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Synthesis and characterization of the first soluble phthalocyaninatorhenium complexes
ELSEVIER
Synthetic Metals 71 (1995) 2285-2286
Synthesis and characterization of the first soluble phthalocyaninatorhenium
complexes
U. Ziener, K. Diirr and M. Hanack Universitat Tubingen, Institut ftir Organ&he Chemie II Auf der Morgenstelle 18, 72076 Tiibingen, Germany Abstract The synthesis and characterization of the first soluble phthalocyaninatorhenium complexes with axial ligands nitride, N3- or oxide, 02‘ and ethoxide, EtO- soluble in common organic solvents are reported. Besides the monomer complexes (t-Bu),PcReN (1) and (f-Bu),PcReO(OEt) (3) a dimeric p-0x0 compound [(t-Bu),PcReOlzO (4) was also prepared. The complexes were characterized by NMR, UV/Vis, IR, MS and CV. The nitrido complex is compared with the already known unsubstituted compound PcReN (2).
1. INTRODUCTION Only few complexes with rhenium as central metal in phthalocyaninatometal complexes are known11~21 and these compounds are all quite insoluble in common organic solvents. Recently we have synthesized the first soluble phthalocyaninatorhenium complex, (t-Bu)4PcReN (1)131.Here we report on this compound and compare it with the already known unsubstituted species, PcReN (2)121. Furthermore we report on the synthesis and characterization of two new soluble phthalocyaninatorhenium complexes, (f-Bu)4PcReO(OEt) (3) and [(f-Bu),PcReO],O (4). These oxoand p-oxo-metallates. respectively are already known with porphyrin as macrocyclic system141.
2. RESULTS AND DISCUSSION 2.1. (t-Bu),PcReN (l), PcReN (2)12,31 The reaction of ammonium perrhenate, NH,ReO,, and 4ferf-butylphthalodinitrile or phthalodinitrile leads to the nitrido complexes (t-Bu),PcReN (1) and PcReN (2), respectively. The products are purified by columnar chromatography on Al,O, with toluene or by extraction with acetone, respectively12v31. The IR spectra of both compounds show a peak at 978 cm-’ which is assigned to the Re-N triple bond vibration. A UV/Vis spectrum of 1 in CH,Cl, exhibits the maximum of the Q band at h,,, = 698 mn (see Table 1). In contrast a solid state electronic spectrum in nujol shows the Q band (&X = 697 nm) with two shoulders (see Table 1). These shoulders are assigned to exciton interactions of dimeric units. A corresponding spectrum of PcReN (2) in nujol exhibits also the = 656 run) with two shoulders (see Table 1). But Q band(hmax in this case the intensity of the two bands at 656 and 805 nm which we again attribute to dimeric units is higher than in the 0379-6779/95/$09.50
SSDI
0
1995 Elsevier
0379-6779(94)03260-D
Science
S.A.
All rights reserved
former case of the substituted product 1. Therefore we assume the dimeric units in 2 to be present in excess in contrast to the upper case. In the cyclic voltammogram of (r-Bu),PcReN (1) two peaks in the reductive region at -0.527 and -0.896 V (vs. SCE) appear representing the reduction of the metal ReiV + Re+*” and of the macrocycle (t-Bu),Pc” -+ (t-Bu),Pc”t, respectively. In the oxidative region only two kinetically irreversible peaks and a shoulder are found. Due to SEC (spectra electrochemical) measurements destruction of the complex is assumed. A ‘H NMR spectrum shows three multiplets in the aromatic region at 6 = 8.39, 9.46 and 9.56 which we assign to the l-H, 2-H and the 2’-H proton, respectively (see Fig.1). Due to the ratio of the signals of the tert-butyl groups at 6 = 1.82-1.83 we assume that different isomers are present but not in the expected statistical ratio 1: 1:2:4 (D2,,:C4&..:Cs). The specific electrical dark conductivity of 2 measured by the four probe technique was found to be 0 = 3.10*t” S/cm, a poor electrical semiconductor. After doping with iodine the conductivity was enhanced to be o = 8.10m7S/cm. This enhancement is rather low relative to PcNi (cr = lo-* S/cm) and PcNiI, (o = 7.10-l S/cm).
2.1. (f-Bu)4PcReO(OEt) (3), [(t-Bu),PcReO],O (4) When rhenium pentachloride is reacted with 4-fert-butylphthalodinitrile a green- brown reaction mixture is obtained. with toluenelethanol on After purification A1203 (f-Bu),PcReO(OEt) (3) as a green compound is eluted from the column. Sometimes a second green band can be obtained which represents the dimeric p-0x0 compound [(t-Bu),PcReOlzO (4). Reaction of 3 with pyridine leads also to the dimer 4. The shapes of the IR spectra of both compounds are similar except of two additional peaks at 908 and 949 cm-’ which are only found in the spectrum of 3 and one at 804 cm-l which is
2286
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Ziener et al. I Synthetic Metals 71 (1995) 2285-2286
only found in the spectrum of 4. Due to the Re-0 double bond vibration of a corresponding porphyrin complex, TTPReO(OEt) at 950 cm-‘141 we assign the band at 949 cm-l of (t-Bu),PcReO(OEt) (3) also to this vibration. Although the Re-0 double bond is present in the dimeric [(t-Bu)4PcRe0]20 (4), too, no corresponding peak is found in the IR spectrum as known from the porphyrins141. The Re-0-Re vibration should be found at about 670 cm-‘141. But in this region typical bands of the phthalocyaninato macrocycle of 4 are placed covering this vibration. The UV/Vis spectrum of 3 in CH,Cl, posesses a broad Q band at h,,, = 726 run with shoulders at 694, 660 and 612 nm (see Table 1). The first one may be caused by small amounts of the dimer 4 which is built from 3 after some time especially in solution. 4 exhibits in CH,Cl, a UV/Vis spectrum with a Q band at hmax = 688 nm about 40 mu blue-shifted relatively to the monomeric compound (r-Bu),PcReO(OEt) (3). A small band at 747 mn is found as expected for dimeric complexes e.g. PC@, indicating a forbidden x-x* transition.
(doublet of a doublet) is assigned to the 1-H proton coupling with the 2-H (J = 8.3 Hz) and the 2’-H (J = 1.5 Hz) (see Fig. 1). The second one represents the 2- and the 2’-H. The rerr-butyl groups exhibit two peaks at 6 = 1.81 and 1.83 in the ratio 3:4. At 6 = -1.64 and -2.47 the quartet of the methylene protons and the triplet of the methyl protons are observed (J = 6.9 Hz), respectively, shifted to high field due to the aromatic ring current. As the splitting pattern is relative simple and the number of the peaks low we again assume different isomers of 3 but not in the statistical ratio (see above) or even not all isomers to be present. In contrast in the tH NMR spectrum of the dimer 4 both in the aromatic region and in the region of the tert-butyl groups much more peaks are found and no more detailled interpretation is possible. The multiplets are centered at 6 = 8.92 and 2.11, respectively. Referred to the monomer 3 the multiplets of the aromatic protons are somewhat shifted to high field and the terfbutyl protons stronger to low field. These effects are also observed in the case of the nitrido compound 1 when higher concentrations are used so that aggregation occurs.
Table 1 UV/Vis data of the compounds 1, 2, 3 and 4 (lg E) Compound 1 (CH,Cl,)
1 2 3 4
(nujol) (nujol) (CH,CI,) (CH,Cl,)
h max,Q band 698 (5.553) 750 805 726 (4.854) 747 (4.715)
697 735 688 (5.437)
h max, B band
363 (5.099) 669 375 656 366 368 (4.847) 374 (5.220)
Figure 1. Fragment of a tert-butyl substituted phthalocyaninato complex
REFERENCES The cyclic voltammograms of both compounds 3 and 4 in CH,Cl, in the reductive region are similar to that of the nitrido compound 1 with two quasi reversible peaks. So again the first reduction at -0.55 (3) and -0.49 V (vs. SCE) (4) is assigned to the reduction of the metal and the second one at -0.87 (3) and -0.88 (4) to the reduction of the macrocycle. But in a SEC measurement it can be seen that the monomer 3 dimerizes to the dimeric complex 4. In the oxidative region the voltammograms of both compounds differ. The one of the dimer 4 exhibits two peaks at 0.68 and 1.12 V and the monomer 3 at 0.99 and 1.50 V and a shoulder. But the SEC measurements give us no clear information about the electrochemistry of the compounds 3 and 4 so that further investigations are neccessary. The complexes show in a FD mass spectrum a molecular ion peak at m/z = 984.7 (3, calculated 984.7) and m/z = 1894.0 (4, calculated 1894.7), respectively, with the typical isotope distribution. In the spectrum of 3 the main peak is found at m/z = 939.4, representing the (r-Bu)4PcRe0 fragment. Sometimes a peak at m/z = 2834.0 occurs which fits well to a O={Mac}Re-0-{Mac}Re-0-{Mac}Re=O trimeric unit [{Mac} = (t-Bu),Pc]. This compound could not be obtained yet by chemical way. The ‘IS NMR spectrum of (t-Bu)4PcReO(OEt) (3) looks similar to that of (t-Bu)4PcReN (1). Two multiplets in the aromatic region are found at 6 = 8.38 and 9.51. The first one
1. a) E. Merz, Nukleonik, 8 (1966) 248-252. - b) K. Yoshihara, G. K. Wolf and F. Baumglrtner, Radiochim. Acta, 21 (1974) 96-100. - c) H. Przywarska-Boniecka, Roczniki Chemii, 40 (1966) 1627-1633. - d) H. Przywarska-Boniecka, Roczniki Chemii, 41 (1967) 1703-1710. - e) H. Przywarska-Boniecka, Roczniki Chemii, 42 (1968) 211-218. - f) G. Pfrepper, Z. Chem., 10 (1970) 76. 2. a) A. Mrwa, S. Rummel and M. Starke, Z. Chem., 25 (1985) 186-187. - b) A. Mrwa, H. Giegenhack and M. Starke, Cryst. Res. Technol., 23 (1988) 773-778. 3. U. Ziener and M. Hanack, Chem. Ber., in press. 4. a) J. W. Buchler, L. Puppe, K. Rohbock and H. H. Schneehage, Chem. Ber., 106 (1973) 2710-2732. - b) J. W. Buchler and S. B. Kruppa, Z. Naturforsch., 45b (1990) 518-530.
Synthetic Metals 71 (1995) 2285-2286
Synthesis and characterization of the first soluble phthalocyaninatorhenium
complexes
U. Ziener, K. Diirr and M. Hanack Universitat Tubingen, Institut ftir Organ&he Chemie II Auf der Morgenstelle 18, 72076 Tiibingen, Germany Abstract The synthesis and characterization of the first soluble phthalocyaninatorhenium complexes with axial ligands nitride, N3- or oxide, 02‘ and ethoxide, EtO- soluble in common organic solvents are reported. Besides the monomer complexes (t-Bu),PcReN (1) and (f-Bu),PcReO(OEt) (3) a dimeric p-0x0 compound [(t-Bu),PcReOlzO (4) was also prepared. The complexes were characterized by NMR, UV/Vis, IR, MS and CV. The nitrido complex is compared with the already known unsubstituted compound PcReN (2).
1. INTRODUCTION Only few complexes with rhenium as central metal in phthalocyaninatometal complexes are known11~21 and these compounds are all quite insoluble in common organic solvents. Recently we have synthesized the first soluble phthalocyaninatorhenium complex, (t-Bu)4PcReN (1)131.Here we report on this compound and compare it with the already known unsubstituted species, PcReN (2)121. Furthermore we report on the synthesis and characterization of two new soluble phthalocyaninatorhenium complexes, (f-Bu)4PcReO(OEt) (3) and [(f-Bu),PcReO],O (4). These oxoand p-oxo-metallates. respectively are already known with porphyrin as macrocyclic system141.
2. RESULTS AND DISCUSSION 2.1. (t-Bu),PcReN (l), PcReN (2)12,31 The reaction of ammonium perrhenate, NH,ReO,, and 4ferf-butylphthalodinitrile or phthalodinitrile leads to the nitrido complexes (t-Bu),PcReN (1) and PcReN (2), respectively. The products are purified by columnar chromatography on Al,O, with toluene or by extraction with acetone, respectively12v31. The IR spectra of both compounds show a peak at 978 cm-’ which is assigned to the Re-N triple bond vibration. A UV/Vis spectrum of 1 in CH,Cl, exhibits the maximum of the Q band at h,,, = 698 mn (see Table 1). In contrast a solid state electronic spectrum in nujol shows the Q band (&X = 697 nm) with two shoulders (see Table 1). These shoulders are assigned to exciton interactions of dimeric units. A corresponding spectrum of PcReN (2) in nujol exhibits also the = 656 run) with two shoulders (see Table 1). But Q band(hmax in this case the intensity of the two bands at 656 and 805 nm which we again attribute to dimeric units is higher than in the 0379-6779/95/$09.50
SSDI
0
1995 Elsevier
0379-6779(94)03260-D
Science
S.A.
All rights reserved
former case of the substituted product 1. Therefore we assume the dimeric units in 2 to be present in excess in contrast to the upper case. In the cyclic voltammogram of (r-Bu),PcReN (1) two peaks in the reductive region at -0.527 and -0.896 V (vs. SCE) appear representing the reduction of the metal ReiV + Re+*” and of the macrocycle (t-Bu),Pc” -+ (t-Bu),Pc”t, respectively. In the oxidative region only two kinetically irreversible peaks and a shoulder are found. Due to SEC (spectra electrochemical) measurements destruction of the complex is assumed. A ‘H NMR spectrum shows three multiplets in the aromatic region at 6 = 8.39, 9.46 and 9.56 which we assign to the l-H, 2-H and the 2’-H proton, respectively (see Fig.1). Due to the ratio of the signals of the tert-butyl groups at 6 = 1.82-1.83 we assume that different isomers are present but not in the expected statistical ratio 1: 1:2:4 (D2,,:C4&..:Cs). The specific electrical dark conductivity of 2 measured by the four probe technique was found to be 0 = 3.10*t” S/cm, a poor electrical semiconductor. After doping with iodine the conductivity was enhanced to be o = 8.10m7S/cm. This enhancement is rather low relative to PcNi (cr = lo-* S/cm) and PcNiI, (o = 7.10-l S/cm).
2.1. (f-Bu)4PcReO(OEt) (3), [(t-Bu),PcReO],O (4) When rhenium pentachloride is reacted with 4-fert-butylphthalodinitrile a green- brown reaction mixture is obtained. with toluenelethanol on After purification A1203 (f-Bu),PcReO(OEt) (3) as a green compound is eluted from the column. Sometimes a second green band can be obtained which represents the dimeric p-0x0 compound [(t-Bu),PcReOlzO (4). Reaction of 3 with pyridine leads also to the dimer 4. The shapes of the IR spectra of both compounds are similar except of two additional peaks at 908 and 949 cm-’ which are only found in the spectrum of 3 and one at 804 cm-l which is
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Ziener et al. I Synthetic Metals 71 (1995) 2285-2286
only found in the spectrum of 4. Due to the Re-0 double bond vibration of a corresponding porphyrin complex, TTPReO(OEt) at 950 cm-‘141 we assign the band at 949 cm-l of (t-Bu),PcReO(OEt) (3) also to this vibration. Although the Re-0 double bond is present in the dimeric [(t-Bu)4PcRe0]20 (4), too, no corresponding peak is found in the IR spectrum as known from the porphyrins141. The Re-0-Re vibration should be found at about 670 cm-‘141. But in this region typical bands of the phthalocyaninato macrocycle of 4 are placed covering this vibration. The UV/Vis spectrum of 3 in CH,Cl, posesses a broad Q band at h,,, = 726 run with shoulders at 694, 660 and 612 nm (see Table 1). The first one may be caused by small amounts of the dimer 4 which is built from 3 after some time especially in solution. 4 exhibits in CH,Cl, a UV/Vis spectrum with a Q band at hmax = 688 nm about 40 mu blue-shifted relatively to the monomeric compound (r-Bu),PcReO(OEt) (3). A small band at 747 mn is found as expected for dimeric complexes e.g. PC@, indicating a forbidden x-x* transition.
(doublet of a doublet) is assigned to the 1-H proton coupling with the 2-H (J = 8.3 Hz) and the 2’-H (J = 1.5 Hz) (see Fig. 1). The second one represents the 2- and the 2’-H. The rerr-butyl groups exhibit two peaks at 6 = 1.81 and 1.83 in the ratio 3:4. At 6 = -1.64 and -2.47 the quartet of the methylene protons and the triplet of the methyl protons are observed (J = 6.9 Hz), respectively, shifted to high field due to the aromatic ring current. As the splitting pattern is relative simple and the number of the peaks low we again assume different isomers of 3 but not in the statistical ratio (see above) or even not all isomers to be present. In contrast in the tH NMR spectrum of the dimer 4 both in the aromatic region and in the region of the tert-butyl groups much more peaks are found and no more detailled interpretation is possible. The multiplets are centered at 6 = 8.92 and 2.11, respectively. Referred to the monomer 3 the multiplets of the aromatic protons are somewhat shifted to high field and the terfbutyl protons stronger to low field. These effects are also observed in the case of the nitrido compound 1 when higher concentrations are used so that aggregation occurs.
Table 1 UV/Vis data of the compounds 1, 2, 3 and 4 (lg E) Compound 1 (CH,Cl,)
1 2 3 4
(nujol) (nujol) (CH,CI,) (CH,Cl,)
h max,Q band 698 (5.553) 750 805 726 (4.854) 747 (4.715)
697 735 688 (5.437)
h max, B band
363 (5.099) 669 375 656 366 368 (4.847) 374 (5.220)
Figure 1. Fragment of a tert-butyl substituted phthalocyaninato complex
REFERENCES The cyclic voltammograms of both compounds 3 and 4 in CH,Cl, in the reductive region are similar to that of the nitrido compound 1 with two quasi reversible peaks. So again the first reduction at -0.55 (3) and -0.49 V (vs. SCE) (4) is assigned to the reduction of the metal and the second one at -0.87 (3) and -0.88 (4) to the reduction of the macrocycle. But in a SEC measurement it can be seen that the monomer 3 dimerizes to the dimeric complex 4. In the oxidative region the voltammograms of both compounds differ. The one of the dimer 4 exhibits two peaks at 0.68 and 1.12 V and the monomer 3 at 0.99 and 1.50 V and a shoulder. But the SEC measurements give us no clear information about the electrochemistry of the compounds 3 and 4 so that further investigations are neccessary. The complexes show in a FD mass spectrum a molecular ion peak at m/z = 984.7 (3, calculated 984.7) and m/z = 1894.0 (4, calculated 1894.7), respectively, with the typical isotope distribution. In the spectrum of 3 the main peak is found at m/z = 939.4, representing the (r-Bu)4PcRe0 fragment. Sometimes a peak at m/z = 2834.0 occurs which fits well to a O={Mac}Re-0-{Mac}Re-0-{Mac}Re=O trimeric unit [{Mac} = (t-Bu),Pc]. This compound could not be obtained yet by chemical way. The ‘IS NMR spectrum of (t-Bu)4PcReO(OEt) (3) looks similar to that of (t-Bu)4PcReN (1). Two multiplets in the aromatic region are found at 6 = 8.38 and 9.51. The first one
1. a) E. Merz, Nukleonik, 8 (1966) 248-252. - b) K. Yoshihara, G. K. Wolf and F. Baumglrtner, Radiochim. Acta, 21 (1974) 96-100. - c) H. Przywarska-Boniecka, Roczniki Chemii, 40 (1966) 1627-1633. - d) H. Przywarska-Boniecka, Roczniki Chemii, 41 (1967) 1703-1710. - e) H. Przywarska-Boniecka, Roczniki Chemii, 42 (1968) 211-218. - f) G. Pfrepper, Z. Chem., 10 (1970) 76. 2. a) A. Mrwa, S. Rummel and M. Starke, Z. Chem., 25 (1985) 186-187. - b) A. Mrwa, H. Giegenhack and M. Starke, Cryst. Res. Technol., 23 (1988) 773-778. 3. U. Ziener and M. Hanack, Chem. Ber., in press. 4. a) J. W. Buchler, L. Puppe, K. Rohbock and H. H. Schneehage, Chem. Ber., 106 (1973) 2710-2732. - b) J. W. Buchler and S. B. Kruppa, Z. Naturforsch., 45b (1990) 518-530.