The first demonstration of photochemical enediyne liberation from a metal complex has led to a new class of enediynes, the cyclopentadienidoenediynes, which are demonstrated to exist as air-stable solids with low ionization potentials and large dipole moments. NMR and IR spectroscopy, X-ray crystallography, and ab initio computations enable a comparison with the ubiquitous benzoenediynes.

The title cluster, which was obtained serendipitously when (η5-C5H5)Co(PPh3)2 was added to a (η5-C5H5)Co metallacyclobutene containing a sulfone group, is the largest cluster known, formed primarily with (η5-C5H5)Co vertices. The closo-(η5-C5H5Co)5S is a closed-shell, octahedral cluster which forms black, monoclinic crystals from methanol.

Three examples of unsupported short, strong hydrogen bonds (SSHBs) between phenolic moieties in aprotic media are reported in three salts of the biphenoxide [{3,5-OC6(CF3)2H3}2H]− anion, analogous to bifluoride, [FHF]−. The compounds were synthesized with three different cobalticinium cations and characterized via solution NMR and UV–Vis spectroscopies, elemental analyses, and single-crystal X-ray diffraction. These SSHB protons do not exchange with the aprotic solvent in solution or in the solid state and are important contributors to the study of SSHBs in enzyme active sites that often exclude water.