Two fluoro compounds of main group elements: Synthesis,characterization, theoretical and spectroscopic study

Two new compounds of fluorine: (C₂H₅)₄N[I₂F] and (C₂H₅)₄N[Br₂F], have been easily synthesized in a nearly quantitative by a direct reaction of (C₂H₅)₄NF, I₂ and Br₂. The products were isolated and characterized by elemental analysis and spectroscopic methods such as: Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). These compounds have been studied computationally with the Scalar ZORA relativistic level of theory using the ADF program package. The molecular parameters, and vibrational spectra were calculated. The excitation energies were found by timedependent perturbation density functional theory (TD-DFT). Molecule optimization, frequencies and excitation energies were calculated with standard Slatertype-orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all atoms. The FTIR, UV-Vis spectra and assignment of principal transitions and total density of state (TDOS) were extracted using the GaussSum 2.2 program. The comparison between experimental and calculated values showes that the experimental results correlate well with the predicted data.     

Aspects of spin-orbit effects in compounds containing heavy elements

This perspective article discusses some widely-known and some less-known consequences of spin-orbit effects in inorganic chemistry, and provides a brief outline of the theoretical methods currently in use, along with a discussion of recent developments and selected applications. This is of critical importance in the interpretation of the electronic delocalization, optical and magnetic properties and Jahn–Teller effects of compounds containing heavy elements.     

Cluster carbonyls of the [Re(6)(mu(3)-Se)(8)](2+) core: synthesis, structural characterization, and computational analysis

The reactions of the previously reported cluster complexes [Re(6)(mu(3)-Se)(8)(PEt(3))(5)I]I, trans-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)I(2)], and cis-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)I(2)] with the [Re(6)(mu(3)-Se)(8)](2+) core with CO in the presence of AgSbF(6) afforded the corresponding cluster carbonyls [Re(6)(mu(3)-Se)(8)(PEt(3))(5)(CO)][SbF(6)](2) (), trans-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)(CO)(2)][SbF(6)](2) (), and cis-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)(CO)(2)][SbF(6)](2) (). Infrared spectroscopy indicated weakening of the bond in CO, suggesting the existence of backbonding between the cluster core and the CO ligand(s). Electrochemical studies focusing on the reversible, one-electron oxidation of the cluster core revealed a large increase in the oxidation potential upon going from the acetonitrile derivatives to their carbonyl analogs, consistent with the depleted electron density of the cluster core upon CO ligation. Disparities between the IR spectra and oxidation potential between and indicate that electronic differences exist between sites trans and cis to the location of a ligand of interest. The active role played by the Se atoms in influencing the cluster-to-CO bonding interactions is suggested through this result and density functional (DF) computational analysis. The computations indicate that molecular orbitals near the HOMO account for backbonding interactions with a high percentage of participation of Se orbitals.     

Electronic structure and molecular properties of the [Mo6X8L6]; X = Cl, Br, I; L = F, Cl, Br, I clusters

Relativistic TDDFT calculations including spin orbit interactions via the ZORA approximation and solvent effects were carried out on the [Mo₆X₈L₆]²⁻ X = Cl, Br, I ; L = F, Cl, Br, I clusters. These calculations indicate that the closely spaced lowest excited states are largely centered on the cubic [Mo₆X₈]⁴⁺ core. Thus, our calculations and the electronic similarities with the strongly luminescent [Mo₆Cl₈Cl₆]²⁻, [Mo₆Br₈Br₆]²⁻ and [Mo₆I₈I₆]²⁻ clusters, suggest that the clusters [Mo₆Cl₈F₆]²⁻, [Mo₆Br₈F₆]²⁻, [Mo₆I₈F₆]²⁻, [Mo₆I₈Cl₆]²⁻ and [Mo₆I₈Br₆]²⁻ studied here might be also luminescent. The calculated bond energies and reactivity indexes indicate that the most labile clusters are those with axial iodide ligands.     

Electronic structure and molecular properties of [Re6−x Os x Se8Cl6](4−x)− (x = 0–3) clusters: A study based on time-dependent density functional theory including spin-orbit and solvent effects

Relativistic time-dependent density functional (TDDFT) calculations including spin-orbit interactions via the zero order regular approximation (ZORA) and solvent effects are carried out on the [Re_6?x Os _x Se₈Cl₆]^(4?x)? (x = 0–3) cluster. These calculations indicate that the lowest energy electronic transitions of the MMCT and LMCT type are similar to those observed in strongly luminescent 24-electron hexanuclear rhenium chalcogenide clusters [Re₆Se₈Cl₆]^4?. Thus our calculations predict that [Re_6?x Os _x Se₈Cl₆]^(4?x)? (x = 0–3) clusters could be luminescent.     

Role of donor-acceptor functional groups in N3P3 cyclic-triphosphazene backbone. Unraveling bonding characteristics from natural orbitals within an extended transition state-natural orbital for the chemical valence scheme

The formation of cyclophosphazenes containing several ligands or substituent groups gives rise to an attractive derivative set, for development of novel applications, with variable properties. Here, it is possible to unravel the role of different functional groups attached to the N₃P₃ backbone, to reach a better understanding of the bonding character in the cyclic [─P─N─] skeleton. We employed the extended transition state-natural orbital for the chemical valence scheme to unravel the σ and π orbital kernels that are involved in the assembling of such structures, by varying the acceptor-donor characteristics of the ─CF₃, ─NO₂, ─COOH, ─CN, ─NH₂, ─OH, and ─OCH₃ groups, where ─NO₂ behaves as a stronger electron-withdrawing substituent rather than ─CF₃, ─COOH, and ─CN, denoting that the nature of the ligand-phosphazene interaction contributes to some degree to the bond strength of the cyclic [─P─N─] backbone. Our results reveal that the electron-withdrawing ─NO₂ group leads to higher σ and π [─P─N─] orbital-energy contributions, which is reflected in a shortening of the [─P─N─] distance, contrasting with the case of electron-donating groups such as ─NH₂, ─OH, and ─OCH₃ within the phosphazene set. These insights allow further variation and modulation of the bonding in the [─P─N─] ring.