Multistate Energy Decomposition Analysis of Molecular Excited States.

A multistate energy decomposition analysis (MS-EDA) method is described to dissect the energy components in molecular complexes in excited states. In MS-EDA, the total binding energy of an excimer or an exciplex is partitioned into a ground-state term, called local interaction energy, and excited-state contributions that include exciton excitation energy, superexchange stabilization, and orbital and configuration-state delocalization. An important feature of MS-EDA is that key intermediate states associated with different energy terms can be variationally optimized, providing quantitative insights into widely used physical concepts such as exciton delocalization and superexchange charge-transfer effects in excited states.

Excimer Energies.

A multistate energy decomposition analysis (MS-EDA) method is introduced for excimers using density functional theory. Although EDA has been widely applied to intermolecular interactions in the ground state, few methods are currently available for excited-state complexes. Here, the total energy of an excimer state is separated into exciton excitation energy Δ(|Ψ·Ψ⟩*), resulting from the state interaction between locally excited monomer states |Ψ·Ψ⟩ and |Ψ·Ψ⟩ , a superexchange stabilization energy Δ, originating from the mutual charge transfer between two monomers |Ψ·Ψ⟩ and |Ψ·Ψ⟩ , and an orbital-and-configuration delocalization term Δ due to the expansion of configuration space and block-localized orbitals to the fully delocalized dimer system.

Minimal-active-space multistate density functional theory for excitation energy involving local and charge transfer states.

Multistate density functional theory (MSDFT) employing a minimum active space (MAS) is presented to determine charge transfer (CT) and local excited states of bimolecular complexes. MSDFT is a hybrid wave function theory (WFT) and density functional theory, in which dynamic correlation is first incorporated in individual determinant configurations using a Kohn-Sham exchange-correlation functional. Then, nonorthogonal configuration-state interaction is performed to treat static correlation.

Block-Localized Excitation for Excimer Complex and Diabatic Coupling.

We describe a block-localized excitation (BLE) method to carry out constrained optimization of block-localized orbitals for constructing valence bond-like, diabatic excited configurations using multistate density functional theory (MSDFT). The method is an extension of the previous block-localized wave function method through a fragment-based ΔSCF approach to optimize excited determinants within a molecular complex. In BLE, both the number of electrons and the electronic spin of different fragments in a whole system can be constrained, whereas electrostatic, exchange, and polarization interactions among different blocks can be fully taken into account of.

Two synthetic approaches for the preparation of tin(ii) dications.

Examples of tin dications without closer contacts to the anion are rare, as are straightforward routes to weakly coordinated tin(ii) dication salts. Here we report on the synthesis of [Sn(MeCN)][Al(OR)] (R = C(CF)) via NO-oxidation of tin metal. Subsequently, [Sn(MeCN)][Al(OR)] was used to prepare the mixed coordinated [Sn(pyr)(MeCN)][Al(OR)] and [Sn(PPh)-(MeCN)][Al(OR)]·MeCN.