| Summary: | 碩士 === 國立臺灣師範大學 === 化學研究所 === 87 === ABSTRACT
Mixed-ligand oxovanadium(IV) complexes of 5-nitro-N-salicylidene-phenylalaninato, N-salicylidenephenylalaninato and 3-methoxy-N-salicylidene-phenylalaninato, [VO(sal-D-phe)(L)], [VO(sal-L-phe)(L)] ,[VO(5-NO2-sal-D-phe)(L)], [VO(5-NO2-sal-L-phe)(L)] and [VO(3-CH3O-sal-L-phe)(L)], where L=1,10-phenanthroline, 2,2’-bipyridine, 4,7-dimethyl-1,10-phenanthroline, H2O and ROH, have been synthesized and characterized by elemental analyses and UV/VIS, CD, IR, and EPR spectroscopic measurements.
By using three-dimensional X-ray diffraction methods, the crystal and molecular structures of the following four complexes have been determined:
(1) [VO(sal-D-phe)(OCH3)(HOCH3)]
Orthorhombic, space group P21212, a = 14.3954(4) A, b = 18.9384(7) A, c = 6.7507(2) A, V = 1840.4(1) A3, Z = 4, R = 0.0534, Rw = 0.1075.
(2) [VO(sal-D-phe)(H2O)]
Monoclinic, space group P21, a = 14.3954(4) A, b = 18.9384(7) A, c = 6.7507(2) A, = 107.897(6)o, V = 795.9(3) A3, Z = 2, R = 0.0536 , Rw = 0.0847.
(3) [VO(sal-L-phe)(OC9H9)(HOC9H9)]
Monoclinic, space group P21, a = 12.7380(1) A, b = 7.9986(2) A, c = 16.1993(3) A, = 110.6570(6)o, V = 1544.375(3) A3, Z = 2, R = 0.0839 , Rw = 0.1603.
(4) [VO(3-CH3O-sal-L-phe)(4,7-dmphen)](H2O)
Monoclinic, space group P21, a = 6.3312(2) A, b = 20.1158(6) A, c = 11.1132(3) A, = 98.158(1)o, V = 1403.29(7) A3, Z = 2, R = 0.0694 , Rw = 0.1298.
Based on EPR, UV/VIS and CD spectral data, the [VO(sal-phe)(L)], [VO(5-NO2-sal-phe)(L)] and [VO(3-CH3O-sal-phe)(L)] complexes have distorted octahedral structures in consistence with the X-ray structures. Gaussion analyses of the visible and CD spectra suggest the sequences of the d orbitals for [VO(sal-phe)(OCH3)(HOCH3)]- and [VO(5-NO2-sal-phe)(OCH3) (HOCH3)]- as dz2＞dyz＞dxz＞dx2-y2＞dxy and for the [VO(sal-phe)(NN)] as dz2＞dyz＞dx2-y2＞dxz＞dxy. The reduction potentials are higher for [VO(sal-phe)(NN)] than for [VO(sal-phe)(OCH3)(HOCH3)]- by about 400 mV, revealing that vanadyl complexes are greatly stabilized by NN ligands.
Preliminary studies on bromination of organic substrates catalyzed by asymmetric vanadyl complexes have been performed.
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