Nb Complexes Research Articles

Preliminary Investigation on the Thermodynamic Evaluation and Phase Evolution of Soda Ash-Assisted Roast Treatment of Alluvial Columbite for Recovery of Niobium and Tantalum

Alkaline roasting of a low-grade alluvial silica-based columbite bearing mineral from the Rayfield–Jos deposits (located in South Jos, Plateau state, Federal Republic of Nigeria) was conducted with specific emphasis on the evaluation of thermodynamic reactions as well as the mineral phase evolution during the extraction of Nb and Ta. An isothermal roasting procedure was investigated in order to understand the effects of different soda ash to sample mass ratios as well as the roasting temperatures on the measure or rate of the recoveries of Nb and Ta complexes. Thus, the feasibility rate of a successful alluvial columbite mineral roasting was determined to be influenced by certain optimal process conditions or optimum values of the study parameters, such as alkali to sample mass ratio and, more essentially, the roasting temperature. Therefore, the thermodynamic feasibility of the alkali-carbothermic roasting procedure was also investigated and the resulting chemical reactions were evaluated using the HSC chemistry 9.0 software. Premised on this, the results obtained as well as the thermodynamic data realized from the study demonstrated the feasibility of successful dissolutions of Nb and Ta into a pregnant leached-liquor stream (PLS), without the use of the conventional harmful, hazardous, toxic, and environmentally unfriendly hydrofluoric (HF) acid.

Unexpected Periodicity in Cationic Group 5 Initiators for the Ring-Opening Polymerization of Lactones.

ε-Caprolactone (ε-CL) adducts of cationic, amine tris(phenolate)-supported niobium(V) and tantalum(V) ethoxides initiate the ring-opening polymerization of lactones. The Ta(V) species prepared and applied catalytically herein exhibits higher activity in the ring-opening polymerization (ROP) of ε-caprolactone than the previously reported, isostructural Nb(V) complex, contradicting literature comparisons of Nb(V)- and Ta(V)-based protocols. Both systems also initiate the ROP of δ-valerolactone and rac-β-butyrolactone, kinetic studies confirming retention of higher activity by the Ta congener. Polymerizations of rac-β-butyrolactone and δ-valerolactone were previously unrealized under Group V- or Ta-mediated conditions, respectively, although the former has afforded only low molecular weight, cyclic poly-3-hydroxybutyrate. Cationic ethoxo-Nb(V) and -Ta(V) δ-valerolactone adducts are also reported, demonstrating the facility of δ-valerolactone as a ligand and the generality of the synthetic method. Both δ-valerolactone-bearing complexes initiate the ROP of ε-caprolactone, δ-valerolactone, and rac-β-butyrolactone. Accordingly, we have elucidated trends in reactivity and investigated the initiation mechanism for such systems, the insertion event being predicated upon intramolecular nucleophilic attack on the coordinated lactone by the adjacent alkoxide moiety. This mechanism enables quantitative, stoichiometric installation of a single monomer residue distinct from the bulk of the polymer chain, and permits modification of polymer properties via both manipulation of the molecular architecture and tuning of the polymerization kinetics, and thus dispersity, through hitherto inaccessible independent control of the initiation event.

Electrodeposition of Niobium Coatings on the Cryogyroscope Rotor

The discharge process of Nb(IV) complexes to Nb was studied by cyclic voltammetry. A galvanostatic electrolysis with the cathodic current density of 1.5·10−2 A cm−2 in the NaCl–KCl–NaF–K2NbF7 melt in contact with Nb anode was used for deposition of niobium coatings on the cryogyroscope rotor at temperature 1023 K, and time of process from 8 to 12 h. The coatings were continuous and smooth due to the special design of the cathode. The rotation speed of the stirrer was set to 35 rpm and did not change in all experiments. Such conditions made it possible to obtain coatings with the thickness up to 150 μm. The main characteristics of the niobium coatings such as purity, roughness, nonsphericity, and superconductivity were investigated.

Syntheses of Group 5 Amide Amidinates and Their Reactions with Water: Different Reactivities of Nb(V) and Ta(V) Complexes.

Chemistries of Nb(V) and Ta(V) compounds are essentially identical as a result of lanthanide contraction. Hydrolysis of M(NMe2)5 (M = Nb, Ta), for example, yields [M(μ3-O)(NMe2)3]4 (M = Nb, 1; Ta, 2) reported earlier. The similar reactivities of Nb(V) and Ta(V) compounds make it challenging, for example, to separate the two metals from their minerals. We have found that the reactions of H2O with amide amidinates M(NMe2)4[MeC(NiPr)2] (M = Nb, 3; Ta, 4) show that the niobium and tantalum analogues take different principal paths. For the Nb(V) complex 3, the amidinate and one amide ligand are liberated upon treatment with water, yielding [Nb(μ3-O)(NMe2)3]4 (1). For the Ta(V) complex 4, the amide ligands are released in the reaction with H2O, leaving the amidinate ligand intact. [Ta(μ3-O)(NMe2)3]4 (2), the analogue of 1, was not observed as a product in the reaction of 4 with H2O. To our knowledge, this is the first example of the formation of two different complexes that maintain the (V) oxidation state in both metals. The new complexes M(NMe2)4[MeC(NiPr)2] (M = Nb, 3; Ta, 4) have been prepared by the aminolysis of M(NMe2)5 (M = Nb, Ta) with iPrN(H)C(Me)=NiPr (5). The hydrolysis of 3 and 4 has been investigated by DFT electronic structure calculations. The first step in each hydrolysis reaction involves the formation of a hydrogen-bonded complex that facilitates a proton transfer to the amidinate ligand in 3 and protonation of an axial dimethylamide ligand in 4. Both proton transfers furnish an intermediate metal-hydroxide species. The atomic charges in 3 and 4 have been computed by Natural Population Analysis (NPA), and these data are discussed relative to which of the ancillary ligands is protonated initially in the hydrolysis sequence. Ligand exchanges in 3 and 4 as well as the exchange in iPrN(H)C(Me)=NiPr (5) were probed by EXSY NMR spectroscopy, giving rate constants of the exchanges: 0.430(13) s-1 (3), 0.033(6) s-1 (4), and 2.23(7) s-1 (5), showing that the rate of the Nb complex Nb(NMe2)4[MeC(NiPr)2] (3) is 13 times faster than that of its Ta analogue 4.

Synthesis, Single Crystal X-ray Structure, Spectroscopy and Substitution Behavior of Niobium(V) Complexes Activated by Chloranilate as Bidentate Ligand

Chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone, caH2) as a bidentate ligand for Nb(V) as a metal center is presented. The different coordination behavior of caH2 is well illustrated by a monomeric (Et4N)cis-[NbO(ca)2(H2O)OPPh3]·3H2O.THF (5) and a novel tetranuclear compound (Et4N)4[Nb4O4(ca)2(μ2-O)2Cl8]·2CH3CN (6) via self-assembly, respectively. These were obtained in >80% yields and characterized by IR, UV/Vis and NMR (1H, 13C{1H}, 31P{1H}) spectroscopy and single crystal X-ray diffraction, and they included a systematic assessment of the solid-state behavior. The anionic metal complexes showed different coordination modes at the Nb(V): [Nb4O4(ca)2(μ2-O)2Cl8]4− (6a; distorted octahedral) and cis-[NbO(ca)2(H2O)(OPPh3)]− (5a; D5h distorted pentagonal bipyramidal), respectively. The tetranuclear complex 6a is substitution inert, while cis-[NbO(ca)2(H2O)OPPh3]− (5a) allowed a systematic ligation kinetic evaluation. The substitution of the coordinated triphenylphosphine oxide by a range of pyridine-type entering nucleophiles, 4-N,N-dimethyl-aminopyridine (DMAP), pyridine (py), 4-methylpyridine (4Mepy), 3-chloropyridine (3Clpy) and 3-bromopyridine (3Brpy) in acetonitrile at 31.2 °C was carefully evaluated. The subtle interplay between the main group ligand systems and the hard, early transition metal Nb(V) complex (5a) was well illustrated. The entering monodentate ligands showed a 15-fold reactivity range increase in the order 3Brpy < 3Clpy < 4Mepy < py < DMAP in broad agreement with the Brønsted-donating ability of the nucleophiles. The activation parameters determined for the reaction of 5a with DMAP as the entering ligand yielded ΔH≠kf = 52 ± 1 kJ mol−1 and ΔS≠kf = −108 ± 3 J K−1 mol−1 for the enthalpy and entropy of activation, respectively, indicating an associative substitution mechanism. The study presents an important contribution to the structure/reactivity relationships in Nb(V) complexes stabilized by chloranilic acid as a bidentate ligand.

(Digital Presentation) Electrodeposition of Electrolytic Niobium Coatings on the Cryogyroscope Rotor

The discharge process of Nb(IV) complexes to Nb was studied by cyclic voltammetry. A galvanostatic electrolysis with the cathodic current density of 1.5·10-2 A cm-2 in the NaCl-KCl-NaF-K2NbF7 melt in contact with Nb was used for deposition of niobium coatings at temperature 1023 K, and time of process from 8 to 12 hours. The coatings were continuous and smooth due to the special design of the cathode. The rotation speed of the stirrer in all experiments did not change and was chosen equal to 35 rpm. Such conditions made it possible to obtain coatings with the thickness up to 150 μm. The main characteristics of the niobium coatings such as purity, roughness, nonsphericity and superconductivity were investigated.

3 + 2] Cycloadditions and Retrocycloadditions of Niobium Imido Complexes: An Experimental and Computational Mechanistic Study.

We demonstrate reactivity between a β-diketiminate-supported niobium(III) imido complex and alkyl azides to form niobatetrazene complexes (BDI)Nb(NtBu)(RNNNNR) (BDI = N,N-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate; R = cyclohexyl (1), benzyl (2)). Intriguingly, niobatetrazene complexes 1 and 2 can be interconverted via addition of an appropriate alkyl azide, likely through a series of concerted [3 + 2] cycloaddition and retrocycloaddition reactions in which π-loaded bis(imido) intermediates are formed. The bis(imido) intermediates were trapped upon addition of alkyl isocyanides to yield five-coordinate bis(imido) complexes (BDI)Nb(NtBu)(NCy)(CNR) (R = tert-butyl (4a), cyclohexyl (4b)). Two computational methods─density functional theory and density functional tight binding (DFTB)─were employed to calculate the lowest energy pathway across the potential energy surface for this multistep transformation. Reaction path calculations for individual cycloaddition or retrocycloaddition processes along the multistep reaction pathway showed that these transformations occur via a concerted, yet highly asynchronous mechanism, in which the two bond-breaking or -making events do not occur simultaneously. The use of the DFTB method in this work highlights its advantages and utility for studying transition metal systems.

Designing efficient metal complex catalysts for acylation: A comparative study with soluble and insoluble catalysts systems

New soluble and insoluble Nb, Ta, Mo, and Sb complex catalysts have been developed using pyridine and polymersupported cross-linked (poly-4-vinyl pyridine) bead (PSCPVP), and characterized using FT-IR, SEM, EDAX, elemental analysis (CHN), and TGA. Their ability to catalyze the acylation of ethanol with acetic anhydride at 303K has been proven. Both soluble and insoluble chemicals have the same order of activity: MoCl5, TaCl5, NbCl5, and SbCl5. The insoluble catalyst outperformed in terms of activity by complex catalysts, although they have significant limitations in terms of solubility and recyclability and soluble homogeneous catalysts in terms of lowest cost and recyclability, whereas all soluble Py-MCl5 catalysts exhibit better activity than insoluble PSCPVP-MCl5 catalysts according to the computed kobs values. Insoluble catalysts are preferable than soluble homogeneous catalysts in terms of recyclability, although all the soluble catalysts of Py-MCl5, M= Nb, Ta, Mo, and Sb have exhibited better activity than insoluble PSCPVP-MCl5 (kobs= 6.51, 6.98, 7.48 & 1.73 x103 min-1) based on the computed kobs values. For acylation process, it has been found that the soluble Py- NbCl5, Py-TaCl5, Py-MoCl5, and Py-SbCl5 catalysts whereas 1.47, 1.63, 1.59, and 1.67 folds more active than PSCPVPNbCl5, PSCPVP-TaCl5, PSCPVP-MoCl5, and PSCPVP-SbCl5 correspondingly.

Ligand non-innocence allows isolation of a neutral and terminal niobium nitride

Complex (PNP)NbCl2(N[tBu]Ar) (1) (PNP- = N[2-PiPr2-4-methylphenyl]2; Ar = 3,5-Me2C6H3) reacts with one equiv. of NaN3 to form a mixture of (PNPN)NbCl2(N[tBu]Ar) (2) and (PNP)NbN(N[tBu]Ar) (3), both of which have been spectroscopically and crystallographically characterized, including 15N isotopic labelling studies. Complex 3 represents the first structurally characterized example of a neutral and mononuclear Nb nitride. Independent studies established 3 to form via two-electron reduction of 2, whereas oxidation of 3 by two-electrons reversed the process. Computational studies suggest the transmetallation step to produce the intermediate [(PNP)NbCl(N3)(N[tBu]Ar)] (A) which extrudes N2 to form the phosphinimide [(PNPN)NbCl(N[tBu]Ar)] (B) followed by disproportionation to 2 and low-valent [(PNPN)Nb(N[tBu]Ar)] (C). The latter then undergoes intramolecular N-atom transfer to form the nitride moiety in 3.

Электродные процессы при электроосаждении, электрополировке и оксидировании ниобия

The electrode processes occurring during the electrodeposition, electropolishing and oxidation of niobium are considered. The discharge of Nb(IV) complexes during Nb electrodeposition was studied by cyclic voltammetry. The anodic polarization curve on niobium in a mixture of acids H2SO4:HF (9:1) was obtained by chronopotentiometry method, the potential range at which the highest quality and speed of electropolishing is achieved was found. The film formation mechanism of niobium pentoxide Nb2O5 on niobium was studied by cyclic voltammetry.

Site-Selective Oxygen Vacancy Formation Derived from the Characteristic Crystal Structures of Sn–Nb Complex Oxides

Divalent tin oxides have attracted considerable attention as novel p-type oxide semiconductors, which are essential for realizing future oxide electronic devices. Recently, p-type Sn2Nb2O7 and SnNb2O6 were developed; however, an enhanced hole mobility by reducing defect concentrations is required for practical use. In this work, we investigated the correlation between the formation of oxygen vacancy (VO··), which may reduce the hole-generation efficiency and hole mobility, and the crystal structure in Sn–Nb complex oxides. Extended X-ray absorption fine structure spectroscopy and a Rietveld analysis of X-ray diffraction data revealed the preferential formation of VO·· at the O site bonded to the Sn ions in both the tin niobates. Moreover, a larger amount of VO·· around the Sn ions was found in the p-type Sn2Nb2O7 than in the p-type SnNb2O6, indicating the effect of VO·· on the low hole-generation efficiency. To elucidate the dependence of the formation of VO·· on the crystal structure, we evaluated the Sn–O bond strength based on the bond valence sum and Debye temperature. The differences in the bond strengths of the two Sn–Nb complex oxides are correlated through the steric hindrance of Sn2+ with an asymmetric electron density distribution. This suggests the importance of the material design with a focus on the local structure around the Sn ions to prevent the formation of VO·· in p-type Sn2+ oxides.

Composition design, microstructure and mechanical properties of novel multiphase Ti–Cu–Ni–Nb complex concentrated alloys

The compositions of novel Ti–Cu–Ni–Nb alloys were designed by the proportional mixing of the Ti2Cu Laves phase and Ni60Nb40 eutectic unit. The Ti28Cu14Ni34.8Nb23.2 alloy is composed of Ti2Ni, NiNb, NbNi3 phases, and a small amount of amorphous structure; the Ti30Cu15Ni33Nb22 alloy is composed of Ti2Ni and NiNb phases; the NiNb phase can form the twin structure with the different twin planes in the two alloys. The Ti32Cu16Ni31.2Nb20.8 alloy is composed of the Ti2Ni, NiNb and Nb phases. The high strength of Ti28Cu14Ni34.8Nb23.2 and Ti30Cu15Ni33Nb22 alloys are attributed to grain refinement and twin strengthening; in addition, the existence of NiNb twins improves the strength and hardness of the two alloys, compared with that of Ti32Cu16Ni31.2Nb20.8 alloy. In this study, the proportional mixing of the Laves phase and eutectic unit is an effective method for the composition design of high entropy alloys with high strength.

Synthesis and characterization of crystalline niobium and tantalum carbonyl complexes at room temperature.

A variety of homoleptic transition metal carbonyl complexes are known as bulk compounds for group 7-12 metals. These metals typically feature a maximum of 6 CO ligands to form complexes with 18 valence electrons. In contrast, group 3-5 metals, with fewer valence electrons, have been shown to form highly coordinated heptacarbonyl and octacarbonyl complexes-although they were only identified by gas-phase mass spectrometry and/or matrix isolation spectroscopy work. Now we have prepared heptacarbonyl cations of niobium and tantalum as crystalline salts that are stable at room temperature. The [M(CO)7]+ (M = Nb or Ta) complexes were formed by the oxidation of [M(CO)6]- with 2Ag+[Al(ORF)4]- (RF, C(CF3)3) under a CO atmosphere; their experimental characterization was supported by density functional theory calculations. Other unusual carbonyl compounds were also synthesized: two isostructural salts that contained the 84-valence-electron cluster cation [Ag6{Nb(CO)6}4]2+, the piano-stool complexes [(1,2-F2C6H4)M(CO)4]+ and two polymorphs of neutral Ta2(CO)12 with a long, unsupported Ta-Ta bond.

Formation of columbite and microlite after alteration of Nb- and Ta-bearing biotite from the Lizaizhai pegmatite (Guangning ore district, Guangdong, South China): Identification of a new potential Nb–Ta mineralization type

The Lizaizhai pegmatite is located in Guangning, Guangdong Province, South China. Unlike common rare-element (Li–Sn–Nb–Ta) pegmatites in Guangning, which contain muscovite as the dominant mica, the Lizaizhai pegmatite represents a different type of rare-element mineralization with biotite as the dominant mica. Our detailed study shows that the Lizaizhai pegmatite can be divided into a border zone and a core zone. Biotite in the border zone contains lower contents of Ta (mean 121 ppm) and higher contents of Ti (mean TiO2 = 0.31 wt%) and Nb (mean 409 ppm) compared with biotite in the core zone, which contains slightly more Ta (mean 381 ppm) than Nb (mean 375 ppm) and Ti (mean TiO2 < 0.1 wt%). The primary Nb–Ta oxide minerals consist of Ta–Nb-rich rutile, columbite-group minerals (CGMs), tapiolite, and microlite, which are found as inclusions in quartz and feldspar. Ta–Nb-rich rutile and tapiolite are present only in the core zone of pegmatite. Biotite in the pegmatite dike has been intensely altered by acidic and F-rich hydrothermal fluids, mostly by chloritization. With H+ and F− being consumed continuously with alteration, Nb and Ta complex anions became unstable. By combining with other ions (e.g. Ca, Fe and Ti), alteration-stage Nb–Ta-bearing minerals (titanite, ilmenite, and rutile) and Nb–Ta oxide minerals (CGMs and microlite) were able to be precipitated in chlorite and alteration-formed muscovite. The border and core zones can be distinguished by distinct assemblages of alteration products: Alteration-stage minerals such as titanite, ilmenite, rutile, and Nb–Ta oxides are present in the border zone, whereas only Nb–Ta oxide minerals are found in the core zone. Considering its distinct petrology, mineralogy, and texture, we propose that the Lizaizhai pegmatite represents a new potential type of Nb–Ta mineralization from biotite alteration.

Structure and High-Temperature Mechanical Properties of High-Carbon Niobium-Based Alloys

Abstract—The structure and the mechanical properties of Nb80C20 and Nb40Mo40C20 alloys have been studied at temperatures 20–1500°C. The mechanical properties of the Nb80C20 alloy from room temperature to 1300°C are shown to be slightly lower than those of complex Nb–Si alloys. The short-time and 100-h strengths of the Nb40Mo40C20 alloy at 1500°C are higher than those of Nb–Si alloys. The Nb40Mo40C20 alloys have a low fracture toughness.

Identification of New DR5 Agonistic Nanobodies and Generation of Multivalent Nanobody Constructs for Cancer Treatment.

Current cancer therapeutics suffer from a lack of specificity in targeting tumor cells and cause severe side effects. Therefore, the design of highly specialized drugs comprising antibody derivatives inducing apoptosis in targeted cancer cells is considered to be a promising strategy. Drugs acting on death receptor 5 (DR5) such as DR5 agonist antibodies replacing “TNF-related apoptosis-inducing ligand” (TRAIL) offer feasible opportunities in this direction. Although such agonists provided good antitumor activity in preclinical studies, they were less effective in clinical studies, possibly due to a disturbed Fc interaction with Fc-γ receptors. Thus, multimerized antigen binding fragments without Fc have been proposed to increase their efficacy. We generated nanobodies (Nbs), recombinant variable domains of heavy chain-only antibodies of camelids, against the DR5 ectodomain. Nb24 and Nb28 had an affinity in the nM and sub-nM range, but only Nb28 competes with TRAIL for binding to DR5. Bivalent, trivalent, and tetravalent constructs were generated, as well as an innovative pentameric Nb complex, to provoke avidity effects. In our cellular assays, these trimeric, tetrameric, and pentameric Nbs have a higher apoptotic capacity than monomeric Nbs and seem to mimic the activity of the natural TRAIL ligand on various cancer cells.

Polymorphs of Neodymium Niobate and Tantalate Thin Films Prepared by Sol-Gel Method

Abstract Neodymium niobate NdNbO4 (NNO) and tantalate NdTaO4 (NTO) thin films (~100 nm) were prepared by sol-gel/spin-coating process on Pb(Zr0.52Ti0.48)O3/Al2O3 substrates with annealing at 1000°C. The precursors of films were synthesized using Nb or Ta tartrate complexes. The XRD results of NNO and NTO films confirmed tetragonal T-NdNbO4 and T-NdTaO4 phases, respectively, with traces of monoclinic MNdNbO4 and M´-NdTaO4. The surface morphology and topography were investigated by SEM and AFM analysis. NTO was smoother with roughness 5.24 nm in comparison with NNO (6.95 nm). In the microstructure of NNO, small spherical (~ 20-50 nm) T-NdNbO4 and larger needle-like particles (~100 nm) of M-NdNbO4 phase were observed. The compact clusters composed of fine spherical T-NdTaO4 particles (~ 50 nm) and cuboidal M´-NdTaO4 particles (~ 100 nm) were found in NTO. The results of this work can contribute to formation of different polymorphs of films for the application in environmental electrolytic thin film devices.

An Efficient Way To Suppress the Competition between Adsorption of H2 and Desorption of nH2–Nb Complex from Graphene Sheet: A Promising Approach to H2 Storage

We performed first-principles calculations to investigate the electronic structure and hydrogen storage capacity of bare niobium (Nb) and niobium-decorated graphene (GR@Nb). The results predict tha...

Ubiquity of cis-Halide → Isocyanide Direct Interligand Interaction in Organometallic Complexes.

We recently reported a density functional theory (DFT) analysis of the Nb(V)-C bond in various NbCl5(L) complexes, discovering that the carbon ligand L receives electronic density from the metal (classical back-donation) and from the chlorides in the cis position (direct interligand interaction). Here we report the synthesis and the structural characterization of two new coordination compounds of niobium pentahalides, i.e., NbX5(CNXyl) (X = Cl, Br; Xyl = 2,6-C6H3Me2), and the corresponding DFT analyses of the Nb(V)-C bond using the Natural Orbitals for Chemical Valence-Charge Displacement (NOCV-CD) approach, confirming the presence of a cis-halide → isocyanide direct interligand interaction. To verify whether the latter is limited to Nb complexes or not, we performed a NOCV-CD analysis on a series of several organometallic complexes based on Ti(IV), Nb(V), Ta(V), Rh(III), Pd(II), and Au(III), all of which bear one halide ligand and m-xylyl-isocyanide in a mutual cis position, revealing that the cis-halide → isocyanide interaction is always present.

Formation and thermochemical properties of oxychlorides of niobium (Nb) and tantalum (Ta): Towards the gas-phase investigation of dubnium (Db) oxychloride

The formation of NbOCl3 and TaOCl3 and their adsorption behavior on quartz surfaces was explored by applying an isothermal gas-chromatographic method. Trace amounts of short-lived Nb and Ta isotopes were used. Adsorption enthalpy values (ΔHads) at zero surface coverage of –ΔHads(NbOCl3) = 102 ± 4 kJ/mol and –ΔHads(TaOCl3) = 128 ± 5 kJ/mol were determined by analyzing the chromatographic behavior of the Nb and Ta complexes with a Monte-Carlo simulation method based on an adsorption–desorption kinetic model. By applying an empirical correlation, the experimental ΔHads values were successively related to the macroscopic standard sublimation enthalpy, ΔH°subl, as a measure of the volatility of each substance. The inferred sublimation enthalpies are in agreement with tabulated thermochemical values. Thus, the linear empirical correlation between ΔHads and ΔH°subl for metal-oxychlorides was updated with the inclusion of the present data. According to the predicted ΔH°subl(DbOCl3), a ΔHads(DbOCl3) value of 135 ± 2 kJ/mol was extrapolated. The future accomplishment of comparative studies with DbOCl3 under the same experimental conditions will provide valuable information on the volatility trend in Group-5 elements, together with an indication on the magnitude of relativistic effects on the electronic structure of dubnium.