Redox reactions of an Mo (V) tetrasulfophthalocyanine

The preparation of an Mo(V) tetrasulfophthalocyanine and some of its thermal and photochemical reactions have been investigated in this work. Electrochemical processes have been followed by means of the UVVis spectral changes and compared with those observed in flash photolysis. Mo(IV) and Mo(V)-ligand-radical species are common intermediates of the electrochemical and photochemical reactions. In 254 nm irradiations of the Mo(V) tetrasulfophthalocyanine in aqueous solutions of 2-propanol, the macrocycle can be photohydrogenated and the product of the photolysis can be reoxidized with O2 back to the parent complex

HOMO–LUMO energy gap control in platinum(ii) biphenyl complexes containing 2,2′-bipyridine ligands

A series of platinum(II) biphenyl 2,2’-bipyridine complexes containing electron-donating and electron-withdrawing moieties on the 4 and 4’ positions of the bipyridine ligand exhibit emission from excited states in the 600 nm region of the spectrum upon excitation in the metal-to-ligand charge transfer transition located near 450 nm. These complexes are distorted from planarity based on both single crystal structure determinations and density functional theory (DFT) calculations of isolated molecules in acetonitrile. The DFT also reveals the geometry of the lowest-lying triplet state (LLTS) of each complex that is important for emission behavior. The LLTS are assigned based on the electron spin density distributions and correlated with the singlet excited states to understand the mechanism of electronic excitation and relaxation. Timedependent DFT calculations are performed to compute the singlet excited state energies of these complexes so as to help interpret their UV-Vis absorption spectra. Computational and experimental results, including absorption and emission energy maxima, electrochemical reduction potentials, LLTS, singlet excited states, and LUMO and HOMO energies, exhibit linear correlations with the Hammett constants for para-substituents σp. These correlations are employed to screen complexes that have not yet been synthesized. The correlation analysis indicates that electronic structure and the HOMO-LUMO energy gap in Pt(II) complexes can be effectively controlled using electron-donating and electron-withdrawing moieties covalently bonded to the ligands. The information presented in this paper provides analysis and better understanding of the fundamental electronic and thermodynamic behavior of these complexes and could be used to design systems with specific applications

Bis(μ-diethyl sulfide-κ2S:S)bis[(biphenyl-2,2′-diyl)platinum(ll)]

The C4S2 donor set in the title compound, [Pt(C12H8){(C2H5)2S}]2, defines a distorted square-planar geometry about the two PtII atoms, with very small deviations from planarity. The bidentate nature of the biphenyl dianionic ligand results in C—Pt—C bond angles of 80.9 (2) and 81.2 (2)°; the S—Pt—S bond angles are 78.08 (5) and 78.09 (5)°. The average Pt—C bond length is 2.023 Å [range 2.016 (5)–2.028 (6) Å] and the average of Pt—S bond length is 2.3790 Å [range 2.3742 (14)–2.3837 (14) Å]