Syntheses, characterizations and properties of [Mo2O2S2]-based oxothiomolybdenum wheels incorporating bisphosphonate ligands

Abstract

We report the syntheses and characterizations of the first polyoxothiometalate complexes isolated from the reaction of the oxothiocationic [Mo(V)(2)O(2)S(2)](2+) precursor and bisphosphonate ligands H(2)O(3)PCR(OH)PO(3)H(2) (R = C(4)H(5)N(2), zoledronic acid; R = C(3)H(6)NH(2), alendronic acid). [(Mo(2)O(2)S(2)(H(2)O))(4)(O(3)PC(O)(C(4)H(6)N(2))PO(3))(4)](8-) (Mo(8)S(8)(Zol)(4)) and [(Mo(2)O(2)S(2)(H(2)O))(4)(O(3)PC(O)(C(3)H(6)NH(3))PO(3))(4)](8-) (Mo(8)S(8)(Ale)(4)) contain four Mo(V) dimers connected via bisphosphonate ligands. These compounds offer a unique opportunity to compare the structures and properties of cyclic compounds obtained with [Mo(2)O(2)S(2)](2+) and with [Mo(2)O(4)](2+). The oxothio compounds appear less stable in solution than the oxo analogue, confirming the higher lability and versatility of [Mo(2)O(2)S(2)]-based compounds compared to [Mo(2)O(4)]-based POMs. Multinuclear and multidimensional solid-state NMR studies were carried out to complement X-ray diffraction analysis. Information on short-range interactions, dynamic behaviors, and local disorder within the crystalline materials are therefore reported. Furthermore, the electrocatalytic properties of Mo(8)S(8)(Ale)(4) and of the analogous [(Mo(2)O(4)(H(2)O))(4)(O(3)PC(O)(C(3)H(6)NH(3))PO(3))(4)](8-) (Mo(8)O(8)(Ale)(4)) immobilized onto the surface of a glassy carbon electrode were studied, thus evidencing the ability of [Mo(2)O(2)S(2)]-based cycles to promote the reduction of protons into hydrogen, whereas the oxo analogue appeared inactive.

Polyoxomolybdate Bisphosphonate Heterometallic Complexes: Synthesis, Structure, and Activity on a Breast Cancer Cell Line

“…The 1D 31 P{ 1 H} MAS NMR spectrum of Mo 12 (AlePy) 4 (Figure 4 a) exhibits four resolved lines at δ =18.1 (23 %), 20.0 (23 %), 25.3 (27 %), and 26.4 ppm (27 %), which is in agreement with the four crystallographic P sites (Figure S10a in the Supporting Information). The 2D 31 P{ 1 H}– 31 P{ 1 H} DQ–SQ correlation experiment shows strong dipolar coupling between the resonances at δ =18.1 and 26.4 ppm, as well as those at δ =20.0 and 25.3 ppm, which is consistent with two distinct AlePy environments, similar to the observation of two pairs of signals in the range of δ =26–27 and 29–33 ppm observed for alendronate in [(Mo 2 O 2 X 2 (H 2 O)) 4 (Ale) 4 ] 8− , in which X=O or S 28. The MAS NMR spectrum of the platinum complex Mo 12 (AlePy) 4 Pt 4 (Figure 4 b) shows two signals, centered at δ ≈21 and 25 ppm; these values are about the same as those observed with Mo 12 (AlePy) 4 , but with clear line broadening.…”

Coordination Polymers of Increasing Complexity Derived from Alkali Metal Cations and (4-Amino-1-hydroxybutylidine)-1,1-bisphosphonic Acid (Alendronic Acid): The Competitive Influences of Coordination and Supramolecular Interactions

“…4c However, for metal complexes, the dominant influence on the isotropic 31 P MAS NMR shifts is most likely to be the metal-phosphonate coordination modes and the number of peaks generally correlates with the number of unique phosphonate sites in the corresponding crystal structure. 8c,9b,24,25 As shown in ESI Figures S3.1-3.3, the data obtained12 for the three structural variants 1a, 2b (phase I) and 3b (phase II) (corresponding to the bulk products) are distinctive, and the number of isotropic peaks matches the number of crystallographically unique phosphorus atoms in the relevant crystal structures. In some cases, peaks are split into doublets due to P-P coupling with J PP ~ 30-60 Hz.…”

“…[5][6][7] More recently, studies of metal coordination compounds of alendronate and related 1,1-bisphosphonate ligands have led to new strategies for their use in the treatment of cancer 8 and other medicinal applications, 9 as well as developing new materials with magnetic, photochromic, and electrocatalytic properties. [10][11][12] In this current contribution we have investigated the syntheses and structures of a series of new coordination polymers of alendronic acid (LH 5 , Scheme 1) with a particular focus on cations from the group 1 metals potassium, rubidium and caesium. As described above, the multi-metal binding capabilities of the bisphosphonate group should be well suited to these large oxophilic cations (K-Cs ionic radii are ca 0.36-0.65 Å greater than for Na at CN = 6 13 ) which generally exhibit more indiscriminate coordination environments in terms of coordination numbers (typically 6-10), irregular geometries and a wider range of bond distances than the smaller group 1 metals, lithium and sodium.…”

Redox and acidic properties of chalcogenido-substituted mixed-metal polyoxoanions: a DFT study of α-[PW11O39ME]4− (M = Nb, Ta; E = O, S, Se)

“…26 To date, two strategies have been developed to synthesize POMs containing sulfur and selenium. 26 To date, two strategies have been developed to synthesize POMs containing sulfur and selenium.…”