Organometallic approaches are of ongoing interest for the development of novel functional 99mTc radiopharmaceuticals, while the basic organotechnetium chemistry seems frequently to be little explored. Thus, structural and reactivity studies with the long-lived isotope 99Tc are of permanent interest as the foundation for further progress in the related radiopharmaceutical research with this artificial element. Particularly the knowledge about the organometallic chemistry of high-valent technetium compounds is scarcely developed. Here, phenylimido complexes of technetium(V) with different isocyanides are introduced. They have been synthesized by ligand-exchange procedures starting from [Tc(NPh)Cl3(PPh3)2]. Different reactivity patterns and products have been obtained depending on the steric and electronic properties of the individual ligands. This involves the formation of 1:1 and 1:2 exchange products of Tc(V) with the general formulae [Tc(NPh)Cl3(PPh3)(isocyanide)], cis- or trans-[Tc(NPh)Cl3(isocyanide)2], but also the reduction in the metal and the formation of cationic technetium(I) complex of the formula [Tc(isocyanide)6]+ when p-fluorophenyl isocyanide is used. The products have been studied by single-crystal X-ray diffraction and spectroscopic methods, including IR and multinuclear NMR spectroscopy. DFT calculations on the different isocyanides allow the prediction of their reactivity towards electron-rich and electron-deficient metal centers by means of the empirical SADAP parameter, which has been derived from the potential energy surface of the electron density on their potentially coordinating carbon atoms.
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Phenylimido complexes of rhenium: fluorine substituents provide protection, reactivity, and solubility
Reactions of [Re(NPhF)Cl 3 (PPh 3 ) 2 ] ({NPhF} 2− = p -fluorophenylimide) with a variety of alkyl and aryl isocyanides have been studied. Different reactivity patterns and products have been obtained depending on the steric and electronic properties of the individual ligands. This involves the formation of 1 : 1 and 1 : 2 exchange products of Re( v ) with the general formulae mer -[Re(NPhF)Cl 3 (PPh 3 )(isocyanide)] and cis - or trans -[Re(NPhF)Cl 3 (isocyanide) 2 ]. The stability of the obtained products is correlated with the substitution pattern of the isocyanide ligands. The products have been studied by single-crystal X-ray diffraction and spectroscopic methods, including IR and multinuclear NMR spectroscopy as well as mass spectrometry. The use of partially fluorinated starting materials and ligands allows the modulation of the solubilities of the starting materials and the products as well as the monitoring of the reactions by means of 19 F NMR. The attachment of the CF 3 or F substituent on the isocyanides gives control over the steric bulk and the electronic properties of the ligands and, thus, their reactivity.
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- Award ID(s):
- 1802646
- NSF-PAR ID:
- 10450664
- Date Published:
- Journal Name:
- Dalton Transactions
- Volume:
- 52
- Issue:
- 15
- ISSN:
- 1477-9226
- Page Range / eLocation ID:
- 4768 to 4778
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d3dt00446e
