Department of Chemistry, NSF ERC for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, CO 80523, USA.
Phys Chem Chem Phys. 2018 Sep 12;20(35):22610-22622. doi: 10.1039/c8cp03157f.
Iron-vanadium sulfur cluster anions are studied by photoelectron spectroscopy (PES) at 3.492 eV (355 nm) and 4.661 eV (266 nm) photon energies, and by density functional theory (DFT) calculations. The structural properties, relative energies of different structural isomers, and the calculated first vertical detachment energies (VDEs) of different structural isomers for cluster anions FeVS1-3- and FemVnSm+n- (m + n = 3, 4; m > 0, n > 0) are investigated at a BPW91/TZVP theory level. The experimental first VDEs for these Fe-V sulfur clusters are reported. The most probable ground state structures and spin multiplicities for these clusters are tentatively assigned by comparing their theoretical and experiment first VDE values. For FeVS1-3- clusters, their first VDEs are generally observed to increase with the number of sulfur atoms from 1.45 eV to 2.86 eV. The NBO/HOMOs of the ground state of FeVS1-3- clusters are localized in a p orbital on a S atom; the partial charge distribution on the NBO/HOMO localized site of each cluster anion is responsible for the trend of their first VDEs. A less negative localized charge distribution is correlated with a higher first VDE. Structure and steric effect differences for FemVnSm+n- (m + n = 3, m > 0, n > 0) clusters are suggested to be responsible for their different first VDEs and properties. Two types of structural isomers are identified for FemVnSm+n- (m + n = 4, m > 0, n > 0) clusters: a tower structure isomer and a cubic structure isomer. The first VDEs for tower like isomers are generally higher than those for cubic like isomers of FemVnSm+n- (m + n = 4, m > 0, n > 0) clusters. Their first VDEs are can be understood through: (1) NBO/HOMO distributions, (2) structures (steric effects), and (3) partial charge numbers on the NBO/HOMO's localized sites. EBEs for excited state transitions for all Fe-V sulfur clusters are calculated employing OVGF and TDDFT approaches at the TZVP level. The OVGF approach for these Fe/V/S cluster anions is better for the higher transition energies than the TDDTF approach. The experimental and theoretical results for these Fe/V/S cluster anions are compared with their related pure iron sulfur cluster anions. Properties of the NBO/HOMO are essential for understanding and estimating the different first VDEs for Fe/V/S, and comparing them to those of the pure Fe/S cluster anions.
采用光电离谱（PES）在 3.492 eV（355nm）和 4.661 eV（266nm）光子能量下，以及密度泛函理论（DFT）计算研究了铁钒硫团簇阴离子。在 BPW91/TZVP 理论水平下，研究了团簇阴离子 FeVS1-3-和 FemVnSm+n-（m+n=3，4；m>0，n>0）的结构性质、不同结构异构体的相对能量以及不同结构异构体的计算第一垂直离解能（VDE）。报道了这些 Fe-V 硫团簇的实验第一 VDE。通过比较它们的理论和实验第一 VDE 值，初步确定了这些团簇最可能的基态结构和自旋多重度。对于 FeVS1-3-团簇，它们的第一 VDE 通常随着硫原子数从 1.45eV 增加到 2.86eV。FeVS1-3-团簇基态的 NBO/HOMO 定域在 S 原子的 p 轨道上；每个团簇阴离子的 NBO/HOMO 定域位点的部分电荷分布负责其第一 VDE 的趋势。带负电的局部电荷分布越小，第一 VDE 越高。FemVnSm+n-（m+n=3，m>0，n>0）团簇的结构和空间位阻效应差异被认为是导致它们不同的第一 VDE 和性质的原因。确定了 FemVnSm+n-（m+n=4，m>0，n>0）团簇的两种结构异构体类型：塔状异构体和立方状异构体。塔式异构体的第一 VDE 通常高于 FemVnSm+n-（m+n=4，m>0，n>0）团簇的立方异构体。可以通过以下方式理解它们的第一 VDE：（1）NBO/HOMO 分布，（2）结构（空间位阻效应）和（3）NBO/HOMO 定域位点上的部分电荷数。在 TZVP 水平上，采用 OVGF 和 TDDFT 方法计算了所有 Fe-V 硫团簇的激发态跃迁的 EBE。OVGF 方法对这些 Fe/V/S 团簇阴离子的较高跃迁能比 TDDTF 方法更好。将这些 Fe/V/S 团簇阴离子的实验和理论结果与它们相关的纯铁硫团簇阴离子进行了比较。NBO/HOMO 的性质对于理解和估计 Fe/V/S 的不同第一 VDE 以及将它们与纯 Fe/S 团簇阴离子进行比较是至关重要的。
