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Molecular Architectures Derived from Metal Ions and the Flexible 3,3'-Bipyridine Ligand: Unexpected Dimer with Hg(II).

Khutia A, Sanz Miguel PJ, Lippert B - Bioinorg Chem Appl (2010)

Bottom Line: H(2)O}(n) (1), with all other metal entities cyclic structures were formed.Interestingly, Hg(CH(3)COO)(2) produced a dinuclear complex [Hg(3,3'-bpy)(CH(3)COO)(2)](2) . 3H(2)O (2), in which the two 3,3'-bpy ligands adopt a cis-orientation of the coordinating pyridyl entities.With cis-(NH(3))(2)Pt(2+), a cyclic complex 4 was isolated in crystalline form which, according to HRMS, is a trimer.

View Article: PubMed Central - PubMed

Affiliation: Fakultät Chemie, Technische Universität Dortmund, 44221 Dortmund, Germany.

ABSTRACT
The flexible ditopic ligand 3,3'-bipyridine (3,3'-bpy) has been reacted with a series of transition metal species (Ag(+), Hg(2+), cis-a(2)M(2+) (a = NH(3) or a(2) = en; M = Pt, Pd), trans-a(2)Pt(2+) (a = NH(3))) in an attempt to produce discrete cyclic constructs. While Ag(+) gave a polymeric structure {[Ag(3,3'-bpy)](ClO(4)) . H(2)O}(n) (1), with all other metal entities cyclic structures were formed. Interestingly, Hg(CH(3)COO)(2) produced a dinuclear complex [Hg(3,3'-bpy)(CH(3)COO)(2)](2) . 3H(2)O (2), in which the two 3,3'-bpy ligands adopt a cis-orientation of the coordinating pyridyl entities. With cis-(NH(3))(2)Pt(2+), a cyclic complex 4 was isolated in crystalline form which, according to HRMS, is a trimer. With trans-(NH(3))(2)Pt(2+), different species are formed according to (1)H NMR spectroscopy, the nature of which was not established.

No MeSH data available.


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1H NMR spectrum of mixture of trans-[Pt(NH3)2(D2O)2]2+ and 3,3′-bpy (L) in ratio 1 : 10 after 2 d, 50°C, D2O, pD = 6.65. Main resonances are assigned to 1 : 2 complex and free ligand; minor resonances (*) are not assigned.
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fig7: 1H NMR spectrum of mixture of trans-[Pt(NH3)2(D2O)2]2+ and 3,3′-bpy (L) in ratio 1 : 10 after 2 d, 50°C, D2O, pD = 6.65. Main resonances are assigned to 1 : 2 complex and free ligand; minor resonances (*) are not assigned.

Mentions: Reaction of 3,3′-bpy with trans-[Pt(NH3)2(D2O)2](NO3)2 was carried out with different ratios between 3,3′-bpy and the Pt species (10 : 1, 2 : 1, 1 : 1, 1 : 10) on the 1H NMR scale in D2O. Without exception, the spectra displayed time-dependent changes, but within 2-3 d at 50°C, constant spectra were obtained. Even then, however, resonances due to multiple products were present. In the case of a large excess of ligand over Pt (10 : 1), the spectrum reveals the presence of a major species attributed to trans-[Pt(NH3)2(3,3′-bpy)2]2+ and excess 3,3′-bpy (Figure 7). The resonances of the free 3,3′-bpy (L) were unambiguously identified by adding solid 3,3′-bpy to the NMR sample. The two sets of pyridine resonances of the coordinated 3,3′-bpy ligands of the 1 : 2 complex are assigned on the basis of their relative intensities. What strikes is that the H2 and H4 resonances of the free ligand are very much broadened (cf. Figure 2(a)) and that H2, H4, and H6 are upfield shifted by ca. 0.2, 0.08, and 0.14 ppm, respectively. As these shifts cannot be interpreted with a pD effect, we propose that the presence of the 1 : 2-Pt complex has an effect on the rotamer equilibrium of the free ligand. Consistent with this proposal, the two resonances closest to the C3–C3 bond, hence H2 and H4, become quite broad. Stacking interactions between free and coordinated 3,3′-bpy could possibly account for this feature.


Molecular Architectures Derived from Metal Ions and the Flexible 3,3'-Bipyridine Ligand: Unexpected Dimer with Hg(II).

Khutia A, Sanz Miguel PJ, Lippert B - Bioinorg Chem Appl (2010)

1H NMR spectrum of mixture of trans-[Pt(NH3)2(D2O)2]2+ and 3,3′-bpy (L) in ratio 1 : 10 after 2 d, 50°C, D2O, pD = 6.65. Main resonances are assigned to 1 : 2 complex and free ligand; minor resonances (*) are not assigned.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig7: 1H NMR spectrum of mixture of trans-[Pt(NH3)2(D2O)2]2+ and 3,3′-bpy (L) in ratio 1 : 10 after 2 d, 50°C, D2O, pD = 6.65. Main resonances are assigned to 1 : 2 complex and free ligand; minor resonances (*) are not assigned.
Mentions: Reaction of 3,3′-bpy with trans-[Pt(NH3)2(D2O)2](NO3)2 was carried out with different ratios between 3,3′-bpy and the Pt species (10 : 1, 2 : 1, 1 : 1, 1 : 10) on the 1H NMR scale in D2O. Without exception, the spectra displayed time-dependent changes, but within 2-3 d at 50°C, constant spectra were obtained. Even then, however, resonances due to multiple products were present. In the case of a large excess of ligand over Pt (10 : 1), the spectrum reveals the presence of a major species attributed to trans-[Pt(NH3)2(3,3′-bpy)2]2+ and excess 3,3′-bpy (Figure 7). The resonances of the free 3,3′-bpy (L) were unambiguously identified by adding solid 3,3′-bpy to the NMR sample. The two sets of pyridine resonances of the coordinated 3,3′-bpy ligands of the 1 : 2 complex are assigned on the basis of their relative intensities. What strikes is that the H2 and H4 resonances of the free ligand are very much broadened (cf. Figure 2(a)) and that H2, H4, and H6 are upfield shifted by ca. 0.2, 0.08, and 0.14 ppm, respectively. As these shifts cannot be interpreted with a pD effect, we propose that the presence of the 1 : 2-Pt complex has an effect on the rotamer equilibrium of the free ligand. Consistent with this proposal, the two resonances closest to the C3–C3 bond, hence H2 and H4, become quite broad. Stacking interactions between free and coordinated 3,3′-bpy could possibly account for this feature.

Bottom Line: H(2)O}(n) (1), with all other metal entities cyclic structures were formed.Interestingly, Hg(CH(3)COO)(2) produced a dinuclear complex [Hg(3,3'-bpy)(CH(3)COO)(2)](2) . 3H(2)O (2), in which the two 3,3'-bpy ligands adopt a cis-orientation of the coordinating pyridyl entities.With cis-(NH(3))(2)Pt(2+), a cyclic complex 4 was isolated in crystalline form which, according to HRMS, is a trimer.

View Article: PubMed Central - PubMed

Affiliation: Fakultät Chemie, Technische Universität Dortmund, 44221 Dortmund, Germany.

ABSTRACT
The flexible ditopic ligand 3,3'-bipyridine (3,3'-bpy) has been reacted with a series of transition metal species (Ag(+), Hg(2+), cis-a(2)M(2+) (a = NH(3) or a(2) = en; M = Pt, Pd), trans-a(2)Pt(2+) (a = NH(3))) in an attempt to produce discrete cyclic constructs. While Ag(+) gave a polymeric structure {[Ag(3,3'-bpy)](ClO(4)) . H(2)O}(n) (1), with all other metal entities cyclic structures were formed. Interestingly, Hg(CH(3)COO)(2) produced a dinuclear complex [Hg(3,3'-bpy)(CH(3)COO)(2)](2) . 3H(2)O (2), in which the two 3,3'-bpy ligands adopt a cis-orientation of the coordinating pyridyl entities. With cis-(NH(3))(2)Pt(2+), a cyclic complex 4 was isolated in crystalline form which, according to HRMS, is a trimer. With trans-(NH(3))(2)Pt(2+), different species are formed according to (1)H NMR spectroscopy, the nature of which was not established.

No MeSH data available.


Related in: MedlinePlus