications in chemiluminescence, sensing, and catalysis. However, most previously reported nanoclusters have been characterized exclusively in the solid state, leaving open questions as to their stability and function in solution. In this work, we report the first detailed solution-phase investigation of speciation, electrochemistry, and decomposition of atomically precise [Cu12S6] supported by a series of mono- and ditopic alkyldiphenylphosphines PPh2R (R = Et, -(CH2)5-, -(CH2)8-). While electronically identical, this series of ligands features monotopic and ditopic binding modes spanning zero, one, or three axes of the [Cu12S6] core, facilitating an in-depth examination of the impact of phosphine binding topology on solution behaviour. We find that binding topology dictates the extent of speciation, with complete solution stability being afforded through use of the longer octane chelate dppo (1,8-bis(diphenylphosphino)octane). Thus, the 1H and DOSY NMR spectra of [Cu12S6(dppo)4] indicate a rigid, stereochemically locked ligand configuration in which substantial stabilizing CH---S interactions are present. Meanwhile, electrochemical analysis coupled with DFT calculations indicates that the [Cu12S6] core undergoes a quasireversible one-electron oxidation at –0.50 V vs Fc0/+. In contrast, prolonged air exposure or treatment with chemical oxidants results in cluster degradation with formation of phosphine sulfide byproducts. This work demonstrates both progress and challenges in controlling the solution-phase behaviour and redox chemistry of phosphine-supported copper chalcogenide nanoclusters.

中文翻译：

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双位配体对原子级精确铜硫族化物纳米团簇溶液相平衡和电化学的影响

原子精确的铜硫族化物纳米团簇是一类极其多样化的纳米材料，在化学发光、传感和催化领域具有潜在的应用前景。然而，大多数先前报道的纳米团簇仅在固态下进行表征，因此对其在溶液中的稳定性和功能留下了悬而未决的问题。在这项工作中，我们报告了由一系列单位和双位烷基二苯基膦 PPh2R (R = Et, -(CH2)5-, - (CH2)8-)。虽然电子结构相同，但该系列配体具有跨越 [Cu12S6] 核心的零、一个或三个轴的单位和双位结合模式，有助于深入研究膦结合拓扑对溶液行为的影响。我们发现结合拓扑结构决定了物种形成的程度，通过使用较长的辛烷螯合物 dppo（1,8-双（二​​苯基膦）辛烷）可提供完整的溶液稳定性。因此，[Cu12S6(dppo)4] 的 1H 和 DOSY NMR 谱表明存在刚性、立体化学锁定的配体构型，其中存在大量稳定的 CH---S 相互作用。同时，电化学分析与 DFT 计算相结合表明，[Cu12S6] 核在 –0.50 V vs Fc0/+ 下经历了准可逆单电子氧化。相反，长时间暴露在空气中或用化学氧化剂处理会导致簇降解，并形成硫化膦副产物。这项工作展示了在控制膦负载的铜硫属化物纳米团簇的溶液相行为和氧化还原化学方面的进展和挑战。