Coordination capacity of Keggin anions as polytopic ligands: case study of [VNb12O40]15.

Reaction of Na9H4[VNb12O40{NbO(CO3)}2] with [(C6H6)RuCl2]2 (molar ratio {VNb12} : {(C6H6)Ru} = 1 : 4) in aqueous solution gives a mixture of [α-{(C6H6)Ru}4VNb12O40]7- and [α-{(C6H6)Ru}3VNb12O40]9-. Direct acetone diffusion into mother liquor leads to crystallization of Na6H[α-{(C6H6)Ru}4VNb12O40]·41.25H2O (1), characterized by single crystal X-ray diffraction (SCXRD). This anion has four organometallic fragments coordinated to the α-Keggin type [VNb12O40]15- backbone in different manner. Three {(C6H6)Ru}2+ groups cap triangular faces and one group a rectangular face of [VNb12O40]15-. Equilibrated mixture of [α-{(C6H6)Ru}4VNb12O40]7- and [α-{(C6H6)Ru}3VNb12O40]9- was studied by 1H DOSY NMR, HPLC-ICP-AES and HPLC-ESI-MS combined techniques. Direct chromatographic separation of these complexes results in unexpected transformation of both species into [α-{(C6H6)Ru}5VNb12O40]5-, isolated and characterized as Na5[α-{(C6H6)Ru}5VNb12O40]·16H2O (2). This anion contains five coordinated organometallic groups occupying both triangular and rectangular faces.

Keggin-type polyoxometalate 1 : 1 complexes of Pb(II) and Bi(III): experimental, theoretical and luminescence studies.

Bi3+ and Pb2+ uptake by a monolacunary Keggin-type [PW11O39]7- anion leads to the formation of [PW11O39Bi]4- and [PW11O39Pb]5- complexes with a stereochemically active lone pair at the incorporated heterometal. The two complexes were isolated as (TBA)4[PW11O39Bi] (1) and (TBA)5[PW11O39Pb] (2) and characterized by 31P and 183W NMR spectroscopy, high-resolution electrospray mass-spectrometry (HR-ESI-MS) and cyclic voltammetry (CV). EXAFS and XANES data confirm the unchanged oxidation state and ψ-square pyramidal geometry of Bi3+ and Pb2+ in 1 and 2. DFT calculations were used in order to (i) confirm the absence of ligands attached to the heterometal sites in both complexes and localize the lone pair, and (ii) assign all signals in the 183W NMR spectra. Complexes 1 and 2 demonstrate photoluminescence (PL). A reversible change in the PL spectra of both complexes in the presence of water vapor has been detected. On the contrary, PL data for sandwich-type ((CH3)4N)4K3[H4(PW11O39)2Bi]·25H2O (3) do not show sensitivity to water vapor.

Easy Ligand Activation in the Coordination Sphere of Ru inside the [PW11O39]7- Backbone.

Irradiation of the Keggin-type [PW11O39{Ru(NO)}]4- (Ru-NO) polyoxometalate in CH3CN results in rapid NO ligand elimination with the formation of [PW11O39{RuIII(CH3CN)}]4- (Ru-CH3CN). This complex offers an easy entry into the Ru-based chemistry of the {PW11Ru} complex. Attempts to substitute N3- for CH3CN in the presence of an NaN3 excess lead a variety of products: (i) [PW11O39{RuIII(N3)}]4- (Ru-N3); (ii) [PW11O39{RuIII(N4HC-CH3)}]4- (Ru-Tz) as a click-reaction product; and (iii) [PW11O39{RuII(N2)}]5- (Ru-N2). UV-VIS, CV, and HR-ESI-MS techniques were used for the reaction monitoring and characterization of the products.

Is It Possible To Prepare a Heterometal Anderson-Evans Type Anion?

Reaction of [SbW9O33]9- with [Pt(H2O)2(OH)4] results in the first example of the mixed addenda Anderson-Evans type PtIV{SbV(OH)2}WVI5O22]7- anion, isolated and characterized as K6Na2[Pt{Sb(OH)2}W5O22](NO3)0.1(OH)0.9̇11H2O (1).

Reactions of [Ru(NO)Cl5]2- with pseudotrilacunary {XW9O33}9- (X = AsIII, SbIII) anions.

Reactions of [Ru(NO)Cl5]2- with pseudotrivacant B-α-[XW9O33]9- (X = AsIII, SbIII) at 160 °C result in the rearrangement of polyoxometalate backbones into {XM18} structures. In the case of arsenic, oxidation of AsIII to AsV takes place with the formation of a mixture of plenary and monosubstituted Dawson [As2W18O62]6- and [As2W17Ru(NO)O61]7- anions, of which the latter was isolated as Me2NH2+ (DMA-1a and DMA-1b) and Bu4N+ (Bu4N-1) salts and fully characterized. Both α1 and α2 isomers of [As2W17Ru(NO)O61]7- were present in the reaction mixture; pure [α2-As2W17Ru(NO)O61]7- was isolated as the Bu4N+ salt. In the case of antimony, [SbW9O33]9- is converted into a mixture of [SbW18O60]9- and [SbW17{Ru(NO)}O59]10-. The formation of trisubstituted [SbW15{Ru(NO)}3O57]12- as a minor byproduct was detected by HPLC-ICP-AES. The monosubstituted [SbW17{Ru(NO)}O59]10- anion was isolated as DMAH+ (DMA-2) and mixed inorganic cation (CsKNa-2) salts and characterized by XRD, HPLC-ICP-AES, EA and TGA techniques. X-ray analysis shows the presence of the {Ru(NO)}-group in the 6-membered ("equatorial") belt of the Sb-free hemisphere. The experimental findings were confirmed and interpreted by means of quantum chemical calculations.