- Stabilizing coordinated radicals via metal-ligand covalency: A structural, spectroscopic, and theoretical investigation of group 9 tris(dithiolene) complexes
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Proper assignment of redox loci in coordination complexes with redox-active ligands to either the metal or the ligand is essential for rationalization of their chemical reactivity. However, the high covalency endemic to complexes of late, third-row transition metals complicates such assignments. Herein, we systematically explore the redox behavior of a series of group 9 tris(dithiolene) complexes, [M(mnt)3]3- (M = Ir, Rh, Co; mnt = maleonitriledithiolate). The Ir species described comprise the first examples of homoleptic Ir dithiolene complexes. The enhanced metal-ligand covalency of the Ir-S interaction leads to remarkable reactivity of [Ir(mnt)3]3- and stabilization of mononuclear [Ir(mnt)3]2- complex ions as well as dimerized versions featuring weak, covalent, intermolecular S-S bonds. The dianionic Rh and Co analogues are, in contrast, highly unstable, resulting in the rapid formation of [Rh2(mnt)5]4- and [Co(mnt)2]22-, respectively. The synthesized complexes were studied by single-crystal X-ray diffraction, X-ray absorption spectroscopy, optical spectroscopy, magnetometry, density functional theory, and spectroscopy-oriented configuration interaction calculations. Spectroscopic and theoretical analyses suggest that the stability of [Ir(mnt)3]2- may be attributed to dilution of ligand radical character by a high degree of Ir 5d character in the singly occupied molecular orbital.
- Morsing, Thorbjorn J.,Macmillan, Samantha N.,Uebler, Jacob W. H.,Brock-Nannestad, Theis,Bendix, Jesper,Lancaster, Kyle M.
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p. 3660 - 3669
(2015/04/14)
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- Bis[dirhodium(II)] complexes with a Rh4(μ-Cl)4 core: Preparation and characterization
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The reaction of [Rh2(O2CPrn)4] or [Rh2(mhp)4] (Hmhp = 2-hydroxy-6-methylpyridine) with a trialkylchlorosilane followed by crystallization from a nitrile unexpectedly gave [Rh4(O2-CPrn)4Cl4(CH 3CN)4] 1 or an isomer of [Rh4(mhp)4Cl4(PhCN)2] both with a 'twisted-cage' Rh4(μ-Cl)4 core, which were studied by X-ray crystallography, cyclic voltammetry and UV/VIS spectroscopy; 1 catalyzed the hydrogenation of acrylic acid in water.
- Yang, Zhiyong,Oki, Hiroki,Ebihara, Masahiro,Kawamura, Takashi
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p. 2277 - 2278
(2007/10/03)
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- Preparation and spectral studies of a series of rhodium(III)-acetonitrile complexes
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A series of rhodium(III)-acetonitrile complexes of the general formula RhClm(CH3CN)n3-m have been prepared and characterized by their visible, infrared (4000-70 cm-1), and proton nmr spectra. The preparation of the trans-RhCl4(CH3CN)2- is reported for the first time. The configurations of the two geometrical isomers of the complex RhCl3(CH3CN)3 are elucidated on the basis of their proton nmr spectra. The visible and far-infrared spectra of these rhodium(III) acetonitrile complexes are quite similar to those exhibited by the analogous rhodium(III) pyridine complexes, thus indicating the considerable strength of acetonitrile as a ligand for second-row transition metals.
- Catsikis, Basil D.,Good, Mary L.
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p. 1095 - 1099
(2008/10/08)
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