A new database of transition metal reaction barrier heights-MOBH35-is presented. Benchmark energies (forward and reverse barriers and reaction energy) are calculated using DLPNO-CCSD(T) extrapolated to the complete basis set limit using a Weizmann1-like scheme. Using these benchmark energies, the performance of a wide selection of density functional theory (DFT) exchange-correlation functionals, including the latest from the Truhlar and Head-Gordon groups, is evaluated. It was found, using the def2-TZVPP basis set, that the ωB97M-V (MAD 1.8 kcal/mol), ωB97X-V (MAD 2.1 kcal/mol) and SCAN0 (MAD 2.1 kcal/mol) hybrid functionals are recommended. The double-hybrid functionals PWPB95 (MAD 1.6 kcal/mol) and B2K-PLYP (MAD 1.8 kcal/mol) did perform slightly better but this has to be balanced by their increased computational cost. File list (3) download file view on ChemRxiv TM Barrier Heights-revision 1-v2-for submission.pdf (1.58 MiB) download file view on ChemRxiv MOBH35-SI.pdf (132.27 KiB) download file view on ChemRxiv mobh35.tar.gz (82.99 KiB)

The first example of a homogeneous catalyst based on an earth-abundant metal for the hydrogenation of organic carbonates to methanol and alcohols is reported. Based on the mechanistic investigation, which indicates metal-ligand cooperation between the manganese center and the N-H group of the pincer ligand, we propose that the hydrogenation of organic carbonates to methanol occurs via formate and aldehyde intermediates. The reaction offers an indirect route for the conversion of CO to methanol, which coupled with the use of an earth abundant catalyst, makes the overall process environmentally benign and sustainable.

No abstract

Direct hydrogenation of a broad variety of cyclic imides to diols and amines using a ruthenium catalyst is reported here. We have applied this strategy toward the development of a new liquid organic hydrogen carrier system based on the hydrogenation of bis-cyclic imide that is formed by the dehydrogenative coupling of 1,4-butanediol and ethylenediamine using a new ruthenium catalyst. The rechargeable system has a maximum gravimetric hydrogen storage capacity of 6.66 wt%.

Double deprotonation of N,N'-bis(2,6-diisopropylphenyl)-o-phenylenediamine (H2L) with n-BuLi in THF yields the dilithium complex Li2L(thf)3. The reaction of Li2L(thf)3 with FeBr2(thf)2 and subsequent replacement of the solvent with toluene yield LFe(η(6)-toluene), which can also be synthesized from Fe(HMDS)2(thf) and H2L in toluene. The NMR data, bond lengths obtained from an X-ray diffraction study, and DFT calculations indicate that the diamide ligand L(2-) undergoes oxidization to a radical ligand L(1-). Reaction of LFe(η(6)-toluene) with 1 atm CO yields the tricarbonyl complex LFe(CO)3. MoCl4(thf)2 reacts with two equivalents of Li2L(thf)3 to yield (LiL)2MoCl2(thf)4 in which the phenylene backbone of the ligand has been dearomatized. One-electron oxidation of Li2L(thf)3 by EuCl3(dme)2 yields the open-shell species LiL(OEt2), which was characterized by X-ray crystallography and EPR spectroscopy.