The generation of hydrogen (H2) using sunlight has become an essential energy alternative for decarbonization. The need for functional nanohybrid materials based on photo- and electroactive materials and accessible raw materials is high in the field of solar fuels. To reach this goal, single-step synthesis of {Ta6Bri12}@GO (GO = graphene oxide) nanohybrids was developed by immobilization of [{Ta6Bri12}Bra2(H2O)a4]·4H2O (i = inner and a = apical positions of the Ta6 octahedron) on GO nanosheets by taking the advantage of the easy ligand exchange of the apical cluster ligands with the oxygen functionalities of GO. The nanohybrids were characterized by spectroscopic, analytical, and morphological techniques. The hybrid formation enhances the yield of photocatalytic H2 from water with respect to their precursors and this is without the presence of precious metals. This enhancement is attributed to the optimal cluster loading onto the GO support and the crucial role of GO in the electron transfer from Ta6 clusters into GO sheets, thus suppressing the charge recombination. In view of the simplicity and versatility of the designed photocatalytic system, octahedral tantalum clusters are promising candidates to develop new and environmentally friendly photocatalysts for H2 evolution.

Ta powder reacts with I 2 at 650 °C with the formation of Ta 6 I 14 , which belongs to the family of {M 6 (μ-X) 12 } clusters. It undergoes aquation with the formation of the intensely colored [Ta 6 I 12 (H 2 O) 6 ] 2+ . The crystal structure was determined for [Ta 6 I 12 2+ shows two consecutive quasi-reversible one-electron oxidations (E 1/2 0.61 and 0.92 V vs Ag/AgCl). Reaction of Ta 6 I 14 with Bu 4 NCN yields (Bu 4 N) 4 [Ta 6 I 12 (CN) 6 ]•xCH 3 CN (Ta−Ta 2.9777(4) Å, Ta−I 2.8165(6) Å, Ta−C 2.2730(7) Å). Quantum chemical calculations reproduce well the experimental geometry of the aqua complex and show the essentially Ta-centered nature of both the HOMO and LUMO. The long-term stability of [Ta 6 I 12 (H 2 O) 6 ] 2+ solutions can be greatly enhanced in the presence of polystyrenesulfonate (PSS), which forms nanoparticle associates with the aqua complex in water (ca. 1 cluster per 3 PSS monomeric units).

No abstract

Synthetic procedures providing straightforward access to the whole family of Nb and Ta halide clusters with terminal cyanide ligands have been developed. Corresponding [M 6 X 12 (CN) 12 ] 4− (M = Nb, Ta; X = Cl, Br) can be accessed by ligand-exchange procedures from K 4 Nb 6 X 18 (X = Cl, Br) and Bu 4 NCN, (Et 4 N) 2 [Ta 6 Cl 1 8 ] and Bu 4 NCN and from [Ta 6 Br 12 (H 2 O) 4 Br 2 ]•4H 2 O and KCN in moderate to high yields (50−80%). The products were isolated as Bu 4 N salts. The compounds were investigated both experimentally and by quantum chemistry, revealing correlations between structural, electrochemical, electrostatic, electronic, and topological features as a function of type of metal, halide, and charge.

No abstract

No abstract

No abstract

No abstract