SYNTHESIS AND CHARACTERIZATION OF HIGH-SPIN IRON(III) 2-HYDROXY-5,10,15,20-TETRAPHENYLPORPHYRIN - THE UNPRECEDENTED EXAMPLE OF THE CYCLIC IRON PORPHYRIN TRIMER

被引:51
作者
WOJACZYNSKI, J [1 ]
LATOSGRAZYNSKI, L [1 ]
机构
[1] UNIV WROCLAW,INST CHEM,PL-50383 WROCLAW,POLAND
关键词
D O I
10.1021/ic00109a009
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
The oligomerization process of a monomeric iron(III) 2-hydroxy-5,10,15,20-tetraphenylporphyrin complex, (2-OH-TPP)(FeCl)-Cl-III, affords the unprecedented cyclic trimeric complex [(2-O-TPP)Fe-III](3). The spectroscopic evidences indicate that this compound has a head-to-tail cyclic trimeric structure with the pyrrolic-alkoxide groups forming bridges from one macrocycle to the iron(III) ion in the adjacent macrocycle PFe-O-PFe-O-PFe-O. The inherent optical asymmetry of the basic oligomerization (2-OH-TPP)Fe-III- unit leads to formation of the enantiomeric iron(III) porphyrin trimers. The H-1 NMR spectrum of trimeric [(2-O-TPP)Fe-III](3) is presented and analyzed. The presence of the three paramagnetic, weakly coupled high-spin iron(III) centers produces marked variation of positions and line widths for the pyrrole resonances. The characteristic upfield positions of the 3-H pyrrole resonances were determined and considered as the diagnostic feature for the iron(III)-pyrrole alkoxide coordination. The large upfield contribution to the 3-H pyrrole contact shift was accounted for by the donation of the electron density from the 2-oxygen on the half-occupied d(z)(2) orbital of the external iron(III) ion. [(2-O-TPP)Fe-III]3 was cleaved by protic acids (HX) to form high-spin, five-coordinate species (2-OH-TPP)Fe(III)X whose H-1 NMR spectra were analyzed, The stepwise cleavage mechanism was determined in the course of the titration with TFA. The process involved the formation of a linear dimeric intermediate [(2-OH-TPP)Fe-III-(2-O-TPP). Fe-III(TFA)]. Addition of an excess of oxygen base (methoxide ion, hydroxide ion in methanolic solutions) to a solution of [(2-O-TPP)Fe-III](3) in chloroform-d resulted in the conversion to the five-coordinate, high-spin complexes [(2-O-TPP)Fe(III)X](-) (X = CH3O-, OH-), The base-catalyzed exchange of the proton at the position next to the hydroxy group (3-H) was observed for [(2-O-TPP)Fe(III)X](-) species due to the keto-enol tautomerism. The characteristic shifts of the 3-H resonances in [(2-O-TPP)Fe-III(OH)](-) (33.4 ppm), (2-OH-TPP)(FeBr)-Br-III (79.1 ppm), and (2-benzoyloxy-TPP)(FeCl)-Cl-III (91.4 ppm) provided direct insight into the electronic structure of tautomeric forms.
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页码:1044 / 1053
页数:10
相关论文
共 53 条
[1]   H-1-NMR STUDIES OF IRON(III) PORPHYRINS WITH AXIAL PHENOXIDE OR THIOPHENOXIDE LIGANDS [J].
ARASASINGHAM, RD ;
BALCH, AL ;
CORNMAN, CR ;
DEROPP, JS ;
EGUCHI, K ;
LAMAR, GN .
INORGANIC CHEMISTRY, 1990, 29 (10) :1847-1850
[2]   REACTIONS OF ARYL IRON(III) PORPHYRINS WITH DIOXYGEN - FORMATION OF ARYLOXY IRON(III) AND ARYL IRON(IV) COMPLEXES [J].
ARASASINGHAM, RD ;
BALCH, AL ;
HART, RL ;
LATOSGRAZYNSKI, L .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1990, 112 (21) :7566-7571
[3]   A COFACIAL, DIMERIC, METALLAOXOPHLORIN COMPLEX - [INDIUM(III)(OCTAETHYLOXOPHLORIN)](2) [J].
BALCH, AL ;
NOLL, BC ;
OLMSTEAD, MM ;
REID, SM .
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1993, (13) :1088-1090
[4]   CHEMISTRY OF IRON OXOPHLORINS .1. H-1-NMR AND STRUCTURAL STUDIES OF 5-COORDINATE IRON(III) COMPLEXES [J].
BALCH, AL ;
LATOSGRAZYNSKI, L ;
NOLL, BC ;
OLMSTEAD, MM ;
ZOVINKA, EP .
INORGANIC CHEMISTRY, 1992, 31 (11) :2248-2255
[5]   COORDINATION PATTERNS FOR OXOPHLORIN LIGANDS - PYRIDINE-INDUCED CLEAVAGE OF DIMERIC MANGANESE(III) AND IRON(III) OCTAETHYLOXOPHLORIN COMPLEXES [J].
BALCH, AL ;
NOLL, BC ;
REID, SM ;
ZOVINKA, EP .
INORGANIC CHEMISTRY, 1993, 32 (12) :2610-2611
[6]  
BALCH AL, 1990, INORG CHEM, V29, P353
[7]  
BARNETT G, 1973, J CHEM SOC P1, P69
[8]   BIOSYNTHESIS OF PHYCOBILINS [J].
BEALE, SI .
CHEMICAL REVIEWS, 1993, 93 (02) :785-802
[9]   PROTON MAGNETIC-RESONANCE STUDIES ON HIGH-SPIN IRON(III) PORPHYRINS [J].
BEHERE, DV ;
BIRDY, R ;
MITRA, S .
INORGANIC CHEMISTRY, 1982, 21 (01) :386-390
[10]  
BERTINI I, 1986, NMR PARAMAGNETIC MOL