The temperature (T) dependences of the emissions from the tetra-n-butylammonium salts of [{Mo₆X₈}Y₆]^2– (X, Y = Cl, Br, and I) in optically transparent polyethylene glycol dimethacrylate matrixes were studied in the T range of 3–300 K. [{Mo₆Cl₈}Y₆]^2–, [{Mo₆Br₈}Y₆]^2–, and [{Mo₆I₈}I₆]^2– showed the T-dependent emission characteristics similar to those of other hexanuclear Mo(II), Re(III), and W(II) clusters reported previously, while [{Mo₆I₈}Br₆]^2– and [{Mo₆I₈}Cl₆]^2– exhibited the emission properties different from those of other [{Mo₆X₈}Y₆]^2– clusters. The photophysical behavior of these clusters was explained by the excited triplet state spin-sublevel (Φ_n, n = 1–4) model irrespective of the nature of X and Y. The zero-magnetic-field splitting energies between the lowest energy (Φ₁) and the higher energy spin sublevels (Φ₄ or Φ₃) caused by the first- or second-order spin–orbit coupling, ΔE₁₄ or ΔE₁₃, were evaluated to be 620–870 or 50–99 cm^–1, respectively. We found the linear correlation between the ΔE₁₄ or ΔE₁₃ value and the fourth power of the atomic number (Z) of the inner halide X: ΔE₁₄ or ΔE₁₃ vs {Z(X)}⁴ (correlation coefficient: cc = ∼ 0.999). Furthermore, we also found the correlation between ΔE₁₄ or ΔE₁₃ and the ⁹⁵Mo NMR chemical shift of the cluster. These findings gave very important insight into the spin–orbit coupling and zero-magnetic-field splitting in the excited triplet states of transition metal complexes.

中文翻译：

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八面体六核钼（II）簇的激发三重态的零磁场分裂：[{Mo ₆ X ₈ } Y ₆ ] ^2–（X，Y = Cl，Br，I）

在光学透明的聚乙二醇二甲基丙烯酸酯基质中，[{Mo ₆ X ₈ } Y ₆ ] ^2-（X，Y = Cl，Br和I）的四正丁基铵盐的排放量的温度（T）依赖性为研究了Ť的范围3-300 K. [{沫₆氯₈ }ÿ ₆ ] ^2-，[{沫₆溴₈ }ÿ ₆ ] ^2-和[{沫₆我₈ }我₆ ] ^2-显示了T依赖的发射特性类似于先前报道的其他六核Mo（II），Re（III）和W（II）团簇，而[{Mo ₆ I ₈ } Br ₆ ] ^2–和[{Mo ₆ I ₈ } Cl ₆ ] ^2–的发射性质不同于其他[{Mo ₆ X ₈ } Y ₆ ] ^{2 –}团簇的发射性质。这些簇的光物理行为是由激发三重态自旋分段解释（Φ _Ñ，Ñ= 1-4）模型而不管最低能量之间的X和Y的零磁场分裂能量（Φ的性质₁）和更高的能量自旋能级（Φ ₄或Φ ₃所引起的第一方）或二阶自旋轨道耦合ΔE ₁₄或ΔE ₁₃分别被评估为620-870或50-99 cm ^-1。我们发现ΔE ₁₄或ΔE ₁₃值与内部卤化物X的原子序数（Z）的四次方之间的线性相关性：ΔE ₁₄或ΔE ₁₃与{ Z（X）} ⁴（相关系数：cc ＝〜0.999）。此外，我们还发现ΔE ₁₄或ΔE ₁₃与簇的⁹⁵ Mo NMR化学位移之间的相关性。这些发现为过渡金属配合物的激发三重态下的自旋-轨道耦合和零磁场分裂提供了非常重要的见识。