Pertosylation of hyperbranched polyglycerol (M(n)=2000; M(w)/M(n)=1.3) followed by partial displacement of the tosyl groups with carboxylic acid functionalized NCN-pincer platinum(II) complexes [PtI-2,6-(NMe(2)CH(2))(2)C(6)H(2)-4-COOH], resulted in covalent attachment of the NCN-pincer complexes to the polyglycerol. These functionalized hyperbranched macromolecules have been characterized by (1)H, (13)C, and (195)Pt NMR, UV-visible, and IR spectroscopy. The presence of Pt and I atoms renders them directly visible by transmission electron microscopy (TEM) without staining procedures, which offers images of associated hyperbranched macromolecules. TEM micrographs show disk-shaped structures with a small size-distribution (15-20 nm), and characteristic core-shell ring structures. The thickness of the corona observed in TEM could be correlated with the substitution degree with pincer platinum moieties.
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http://dx.doi.org/10.1002/chem.200305454 | DOI Listing |
Molecules
March 2021
Organic Chemistry and Catalysis, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
Post-modification of a series of NCN-pincer platinum(II) complexes [PtX(NCN-R-4)] (NCN = [CH(CHNMe)-2,6], R = C(O)H, C(O)Me and C(O)Et), X = Cl or Br) at the -position using the McMurry reaction was studied. The synthetic route towards two new [PtCl(NCN-R-4)] (R = C(O)Me and C(O)Et) complexes used above is likewise described. The utility and limitations of the McMurry reaction involving these pincer complexes was systematically evaluated.
View Article and Find Full Text PDFChemistry
December 2020
Organic Chemistry and Catalysis, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CH, Utrecht, The Netherlands.
Density Functional Theory studies of square-planar Pt pincer structures, (4-Z-NCN)PtCl ([4-Z-NCN] =[4-Z-2,6-(Me NCH ) C H -N,C,N] , Z=H, NO , CF , CO H, CHO, Cl, Br, I, F, SMe, SiMe , tBu, OH, NH , NMe ), enable characterisation of mesomerism for the pincer-Pt interaction. Relationships between Hammett σ substituent parameters of Z and DFT data obtained from NBO6 and AOMix computation are used to probe the interaction of the 5d orbital of platinum with π-orbitals of the arene ring. Analogous computation for 2,6-(Me CH ) C H Z (Z=H, CF , CHO, Cl, Br, I, F, SMe, SiMe , tBu, OH, NH ) and (4-H-NCN)PtZ allows an estimation of the relative substituent effects of "(CH NMe ) PtZ" on π-delocalisation in the pincer system.
View Article and Find Full Text PDFRSC Adv
July 2019
University of Cincinnati, Department of Chemistry 2600 Clifton Ave. Cincinnati OH 45221 USA.
An important factor in obtaining reversible multi-electron transfer is overcoming large changes in coordination geometry. One strategy is to use ligands that can support the geometries favored before and after the electron transfer. PipNCN pincer and terpyridine ligands are used to support square planar Pt(ii) and octahedral Pt(iv).
View Article and Find Full Text PDFInorg Chem
September 2005
Organic Chemistry and Catalysis, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Two homoleptic pyridyl-functionalized C,N-ortho-chelating aminoaryl platinum(II) complexes, cis-[Pt(eta(2)-C,N)] (3a,b), were prepared via an unconventional method involving the initial synthesis of a bromide-functionalized C,N-chelating aminoaryl platinum(II) precursor complex 8, to which subsequently pyridyl groups were attached via a Suzuki-Miyaura C-C coupling reaction. The electron-donating properties of the pyridyl nitrogen atoms of the resulting complexes (3a,b) were used in complexation reactions with monocationic NCN-pincer (NCN = [C6H3(CH2NMe2)(2-)2,6]-) platinum(II) (11a) and palladium(II) (12a) nitrate complexes [M(NCN)(NO3)], thereby obtaining four trimetallic coordination complexes 16-19. The difference in the pyridine-metal coordination behavior between platinum and palladium was studied by varying the ratios of the reagents and by variable-temperature NMR experiments.
View Article and Find Full Text PDFChemistry
March 2004
Debye Institute, Department of Metal-Mediated Synthesis, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
A variety of para-substituted NCN-pincer palladium(II) and platinum(II) complexes [MX(NCN-Z)] (M=Pd(II), Pt(II); X=Cl, Br, I; NCN-Z=[2,6-(CH(2)NMe(2))(2)C(6)H(2)-4-Z](-); Z=NO(2), COOH, SO(3)H, PO(OEt)(2), PO(OH)(OEt), PO(OH)(2), CH(2)OH, SMe, NH(2)) were synthesised by routes involving substitution reactions, either prior to or, notably, after metalation of the ligand. The solubility of the pincer complexes is dominated by the nature of the para substituent Z, which renders several complexes water-soluble. The influence of the para substituent on the electronic properties of the metal centre was studied by (195)Pt NMR spectroscopy and DFT calculations.
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