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论文类型：期刊论文

发表时间：2015-05-18

发表刊物：INORGANIC CHEMISTRY

收录刊物：SCIE、PubMed、Scopus

卷号：54

期号：10

页面范围：4752-4760

ISSN号：0020-1669

摘要：The salt elimination reactions of (IPr2Me2)(2)FeCl2 (IPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with the corresponding aryl Grignard reagents afford [(IPr2Me2)(2)FeAr2] (Ar = Ph, 3; C6H4-p-Me, 4; C6H4-p-tBu, 5; C6H3-3,5-(CF3)(2), 6) in good yields. X-ray crystallographic studies revealed the presence of both tetrahedral and trans square planar isomers for 3 and 6 and the tetrahedral structures for 4 and 5. Magnetic susceptibility and Fe-57 Mossbauer spectrum measurements on the solid samples indicated the high-spin (S = 2) and intermediate-spin (S = 1) nature of the tetrahedral and square planar structures, respectively. Solution property studies, including solution magnetic susceptibility measurement, variable-temperature H-1 and F-19 NMR, and absorption spectroscopy, on 3-6, as well as an Fe-57 Mossbauer spectrum study on a frozen tetrahydrofuran solution of tetrahedral [(IPr2Me2)(2)(FePh2)-Fe-57] suggest the coexistence of tetrahedral and trans square planar structures in solution phase. Density functional theory calculations on (IPr2Me2)(2)FePh2 disclosed that the tetrahedral and trans square planar isomers are close in energy and that the geometry isomerization can occur by spin-change-coupled geometric transformation on four-coordinate iron(II) center.