This account describes a current summary of our computational studies intended to elucidate the mechanism underlying water oxidation by the tetranuclear Mn cluster in the oxygen-evolving complex of photosystem II, the most fundamental bioenergetic process required for the maintenance of life. We focus herein on several important findings about the relatively high oxidation (S2 and S3) states of the cluster that involve three or four MnIV and one or no MnIII ions. The presentation is designed to highlight how the cluster stores the oxidizing power, binds substrate water molecules, and activates them. We discuss the fundamental importance of the cooperative effects of multiple Jahn–Teller axes on MnIII ions, which inevitably deform the cluster structure in such a direction as to promote substrate binding during S2 → S3 transition and O–O bond formation in the S3 state. Our interpretation is that the “distorted chair” topology of the cluster is the heart of efficient catalysis for oxygen evolution, and the presentation attempts to reflect this view.

Planar-chiral transition-metal complexes are important chiral scaffolds in organic and organometallic chemistry and have been utilized as chiral ligands, chiral catalysts, or chiral building blocks. In spite of the usefulness of the planar-chiral species in asymmetric synthesis, enantiomerically enriched forms of these compounds are primarily obtained by rather classical methods. Indeed, examples of catalytic enantio-control of planar chirality in transition-metal complexes have been extremely rare, and this has been still a developing area in this fi eld. In this account, recent results from our research group on the catalytic asymmetric synthesis of various planar-chiral transition-metal complexes are outlined. The Mo-catalyzed asymmetric ring-closing metathesis has been found to be a powerful method to control the planar chirality in various transition-metal complexes such as ferrocenes, ruthenocenes, (π-arene)chromium complexes, cymantrene derivatives, etc. Application of the highly enantiomerically enriched planar-chiral complexes in asymmetric synthesis has been also demonstrated.

In this account, recent advances in the design of bioorganometallic complexes by the conjugation of organometallic complexes with nucleobases are focused on to exhibit specific properties based on functional organization. A guanosine-based Au(I) bioorganometallic complex is demonstrated to serve as the reliable G-octamer scaffold via self-organization, showing a switchable emission based on aurophilic Au(I)-Au(I) interaction. The formation of the empty quartet, octamer, and polymeric columnar aggregate is able to be controlled by the amount of potassium ion. The tuning of the emission properties of the bioorganometallic platinum(II) complexes bearing a uracil moiety is also achieved by changing the direction of hydrogen bonding sites and the molecular scaffold having complementary hydrogen bonding sites for the uracil moiety. The semirigid bridging diphosphine ligand is performed to be a key factor in the arrangement of the phosphorus atoms on the same side to induce intramolecular Au(I)-Au(I) interaction, wherein R- and S-enantiomers based on Au(I)-Au(I) axis exist. It is noteworthy that the chirality of Au(I)- Au(I) axis is induced by the utilization of (R)-BINAP as the axially chiral bridging diphosphine ligand. Another interesting feature of bioorganometallic complexes is their strong tendency to self-assemble through intermolecular hydrogen bonds between their nucleobase moieties.