High-nuclearity oxomolybdenum(V) complexes

Imparting structural robustness of metal-organic cages based on oxo-dimolybdenum clusters

A family of robust and stable molybdenum-based metal-organic cages have been obtained based on the [Mo2O2(μ2-O)2]2+ secondary building unit. The resulting cages are decorated with different pyrdine derivatives that impart structural stability, resulting in the structural elucidation of the activated cage with single-crystal diffraction. The chemical robustness of the cage is also demonstrated by the post-synthetic modification of the cage, which allows the exchange of the pyridine derivatives without rupture of the cage.

Binuclear, tetranuclear and hexadecanuclear thio-oxomolybdenum(V/IV) glycolates with selective adsorptions of gases

By adjusting the pH values of the solutions, binuclear, tetranuclear and hexadecanuclear glycolato thio- and oxomolybdenum(V/IV) complexes [MoV2O₂(μ₂-O)(μ₂-S)(Hglyc)₂(Hpz)₂]·H₂O (1, H₂glyc = glycolic acid, Hpz = pyrazole), (Hdpa)[MoV2O₂(μ₂-S)₂(Hglyc)(glyc)(H₂O)] (2, dpa = 2,2'-dipyridylamine), (Hdpa)₄[MoV4O₄(μ₃-O)₂(μ₂-S)₂(glyc)₂(S₂O₃)₂] (3) and Na₂[MoIV4MoV12O₁₂(μ₂-O)₆(μ₂-OH)₂(μ₃-O)₁₂(glyc)₄(Hpz)₄(pz)₈]·28H₂O (4) have been obtained successfully. Here the glycolates existed in varying aggregates with different degrees of protonation and deprotonation in 1-4. The stable formations of 1 and 2 are attributed to strong hydrogen bonds formed between the molecules. In particular, the asymmetric unit in 2 is a tetramer linked by hydrogen bonding [2.574(9) Å] between α-hydroxy and α-alkoxy groups for further construction of unsaturated penta-coordination environments. Moreover, deprotonated glycolates act as bridging ligands to form tetra- and hexadecanuclear compounds 3 and 4, respectively. The smallest unit in 4 exhibits mixed valences of 4+ and 5+ simultaneously, where its gas adsorption experiments manifest that 4 is obviously beneficial for O₂ and CO₂ compared with no adsorption of N₂, CH₄ and H₂ at different pressures.

Microbiological Reduction of Molybdenum to Molybdenum Blue as a Sustainable Remediation Tool for Molybdenum: A Comprehensive Review

Molybdenum (Mo) microbial bioreduction is a phenomenon that is beginning to be recognized globally as a tool for the remediation of molybdenum toxicity. Molybdenum toxicity continues to be demonstrated in many animal models of spermatogenesis and oogenesis, particularly those of ruminants. The phenomenon has been reported for more than 100 years without a clear understanding of the reduction mechanism, indicating a clear gap in the scientific knowledge. This knowledge is not just fundamentally important-it is specifically important in applications for bioremediation measures and the sustainable recovery of metal from industrial or mine effluent. To date, about 52 molybdenum-reducing bacteria have been isolated globally. An increasing number of reports have also been published regarding the assimilation of other xenobiotics. This phenomenon is likely to be observed in current and future events in which the remediation of xenobiotics requires microorganisms capable of degrading or transforming multi-xenobiotics. This review aimed to comprehensively catalogue all of the characterizations of molybdenum-reducing microorganisms to date and identify future opportunities and improvements.

A Giant Mo/Ta/W Ternary Mixed-Addenda Polyoxometalate with Efficient Photocatalytic Activity for Primary Amine Coupling

The reactivity and properties of polyoxometalates (POMs) vary remarkably as a function of the kind of addenda atoms, so the design and synthesis of new mixed-addenda POMs is a promising approach for the further development of the POM-related areas. In the present work, the first Mo/Ta/W ternary mixed-addenda POM (NH₄)₄₁H₇[K₃(H₂O)₃(P₂W₁₅Ta₃O₆₂)₆(Mo₂O₄CH₃CO₂)₃(MoO₃)₂]·85H₂O (1), which is composed of 6 {P₂W₁₅Ta₃O₆₂} linked by 3 {Mo^V₂O₄(OOCCH₃)⁺} and 2 {Mo^VIO₃} via 18 novel Mo-O-Ta bridges has been synthesized. The precursor {P₂W₁₅Ta₃}, which has lower redox potential, is crucial for the formation of 1. The red-brown solid sample of 1 shows strong absorption in the visible region. The visible-light responsive charge transfer from benzylamine to 1 was observed experimentally. 1 was proved to be an efficient photocatalyst under simulated sunlight (AM 1.5G) radiation for the oxidative coupling of primary amines to imines using atmospheric O₂.

Tetra- to dodecanuclear oxomolybdate complexes with functionalized bisphosphonate ligands: activity in killing tumor cells

We report the synthesis and characterization of five novel Mo-containing polyoxometalate (POM) bisphosphonate complexes with nuclearities ranging from 4 to 12 and with fully reduced, fully oxidized, or mixed-valent (Mo(V), Mo(VI)) molybdenum, in which the bisphosphonates bind to the POM cluster through their two phosphonate groups and a deprotonated 1-OH group. The compounds were synthesized in water by treating [Mo(V)(2)O(4)(H(2)O)(6)](2+) or [Mo(VI)O(4)](2-) with H(2)O(3)PC(C(3)H(6)NH(2))OPO(3)H(2) (alendronic acid) or its aminophenol derivative, and were characterized by single-crystal X-ray diffraction and (31)P NMR spectroscopy. (NH(4))(6)[(Mo(V)(2)O(4))(Mo(VI)(2)O(6))(2)(O(3)PC(C(3)H(6)NH(3))OPO(3))(2)]·12H(2)O (1) is an insoluble mixed-valent species. [(C(2)H(5))(2)NH(2)](4)[Mo(V)(4)O(8)(O(3)PC(C(3)H(6)NH(3))OPO(3))(2)]·6H(2)O (2) and [(C(2)H(5))(2)NH(2)](6)[Mo(V)(4)O(8)(O(3)PC(C(10)H(14)NO)OPO(3))(2)]·18H(2)O (4) contain similar tetranuclear reduced frameworks. Li(8)[(Mo(V)(2)O(4)(H(2)O))(4)(O(3)PC(C(3)H(6)NH(3))OPO(3))(4)]·45H(2)O (3) and Na(2)Rb(6)[(Mo(VI)(3)O(8))(4)(O(3)PC(C(3)H(6)NH(3))OPO(3))(4)]·26H(2)O (5) are alkali metal salts of fully reduced octanuclear and fully oxidized dodecanuclear POMs, respectively. The activities of 2-5 (which are water-soluble) against three human tumor cell lines were investigated in vitro. Although 2-4 have weak but measurable activity, 5 has IC(50) values of about 10 μM, which is about four times the activity of the parent alendronate molecule on a per-alendronate basis, which opens up the possibility of developing novel drug leads based on Mo bisphosphonate clusters.

Organoruthenium derivative of the cyclic [H7P8W48O184]33? anion: [{K(H2O)}3{Ru(p-cymene)(H2O)}4P8W49O186(H2O)2]27?

Reaction of [Ru(p-cymene)Cl2]2 with [H7P8W48O184]33- (P8W48) in aqueous acidic medium results in the organometallic derivative [{K(H2O)}3{Ru(p-cymene)(H2O)}4P8W49O186(H2O)2]27- (1); in addition to the four {Ru(p-cymene)(H2O)} units, an unusual WO6 group with four equatorial, terminal ligands is also grafted to the crown-shaped P8W48 precursor.