Density Functional Study on the Photopolymerization of Styrene Using Dinuclear Ru–Pd and Ir–Pd Complexes with Naphthyl-Substituted Ligands

A density functional study was performed to investigate the mechanism of the photocatalytic reactivity of styrene polymerization using dinuclear Ru–Pd and Ir–Pd catalytic complexes. In previous experiments with these catalysts, the reactivity increased, and more polymer products were yielded compared to dimers under visible light irradiation. The best catalytic reactivity was obtained using an Ir–Pd complex containing naphthyl substituents at the phenyl ligands coordinated to Ir (Ir–Pd1). In contrast, Ir–Pd2, an isomer of Ir–Pd1, containing naphthyl substituents at the pyridine ligands, did not show good reactivity, which may be related to the stability of the excited state of the catalytic complexes. In this study, we calculated the radiative lifetimes of these catalytic complexes and Ir–Pd1 had the longest lifetime; this result was consistent with the experimental results. The longest lifetime of the Ir–Pd1 was attributed to the destabilization of the highest occupied molecular orbital (HOMO) energy by π*−π* interactions between the naphthyl and phenyl ligands. Further, this destabilization of the HOMO energy afforded a small energy gap between the HOMO and lowest unoccupied molecular orbital, enhancing the metal-to-ligand charge transfer to the bridging ligand between Ir and Pd. Additionally, we focused on the reaction of the second insertion of styrene, which was identified as the rate-determining step of the polymerization cycle in a previous study. The singlet–triplet crossing points of the intermediates were estimated, and the barrier heights of the intersystem crossing were much lower than those in the thermal paths, which explained the efficiency of the photocatalytic reactivity in the experiment

Density Functional Study on the Photopolymerization of Styrene Using Dinuclear Ru–Pd and Ir–Pd Complexes with Naphthyl-Substituted Ligands

A density functional study was performed to investigate the mechanism of the photocatalytic reactivity of styrene polymerization using dinuclear Ru–Pd and Ir–Pd catalytic complexes. In previous experiments with these catalysts, the reactivity increased, and more polymer products were yielded compared to dimers under visible light irradiation. The best catalytic reactivity was obtained using an Ir–Pd complex containing naphthyl substituents at the phenyl ligands coordinated to Ir (Ir–Pd1). In contrast, Ir–Pd2, an isomer of Ir–Pd1, containing naphthyl substituents at the pyridine ligands, did not show good reactivity, which may be related to the stability of the excited state of the catalytic complexes. In this study, we calculated the radiative lifetimes of these catalytic complexes and Ir–Pd1 had the longest lifetime; this result was consistent with the experimental results. The longest lifetime of the Ir–Pd1 was attributed to the destabilization of the highest occupied molecular orbital (HOMO) energy by π*−π* interactions between the naphthyl and phenyl ligands. Further, this destabilization of the HOMO energy afforded a small energy gap between the HOMO and lowest unoccupied molecular orbital, enhancing the metal-to-ligand charge transfer to the bridging ligand between Ir and Pd. Additionally, we focused on the reaction of the second insertion of styrene, which was identified as the rate-determining step of the polymerization cycle in a previous study. The singlet–triplet crossing points of the intermediates were estimated, and the barrier heights of the intersystem crossing were much lower than those in the thermal paths, which explained the efficiency of the photocatalytic reactivity in the experiment

Density Functional Study on the Photopolymerization of Styrene Using Dinuclear Ru–Pd and Ir–Pd Complexes with Naphthyl-Substituted Ligands

A density functional study was performed to investigate the mechanism of the photocatalytic reactivity of styrene polymerization using dinuclear Ru–Pd and Ir–Pd catalytic complexes. In previous experiments with these catalysts, the reactivity increased, and more polymer products were yielded compared to dimers under visible light irradiation. The best catalytic reactivity was obtained using an Ir–Pd complex containing naphthyl substituents at the phenyl ligands coordinated to Ir (Ir–Pd1). In contrast, Ir–Pd2, an isomer of Ir–Pd1, containing naphthyl substituents at the pyridine ligands, did not show good reactivity, which may be related to the stability of the excited state of the catalytic complexes. In this study, we calculated the radiative lifetimes of these catalytic complexes and Ir–Pd1 had the longest lifetime; this result was consistent with the experimental results. The longest lifetime of the Ir–Pd1 was attributed to the destabilization of the highest occupied molecular orbital (HOMO) energy by π*−π* interactions between the naphthyl and phenyl ligands. Further, this destabilization of the HOMO energy afforded a small energy gap between the HOMO and lowest unoccupied molecular orbital, enhancing the metal-to-ligand charge transfer to the bridging ligand between Ir and Pd. Additionally, we focused on the reaction of the second insertion of styrene, which was identified as the rate-determining step of the polymerization cycle in a previous study. The singlet–triplet crossing points of the intermediates were estimated, and the barrier heights of the intersystem crossing were much lower than those in the thermal paths, which explained the efficiency of the photocatalytic reactivity in the experiment

Hyperfine and P, T odd properties in BiO: comparison between coupled-cluster method and multi-reference perturbation method based on a Dirac Hamiltonian

Polar diatomic molecules are attractive in the search for the electron electric dipole moment (eEDM) and the scalar-pseudoscalar (S-PS) interaction, both of which violate time-reversal and parity symmetries. In this study, we examined the electronic ground state of BiO and evaluated the effective electric field (Eeff) of eEDM and the Ws coefficients of the S-PS interaction. BiO forms a complex chemical bond due to the open-shell configurations of Bi (6p) and O (2p). Consequently, we performed four-component relativistic calculations using complete-active-space second-order perturbation theory (CASPT2), as well as coupled-cluster singles and doubles (CCSD) and CCSD perturbative triples (CCSD(T)) methods. Our analysis revealed that BiO exhibited a multiconfigurational character, as the Hartree-Fock configuration accounted for only 68% of the reference wave function for CASPT2. Nevertheless, for the hyperfine coupling constant (A//), CCSD and CCSD(T) reproduced the experimental value better than CASPT2, indicating that CC methods can capture important excited configurations, rendering multireference treatment unnecessary. The deficiency of CASPT2 in reproducing A// could be attributed to the inadequate treatment of orbital relaxation effects. Our proposed values of Eeff and Ws for BiO (17 GV/cm and −36 kHz, respectively), derived at the CCSD level, were moderately large for the parity, time-odd experiment.</p

Calculations of electronic properties and vibrational parameters of alkaline-earth lithides: MgLi⁺ and CaLi⁺

The 1Σ+ electronic ground states of MgLi+ and CaLi+ molecular ions are investigated for their spectroscopic constants and properties such as the dipole - and quadrupole moments, and static dipole polarisabilities. The quadrupole moments and the static dipole polarisabilities for these ions have been calculated and reported here, for the first time. The maximum possible error bars, arising due to the finite basis set and the exclusion of higher correlation effects beyond partial triples, are quoted for reliability. Further, the adiabatic effects such as diagonal Born-Oppenheimer corrections are also calculated for these molecules. The vibrational energies, the wavefunctions, and the relevant vibrational parameters are obtained by solving the vibrational Schrödinger equation using the potential energy curve and the permanent dipole moment curve of the molecular electronic ground state. Thereafter, spontaneous and black-body radiation induced transition rates are calculated to obtain the lifetimes of the vibrational states. The lifetime of rovibronic ground state for MgLi+, at room temperature, is found to be 2.81s and for CaLi+ it is 3.19s. It has been observed that the lifetime of the highly excited vibrational state is several times larger than (comparable to) that of the vibrational ground state of MgLi+ (CaLi+). In addition, a few low-lying electronic excited states of Σ and Π symmetries have been investigated for their electronic and vibrational properties, using EOM-CCSD method together with the QZ basis sets.</p

Test of mp/me changes using vibrational transitions in N2+

In this paper we propose to utilize the X2Sg(?,N,F,M)=(0,0,1/2,±1/2)?(1,0,1/2,±1/2) or (2,0,1/2,±1/2) transition of N2+ (I=0) to test variations of the proton-to-electron mass ratio. The X2Sg ground state exhibits no quadrupole shift and the Zeeman shift of the N=0?N=0 transition is exactly zero. Because N2+ is nonpolar, systematic level shifts such as Stark shifts induced by trap electric field or blackbody radiation are very small and the thermalization of the rotational states is inhibited. This eases the requirements on the experimental setup significantly. Employing Raman transitions at the “magic” wavelength the (0,0,1/2,±1/2)?(1,0,1/2,±1/2) or (2,0,1/2,±1/2) transition frequency can be measured very precisely