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1.
Dalton Trans ; 50(22): 7610-7620, 2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-33988637

RESUMO

Three structurally intriguing polyoxoniobates (PONbs) based on the trivacant B-type α-Keggin ion {TeNb9O33}, H4K(CN3H6)2{[Cu4(2,2'-bipy)4(H2O)2][TeNb9V2O37]}·29H2O (1, 2,2'-bipy = 2,2'-bipyridine), H0.5K5Na2.5{[Cu(en)H2O]3[TeNb9V3O39]}·10H2O (2, en = ethylenediamine), and K3Na5{[Cu(1,3-dap)H2O]3[TeNb9V3O39]}·11H2O (3, 1,3-dap = 1,3-diaminopropane), are assembled by the conventional aqueous solution methods using a series of N-containing organic ligands. In 1, each of the two {VO4} units is attached to two coplanar NbO6 octahedra on the {Nb3O13} cluster of the {TeNb9O33} unit. Differently, three {VO4} units in 2 and 3 are linked to two edge-sharing NbO6 octahedra, respectively. Compounds 1-3 represent the first oxo NbTeV clusters and also the first vanadoniobates based on the trivacant Keggin PONb units. All three compounds were characterised by single-crystal X-ray structural analysis, TGA and IR, ESI-MS and 51V NMR spectroscopy. Furthermore, the magnetic properties of compounds 1 and 2 were also studied.

2.
Dalton Trans ; 49(22): 7420-7425, 2020 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-32428050

RESUMO

Three sandwich-type TM-containing (TM = transition metal) organophosphonate-based polyoxotungstate clusters, [TM(H2O)4(SeW6O21)2{Co(OOCCH2NCH2PO3)2}3]12- (TM = Co, Ni), have been successfully synthesized, which are the first reported TM-containing organophosphonate-based selenotungstates. They were structurally characterized by PXRD analyses, IR spectroscopy, TGA analyses, etc. Magnetic measurements show that all three compounds exhibit antiferromagnetic interactions. Besides, Co1 can be used as an efficient heterogeneous catalyst in the Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate under mild conditions (60 °C), and exhibits satisfactory conversion (93%) and high selectivity (99%).

3.
Inorg Chem ; 59(3): 1967-1972, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31940183

RESUMO

A novel polyoxoniobate cluster directed by AsO33-, {[Cu(phen)]5[Nb6O19][As2Nb6O22]}2 (1a), has been successfully synthesized by a "two-pot" strategy, namely, the conventional aqueous solution and diffusional methods. It incorporates two {[Cu(phen)]2Nb6O19} and two {[Cu(phen)]3As2Nb6O22} subunits. Surprisingly, by changing the reaction conditions, one of the subunits {[Cu(phen)]2Nb6O19} was isolated as a guanidinium salt. These architectures were structurally characterized by single crystal X-ray diffraction, TGA, IR, elemental analysis and PXRD, etc. Furthermore, the behavior of 1 in aqueous solution was measured by electrospray ionization mass spectrometry, and the magnetic property in the low temperature range indicates the presence of antiferromagnetic interactions.

4.
Dalton Trans ; 48(45): 16857-16860, 2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31702746

RESUMO

A novel tungstophosphate H12Na4K3[{Fe5O5(OH)2(OAc)2}2{W2-O2(OH)}{P2W14O54}2]·36H2O (1) containing an unprecedented [{Fe5O5(OH)2(OAc)2}2{W2O2(OH)}] unit has been successfully obtained and characterized by IR, TGA, magnetic susceptibility measurements and single-crystal X-ray diffraction. It shows a decameric FeIII molecular assembly formed through two {Fe5O23} subunits bridged by a {W2O3} motif.

5.
Dalton Trans ; 48(35): 13135-13138, 2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31424470

RESUMO

A novel hetero selenato-phosphato-peroxopolyoxoniobate with the formula Cs4H4[P2Se2Nb6(O2)6O22]·10H2O has been successfully isolated in an acidified aqueous hydrogen peroxide solution. The synthesized cluster represents the first example of a selenium-containing polyoxoniobate. Furthermore, the ESI-MS spectra show that the polyoxoanion structural unit [P2Se2Nb6(O2)6O22]8- remains intact in aqueous solution.

6.
Dalton Trans ; 45(41): 16173-16176, 2016 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-27711767

RESUMO

[H4Ni10(H2O)8Nb32O102]20-, representing the first high-nuclear nickel-cation-bridged polyoxoniobate, has been synthesized. It incorporates two [{Ni2O4}(H2O)2(Nb6O19)]12- and two [Ni3(H2O)2Nb10O34]12- subunits exhibiting a rhombus-like architecture. Furthermore, the solution behaviour was examined by electrospray ionization mass spectrometry and the magnetic properties in the low temperature range indicate the presence of ferromagnetic interactions.

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