163237-58-9Relevant academic research and scientific papers
Characterization of sites of different thermodynamic affinities on the same metal center via isothermal titration calorimetry
Moschetta, Eric G.,Gans, Kristina M.,Rioux, Robert M.
, p. 1 - 9 (2013/07/05)
We investigate the binding thermodynamics of a series of phosphorus ligands to a model compound, PdCl2(solv)2, where solv refers to a molecule of solvent, using isothermal titration calorimetry (ITC). ITC allows for the quantification of the equilibrium binding constant, the binding enthalpy, and the binding stoichiometry all in a single experiment. For systems in which two equivalents of ligand were able to bind to the Pd center, the binding sites on each Pd center in solution showed a different thermodynamic affinity for the same ligand. Changes in binding modes between different phosphorus ligands were due to steric bulk and poor electron-donating ability of such ligands. Our results demonstrate ligand binding was strongly enthalpy-driven due to solvent reorganization, which is the rearrangement of solvent molecules in the bulk solvent and the solvent molecules surrounding the solvated species.
Syntheses and reactivities of indole and indolyl complexes of (cymene)ruthenium(II)
Chen,Carperos,Noll,Swope,DuBois
, p. 1221 - 1231 (2008/10/09)
In this paper, we report the synthesis and characterization of related sandwich complexes of (cymene)Ru-(II) containing the indole and indolyl ligands. We wished to compare the effect of metal π-coordination on the reactivities ofthe pyrrole and indole rings. Both indole and indolyl derivatives of (cymene)Ru-(II) have been synthesized and characterized. The η6-coordination of the carbocyclic ring of the bicyclic ligand has been confirmed by X-ray diffraction studies for both the indole and indolyl complexes. The aqueous pKa values of the coordinated indole, 2-methyl- and 2,3-dimethylindole ligands were determined to be 7.71, 8.02, and 8.15, respectively. Coordination of a second metal ion to [(cymene)Ru(2,3-dimethylindolyl)]OTf occurred at the anionic nitrogen of the pyrrolyl ring and the heteronuclear η6-η1 complexes ](cymene)Ru(2,3-dimethylindolyl)PdCl2PPh3]OTf (5) and (](cymene)Ru(2,3-dimethylindolyl)]2Cu)(OTf)3 (6) have been isolated. The coordination of the Cu(I) ion in the indolyl complex led to a pattern of nucleophilic addition for 6 similar to that observed for [(cymene)Ru(1-methylindole]2+ (3b). However, the selectivity of the reaction with 6 was significantly enhanced, and only a single regioisomer of the hydride addition product was formed at -78°C. In these studies of the (cymene)Ru(II) derivatives, no evidence for η5-coordination of the indolyl ligand or for activation of the hyeterocyclic ring toward nucleophilic attack has been observed.
