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Claude G, Genz J, Weh D, Roca Jungfer M, Hagenbach A, Gembicky M, Figueroa JS, Abram U. Mixed-Isocyanide Complexes of Technetium under Steric and Electronic Control. Inorg Chem 2022; 61:16163-16176. [PMID: 36167508 DOI: 10.1021/acs.inorgchem.2c02730] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reactions of the alkyl isocyanide fac-[Tc(CO)3(CNR)2Cl] complexes (2) (CNR = CNnBu or CNtBu) with the sterically encumbered isocyanide CNp-FArDarF2 [DArF = 3,5-(CF3)2C6H3] allow a selective exchange of the carbonyl ligands of 2 and the isolation of the mixed-isocyanide complexes mer,trans-[Tc(CNp-FArDarF2)3(CNR)2Cl] (3). Depending on the steric requirements of the residues R, the remaining chlorido ligand can be replaced by another isocyanide ligand. Cationic complexes such as mer-[Tc(CNp-FArDarF2)3(CNnBu)3]+ (4a) or mer,trans-[Tc(CNp-FArDarF2)3(CNnBu)2(CNtBu)]+ (6) have been prepared in this way and isolated as their PF6- salts. mer,trans-[Tc(CNp-FArDarF2)3(CNnBu)2(CNtBu)](PF6) represents to the best of our knowledge the first transition-metal complex with three different isocyanides in its coordination sphere. Since the degree of the ligand exchange seems to be controlled both by the electronic and steric measures of the incoming isocyanides, we undertook similar reactions with the sterically less demanding p-fluorophenyl isocyanide, CNPhpF, which indeed readily led to the hexakis(isocyanide)technetium(I) cation through an exchange of all ligands in the staring materials [Tc2(CO)6(μ-Cl)3]- or fac-[Tc(CO)3(CNR)2Cl]. The influence of the substituents at the isocyanide ligands in such reactions has been reasoned with the density functional theory-derived electrostatic potential at the accessible surface of the corresponding isocyanide carbon atoms.
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Affiliation(s)
- Guilhem Claude
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34/36, Berlin 14195, Germany
| | - Jonas Genz
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34/36, Berlin 14195, Germany
| | - Dominik Weh
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34/36, Berlin 14195, Germany
| | - Maximilian Roca Jungfer
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34/36, Berlin 14195, Germany
| | - Adelheid Hagenbach
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34/36, Berlin 14195, Germany
| | - Milan Gembicky
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, San Diego, California 92093, United States
| | - Joshua S Figueroa
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, San Diego, California 92093, United States
| | - Ulrich Abram
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34/36, Berlin 14195, Germany
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Freiberg E, Davis WM, Davison A, Jones AG. Synthesis and characterization of technetiumtetrakis(acetonitrile)bis(triphenylphosphine) cationic complexes. Inorg Chem 2002; 41:3337-9. [PMID: 12079449 DOI: 10.1021/ic020017d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new route to low-valent technetium complexes containing multiple acetonitrile ligands has been developed. The reduction of TcCl(4)(PPh(3))(2) with zinc metal dust in acetonitrile results in the formation of [Tc(CH(3)CN)(4)(PPh(3))(2)][Zn(2)Cl(6)](1/2). The hexafluorophosphate salt of the analogous Tc(II) cation can be prepared via chemical oxidation of the Tc(I) species, and the Tc(I) cation can be regenerated via chemical reduction. The compounds have been characterized in the solid state via single-crystal X-ray crystallography, and in solution via a combination of spectroscopic techniques and cyclic voltammetry. The structural parameters found in the two complexes are similar to each other; however, the difference in oxidation state is reflected, as expected, in the spectroscopic results. The electrochemical data, obtained from cyclic voltammograms of Tc(CH(3)CN)(4)(PPh(3))(2)](PF(6))(n)() (n = 1,2), mirror the synthetic results in that both compounds possess a reversible redox couple at -0.55 V versus ferrocene, which has been assigned to the Tc(II)/Tc(I) couple.
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Affiliation(s)
- Evan Freiberg
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Rochon FD, Melanson R, Kong PC. Synthesis and crystal structure of mixed-ligand Tc(I) complexes, with dimethylphenylphosphine and t-butylisonitrile. Inorganica Chim Acta 1996. [DOI: 10.1016/0020-1693(95)04820-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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