X-ray diffraction studies demonstrate that crystals of the carbodiphosphorane, (PhP)C, obtained from solutions in benzene, exhibit a linear P-C-P interaction. This observation is in contrast to the highly bent structures that have been previously reported for this molecule, thereby providing experimental evidence that the coordination geometry at zerovalent carbon may be very flexible. Density functional theory calculations support the experimental observations by demonstrating that the energy of (PhP)C varies relatively little over the range 130-180°.

Hydrogen atom (H•) donors generated from H2 facilitate the atom efficient reduction of small molecule substrates. However, generating H• donors with X–H bond dissociation free energies (BDFEs) below 52 kcal mol–1 is especially challenging because they thermodynamically favor the bimolecular evolution of H2. We have recently proposed that [CpV­(CO)3H]− catalyzes the conversion of H2 into a proton, an electron, and a hydrogen atom in the presence of a sacrificial base. In order to understand the driving force for H• transfer, the free energies of H+/H•/H–/e– transfer from [CpV­(CO)3H]− have been evaluated using solution phase techniques and state-of-the-art quantum chemical calculations. Thermochemical cycles have been constructed in order to anchor the computational values against experimental observations. This facilitates a quantitative comparison of the thermodynamic driving force for H+/H•/H–/e– transfer between isoelectronic anionic/neutral hydrides of the same row (the corresponding values are already available for CpCr­(CO)3H). The overall charge greatly influences the thermodynamics of transferring H+, H–, and e– (i.e., [CpV­(CO)3H]− is a much weaker acid, a stronger hydride donor, and a stronger reductant than CpCr­(CO)3H); there is almost no change in the thermodynamics of H• transfer (V–H BDFE 54.7 kcal mol, Cr–H BDFE 57.0 kcal mol–1). In MeCN, the one electron oxidation of [CpV­(CO)3H]− (−0.83 V vs Fc/Fc+) generates CpV­(CO)3H, which spontaneously evolves H2. The resulting CpV­(CO)3 is trapped as the solvent adduct CpV­(CO)3(MeCN). Because H• transfer is now coupled to metal–solvent binding, the V–H bond is substantially weakened for CpV­(CO)3H (V–H BDFE 36.1 kcal mol–1), amounting to a strategy for obtaining very reactive H atoms from H2.

The first terminal zinc hydride complex that features a sulfur-rich coordination environment, namely the tris(2-mercapto-1-tert-butylimidazolyl)hydroborato compound, [Tm(Bu(t))]ZnH, has been synthesized via the reaction of [Tm(Bu(t))]ZnOPh with PhSiH3. The Zn-H bond of [Tm(Bu(t))]ZnH is subject to insertion of CO2 and facile protolytic cleavage, of which the latter provides access to heterobimetallic [Tm(Bu(t))]ZnMo(CO)3Cp.

The zerovalent carbodiphosphorane, (Ph3P)2C, reacts with Me3Al and Me3Ga to afford the adducts, [(Ph3P)2C]MMe3 (M = Al, Ga), whereas Me2Zn and Me2Mg react to afford mononuclear and dinuclear cyclometalated derivatives.