The binary synthetic compounds of Pt with chalcogens (O, S, Se, Te), pnictogens (As, Sb, Bi), and intermetallic compounds with Ga, In, and Sn of various stoichiometry were studied via X-ray absorption spectroscopy (XAS). The partial atomic charges of Pt in the compounds were computed using quantum chemical density functional theory (DFT) based methods: the Bader (QTAIM) method, and the density-derived electrostatic and chemical (DDEC6) approach. Strong positive correlations were established between the calculated partial atomic charges of Pt and the electronegativity (χ) of ligands. The partial charge of Pt in PtL₂ compounds increases much sharply when the ligand electronegativity increases than the Pt partial charge in PtL compounds. The effect of the ligand-to-Pt atomic ratio on the calculated Pt partial charge depended on ligand electronegativity. The DDEC6 charge of Pt increases sharply with the growth of the number of ligands in PtS_n (n = 1, 2; electronegativity χ(S) >> χ(Pt)), weakly depends on the phase composition in PtTe_n (n = 1, 2; χ(Te) is slightly lower than χ(Pt)), and decreases (becomes more negative) with increase of the ligand-to-Pt ratio in intermetallic compounds with electron donors (χ(L) < χ(Pt), L = Ga, In, Sn). According to XANES spectroscopy, the number of 5d (L_2,3 absorption edges) and 6p (L₁-edge) electrons at the Pt site decreased when ligand electronegativity increased in chalcogenides and pnictides groups. An increase of the ligand-to-Pt ratio resulted in the increase of the Pt L₃-edge white line intensity and area in all studied compounds. In the case of chalcogenides and pnictides, this behavior was consistent with the electronegativity rule as it indicated a loss of Pt 5d electrons caused by the increase of the number of ligands, i.e., acceptors of electrons. However, in the case of ligands–electron donors (Te, Sn, Ga, In) this observation is in apparent contradiction with the electronegativity arguments as it indicates the increase of the number of Pt 5d-shell vacancies (holes) with the increase of the number of the ligands, for which the opposite trend is expected. This behavior can be explained in the framework of the charge compensation model. The loss of the Pt d-electrons in compounds with low ligand electronegativity (χ(Pt) > χ(L)) was overcompensated by the gain of the hybridized s-p electron density, which was confirmed by Pt L₁ - edge spectra analysis. As a result, the total electron density at the Pt site followed the electronegativity rule, i.e., it increased with the growth of the number of the ligands-electron donors. The empirical correlations between the Pt partial atomic charges and parameters of XANES spectral features were used to identify the state of Pt in pyrite, and can be applied to determine the state of Pt in other ore minerals.

中文翻译：

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X射线吸收光谱法和量子化学计算确定二元化合物和合成矿物中Pt的电荷态

通过X射线吸收光谱法（XAS）研究了Pt与硫属元素（O，S，Se，Te），光生生物（As，Sb，Bi）的二元合成化合物以及具有化学计量比的Ga，In和Sn的金属间化合物）。使用基于量子化学密度泛函理论（DFT）的方法：Bader（QTAIM）方法和基于密度的静电与化学（DDEC6）方法，计算化合物中Pt的部分原子电荷。在计算出的Pt部分原子电荷与配体的电负性（χ）之间建立了强正相关。PtL ₂中Pt的部分电荷当配体电负性增加时，PtL化合物会比PtL化合物中的Pt部分电荷急剧增加。配体与Pt原子比对计算的Pt部分电荷的影响取决于配体的电负性。Pt的DDEC6电荷随着PtS _n中的配体数量的增加而急剧增加（n = 1，2;电负性χ（S）>>χ（Pt）），弱依赖于PtTe _n中的相组成（n = 1，2;χ（Te）略低于χ（Pt）），并且在带电子给体的金属间化合物中，随着配体对Pt比的增加而降低（变得更负）（χ（L）<χ（Pt ），L = Ga，In，Sn）。根据XANES光谱，5 d（L _2,3个吸收边）和6 p当硫族化物和磷化物基团中配体电负性增加时，Pt位点的（L ₁ -edge）电子减少。配体与Pt之比的增加导致所有研究化合物中Pt L ₃边缘白线强度和面积的增加。在硫族化物和磷化物的情况下，此行为与电负性规则一致，因为它表明由于配体（即电子的受体）数量增加而导致Pt 5 d电子损失。但是，在配体-电子供体（Te，Sn，Ga，In）的情况下，该观察结果与电负性论点明显矛盾，因为它表明Pt 5 d的数量增加了。壳空位（孔）随着配体数量的增加而增加，其趋势相反。可以在电荷补偿模型的框架中解释此行为。具有低配体电负性（χ（Pt）>χ（L））的化合物中Pt d电子的损失被杂化s - p电子密度的增加所过度补偿，这已由Pt L ₁证实。-边缘光谱分析。结果，Pt位点的总电子密度遵循电负性规则，即，其随着配体-电子供体的数量的增加而增加。Pt部分原子电荷与XANES光谱特征参数之间的经验相关性可用于识别黄铁矿中Pt的状态，并可用于确定其他矿石矿物中Pt的状态。