DFT Calculation of Static First Hyperpolarizabilities and Linear Optical Properties of Metal Alkynyl Complexes

Abstract

Density functional theory (DFT) and timedependent density functional theory (TD-DFT) calculations are reported for a set of organometallic compounds for which the first hyperpolarizability values, β, have previously been determined in the laboratory. These calculations, which utilized a variety of density functionals and basis sets, address such aspects as the implications of molecular conformation and the extent of bond delocalization on the calculated β values. We also explore here the simplification of ligands for computational expedience and the influence of incorporation or exclusion of solvent corrections on β. The results of our study are likely to be of value in guiding subsequent efforts toward the reliable predictive calculation of the first hyperpolarizabilities and linear optical properties for organometallic compounds of interest to experimentalists.

Linear Optical, Quadratic and Cubic Nonlinear Optical, Electrochemical, and Theoretical Studies of “Rigid‐Rod” Bis‐Alkynyl Ruthenium Complexes

“…Note that 17M and 4M have two or more aryl groups in one of their alkynyl ligands, and the addition of the extra aryl groups will increase the number of probable (twisted) conformations at ambient temperature. Each extra ring, distal to Ru, can rotate around the C sp −C bond and the barrier to such rotation is generally small . As previously shown, the internal rotation of the phenylene groups along the axis of the triple bonds in an alkynyl ligand can also contribute to the experimental observation of a blueshift in the low‐energy absorption band upon π‐system lengthening.…”

“…Low‐energy linear optical behavior is expected to be significantly affected by planarity of the π bridge, as shown by previous related studies . We assessed the influence of the orientation of the alkynyl ligands with respect to the metal center, as well as the relative orientation of the planes of the two alkynyl ligands, on the low‐lying linear optical data in 16M , the smallest bis‐alkynyl complex in the set.…”

Long‐Range Corrected DFT Calculations of First Hyperpolarizabilities and Excitation Energies of Metal Alkynyl Complexes

“…However, it is important to note that calculations on the coplanar rotamers reproduce the experimental and two‐level hyperpolarizability trends. The relative values computed in this study for coplanar and noncoplanar rotamers of 5 are consistent with our previous data …”

“…Again, the two hybrid functionals significantly improve the calculated band position; in fact, PBE0 outperforms all other functionals (see Table ). In comparison with our previous data, there is excellent agreement. The RS functionals overestimate the excitation energy, as found for 2 , with the shift from the experimental data being method‐dependent.…”

“…According to Table , the lowest‐energy band for 5 calculated by BLYP appears in the NIR region (1030 nm). This is a significant underestimation of the CT energy corresponding to the lowest‐energy peak at 464 nm in the experimental UV‐Vis but is comparable to our previous TD‐DFT results predicted for 5 . Similarly, the hybrid functionals also overestimate the excitation energies, but the absolute errors are much smaller.…”