Schröder D, Loos J, Schwarz H, Thissen R, Dutuit O
Institut für Chemie der Technischen Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany.
Inorg Chem. 2001 Jun 18;40(13):3161-9. doi: 10.1021/ic0100020.
Sector-field mass spectrometry is used to probe the fragmentation patterns of cationic dinuclear iron chloride clusters Fe(2)Cl(n)()(+) (n = 1-6). For the chlorine-rich, high-valent Fe(2)Cl(n)()(+) ions (n = 4-6), losses of atomic and molecular chlorine prevail in the unimolecular and collision-induced dissociation patterns. Instead, the chlorine deficient, formally low-valent Fe(2)Cl(n)()(+) clusters (n = 1-3) preferentially undergo unimolecular degradation to mononuclear FeCl(m)()(+) ions. In addition, photoionization is used to determine IE(Fe(2)Cl(6)) = 10.85 +/- 0.05 eV along with appearance energy measurements for the production of Fe(2)Cl(5)(+) and Fe(2)Cl(4)(+) cations from iron(III) chloride vapor. The combination of the experimental results allows an evaluation of some of the thermochemical properties of the dinuclear Fe(2)Cl(n)()(+) cations: e.g., Delta(f)H(Fe(2)Cl(+)) = 232 +/- 15 kcal/mol, Delta(f)H(Fe(2)Cl(2)(+)) = 167 +/- 4 kcal/mol, Delta(f)H(Fe(2)Cl(3)(+)) = 139 +/- 4 kcal/mol, Delta(f)H(Fe(2)Cl(4)(+)) = 113 +/- 4 kcal/mol, Delta(f)H(Fe(2)Cl(5)(+)) = 79 +/- 5 kcal/mol, and Delta(f)H(Fe(2)Cl(6)(+)) = 93 +/- 2 kcal/mol. The analysis of the data suggests that structural effects are more important than the formal valency of iron as far as the Fe-Cl bond strengths in the Fe(2)Cl(n)()(+) ions are concerned.
扇形场质谱法用于探测阳离子双核氯化铁簇Fe₂Clₙ⁺（n = 1 - 6）的碎裂模式。对于富含氯的高价Fe₂Clₙ⁺离子（n = 4 - 6），在单分子解离和碰撞诱导解离模式中，原子氯和分子氯的损失占主导。相反，贫氯的、形式上低价的Fe₂Clₙ⁺簇（n = 1 - 3）优先经历单分子降解生成单核FeClₘ⁺离子。此外，利用光电离测定出IE(Fe₂Cl₆) = 10.85 ± 0.05 eV，同时还进行了从氯化铁蒸气生成Fe₂Cl₅⁺和Fe₂Cl₄⁺阳离子的出现能测量。实验结果的结合使得能够评估双核Fe₂Clₙ⁺阳离子的一些热化学性质：例如，ΔfH(Fe₂Cl⁺) = 232 ± 15 kcal/mol，ΔfH(Fe₂Cl₂⁺) = 167 ± 4 kcal/mol，ΔfH(Fe₂Cl₃⁺) = 139 ± 4 kcal/mol，ΔfH(Fe₂Cl₄⁺) = 113 ± 4 kcal/mol，ΔfH(Fe₂Cl₅⁺) = 79 ± 5 kcal/mol，以及ΔfH(Fe₂Cl₆⁺) = 93 ± 2 kcal/mol。数据分析表明，就Fe₂Clₙ⁺离子中的Fe - Cl键强度而言，结构效应比铁的形式化合价更重要。
