The functionalisation of the 16-electron complex [Os(η(6)-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)] (1) with a series of Lewis bases to give the 18-electron complexes of general formula [Os(η(6)-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)(L)] (L = pyridine (2), 4-dimethylaminopyridine (3), 4-cyanopyridine (4), 4-methoxypyridine (5), pyrazine (6), pyridazine (7), 4,4'-bipyridine (8) and triphenylphosphine (9)) is reported. All 18-electron complexes are in equilibrium in solution with the 16-electron precursor, and thermochromic properties are observed in some cases (2, 3, 5, 8, and 9). The binding constants and Gibbs free energies of the equilibria are determined using UV-visible titrations and their stabilities investigated. Synthetic routes for forcing the formation of the 18-electron species are proposed, and analytical methods to characterise the equilibria are described.
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http://dx.doi.org/10.1039/c5dt04398k | DOI Listing |
Phys Chem Chem Phys
December 2024
MOE Key Laboratory for Non-Equilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, China.
Electron-counting rules are promising for determination of chemically stable complexes for various elemental groups. While the 18-electron rule has been established for transition metals, recent experiments have discovered that alkaline-earth metals may follow a 20-electron rule when coordinated with CO or benzene. Herein, by employing first-principles calculations at the level of the generalized gradient approximation functional combined with the def2-SVP basis set, we theoretically predict a series of stable 20-electron exohedral alkaline-earth metallofullerenes, in which each alkaline-earth metal is η-coordinated with three Cs, leading to stable trigonal pyramidal structures.
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November 2024
Department of Chemistry, Bielefeld Universtity, Universitätsstr. 25, D-33615, Bielefeld, Germany.
We have developed a family of dinuclear complexes using 2,7-disubstituted 1,8-naphthalenediol ligands that bind by molecular recognition to two neighboring phosphate diesters of the DNA backbone with the dinuclear Cu and Ni complexes exhibiting a severe cytotoxicity for human cancer cells. To increase the binding affinity, we intended to synthesize the corresponding dinuclear Fe complex. Surprisingly, we obtained a tetranuclear Fe perylene-based complex instead of the expected dinuclear Fe naphthalene-based complex.
View Article and Find Full Text PDFInorg Chem
November 2024
Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan 420088, Russian Federation.
This study employs an analysis of the per-electron potentials and the superposition of the electrostatic and kinetic force fields, () and (), and the gradients of the potential energy and one-electron densities to investigate the binding mechanism in trimethylenemethane iron tricarbonyl complex (TMM)Fe(CO). Our approach permits the delineation of the "ligand-binding" force field generated by the metal nucleus but partially operating within the ligand atoms. A mechanical rationale for metal-ligand interactions is thus presented: In the corresponding area, the attractive force () provides the backdrop against which the homotropic static force () and the heterotropic kinetic force () exert attractive and repulsive influences, respectively, toward the metal nucleus on a portion of the electrons belonging to the ligand atoms.
View Article and Find Full Text PDFInorg Chem
November 2024
Center for Science at Extreme Conditions (CSEC) and the School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH3 9FD, U.K.
The Na-W-H and Na-Re-H ternary systems were studied in a diamond anvil cell through X-ray diffraction and Raman spectroscopy, supported by density functional theory and molecular dynamics calculations. NaWH can be synthesized above 7.8 GPa and 1400 K, remaining stable between at least 0.
View Article and Find Full Text PDFDalton Trans
November 2024
Department of Chemistry, University of Georgia, Athens, Georgia, 30602, USA.
The structures and energetics of the binuclear methylphosphinidene complexes of cyclopentadienylruthenium carbonyls of the type [MePRu(CO)Cp] ( = 4, 3, 2, 1) have been investigated for comparison with their previously studied iron analogues. For the tetracarbonyls and tricarbonyls [MePM(CO)Cp] ( = 4, 3) substituting ruthenium for iron has relatively little effect on the energetically preferred structures. Thus such structures have two-electron donor bridging MeP groups with no metal-metal bond for the tetracarbonyls and a metal-metal single bond for the tricarbonyls.
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