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Metal(II) complexes of a new water-soluble porphyrin, 5,10,15,20-tetrakis(4-phosphonato-methylphenyl)porphyrin
SPECTROSCOPY, SPECIFIC APPLICATIONS 349
G28
METAL(II) COMPLEXES OF A NEW WATER-SOLUBLE P O R P H Y R I N , 5,10,15,20-TETRAKIS(4-PHOSPHONATOMETHYLPHENYL)PORPHYRIN
J. W. Buchler a, A. de Clan b, J. Fischer b, H. Katzenmeier a, and R. Weiss b a Institut fi~r Anorganische Chemie, Technische Hochschule Darmstadt, Petersenstrafle 18, D-64287 Darmstadt, Germany; b Laboratoire de Cristallochimie et de Chimie Structurale (UA 424), Institut Le Bel, Universit# Louis Pasteur, 4 rue B. Pascal, F-67070 Strasbourg, France
5,10,15,20-Tetrakis(4-diethoxyphosphonylmethylphenyl)porphyrin, H2(P404{OEt} 8mpp), was synthesized from 5,10,15,20-tetrakis(4-methoxycarbonylphenyl)Ix~phyrin via reduction with LiA1H4 to the tetrakis(4-hydroxymethyl) derivative, transformation of the latter with PBr3 to the tetrakis(bromomethyl) derivative and Arbusov reaction of the latter with P(OEt) 3. The resulting nicely crystalline oetaethyl tetraphosphonate was fully characterized by 1H and 31p resonance, UVNis, IR, and mass spectra as well as by X-ray crystallography. H2(P404{OEt} 8mpp) was treated with SiMe3Br and NaOH to yield, after ultrafiltration in water, Na4[H2(P408{OH}4mpp)], a tetra(hydrogenphosphonate) the four protons of which dissociated in excess NaOH; in excess acid (pH < 3), the porphyrin tetraphosphonic acid H2(P404 {OH} 8mpp) precipitated. The tetra(hydrogenphosphonate) was metalated with nickel or zinc acetylacetonate in water yielding [M(P408{OH}4mpp)] 4" (M = Ni, Zn). On the other hand, the octaester H2(P404{OEt}8mpp) was metalated with Cu(OAc)2 in EtOH or with PtCI2 in PhCN to yield the metal(II) complexes, M(P404{OEt}8mpp) (M = Cu, Pt), from which the water-soluble salts, e. g., Na4[Cu(P408{OH}4mpp)].8H2 O, were obtained as described above. 31p NMR spectra of H2(P404{OEt}8mpp) or Na4[H2(P408{OH}4mpp)] (CDCI 3 or D20, ext. H3PO4) showed a single peak at 27.2 ppm or two peaks at 19.8 and 17.9 ppm, respectively, which appear in broader shape and slightly shifted to higher field in the spectra of the respective paramagnetic COlVer(ID complexes. All the tetraphosphonates [M(P404+n{OH}4.nmpp)](4+n) - (M = Cu, Ni, Pt, Zn) are watersoluble (4 < pH < 14) up to c = 0.1 mol/l. They show the aggregation phenomena known for the corresponding tetra(sulfonatophenyl)porphyrin derivatives. Electrophoresis at agarose gels proved that uniform water-soluble species have been prepared. The migration rates and UV/Vis data showed that for 3 < pH < 5, the phosphonate exists as an inner salt, [H4(P408(OH}4mpp)] 2", which is progressively deprotonated at the pyrrole nitrogen atoms and at the phosphonate groups when the pH value is increased. The dependence of the migration paths on pH and nature of the central metal (M = Cu, Ni, Pt, Zn) was studied. Thus, [M(P408{OH}4mpp)] 4- (M = Cu, Ni, Pt) migrate with different but constant speeds for 5 < pH < 10. This is difficult to explain in view of the progressive deprotonation with increasing pH which was observed via acid/base titrations. It appears that aggregation phenomena are responsible for this peculiar behavior. The rather slow migration of the nickel phosphonate is explained by axial diaqna complex formation of the nickel(II) ion.
G28
METAL(II) COMPLEXES OF A NEW WATER-SOLUBLE P O R P H Y R I N , 5,10,15,20-TETRAKIS(4-PHOSPHONATOMETHYLPHENYL)PORPHYRIN
J. W. Buchler a, A. de Clan b, J. Fischer b, H. Katzenmeier a, and R. Weiss b a Institut fi~r Anorganische Chemie, Technische Hochschule Darmstadt, Petersenstrafle 18, D-64287 Darmstadt, Germany; b Laboratoire de Cristallochimie et de Chimie Structurale (UA 424), Institut Le Bel, Universit# Louis Pasteur, 4 rue B. Pascal, F-67070 Strasbourg, France
5,10,15,20-Tetrakis(4-diethoxyphosphonylmethylphenyl)porphyrin, H2(P404{OEt} 8mpp), was synthesized from 5,10,15,20-tetrakis(4-methoxycarbonylphenyl)Ix~phyrin via reduction with LiA1H4 to the tetrakis(4-hydroxymethyl) derivative, transformation of the latter with PBr3 to the tetrakis(bromomethyl) derivative and Arbusov reaction of the latter with P(OEt) 3. The resulting nicely crystalline oetaethyl tetraphosphonate was fully characterized by 1H and 31p resonance, UVNis, IR, and mass spectra as well as by X-ray crystallography. H2(P404{OEt} 8mpp) was treated with SiMe3Br and NaOH to yield, after ultrafiltration in water, Na4[H2(P408{OH}4mpp)], a tetra(hydrogenphosphonate) the four protons of which dissociated in excess NaOH; in excess acid (pH < 3), the porphyrin tetraphosphonic acid H2(P404 {OH} 8mpp) precipitated. The tetra(hydrogenphosphonate) was metalated with nickel or zinc acetylacetonate in water yielding [M(P408{OH}4mpp)] 4" (M = Ni, Zn). On the other hand, the octaester H2(P404{OEt}8mpp) was metalated with Cu(OAc)2 in EtOH or with PtCI2 in PhCN to yield the metal(II) complexes, M(P404{OEt}8mpp) (M = Cu, Pt), from which the water-soluble salts, e. g., Na4[Cu(P408{OH}4mpp)].8H2 O, were obtained as described above. 31p NMR spectra of H2(P404{OEt}8mpp) or Na4[H2(P408{OH}4mpp)] (CDCI 3 or D20, ext. H3PO4) showed a single peak at 27.2 ppm or two peaks at 19.8 and 17.9 ppm, respectively, which appear in broader shape and slightly shifted to higher field in the spectra of the respective paramagnetic COlVer(ID complexes. All the tetraphosphonates [M(P404+n{OH}4.nmpp)](4+n) - (M = Cu, Ni, Pt, Zn) are watersoluble (4 < pH < 14) up to c = 0.1 mol/l. They show the aggregation phenomena known for the corresponding tetra(sulfonatophenyl)porphyrin derivatives. Electrophoresis at agarose gels proved that uniform water-soluble species have been prepared. The migration rates and UV/Vis data showed that for 3 < pH < 5, the phosphonate exists as an inner salt, [H4(P408(OH}4mpp)] 2", which is progressively deprotonated at the pyrrole nitrogen atoms and at the phosphonate groups when the pH value is increased. The dependence of the migration paths on pH and nature of the central metal (M = Cu, Ni, Pt, Zn) was studied. Thus, [M(P408{OH}4mpp)] 4- (M = Cu, Ni, Pt) migrate with different but constant speeds for 5 < pH < 10. This is difficult to explain in view of the progressive deprotonation with increasing pH which was observed via acid/base titrations. It appears that aggregation phenomena are responsible for this peculiar behavior. The rather slow migration of the nickel phosphonate is explained by axial diaqna complex formation of the nickel(II) ion.