Steric Titration of Arylthiolate Coordination Modes at Pseudotetrahedral Nickel(II) Centers
| Autor: | Swarup Chattopadhyay, Victor G. Young, Tapash Deb, Jeffrey L. Petersen, Michael P. Jensen |
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| Rok vydání: | 2009 |
| Předmět: |
Models
Molecular Steric effects Magnetic Resonance Spectroscopy Chemistry chemistry.chemical_element Stereoisomerism Crystallography X-Ray Hydrocarbons Aromatic Inorganic Chemistry Crystallography Nickel Spectrophotometry Quantum Theory Titration Sulfhydryl Compounds Physical and Theoretical Chemistry Boron |
| Zdroj: | Inorganic Chemistry. 49:457-467 |
| ISSN: | 1520-510X 0020-1669 |
| DOI: | 10.1021/ic901347p |
| Popis: | Several derivatives of the pseudotetrahedral phenylthiolate complex Tp(Me,Me)Ni-SPh (1), Tp(Me,Me-) = hydrotris(3,5-dimethyl-1-pyrazolyl)borate, were prepared incorporating substituted arylthiolates, including a series of ortho-substituted ligands Tp(Me,Me)Ni-SR (R = 2,6-Me(2)C(6)H(3), 2; 2,4,6-Me(3)C(6)H(2), 3; 2,4,6- (i)Pr(3)C(6)H(2), 4; and 2,6-Ph(2)C(6)H(3), 5) and a series of para-substituted complexes (R = C(6)H(4)-4-OMe, 6; C(6)H(4)-4-Me, 7; and C(6)H(4)-4-Cl, 8). The products were characterized by (1)H NMR and UV-vis spectroscopy. Spectra of 6-8 were consistent with retention of a common structure across the para-substituted series with modest perturbation of the spectral features of 1 assisting their assignment. In contrast, spectra of 2-5 were indicative of a significant change in configuration across the ortho-disubstituted series. The structure of complex 5 was determined by X-ray crystallography and a distinctive arylthiolate ligation mode was found, in which the N(3)S ligand field was significantly distorted toward a sawhorse, compared to a more common trigonal pyramidal shape (e.g., 1). Moreover, the arylthiolate substituent rotated from a vertical orientation co-directional with the pyrazole rings and disposed between two of them in 1, to a horizontal orientation perpendicular to and over a single pyrazole ring in 5. This reorientation is necessary to accommodate the large ortho substituents of the latter complex. The divergent Ni-S coordination modes result in distinct (1)H NMR and electronic spectra that were rationalized by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. These results demonstrate rich coordination chemistry for arylthiolates that can be elicited by steric manipulation at the periphery of pseudotetrahedral ligand fields. |
| Databáze: | OpenAIRE |
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