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摘要
Heating the toluene solution of 4,4-dimethyl-4,5-dihydro-3H-pyrazole (N2C5H10) and Fe-3(CO)(12) at reflux for 1 h produces diiron hexacarbonyls Fe-2(N2C5H10)(CO)(6) (1, vco(CH2Cl2): 2069, 2022, 1986 cm(-1)). Compound 1 exhibits 34 e(-) configuration, in which (N2C5H10)(2-) coordinates to diiron ((FeFeI)-Fe-I) centers featuring a butterfly structure. To a solution of 1 in toluene was added one equiv. of decarbonyl agent Me3NO in MeCN, and the mixture was stirred at room temperature for 20 min. Then, one equiv. of monophosphine was added. After 3 h, the solvent was removed and the residue was extracted into 5 mL CH2Cl2. The product Fe-2(N2C5H10)(CO)(5)(PR3) (PR3=PPh3, 2a; PCy3, 2b) was obtained as brown crystals by allowing a pentane layer to diffuse into the CH2Cl2 solution at -20 degrees C. P-31 NMR spectra exhibit a singlet at 6 67 for 2a and 8 70 for 2b in CH2Cl2, respectively. In IR spectra, the vco bands for 2a were displayed at 2032, 1968, 1952, 1907 cm 1, which are compared to 2024, 1959, 1937, 1893 cm(-1) for 2b. Photolysis the toluene solution of 1 in the presence of chelating diphosphine ligands such as dppe [dppe=1,2-C2H4(PPh2)(2)] and dppbz [dppbz=1,2-C6H4(PPh2)(2)] affords diiron diphosphine carbonyl compounds. For dppe, the product was Fe-2(N2C5H10)(Co)(4)(mu-dppe) (3a, P-31 NMR (CD2Cl2): a 95, FT-IR (CH2Cl2, vco): 1984, 1940, 1925 and 1900 cm(-1)), in which dppe is bridging the two iron centers. For more rigid diphosphine ligand dppbz, X-ray crystallographic analysis reveals the structure of Fe-2(N2C5H10)(mu-CO)(CO)(4)(dPPbz) [3b, P-31 NMR (CD2C12): delta 93]. In 3b, (N2C5H10)(2-) coordinates to diiron centers in a planar mode, and dppbz chelates at one Fe site by the replacement of one CO ligand. Compound 3b features a Fe-CO-Fe rotated structure with a bridging CO ligand between the two Fe centers. The vco bands for 3b were displayed at 1990, 1947, 1919, 1895 cm-1. With such a rotated structure, compound 3b provides a new approach for synthetic models of H-red state of [FeFe]-H(2)ase. The CCDC number for 1, 2a, 2b, 3a and 3b are 1494954, 1494955, 1494956, 1494966 and 1494957. All the compounds were well characterized by NMR, IR spectroscopy and elemental analysis.
- 出版日期2017-1-15
- 单位山东大学
