(Ni,Mg)3Si2O5(OH)4 solid-solution nanotubes supported by sub-0.06 wt % palladium as a robust high-efficiency catalyst for Suzuki-Miyaura cross-coupling reactions

Article abstract of DOI:10.1021/ic2024378

(Ni_1-x,Mg_x)₃Si₂O ₅(OH)₄ solid-solution nanotubes (NTs) with tunable compositions were hydrothermally synthesized by altering the molar ratio of Mg²⁺ to Ni²⁺. The as-synthesized NTs were loaded with sub-0.06 wt % palladium (Pd; ～0.045 wt %) for Suzuki-Miyaura (SM) coupling reactions between iodobenzene or 4-iodotoluene and phenylboronic acid. The (Ni,Mg)₃Si₂O₅(OH)₄ (Mg ²⁺:Ni²⁺ = 1.0:1.0) NTs supported by 0.045 wt % Pd promoted the iodobenzene-participated coupling reaction with a high yield of >99%, an excellent recycling catalytic performance during 10 cycles of catalysis with yields of ～99%, and also an extremely low Pd releasing level of ～0.02 ppm. High-activity Pd and PdO clusters, multitudes of dislocations, and defects and terraces contained within the NTs should contribute to the (Ni,Mg) ₃Si₂O₅(OH)₄ (Mg²⁺:Ni ²⁺ = 1.0:1.0) NTs supported by 0.045 wt % Pd as a robust, reusable, and high-efficiency catalyst for SM coupling reactions with an extremely low Pd releasing level. The present hydrothermally stable (Ni,Mg)₃Si ₂O₅(OH)₄ (Mg²⁺:Ni²⁺ = 1.0:1.0) solid-solution silicate NTs provided an ideal alternative tubular-structured support for noble- or transition-metal catalysts with low Pd loading, good recycling, and extremely low ppb levels of Pd release, which could also be extended to some other SM coupling reactions.