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Table 5. Electronic spectra and ligand field parameters of low-spin ruthenium(u1) complexes (cm™ !) The two spin-forbidden transitions *T, > *T, and *T, > ‘*T, are separated by 8B; by assuming C/B = 41° we can calculate B and C, then 10Dg, using the transition 2T, + 7A,,?T, (Table 4). With these values the other d—d transitions were calculated in order to check the exact assignment of the d-d bands in our complexes. As shown in Table 5 the calculated energies for the excited configuration 1344 fall in the same

Table 5 Electronic spectra and ligand field parameters of low-spin ruthenium(u1) complexes (cm™ !) The two spin-forbidden transitions *T, > *T, and *T, > ‘*T, are separated by 8B; by assuming C/B = 41° we can calculate B and C, then 10Dg, using the transition 2T, + 7A,,?T, (Table 4). With these values the other d—d transitions were calculated in order to check the exact assignment of the d-d bands in our complexes. As shown in Table 5 the calculated energies for the excited configuration 1344 fall in the same

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Another ramification of this research is the correlation of the actions and effects of drugs with their chemical structures. Such structural activity relationships are an integral link in the analysis of drug action, and exploitation of this relationship among established therapeutic agents has often led to the development of improved drugs. Finally, we have to bear in mind the possible interactions between drugs and metal-containing enzymatic systems, because these interactions are very often danger- ous to living organisms. Tn a nreviainc naner® we rannrted the terizidane derivatives af cohalttn) nickelftr). Furthermore, this study has been stimulated by the fact that the metal complexes with ligands showing biological activity are more active than the free ligands.*> The use of terizidone as a metal complex instead of the free molecule could be a better route of administration associated with a smaller risk of toxic side effects and could be a double sustained-release pharmaceutical preparation.
Another ramification of this research is the correlation of the actions and effects of drugs with their chemical structures. Such structural activity relationships are an integral link in the analysis of drug action, and exploitation of this relationship among established therapeutic agents has often led to the development of improved drugs. Finally, we have to bear in mind the possible interactions between drugs and metal-containing enzymatic systems, because these interactions are very often danger- ous to living organisms. Tn a nreviainc naner® we rannrted the terizidane derivatives af cohalttn) nickelftr). Furthermore, this study has been stimulated by the fact that the metal complexes with ligands showing biological activity are more active than the free ligands.*> The use of terizidone as a metal complex instead of the free molecule could be a better route of administration associated with a smaller risk of toxic side effects and could be a double sustained-release pharmaceutical preparation.
Table 1. Analytical data and other physical properties
Table 1. Analytical data and other physical properties
Band / are taken to be 918 and 90 cm~! respectively for the free gaseous Cr?* ion Electronic Spectral Study and Magnetic Susceptibility Measurements Table 3. Electronic spectra and ligand field parameters of chromium(1) complexes (em~ ') conversion of the resultant halide into the oxide suggests that the decompositions are complicated in character and most likely involve thermal breakdown of the ligand. The t.g. and d.t.g. curves of the ruthenium derivatives are more clear than those described above and show a significantly different profile. The complex [Ru(trz)- (H,0),C13],2H,O, for example, decomposes in a four-stage process: it loses two molecules of crystallization water in the 50-120° temperature range, the second step is the loss of two molecules of coordination water in the range 140-185°, followed by the loss of three chlorine atoms between 200 and 290° and finally by the loss of the ligand in the 290-650° region, giving Ru,O, as end-product. The behaviour of the analogous bromo derivative is similar.
Band / are taken to be 918 and 90 cm~! respectively for the free gaseous Cr?* ion Electronic Spectral Study and Magnetic Susceptibility Measurements Table 3. Electronic spectra and ligand field parameters of chromium(1) complexes (em~ ') conversion of the resultant halide into the oxide suggests that the decompositions are complicated in character and most likely involve thermal breakdown of the ligand. The t.g. and d.t.g. curves of the ruthenium derivatives are more clear than those described above and show a significantly different profile. The complex [Ru(trz)- (H,0),C13],2H,O, for example, decomposes in a four-stage process: it loses two molecules of crystallization water in the 50-120° temperature range, the second step is the loss of two molecules of coordination water in the range 140-185°, followed by the loss of three chlorine atoms between 200 and 290° and finally by the loss of the ligand in the 290-650° region, giving Ru,O, as end-product. The behaviour of the analogous bromo derivative is similar.
Table 4. Electronic spectratand ligand field parameters of low-spin ruthenium(i11) complexes (em~*): first approach
Table 4. Electronic spectratand ligand field parameters of low-spin ruthenium(i11) complexes (em~*): first approach
Bis taken to be 720 cm™! for the free gaseous Rh*+ ion Table 6. Electronic spectra and ligand field parameters of rhodium(i1) complexes (cm™ ')
Bis taken to be 720 cm™! for the free gaseous Rh*+ ion Table 6. Electronic spectra and ligand field parameters of rhodium(i1) complexes (cm™ ')
Table 7. Far-infrared bands of terizidone complexes (450-50 cm~+) modes,?17-18:32.35 Qn the basis of these i.r. results the greatest attainable symmetry is C,, (mer-isomers) with 2a, +b, representations for the ML, and MX; stretching modes. In fac-isomers, with C3, symmetry, only two v(M-L) and two v(M=X) vibra- tions are infrared active (a,;+e). As for the v(M-X) vibrations, we thus assign the two bands at higher frequencies to the two vibrations involving predominantly the mutually trans halides and the band at lower energy to the chromium-halide stretching mode of the halide in trans position to the donor ligand atom. The ratio v(Cr~Br)/ w(Cr—-Cl), equal to 0-77, lies just at the end of the range where this value is usually. found for octahedral chromium complexes in a C, symmetry, while the ratio v(Ru-Br)/v(Ru-Cl), 0:62, is in accord with literature data for octahedral complexes in the symmetry suggested above.'”
Table 7. Far-infrared bands of terizidone complexes (450-50 cm~+) modes,?17-18:32.35 Qn the basis of these i.r. results the greatest attainable symmetry is C,, (mer-isomers) with 2a, +b, representations for the ML, and MX; stretching modes. In fac-isomers, with C3, symmetry, only two v(M-L) and two v(M=X) vibra- tions are infrared active (a,;+e). As for the v(M-X) vibrations, we thus assign the two bands at higher frequencies to the two vibrations involving predominantly the mutually trans halides and the band at lower energy to the chromium-halide stretching mode of the halide in trans position to the donor ligand atom. The ratio v(Cr~Br)/ w(Cr—-Cl), equal to 0-77, lies just at the end of the range where this value is usually. found for octahedral chromium complexes in a C, symmetry, while the ratio v(Ru-Br)/v(Ru-Cl), 0:62, is in accord with literature data for octahedral complexes in the symmetry suggested above.'”
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Chemistrychromium (III)Ruthenium (III)
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