TY - JOUR
T1 - Binary Pd-polyoxometalates and isolation of a ternary Pd-V-polyoxomolybdate active species for selective aerobic oxidation of alcohols
AU - Huang, Xianqiang
AU - Zhang, Xiaomei
AU - Zhang, Dan
AU - Yang, Song
AU - Feng, Xiao
AU - Li, Jikun
AU - Lin, Zhengguo
AU - Cao, Jie
AU - Pan, Ran
AU - Chi, Yingnan
AU - Wang, Bo
AU - Hu, Changwen
PY - 2014/2/24
Y1 - 2014/2/24
N2 - Binary Pd-polyoxometalates [Pd(dpa)2]3[PW 12O40]2×12 DMSO (2), [Pd(dpa) 2]3[PMo12O40]2×12 DMSO×2 H2O (3), and [Pd(dpa)(DMSO)2] 2[HPMo10V2O40]×4 DMSO (4) were synthesized by reaction of [Pd(dpa)(OAc)2]×2 H2O (1; dpa=2,2′-dipyridylamine) with three Keggin-type polyoxometalates and fully characterized by single-crystal and powder XRD analyses, IR spectroscopy, and elemental analyses. The synthesis is facile and straightforward, and the complicated ligand-modification procedure often used in the traditional charge-transfer method can be omitted. In 2-4, Pd complexes and polyoxometalate anions are coupled through electrostatic interaction. Compound 4 is more active than the other three compounds in the selective aerobic oxidation of alcohols at ambient pressure. Interestingly, during catalytic recycling of compound 4, unprecedented ternary Pd-V-polyoxometalate [Pd(dpa)2{VO(DMSO) 5}2][PMo12O40]2×4 DMSO (5), which was captured and characterized by single-crystal XRD, proved to be the true active species and showed high catalytic activity for the selective aerobic oxidation of aromatic alcohols (98.1-99.8 % conversion, 91.5-99.1 % selectivity). Moreover, on the basis of control experiments and EPR and UV/Vis spectra, a plausible reaction mechanism for the oxidation of alcohols catalyzed by 5 was proposed. Binary noble metal-POM compounds: The unprecedented ternary Pd-V-POM compound (POM=polyoxometalate) [Pd(dpa)2{VO(DMSO) 5}2][PMo12O40]2×4 DMSO, which was isolated during the catalytic recycling of [Pd(dpa)(DMSO) 2]2[HPMo10V2O40]×4 DMSO (dpa=2,2′-dipyridylamine) and characterized by single-crystal X-ray diffraction, proved to be the true active species and showed high catalytic activity for the aerobic oxidation of aromatic alcohols (see figure).
AB - Binary Pd-polyoxometalates [Pd(dpa)2]3[PW 12O40]2×12 DMSO (2), [Pd(dpa) 2]3[PMo12O40]2×12 DMSO×2 H2O (3), and [Pd(dpa)(DMSO)2] 2[HPMo10V2O40]×4 DMSO (4) were synthesized by reaction of [Pd(dpa)(OAc)2]×2 H2O (1; dpa=2,2′-dipyridylamine) with three Keggin-type polyoxometalates and fully characterized by single-crystal and powder XRD analyses, IR spectroscopy, and elemental analyses. The synthesis is facile and straightforward, and the complicated ligand-modification procedure often used in the traditional charge-transfer method can be omitted. In 2-4, Pd complexes and polyoxometalate anions are coupled through electrostatic interaction. Compound 4 is more active than the other three compounds in the selective aerobic oxidation of alcohols at ambient pressure. Interestingly, during catalytic recycling of compound 4, unprecedented ternary Pd-V-polyoxometalate [Pd(dpa)2{VO(DMSO) 5}2][PMo12O40]2×4 DMSO (5), which was captured and characterized by single-crystal XRD, proved to be the true active species and showed high catalytic activity for the selective aerobic oxidation of aromatic alcohols (98.1-99.8 % conversion, 91.5-99.1 % selectivity). Moreover, on the basis of control experiments and EPR and UV/Vis spectra, a plausible reaction mechanism for the oxidation of alcohols catalyzed by 5 was proposed. Binary noble metal-POM compounds: The unprecedented ternary Pd-V-POM compound (POM=polyoxometalate) [Pd(dpa)2{VO(DMSO) 5}2][PMo12O40]2×4 DMSO, which was isolated during the catalytic recycling of [Pd(dpa)(DMSO) 2]2[HPMo10V2O40]×4 DMSO (dpa=2,2′-dipyridylamine) and characterized by single-crystal X-ray diffraction, proved to be the true active species and showed high catalytic activity for the aerobic oxidation of aromatic alcohols (see figure).
KW - homogeneous catalysis
KW - oxidation
KW - palladium
KW - polyoxometalates
KW - vanadium
UR - http://www.scopus.com/inward/record.url?scp=84897671767&partnerID=8YFLogxK
U2 - 10.1002/chem.201303714
DO - 10.1002/chem.201303714
M3 - Article
AN - SCOPUS:84897671767
SN - 0947-6539
VL - 20
SP - 2557
EP - 2564
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 9
ER -