Inorganic Chemistry 2012-06-04

(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.

Wancheng Zhu, Yan Yang, Shi Hu, Guolei Xiang, Biao Xu, Jing Zhuang, Xun Wang

Index: Inorg. Chem. 51(11) , 6020-31, (2012)

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Abstract

(Ni(1-x),Mg(x))(3)Si(2)O(5)(OH)(4) solid-solution nanotubes (NTs) with tunable compositions were hydrothermally synthesized by altering the molar ratio of Mg(2+) to Ni(2+). 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)(3)Si(2)O(5)(OH)(4) (Mg(2+):Ni(2+) = 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)(3)Si(2)O(5)(OH)(4) (Mg(2+):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)(3)Si(2)O(5)(OH)(4) (Mg(2+):Ni(2+) = 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.