Hexaazide octahedral molybdenum cluster complexes: synthesis, properties and the evidence of hydrolysis

This article reports the synthesis, crystal structure of new molybdenum hexaazide cluster complex (ⁿBu₄N)₂[{Mo₆I₈}(N₃)₆] (3) and comparison of its photophysical and electrochemical properties to those of earlier reported analogues (ⁿBu₄N)₂[{M₆X₈}(N₃)₆] (X = Cl, Br). Additionally, the dimerisation of 3 as a result of hydrolysis was revealed by mass spectrometry and single crystal X-Ray diffraction. Indeed, the structurally characterised compound (ⁿBu₄N)₄[{Mo₆I₈}(N₃)₅)₂O] represents the first example of oxo-bridged dimer of octahedral molybdenum clusters complexes

A comparative study of optical properties and X-ray induced luminescence of octahedral molybdenum and tungsten cluster complexes

© 2017 The Royal Society of Chemistry. Octahedral metal cluster complexes have high potential for biomedical applications. In order to evaluate the benefits of these moieties for combined CT/X-ray luminescence computed tomography, this paper compares photoluminescence, radiodensity and X-ray induced luminescence properties of eight related octahedral molybdenum and tungsten cluster complexes [{M 6 I 8 }L 6 ] n (where M is Mo or W and L is I - , NO 3 - , OTs - or OH - /H 2 O). This article demonstrates that despite the fact that molybdenum cluster complexes are better photoluminescence emitters, tungsten cluster complexes, in particular (Bu 4 N) 2 [{W 6 I 8 }I 6 ], demonstrate significantly higher X-ray induced luminescence due to a combination of relatively good photoluminescence properties and high X-ray attenuation. Additionally, photo-degradation of [{M 6 I 8 }(NO 3 ) 6 ] 2- was evaluated

New NIR-emissive tetranuclear Er(III) complexes with 4-hydroxo-2,1,3-benzothiadiazolate and dibenzoylmethanate ligands: synthesis and characterization

New tetranuclear heteroleptic complexes [Er4(dbm)6(O-btd)4(OH)2] (1) and [Er4(dbm)4(O-btd)6(OH)2] (2) (O-btd = 4-hydroxo-2,1,3-benzothiadiazolate and dbm = dibenzoylmethanide) and their solvates with toluene, THF and CH2Cl2 were prepared using two synthetic approaches. The structures of the products were confirmed by single-crystal X-ray diffraction. Magnetic properties of 1 and 2 are in good agreement with X-ray data. The effective magnetic moment (μeff) values at 300 K for 1 and 2 corresponds to a system of 4 non-interacting Er(III) ions in the ground state 4J15/2 with g = 6/5. At ambient temperature and upon excitation with λexc = 450 nm, complexes 1 and 2 exhibit luminescence at ∼1530 nm, i.e. in the near infra-red (NIR) region. The luminescence intensity grows with increasing the number of the (O-btd)−ligands in the complexes. This observation suggests (O-btd)− as a new efficient antenna ligand for the lanthanide-based NIR luminescence

From photoinduced to dark cytotoxicity via an octahedral cluster hydrolysis

Octahedral molybdenum and tungsten clusters have potential biological applications in photodynamic therapy and bioimaging. However, poor solubility and hydrolysis stability of these compounds hinder their application. The first water-soluble photoluminescent octahedral tungsten cluster [{W6I8}(DMSO)6](NO3)4 was synthesised and demonstrated to be at least one order of magnitude more stable towards hydrolysis than its molybdenum analogue. Biological studies of the compound on larynx carcinoma cells suggest that it has a significant photoinduced toxicity, while the dark toxicity increases with the increase of the degree of hydrolysis. The increase of the dark toxicity is associated with the in situ generation of nanoparticles that clog up the cisternae of rough endoplasmic reticulum

23-electron octahedral molybdenum cluster complex [{Mo 6 I 8 }Cl 6 ] –

Photoactive transition metal compounds that are prone to reversible redox reactions are important for myriad applications, including catalysis, optoelectronics and sensing. This article describes chemical and electro-chemical methods to prepare cluster complex (Bu4N)[{Mo6I8}Cl6], a rear example of 23ē cluster complex within the family of octahedral clusters of Mo, W, and Re. The low temperature and room temperature crystal structures, electronic structure and the magnetic, optical and electrochemical properties of this complex are described

Octahedral molybdenum cluster complexes with aromatic sulfonate ligands

This article describes the synthesis, structures and systematic study of the spectroscopic and redox properties of a series of octahedral molybdenum metal cluster complexes with aromatic sulfonate ligands (nBu4N)2[{Mo6X8}(OTs)6] and (nBu4N)2[{Mo6X8}(PhSO3)6] (where X- is Cl-, Br- or I-; OTs- is p-toluenesulfonate and PhSO3 - is benzenesulfonate). All the complexes demonstrated photoluminescence in the red region and an ability to generate singlet oxygen. Notably, the highest quantum yields (>0.6) and narrowest emission bands were found for complexes with a {Mo6I8}4+ cluster core. Moreover, cyclic voltammetric studies revealed that (nBu4N)2[{Mo6X8}(OTs)6] and (nBu4N)2[{Mo6X8}(PhSO3)6] confer enhanced stability towards electrochemical oxidation relative to corresponding starting complexes (nBu4N)2[{Mo6X8}X6]

Synthesis and properties of the heterospin (S1 = S2 = 1/2) radical-ion salt bis(mesitylene)molybdenum(I) [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazolidyl

The authors are grateful to the Presidium of the Russian Academy of Sciences (Project 8.14), the Royal Society (RS International Joint Project 2010/R3), the Leverhulme Trust (Project IN-2012-094), the Siberian Branch of the Russian Academy of Sciences (Project 13), the Ministry of Education and Science of the Russian Federation (Project of Joint Laboratories of Siberian Branch of the Russian Academy of Sciences and National Research Universities), and the Russian Foundation for Basic Research (Projects 13-03-00072 and 15-03-03242) for financial support of various parts of this work. N.A.S. thanks the Council for Grants of the President of Russian Federation for postdoctoral scholarship (grant MK-4411.2015.3). B.E.B. is grateful for an EaStCHEM Hirst Academic Fellowship. A.V.Z. thanks the Foundation named after D. I. Mendeleev, Tomsk State University, for support of his work.Low-temperature interaction of [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (1) with MoMes2 (Mes = mesitylene / 1,3,5-trimethylbenzene) in tetrahydrofuran gave the heterospin (S1 = S2 = 1/2) radical-ion salt [MoMes2]+[1]– (2) whose structure was confirmed by single-crystal X-ray diffraction (XRD). The structure revealed alternating layers of the cations and anions with the Mes ligands perpendicular, and the anions tilted by 45°, to the layer plane. At 300 K the effective magnetic moment of 2 is equal to 2.40 μB (theoretically expected 2.45 μB) and monotonically decreases with lowering of the temperature. In the temperature range 2−300 K, the molar magnetic susceptibility of 2 is well-described by the Curie-Weiss law with parameters C and θ equal to 0.78 cm3⋅K⋅mol–1 and −31.2 K, respectively. Overall, the magnetic behavior of 2 is similar to that of [CrTol2]+[1]– and [CrCp*2]+[1]–, i.e. changing the cation [MAr2]+ 3d atom M = Cr (Z = 24) with weak spin-orbit coupling (SOC) to a 4d atom M = Mo (Z = 42) with stronger SOC does not affect macroscopic magnetic properties of the salts. For the XRD structure of salt 2, parameters of the Heisenberg spin-Hamiltonian were calculated using the broken-symmetry DFT and CASSCF approaches, and the complex 3D magnetic structure with both the ferromagnetic (FM) and antiferromagnetic (AF) exchange interactions was revealed with the latter as dominating. Salt 2 is thermally unstable and slowly loses the Mes ligands upon storage at ambient temperature. Under the same reaction conditions, interaction of 1 with MoTol2 (Tol = toluene) proceeded with partial loss of the Tol ligands to afford diamagnetic product.PostprintPostprintPeer reviewe

A Neutral Heteroleptic Molybdenum Cluster <i>trans</i>-[{Mo₆I₈}(py)₂I₄]

Despite that the chemistry of octahedral cluster complexes has been actively developed recently, there are still a lot of unexplored areas. For example, to date, only a few halide M6-clusters with N-heterocycles are known. Here, we obtained an apically heteroleptic octahedral iodide molybdenum cluster complex with pyridine ligands—trans-[{Mo6I8}(py)2I4] by the direct substitution of iodide apical ligands of [{Mo6I8}I6]2– in a pyridine solution. The compound co-crystalized with a monosubstituted form [{Mo6I8}(py)I5]– in the ratio of 1:4, and thus, can be described by the formula (pyH)0.2[{Mo6I8}(py)1.8I4.2]·1.8py. The composition was studied using XRPD, elemental analyses, and 1H-NMR and IR spectroscopies. According to the absorption and luminescence data, the partial substitution of apical ligands weakly affects optical properties

Two Oxygen-Coordinated Metastable Ru–ON States for Ruthenium Mononitrosyl Complex

The properties of Ru–ON states were studied in <i>cis</i>-[RuNO­(NH₃)₂(NO₂)₂OH] under illumination. The structure contains two nonequivalent complexes, and the metastable state was generated for both molecules with 19(1) and 31(1)% populations. The MS1 thermal decay occurs as a one-step process at about 240 K according to differential scanning calorimetry (DSC). For the first-order reaction, the frequency factor and activation energy for the decay process were determined as 2.0(2) × 10¹³ s^–1 and 68.3(4) kJ mol^–1, respectively. Also, the simultaneous metastable state decay observed via DSC was in agreement with IR spectroscopy