A Monoclinic Form of Tetrakis(1-methylimidazole-N3)platinum(II) Diperchlorate

Roszak, A.W.; Clement, Omoshile; Buncel, Erwin

doi:10.1107/s0108270196000984

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…For the other complexes, intercalation implies, more likely, only part of the molecule. In [Pt(bipy)(py) 2 ] 2+ and [Pt(terpy)(py)] 2+ the pyridine ligands, which are skew , to the square plane, prevent the insertion of the whole cation between the nucleobases. Likewise, in [Pt(bipy) 2 ] 2+ , the arrangement of the nitrogen atoms around the platinum atom is not planar but is distorted toward a tetrahedral configuration, the dihedral angle between the bipyridine planes being about 23°.…”

Section: Discussionmentioning

confidence: 99%

Stacking Surface Effect in the DNA Intercalation of Some Polypyridine Platinum(II) Complexes

1999

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The interaction of the platinum(II) polypyridine complexes [Pt(bipy)(2)](2+), [Pt(quaterpy)](2+), [Pt(terpy)(n-Rpy)](2+) and [Pt(bipy)(py)(2)](2+) (bipy = 2,2'-bipyridine; terpy = 2,2':6',2' '-terpyridine; quaterpy = 2,2':6',2' ':6' ',2' "-quaterpyridine; n-R = H, 2-CH(3), or 4-CH(3) ) with double-helix DNA has been studied with a variety of experimental techniques. Induced circular dichroism, strong hypochromism and red shifts of the absorption maxima of the complexes, increase in melting temperature and viscosity of DNA, and inhibition of the reaction of the complexes with thiourea in the presence of DNA, characterize the processes. Intercalation, implying the whole molecule or part of it, is the suggested binding mode. The binding constants, K(B), determined spectrophotometrically at 25 degrees C, pH 7, and I = 0.15 M, using the McGhee-von Hippel approach, increase in the order [Pt(bipy)(py)(2)](2+)< [Pt(terpy)(py)](2+)< [Pt(quaterpy)](2+), on increasing aromatic planar surface extension. The steric interference with double helix of the methyl group in [Pt(terpy)(2-Mepy)](2+) destabilizes the interaction by reducing the stacking surface.

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Section: Discussionmentioning

confidence: 99%

Stacking Surface Effect in the DNA Intercalation of Some Polypyridine Platinum(II) Complexes

1999

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“…The structure was solved by heavy-atom techniques (Patterson and Fourier maps) using the program SHELXS86 . Full-matrix least-squares refinement on F 2 data with the anisotropic displacement parameters for all non-H atoms except the O atoms of the perchlorate ion was performed using the program SHELXL92 (the atomic scattering factors used were those from the International Tables of Crystallography) . The ClO 4 - ion was found disordered and showed two different orientations of the O atoms around the central Cl atom; the restrained refinement was used to maintain a similar geometry of these two orientations, and O atoms were refined with isotropic thermal displacement parameters.…”

Section: Methodsmentioning

confidence: 99%

“…The values so obtained were corrected by inclusion of a factor corresponding to the number of equivalent exchangeable sites. The resulting corrected values have been listed as k obs in Table 4 35,36 Crystals suitable for X-ray study were harvested from the reaction solution (Vide supra). A crystal of dimension 0.28 × 0.15 × 0.07 mm was used in data collection.…”

Section: C Reactivity Of Pt(ii) Ws H + or Ch 3 + In H/d Exchangementioning

confidence: 99%

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Hydrogen−Deuterium Exchange Studies in Platinum(II) Complexes of 1-Methylimidazole¹

1996

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A kinetic study of hydrogen-deuterium (H/D) exchange in Pt(II)-1-methylimidazole complexes has been performed in D 2 O/NaOD solution, at 60°C, by means of 1 H NMR spectroscopy. Isotopic exchange has been observed at C(2)-H, C(4)-H, and C(5)-H of the imidazole moiety. Kinetic data analysis of H/D exchange in the complexes cis-[Pt(NH 3 ) 2 (MeIm) 2 ]Cl 2 (3), trans-[Pt(NH 3 ) 2 (MeIm) 2 ]Cl 2 (4), [Pt(en)(MeIm) 2 ]Cl 2 (5), and [Pt(MeIm) 4 ](ClO 4 ) 2 (6) revealed that Pt(II) enhances C(2)-H exchange in the coordinated 1-methylimidazole (MeIm) by ca. 10 2 to 10 3 , relative to the neutral substrate. However, it is ca. 10 4 -10 5 times less effective compared to H + and CH 3 + . In complex 5, C(5)-H exchange is ca. 6 times faster than C(4)-H exchange, in contrast with expectations based on an inductive/field effect by Pt(II). The observation of the relative reactivity order, C(5)-H exchange > C(4)-H exchange in 5, is discussed by consideration of contributing resonance structures of the intermediates formed upon abstraction of C(4)-H and C(5)-H, which would place the positive charge at the more favorable N(1)-CH 3 position. An X-ray crystal structure determination of 6 was also performed. The complex crystallizes in the triclinic space group P1 h, with a ) 8.219 (1) Å, b ) 9.424(1) Å, c ) 9.139(3) Å; R ) 107.68(2)°, ) 83.72(2)°, γ ) 114.87(1)°; and Z ) 1. The complex has a center of symmetry with the 1-methylimidazole ligands coordinated in a square-planar arrangement around the Pt(II) atom.

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Stereochemistry of platinum coordination compounds

Melnı́k

Holloway

2006

Coordination Chemistry Reviews

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A Monoclinic Form of Tetrakis(1-methylimidazole-N3)platinum(II) Diperchlorate

Cited by 4 publications

References 9 publications

Stacking Surface Effect in the DNA Intercalation of Some Polypyridine Platinum(II) Complexes

Stacking Surface Effect in the DNA Intercalation of Some Polypyridine Platinum(II) Complexes

Hydrogen−Deuterium Exchange Studies in Platinum(II) Complexes of 1-Methylimidazole¹

Stereochemistry of platinum coordination compounds

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A Monoclinic Form of Tetrakis(1-methylimidazole-N3)platinum(II) Diperchlorate

Cited by 4 publications

References 9 publications

Stacking Surface Effect in the DNA Intercalation of Some Polypyridine Platinum(II) Complexes

Stacking Surface Effect in the DNA Intercalation of Some Polypyridine Platinum(II) Complexes

Hydrogen−Deuterium Exchange Studies in Platinum(II) Complexes of 1-Methylimidazole1

Stereochemistry of platinum coordination compounds

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Hydrogen−Deuterium Exchange Studies in Platinum(II) Complexes of 1-Methylimidazole¹