fac-Re(CO)3L complexes containing tridentate monoanionic ligands (L-) with a seldom-studied sulfonamido group as one terminal ligating group
| Autor: | Patricia A. Marzilli, Frank R. Fronczek, Luigi G. Marzilli, Anna Maria Christoforou |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
chemistry.chemical_classification
Anions Sulfonamides Magnetic Resonance Spectroscopy Molecular Structure Chemistry Hydrogen bond Stereochemistry Technetium Ring (chemistry) Crystallography X-Ray Ligands Sulfonamide Inorganic Chemistry chemistry.chemical_compound Deprotonation Rhenium Intramolecular force Diethylenetriamine Organometallic Compounds Moiety Physical and Theoretical Chemistry Radiopharmaceuticals Chirality (chemistry) |
| Zdroj: | Inorganic chemistry. 46(17) |
| ISSN: | 0020-1669 |
| Popis: | To achieve a net-neutral coordination unit in radiopharmaceuticals with a fac-M(CO) 3 + core (M = Tc, Re), facially coordinated monoanionic tridentate ligands are needed. New neutral fac-Re(CO) 3 L complexes were obtained by treating fac-[Re(CO) 3 (H 2 O) 3 ] + with unsymmetrical tridentate NNN donor ligands (LH) based primarily on a diethylenetriamine (dien) moiety with an aromatic group linked to a terminal nitrogen through a sulfonamide. LHs contain 2,4,6-trimethylbenzenesulfonyl (tmbSO 2 ) and 5-(dimethylamino)naphthalene-1-sulfonyl (DNS) groups. X-ray crystallographic and NMR analyses confirm that in both the solid and the solution states all L - in fac-Re(CO) 3 L complexes are bound in a tridentate fashion with one donor being nitrogen from a deprotonated sulfonamido group. Another fundamental property that is important in radiopharmaceuticals is shape, which in turn depends on ring pucker. For L- = tmbSO 2 -dien - , tmbSO 2 -N'-Medien - , and tmbSO 2 -N,N-Me 2 dien - , the two chelate rings have a different pucker chirality, as is commonly found for a broad range of metal complexes. However, for fac-Re-(CO) 3 (DNS-dien), both chelate rings have the same pucker chirality because the sulfonamido ring has an unusual pucker for the absolute configuration at Re; a finding that is attributable to intramolecular and intermolecular hydrogen bonds from the sulfonamido oxygens to the NH 2 groups. Averaging of tmb NMR signals, even at -90 °C for Re(CO)3(tmbSO 2 -N,N-Me2dien), indicates rapid dynamic motion in the complexes with this group. However, examination of the structures suggests that free rotation about the S-C(tmb) bond is not possible but that concerted coupled rotations about the N-S and the S-C bonds can explain the NMR data. |
| Databáze: | OpenAIRE |
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