Synthesis and structures of heterobimetallic Ir2M (MPd, Pt) sulfido clusters and their catalytic activity for regioselective addition of alcohols to internal 1-aryl-1-alkynes

Rapid Adsorption Enables Interface Engineering of PdMnCo Alloy/Nitrogen-Doped Carbon as Highly Efficient Electrocatalysts for Hydrogen Evolution Reaction

The catalytic performance of Pd-based catalysts has long been hindered by surface contamination, particle agglomeration, and lack of rational structural design. Here we report a simple adsorption method for rapid synthesis (∼90 s) of structure-optimized Pd alloy supported on nitrogen-doped carbon without the use of surfactants or extra reducing agents. The material shows much lower overpotential than 30 wt % Pd/C and 40 wt % Pt/C catalysts while exhibiting excellent durability (80 h). Moreover, unveiled by the density functional theory (DFT) calculation results, the underlying reason for the outstanding performance is that the PdMnCo alloy/pyridinic nitrogen-doped carbon interfaces weaken the hydrogen-adsorption energy on the catalyst and thus optimize the Gibbs free energy of the intermediate state (ΔG_H*), leading to a remarkable electrocatalytic activity. This work also opens up an avenue for quick synthesis of a highly efficient structure-optimized Pd-based catalyst.

π-back-bonding interaction depending on the bridging chain lengths of chelated N-heterocyclic carbene platinum units in heterometallic trinuclear complexes affecting their electrochemical property

Newly synthesized heterometallic trinuclear M2Pt complexes (M = Rh, Ir) containing a platinum moiety having a chelated bis-N-heterocyclic carbene (bisNHC) ligand with a variety of alkylene chain lengths of the bridging part showed two reversible reduction waves in cyclic voltammetry. Only the second reduction potentials were affected by the alkyl chain lengths, which afforded different dihedral angles between the imidazolylidene rings and the platinum coordination plane resulting in the variation of π-back-donation from the platinum center to the carbene carbon atoms.

Organometallic Gold(III) Compounds as Catalysts for the Addition of Water and Methanol to Terminal Alkynes

Different inorganic and organometallic gold(III) and gold(I) complexes have been tested in the addition of water and methanol to terminal alkynes. Anionic and neutral organometallic gold(III) compounds can efficiently mediate these reactions in neutral media in refluxing methanol. The compounds are added in catalytic amounts (1.6-4.5 mol % with respect to the alkyne). Thus, compounds of the general formula Q[AuRCl(3)], Q[AuR(2)Cl(2)], [AuRCl(2)](2), and [AuR(2)Cl](2) (Q = BzPPh(3)(+), PPN: N(PPh(3))(2)(+) or N(Bu)(4)(+); R = C(6)F(5) or 2,4,6-(CH(3))(3)C(6)H(2)) seem to behave as Lewis acids in nucleophilic additions to triple bonds. Some intermediates could be detected in the stoichiometric reaction between [Au(C(6)F(5))(2)Cl](2) and phenylacetylene that was followed by variable temperature (1)H, (19)F[(1)H], COSY (19)F[(1)H]-(19)F[(1)H], and (2)H[(1)H] NMR experiments. Compound [Au(C(6)F(5))(2)Cl](2) is also able to catalyze the hydration of phenylacetylene at room temperature. A plausible mechanism for the hydration reaction has been proposed.

Sulfur-bridged early-late heterobimetallics synthesized by incorporation of titanium, vanadium, and molybdenum into bis(hydrosulfido) templates of group 9 metals

Reactions of the bis(hydrosulfido) complexes [Cp*Rh(SH)(2)(PMe(3))] (1a; Cp* = eta(5)-C(5)Me(5)) with [CpTiCl(3)] (Cp = eta(5)-C(5)H(5)) and [TiCl(4)(thf)(2)] in the presence of triethylamine led to the formation of the sulfido-bridged titanium-rhodium complexes [Cp*Rh(PMe(3))(micro(2)-S)(2)TiClCp] (2a) and [Cp*Rh(PMe(3))(micro2-S)(2)TiCl(2)] (3a), respectively. Complex 3a and its iridium analogue 3b were further converted into the bis(acetylacetonato) complexes [Cp*M(PMe(3))(micro(2)-S)(2)Ti(acac)(2)] (4a, M = Rh; 4b, M = Ir) upon treatment with acetylacetone. The hydrosulfido complexes 1a and [Cp*Ir(SH)(2)(PMe(3))] (1b) also reacted with [VCl(3)(thf)(3)] and [Mo(CO)(4)(nbd)] (nbd = 2,5-norbornadiene) to afford the cationic sulfido-bridged VM2 complexes [(Cp*M(PMe(3))(micro2-S)(2))2V](+) (5a(+), M = Rh; 5b(+), M = Ir) and the hydrosulfido-bridged MoM complexes [Cp*M(PMe(3))(micro2-SH)(2)Mo(CO)(4)] (6a, M = Rh; 6b, M = Ir), respectively.