| 11670055 |
Belanger S, Beauchamp AL: Oxo Ligand Reactivity in the [ReO (2) L (4)](+) Complex of 1-Methylimidazole. Inorg Chem. 1997 Aug 13;36(17):3640-3647.
Preparation and Crystal Structures of Salts Containing the ReOL (4)(3+) Core and Apical CH (3) O (-), BF (3) O (2)(-), and (CH (3) O)(2) PO (2)(-) Groups.. The oxo group of [ReO (2)(1-MeIm)(4)](+) can be methylated with excess methyl trifluoromethanesulfonate in CH (2) Cl (2) under mild conditions, leading to [ReO (OCH (3))(1-MeIm)(4)](CF (3) SO (3))(2), which is converted to the B (C (6) H (5))(4)(-) and PF (6)(-) salts. When the reaction is carried out in methanol in the presence of excess PF (6)(-), the phosphate ester complex [ReO{OP (O)(OCH (3))(2)}(1-MeIm)(4)](PF (6))(2) is isolated. [ReO (2)(1-MeIm)(4)](+) in the presence of acid, 2,2-dimethoxypropane, and excess BF (4)(-) transforms to the oxo-boron adduct [ReO (OBF (3))(1-MeIm)(4)](+). The presence of the trans-O=Re-OR core was demonstrated by crystallographic studies on one compound of each type: [ReO (OCH (3))(1-MeIm)(4)](PF (6))(2), tetragonal, P4/ncc, Z = 4, a = 13.022 (3) A, c = 17.218 (5) A, R = 0.0271; [ReO{OP (O)(OCH (3))(2)}(1-MeIm)(4)](PF (6))(2).toluene, monoclinic, P2 (1)/c, Z = 4, a = 14.165 (4) A, b = 13.052 (6) A, c = 20.931 (6) A, beta = 95.83 (2) degrees, R = 0.0373; [ReO (OBF (3))(1-MeIm)(4)](I (3)), monoclinic, P2 (1)/c, Z = 4, a = 13.373 (4) A, b = 13.237 (3) A, c = 16.689 (6) A, beta = 103.67 (3) degrees, R = 0.0445. The IR spectra show nu (Re=O) vibrations near 960 cm (-)(1) in all cases. The solution UV-vis spectra of the CH (3) O (-) and BF (3) O (2)(-) compounds are similar to that of the parent oxo-hydroxo [ReO (OH)(1-MeIm)(4)](2+) species, whereas the visible spectrum of the blue phosphate ester compound resembles that of the oxo-aquo [ReO (OH (2))(1-MeIm)(4)](3+) ion. The compounds were also characterized by solution (1) H, (13) C, and (31) P NMR spectroscopy. This work confirms earlier conclusions that ReO (2) L (4)(+) units with good sigma-donor imidazole ligands are more resistant to ligand loss than the pyridine analogues. |
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