Planar Platinum Complexes Research Articles

73Ge, 119Sn and 207Pb: general cooperative effects of single atom ligands on the NMR signals observed in tetrahedral [MXnY4-n] (M = Ge, Sn, Pb; 1 ≤ n ≤ 4; X, Y = Cl, Br, I) coordination compounds of heavier XIV group elements.

An inverse linear relationship between 73Ge, 119Sn and 207Pb NMR chemical shifts and the overall sum of ionic radii of coordinated halido ligands has been discovered in tetrahedral [MXnY4-n] (M = Ge, Sn, Pb; 1 ≤ n ≤ 4; X, Y = Cl, Br, I) coordination compounds. This finding is consistent with a previously reported correlation found in octahedral, pentacoordinate and square planar platinum complexes. The effect of the coordinated halido ligands acting on the metal as shielding conducting rings is therefore confirmed also by 73Ge, 119Sn and 207Pb NMR spectroscopy.

Rational shaping of liquid crystalline diacylaminophenyl platforms equipped with chelating fragments, fluorescent dyes, and square planar platinum complexes

Recent investigations from our laboratory have described compelling experimental evidences that the use of a central 4-methyl-3,5-diacylaminophenyl platform functionalized with two lateral aromatic rings each bearing three appended aliphatic chains is well-suited to produce liquid crystalline materials, some of which carrying at the tips (A-substitution position) chelating fragments such as phenanthroline, terpyridine, alkynyl functions, crown ethers or highly luminescent subunits such as difluoroboradiazaindacene or cationic platinum-terpyridine complexes. An important carvet of this research program is that the presence of amide functions likely stabilizes the mesophases by hydrogen bondings. Judicious grafting of polycatenar tails to the platform insures formation of mesomorphic materials over a large temperature range. Careful design of the system by the direct connection of the platform via alkyne bonds to square planar platinum centers give rise to intriguing phosphorescent metallomesogens.

Supramolecular recognition: association of palladium molecular clefts with planar platinum complexes

The crystal structures of two new molecular recognition adducts formed between a dicationic, di-terpyridyl-Pd–Cl molecular cleft and two square planar platinum complexes are reported. In both structures, the planar platinum-containing guests are located within the molecular cleft formed by the two parallel disposed terpyridyl-Pd–Cl + units of the receptor. The crystal structure of the adduct formed between the molecular cleft and a neutral platinum complex has interplanar distances between the host and guest of 3.24 Å, a distance shorter than that usually ascribed to π-stacking interaction (∼3.45 Å). The short distance is likely the result of metal–metal interaction between the host and guest. The second adduct, that between the dicationic molecular receptor and an anionic platinum complex, also bears the guest within the molecular cleft. The interplanar distances between the cationic terpyridyl-Pd–Cl units of the host and the anionic guest (3.21 and 3.29 Å) are also shorter than typical π-stacking distances but no metal–metal interaction is present. Coulombic attraction between the host and guest is believed to be responsible for the short interplanar separation. These data are discussed in relation to analogous systems that associate through π–π and metal–metal interaction.

The interactions of square platinum(II) complexes with guanine and adenine: a quantum-chemical ab initio study of metalated tautomeric forms.

The influence of binding of square planar platinum complexes on tautomeric equilibria of the DNA bases guanine and adenine was investigated using the density functional B3LYP method. Neutral trans-dichloro(amine)-, +1 charged chloro(diamine)-, and +2 charged triamine-platinum(II) species were chosen for coordination to bases. Only the N7 interaction site of the bases was considered. The calculations demonstrate that the neutral platinum adduct does not change the tautomeric equilibria of the bases. Furthermore, N7 binding of the neutral Pt adduct moderately reduces the probability of protonation of the N1 position of adenine. Larger effects can be observed for +1 and mainly +2 adducts, but these can be rationalized by electrostatic effects. Since the electrostatic effects are expected to be efficiently compensated for by a charged backbone of DNA and counterions in a polar solvent, no dramatic increase in mispair formation is predicted for Pt(II) adducts, which is in agreement with experiment. The interaction energies between Pt adducts and the nucleobases were also evaluated. These interaction energies range from ca. 210 kJ/mol for neutral adducts, interacting with both bases and their tautomers, up to 500 kJ/mol for the +2 charged adducts, interacting with the keto-guanine tautomer and the anti-imino-adenine tautomer. The surprisingly large interaction energy for the latter structure is due to the strong H-bond between the NH3 ligand group of the metal adduct and the N6 nitrogen atom of the base.

Magnetic, optical, and electrochemical properties of spin transition metal complexes

Two types of metal complexes were investigated Square planar platinum complexes, which are typical low spin complexes, have large third-order nonlinear susceptibility. Octahedral iron complex, which is typical high spin complex, does not exhibit nonlinear optical effect. Spectral changes of evaporated thin films of above complexes were carried out in the high magnetic field. MHD effect was found by chronoamperometric measurements of metal complex in the high magnetic field. The possibility of the fabrication of magneto-optical device, which is made from metal complexes, is discussed.

High Pressure Studies on One-Dimensional Platinum Complexes–Periodical Modulation and Phase Transition

Abstract The correlation between the superstructures observed at ambient pressure and the possible high-pressure modifications of the crystal structures of partially oxidized platinum complexes was examined. The examples of the 2kF-modulation of the platinum chains and the planar platinum complexes were presented. Besides the Peierls and mixed-valence transitions, another type of pressure-induced modulation of the platinum chain was observed in KCP(Br) and RbCP(FHF), which appears to show that there is a real phase transition at the pressure and temperature where the fluctuating periodical lattice distortion wave begins to appear in the crystal. The brief description of the high pressure X-ray single crystal structure analyses at 6, 14 and 21 Kbar will be presented.

Inelastic neutron scattering studies of ethylene-containing square planar platinum complexes

The low frequency (0–850 cm −1) modes of vibration of the complexes trans-PtCl 2(C 2H 4)·L (where L = ND 3, CD 3CN, DCON(CD 3) 2 and C 6D 5ND 2) and cis-PtCl 2(C 2H 4)·(CD 3) 2 SO have been studied by inelastic neutron scattering, i.r. and Raman spectroscopy. In all complexes, motions of the C 2H 4 moiety relative to the platinum atom (including torsional modes) have been assigned and the barrier to rotation of the C 2H 4 ligand about an axis projected from the platinum atom through the centre of the CC bond determined. The barriers thus calculated have been compared with energies of activation obtained from nuclear magnetic resonance studies of similar complexes.

The electrical semiconductivity in polycrystalline samples of a planar platinum complex at high pressures

The electrical semiconductivity in polycrystalline samples of a planar platinum complex at high pressures

A one dimensional band calculation of a linear, square planar platinum complex

A simple model for the one-dimensional energy band structure of the mixed valency planar (MVP) platinum compounds is presented. The band structure was computed with a multiple scattering technique using a potential determined by a self-consistent calculation of the unit cell.