Ruthenium tetracarbonyl polymer, [Ru(CO)4]n, a chainlike compound formed by metal-metal interactions, was studied computationally. We first performed tests with selected pure and hybrid GGA density functionals and ab initio methods at HF and MP2 levels of theory to find the most suitable method. Calculated geometries and molecular orbitals were compared to see effectiveness and possible differences of the methods. Hybrid functionals, especially PBE1PBE and MPW1K, were found to produce accurate geometrical parameters compared to the experimental structure, with reasonable computational cost. Bonding in [Ru(CO)4]n chains was studied by calculation of Mayer bond order and theoretical structure factors followed by multipole refinement to get bond critical points according to the quantum theory of atoms in molecules. Ruthenium-ruthenium bonding comparable to that in a Ru3(CO)12 cluster was found with both methods.

Conjugated copolymers with an alternating donor-acceptor (D-A) architecture are exploited as low-bandgap and high-hole-mobility materials in organic electronics. However, several of the presently available modeling methods predict different geometries and electronic properties for the same copolymer. In this work, the effect of the amount of exact Hartree-Fock (HF) exchange in density functionals on the planarity of the geometry and the electronic properties of the single oligomer chains of one benzodithiophene- and benzotriazole-based donor-acceptor copolymer and two fluorene-, thiophene-, and benzotriazole-based donor-acceptor copolymers is assessed. The functionals are B3LYP, PBE, PBE0, HSE06, LC-ωPBE, ωB97XD, M06, M06L, M062X, M06HF, and the optimally tuned OT-ωB97X. Benchmarking of the methods is useful for understanding the results of a particular functional and allows, to a certain degree, comparison between results obtained with different functionals. Additionally, the applicability of the one-dimensional periodic boundary condition (PBC) for modeling the D-A copolymers with long constitutional repeating units (CRUs) is evaluated.

A new type of concerted halogen bond-hydrogen bond interaction was found in the solid state structure of [RuI(2)(H(2)dcbpy)(CO)(2)]···I(2)···(MeOH)···I(2)···[RuI(2)(H(2)dcbpy)(CO)(2)]. The iodine atoms of the two I(2) molecules interact simultaneously with each other and with the OH group of methanol of crystallization. The interaction was characterized by single crystal X-ray measurements and by computational charge density analysis based on DFT calculations.

Here, we investigate the effects of both tuning the range-separation parameter of long-range corrected (LRC) density functionals and including dispersion corrections on describing the local optoelectronic properties of polymer-fullerene interfaces that are critical to the performance of polymer solar cells (PSCs). Focusing on recently studied (Chen, et al., Chem. Mater., 2012, 24, 4766-4772) PSC active layers derived from poly(benzodithiophene-co-quinoxaline) and substituted fullerene PCBM, we compare the performance of global hybrid functionals (B3LYP and B3LYP-D) alongside two LRC functionals (ωB97X and ωB97X-D) and their optimally tuned (OT) analogs (OT-ωB97X and OT-ωB97X-D). Our results confirm that OT-LRC functionals generally improve the description of the optical properties of the individual materials with respect to experiment. For electron-donor (eD)-electron-acceptor (eA) complexes used to describe the local optoelectronic properties of the material interface, PCBM is found to preferentially settle near the quinoxaline acceptor units on the copolymer backbone, regardless of the functional, though dispersion corrections have a strong influence on the intermolecular distances and, in turn, the nature of the excited states. All functionals yield very similar descriptions of the transition maxima for the complexes, i.e. predominant local excitations on the copolymer. Importantly, tuning the range-separation parameter of the LRC functional is shown to have a profound effect, as the OT functionals allow for the description of the charge transfer states of the eD-eA complexes, while the non-tuned LRC functionals predict only local intramolecular excitations. These results hold considerable importance for deriving the appropriate physical understanding of the interfacial structure-property-function relationships of PSCs.