Nielsen Ida Gjerlevsen, Sommer Sanna, Dippel Ann-Christin, Skibsted Jørgen, Iversen Bo Brummerstedt
Center for Materials Crystallography, Department of Chemistry, Interdisciplinary Nanoscience Center (iNANO), Aarhus University 8000 Aarhus C Denmark
Deutsches Elektronen-Synchrotron DESY D-22607 Hamburg Germany.
Chem Sci. 2021 Oct 14;12(43):14420-14431. doi: 10.1039/d1sc05190c. eCollection 2021 Nov 10.
The atomic structures, and thereby the coordination chemistry, of metal ions in aqueous solution represent a cornerstone of chemistry, since they provide first steps in rationalizing generally observed chemical information. However, accurate structural information about metal ion solution species is often surprisingly scarce. Here, the atomic structures of Ga ion complexes were determined directly in aqueous solutions across a wide range of pH, counter anions and concentrations by X-ray pair distribution function analysis and Ga NMR. At low pH (<2) octahedrally coordinated gallium dominates as either monomers with a high degree of solvent ordering or as Ga-dimers. At slightly higher pH (pH ≈ 2-3) a polyoxogallate structure is identified as either Ga or Ga in contradiction with the previously proposed Ga Keggin structures. At neutral and slightly higher pH nanosized GaOOH particles form, whereas for pH > 12 tetrahedrally coordinated gallium ions surrounded by ordered solvent are observed. The effects of varying either the concentration or counter anion were minimal. The present study provides the first comprehensive structural exploration of the aqueous chemistry of Ga ions with atomic resolution, which is relevant for both semiconductor fabrication and medical applications.
水溶液中金属离子的原子结构以及由此产生的配位化学是化学的基石，因为它们为合理解释普遍观察到的化学信息提供了第一步。然而，关于金属离子溶液物种的准确结构信息往往出奇地匮乏。在此，通过X射线对分布函数分析和镓核磁共振，直接测定了在广泛的pH值、抗衡阴离子和浓度范围内的水溶液中镓离子配合物的原子结构。在低pH值（<2）时，八面体配位的镓以具有高度溶剂有序性的单体或镓二聚体为主。在略高的pH值（pH≈2 - 3）下，一种聚氧镓酸盐结构被确定为镓或镓，这与先前提出的镓凯gin结构相矛盾。在中性和略高的pH值下形成纳米级的GaOOH颗粒，而在pH>12时观察到被有序溶剂包围的四面体配位镓离子。改变浓度或抗衡阴离子的影响很小。本研究首次以原子分辨率对镓离子的水相化学进行了全面的结构探索，这对半导体制造和医学应用都具有重要意义。
