Copper(II) complex with salicylaldehyde <Emphasis Type="Italic">N</Emphasis>-(2-salicylideneiminoglutaryl)hydrazone: Synthesis and structure

A copper(II) complex with salicylaldehyde N-(2-salicylideneiminoglutaryl)hydrazone (H₄L) of the formula [Cu₂L · 2Py]₂ · 8H₂O (I) was obtained and characterized by X-ray diffraction. The crystals are monoclinic, space group P2₁, a = 13.0663 Å, b = 16.5553 Å, c = 17.7650 Å, β = 97.9420°; Z = 4. The complex is tetranuclear with a “dimer-of-dimers” structure in which the copper cations of two binuclear subunits are linked by phenoxy bridges. The EPR spectra of solutions of complex I show a superposition of two signals of four HFS lines (g ₁ = 2.111, a ₁ = 56.8 × 10^?4 cm^?1 and g ₂ = 2.183, a ₂ = 71.0 × 10^?4 cm^?1).     

Binuclear copper(II) complexes with acyldihydrazones of <Emphasis Type="Italic">N</Emphasis>-benzenesulfonyl-<Emphasis Type="Italic">L</Emphasis>-aspartic acid

The structure and the EPR spectra of copper(II) coordination compounds with acyldihydrazones of N-benzenesulfonyl-L-aspartic acid and salicylaldehyde (2-hydroxyacetophenone) were described. The compounds were studied by chemical and thermal analyses, IR spectroscopy, and EPR. The molecular and crystal structures of copper(II) complexes with N-benzenesulfonyl-L-aspartic acid bis(salicylidene)hydrazone (H₄L¹) [Cu₂L¹ · 2Py] · 1.5 H₂O was determined by X-ray diffraction. The crystals are triclinic: a = 10.4714(4) Å, b = 12.9702(5) Å, c = 14.6187(9) Å, α = 104.763(2)°, β = 93.082(2)°, γ = 111.4240(10)°, space group P \(\bar 1\), Z = 2. The binuclear complexes containing copper cations whose coordination polyhedra are connected by an aliphatic spacer (Cu...Cu, 8.669 Å) are additionally linked by phenoxy bridges (Cu...Cu, 3.398 Å). The EPR spectra of these compounds in solutions exhibit an isotropic signal of seven HFS lines due to two equivalent copper ions with the spin Hamiltonian parameters g = 2.115?2.120, a _Cu = (35.5?38.0) × 10^?4 cm^?1, which is indicative of weak exchange interactions between the paramagnetic sites.     

Spacer-armed binuclear copper(ii) complexes with salicylidene hydrazones of N-benzoylaminodicarboxylic acids

The structure and EPR spectra of copper(II) complexes with bis(salicylidene)hydrozones of N-benzoyl-L-aspartic and N-benzoyl-L-glutamic acids have been described. The compounds have been studied by chemical and thermal analyses, IR spectroscopy, and EPR spectroscopy. The molecular and crystal structure of the copper(II) complex with bis(salicylidene)hydrozone of N-benzoyl-L-aspartic acid (H₄L) of composition [Cu₂L · 2Py] · 2CH₃OH · H₂O has been determined by X-ray single-crystal diffraction. The crystals are monoclinic: a = 10.3316(7) Å, b = 16.7552(9) Å,c = 11.0137(6) Å, β = 105.758(3)°, space group P2₁, Z = 2. The complex has a polymeric structure composed of alternating copper-containing binuclear fragments bound to each other either via phenoxy bridges or via an aliphatic spacer (the Cu…Cu distances are 3.471 Å and 8.939 Å, respectively). The EPR spectra of the solutions of the complexes under study shows an isotropic signal comprising seven HFS lines due to two equivalent copper nuclei with the spin Hamiltonian parameters g = 2.115–2.122 and a _Cu = (36.1–36.9) × 10^?4 cm^?1, which indicates the reaization of weak exchange coupling of the paramagnetic centers.     

Binuclear copper(II) complexes with acyldihydrazones of saturated carboxylic acids and pyruvic acid

Copper(II) binuclear complexes with acyldihydrazones of saturated carboxylic acids and pyruvic acid in which the coordination polyhedra are connected by polymethylene chains of different length (1 to 5 units) were synthesized and studied by chemical and thermogravimetric analysis, IR spectroscopy, and EPR. The structure of binuclear copper(II) complex with succinic acid acyldihydrazone [Cu₂L · 4Py] · 2Py was determined by X-ray diffraction. The crystals are monoclinic: a = 14.3795(6), b = 8.8736(4), c = 15.9147(7) Å, β = 101.062(3)°, space group P2₁/c, Z = 2. The number of independent reflections with I > 2σ(I) = 2804, R = 0.042, R _w = 0.087. The copper atoms are spaced by a chain of seven σ bonds at 8.922 Å. The coordination polyhedron can be described as a tetragonal pyramid highly distorted toward a trigonal bipyramid. The EPR spectra of solutions of complexes based on malonic, succinic, glutaric, and adipinic acids exhibit a poorly resolved signal of seven HFS lines with a constant of (26.3–27.0) × 10^?4 cm^?1, which attests to the presence of weak exchange interactions between paramagnetic centers. An increase in the length of the polymethylene spaur suppresses exchange interactions, and the EPR spectrum of the complex based on pimelic acid acyldihydrazone shows a signal of four HFS lines with a constant of 43.8 × 10^?4 cm^?1 typical of monomeric copper(II) complexes.     

Structure and EPR spectra of binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acids and trifluoroacetylacetone

Binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acid and trifluoroacetylacetone have been synthesized and studied. The structure of the copper(II) complex with diacylhydrazone of 1,3-benzenedicarboxylic acid (H₄L) of composition [Cu₂L · 2LPy] has been studied by X-ray diffraction. The crystals are triclinic: a = 9.2298(4) Å, b = 11.8510(6) Å, c = 13.8314(7) Å, α = 90.780(3)°, β = 96.124(3)°, γ = 99.264(3)°, space group \(P\bar 1\), Z = 2. The number of symmetry-unrelated reflections with I > 2σ(I) 5941; R = 0.0357, R _w = 0.0589. The complex contains two equivalent copper atoms at a distance of 9.56 Å from each other in the square-planar coordination environment. The high-temperature EPR spectra of the complexes show a signal of seven HFS lines indicating the coupling of unpaired electrons to two equivalent copper nuclei (g = 2.113?2.116, a _Cu = 37.0?37.2 × 10^?4 cm^?1).     

Synthesis and study of ammonium decamolybdodimetallates

Ammonium decamolybdodimetallates (NH₄)_n[M₂Mo₁₀O₃₄(OH)₄] · 7H₂O, where M = Cr³⁺ (n = 6), Cu²⁺ (n = 8), or Ni²⁺ (n = 8), were synthesized for the first time and studied by X-ray diffraction, thermogravimetry, and IR spectroscopy. The compounds crystallize in the triclinic system with the following unit cell parameters: a = 10.68(2) Å, b = 9.46(2) Å, c = 7.97(2) Å, α = 75.12(3)°, β = 96.82(3)°, γ = 102.21(3)°, V = 754.4(3) ų, ρ_calcd = 4.05 g/cm³, Z = 1 for the chromium compound; and a = 10.57(2) Å, b = 9.29(2) Å, c = 8.47(2) Å, α = 73.91(3)°, β = 96.05(3)°, γ = 104.71(3)°, V = 854.3(3) ų, ρ_calcd = 3.68 g/cm³, Z = 1 (for the copper compound); and a = 10.96(2) Å, b = 8.95(2) Å, c = 7.40(2) Å, α = 71.76(3)°, β = 97.04(3)°, γ = 102.91(3)°, V = 875.3(3)ų, ρ_calcd = 3.65 g/cm₃, Z = 1 for the nickel compound.     

Novel copper(II) complex with unusual π-stacking structure, [Cu(SSC)Cl]<Subscript>2</Subscript>·CH<Subscript>3</Subscript>OH·2H<Subscript>2</Subscript>O (SSC = salicylaldehyde semicarbazone anion)

The crystal structure of [Cu^II(SSC)Cl]₂·CH₃OH·2H₂O (SSC = salicylaldehyde semicarbazone anion) was determined by the single crystal X-ray diffraction method at 293 K. Crystal data for Cu₂C₁₇H₂₄Cl₂N₆O₇: a = 10.272(2) Å, b = 10.297(2) Å, c = 11.462(2) Å, α = 82.860(3)°, β = 78.384(3)°, γ = 81.330(2)°, triclinic, space group P1¯, Z = 2, d _calc = 1.769 g/cm³, R ₁ = 0.038. One N and two O atoms of SSC^? occupy three coordination sites around Cu(II). The fourth site is occupied by Cl^? to yield distorted square-planar environment. Two molecules of the complex form a planar dimer through intermolecular N-H?O hydrogen bonds. The most striking feature of the crystal structure is the packing of the planar dimers within the crystal. The interplanar distances between adjacent two layers are 3.280 Å, indicative of strong π-π noncovalent interactions. The methanol solvent and water molecules are included as additional components in the crystal.     

Structure and EPR spectra of binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acids and 5-substituted 2-hydroxyacetophenones

Binuclear copper(II) complexes with acyldihydrazones of 1,3- or 1,4 benzenedicarboxylic acid and 5-methyl- or 5-bromo-2-hydroxyacetophenone in which coordination polyhedra are connected by an aromatic bridge have been synthesized and studied. The structure of the copper(II) complex with diacylhydrazone of isophthalic acid and 2-hydroxy-5-methylacetophenone (H₄L) of composition [Cu₂L · 3Py] was studied by X-ray diffraction. The crystals are monoclinic: a = 12.1996(12) Å, b = 17.7295(17) Å, c = 17.9339(17) Å, β = 109.7450(10)°, space group P2₁/n, Z = 4. The complex is of the “dimer of dimers” type and contains two binuclear subunits that bind together into a centrosymmetric dimer owing to the coordination of the copper cation to the phenoxyl oxygen atom of a neighboring binuclear molecule to form the Cu₂O₂ moiety, in which the copper atoms are 3.409 Å apart. The distance between the copper(II) cations in the binuclear subunit is 8.56 atoms (2N + O) of the doubly deprotonated acylhydrazone moiety and the nitrogen atom of the pyridine molecule. One of the copper cation is additionally coordinated to an extra pyridine molecule so that its coordination sphere is completed to a tetragonal pyramid. The second copper atom is involved in additional interaction with the phenoxyl oxygen atom of the neighboring molecule. The EPR spectra of solutions of the binuclear complexes show an isotropic signal of four HFS lines (g _o = 2.065–2.143, a _Cu = 52.1–66.5 × 10^?4 cm^?1) typical of mononuclear copper(II) complexes.     

Tetramminenickel hydrogen hexamolybdometalates(III)

Tetramminenickel hydrogen hexamolybdoaluminate and hexamolybdogallate(III) of compositions [Ni(NH₃)₄] · H[AlMo₆O₁₈(OH)₆] · 10H₂O (I) and [Ni(NH₃)₄] · H[GaMo₆O₁₈(OH)₆] · 10H₂O (II) were synthesized and characterized by mass spectrometry, thermogravimetry, X-ray powder diffraction, and IR spectroscopy. Their crystals are triclinic. For compound I, a= 17.30 Å, b= 14.69 Å, c= 10.45 Å, α = 129.07, β = 65.91°, γ = 138.01°, V = 1338.7l ų, ρ_calcd = 2.75g/cm³, Z = 2; for compound II, a = 17.38 Å, b= 14.75 Å, c= 10.51 Å, α = 131.38°, β= 65.96°, γ = 138.09, V = 1338.15 ų, ρ_calcd = 2.68 g/cm³, Z = 2.     

Synthesis and crystal structure of <Emphasis Type="Italic">N,N</Emphasis>-dimethylbiguanidinium hexafluorosilicate

The complex [(CH₃)₂NC(NH₂)NHC(NH₂)NH₂]SiF₆ (I) was synthesized and its structure was determined by X-ray crystallography. The crystals are monoclinic: a = 7.4346(10) Å, b = 12.7628(10) Å, c = 11.0828(10) Å, β 104.080(10)°, V = 1020.01(18) ų, ρ_calc = 1.780 g/cm³, μ(MoK _α) = 0.302 mm^?1, Z = 4, space group P2₁/c. The crystals of I are composed of SiF ₆ ^2? anions (Si-F, 1.657(2)–1.699(2) Å) and N,N-dimethylbiguanidinium (H₂L²⁺) cations combined in a framework by interionic H-bonds NH···F. In the cations, protonation sites are the terminal imide groups.     

Preparation and physicochemical study of sodium hexamolybdometallates(III)

Sodium hexamolybdocobaltate(III) Na₃[CoMo₆O₁₈(OH)₆] · 8H₂O (I) and sodium hexamolybdochromate Na₃[CrMo₆O₁₈(OH)₆] · 8H₂O (II) were synthesized and studied by mass spectrometry, thermogravimetry, powder X-ray diffraction, and IR spectroscopy. The crystals are monoclinic. For compound a = 10.31 Å, b = 10.31 Å, c = 17.55 Å, β = 100.93°, V = 1834.77 ų, ρ_calcd = 3.04 g/cm³, Z = 3; for compound II: a = 10.33 Å, b = 10.33 Å, c = 17.59 Å, β = 100.98°, V = 1835.09 Å3, ρ_calcd = 3.01 g/cm³, Z = 3.     

Synthesis,crystal structure,and thermal behavior of dimethylgold(III) acetate

A dimethylgold(III) compound with an acetate fragment [(CH₃)₂AuOCOCH₃]₂ has been synthesized. The complex was identified from the melting point, IR, ¹H NMR, and mass spectrometry data. The temperature dependence of saturated vapor pressure over crystals has been measured and the thermodynamic parameters of sublimation have been determined by Knudsen’s effusion method with mass spectrometric measurements of the composition of the gas phase: ΔH _subl = 100.87 kJ·mol^?1, ΔS _subl = 216.67 J·mol^?1·K^?1. The thermal behavior of the solid compound was investigated by differential thermal analysis. The compound was studied by X-ray diffraction. Crystal data for C₈H₁₈Au₂O₄: a = 12.214(5) Å, b = 14.307(3) Å, c = 7.6635(15) Å; β = 103.39(3)°, Z = 4, d _calc = 2.917 g/cm³, space group P2(1)/c, R = 0.0261. The [(CH₃)₂AuOCOCH₃]₂ dimer complex with an Au...Au distance of 2.989 Å is the structural unit. The gold atom has a square plane environment of two carbon and two oxygen atoms; the Au-O distances vary from 2.118 Å to 2.139 Å. The molecules are arranged in chains linked by van der Waals interactions.     

Synthesis and study of hexaamminecadmium hydrogen hexamolybdocobaltate(III) and hexamolybdochromate(III)

Hexaamminecadmium hydrogen hexamolybdocobaltate(III) and hydrogen hexamolybdochromate(III) of compositions [Cd(NH₃)₆] · H[CoMo₆O₁₈(OH)₆] · 6H₂O (I) and [Cd(NH₃)₆] · H[CrMo₆O₁₈(OH)₆] · 6H₂O (II), respectively, were synthesized and studied by mass spectroscopy, thermo-gravimetry, X-ray powder diffraction, and IR spectroscopy. Crystals of I and II are monoclinic. For I: a = 10.79 Å, b = 3.70 Å, c = 11.95 Å, β = 91.05°, V = 470.12 ų, ρ_calc = 2.37 g/cm³, Z = 2; and for II: a = 10.80 Å, b = 3.68 Å, c = 11.97 Å, β = 91.07°, V = 468.98 ų, ρ_calc = 2.36 g/cm³, Z = 2.     

Disordered crystal structure of 4,7,13,16,21,24-hexaoxa-1-aza-10-azoniabicyclo[8.8.8]hexacosane perchlorate monohydrate

The disordered crystal structure of 4,7,13,16,21,24-hexaoxa-1-aza-10-azoniabicyclo[8.8.8]-hexacosane perchlorate monohydrate, [H(Crypt-222)·H₂O]⁺·ClO ₄ ^? (I), has been determined by XRD. The triclinic structure of I (space group \(P\overline 1 \), a = 9.748 Å, b = 10.570 Å, c = 13.820 Å; α = 109.40°, β = 109.75°, γ = 93.04°, Z = 2) was solved by direct methods and refined by full-matrix least-squares in the anisotropic approximation to R = 0.072 over all 3675 independent reflections collected (CAD-4 automatic diffractometer, λCuK_α). This compound is the first crystal salt containing the 2.2.2-cryptand cation with one protonated nitrogen atom that was synthesized and structurally investigated.     

Synthesis,crystal structure,and kinetics of thermal decomposition of the Zn(II) complex with vanillin

A complex [Zn(C₈H₇O₃)₂(H₂O)₂] (C₈H₈O₃ is vanillin) has been synthesized and characterized by IR, elemental analysis, and X-ray diffraction single-crystal analysis. The crystals are monoclinic, space group C2/c, a = 22.236(8) Å, b = 10.594(2) Å, c = 7.8190(16) Å, α = 89.90(3)°, β = 106.87(4)°, γ = 89.99(3)°, V = 1762.6(8) ų, Z = 4, F(000) = 832, S = 1.079, ρ _c = 1.521g cm^?3, R = 0.0221, R _w = 0.0604, μ = 1.433 mm^?1. The Zn²⁺ ion is six-coordinated with a distorted octahedron geometry. The complex forms a three-dimensional network through intermolecular hydrogen bonds. The thermal decomposition kinetics of the complex for the second stage was studied under non-isothermal conditions by the TG and DTG methods. The kinetic equation can be expressed as dα/dt = Ae^?E/RT 2(1 ? α)[1 ? ln(1 ? α)]^1/2. The kinetic parameters (E, A), activation entropy ΔS ^≠, and activation free-energy ΔG ^≠ were also gained.     

Erbium(III) and lutecium(III) complexes [Ln(H<Subscript>2</Subscript>O)<Subscript>8</Subscript>][Cr(NCS)<Subscript>6</Subscript>] · 5H<Subscript>2</Subscript>O: Synthesis and crystal structure

[Ln(H₂O)₈][Cr(NCS)₆] · 5H₂O aqua complexes, where Ln = Er (1), Lu (2), have been found in an aqueous solution instead of binary complex salts with an organic ligand in their cation, when crystal products of the reaction between Ln(NO₃)₃ · 6H₂O (Ln = Er, Lu), K₃[Cr(NCS)₆] · 4H₂O, and 8-oxyquinoline (C₉H₇NO) were studied by X-ray diffraction. Crystals of complexes 1 and 2 are isostructural and crystallize in triclinic system, space group P\(\bar 1\), Z = 2. For complex 1: a = 9.0677(4) Å, b = 9.3115(4) Å, c = 16.9595 Å, α = 81.526(2)°, β = 86.153(2)°, γ = 83.879(2)°, V = 1406.33(10) ų, ρ_calc = 1.894 g/cm³; for complex 2: a = 9.0438(3) Å, b = 9.2880(3) Å, c = 16.9181(3) Å, α = 81.7250(10)°, β = 86.1600(10)°, γ = 83.8850(10)°, V = 1396.38(7) ų, ρ_calc = 1.926 g/cm³.     

Palladium clusters Pd<Subscript>4</Subscript>(SR)<Subscript>4</Subscript>(OAc)<Subscript>4</Subscript> and Pd<Subscript>6</Subscript>(SR)<Subscript>12</Subscript> (R = Bu,Ph): Structure and properties

The structures of the Pd₄(SBu)₄(OAc)₄ (I) and Pd₆ (SBu)₁₂ (II) palladium clusters are determined by the X-ray diffraction method. For cluster I: a = 8.650(2), b = 12.314(2), c = 17.659(4) Å, α = 78.03(3)°, β = 86.71(2)°, γ = 78.13(3)°, V = 1800.8(7) ų, ρcalcd = 1.878 g/cm³, space group P \(\bar 1\), Z = 4, N = 3403, R = 0.0468; for structure II: a = 10.748(2), b = 12.840(3), c = 15.233(3) Å, α = 65.31(3)°, β = 70.10(3)°, γ = 72.91(3)°, V = 1767.4(6) ų, ρ calcd = 1.605 g/cm³, space group P \(\bar 1\), Z = 1, N = 3498, R = 0.0729. In cluster I, four Pd atoms form a planar cycle. The neighboring Pd atoms are bound by two acetate or two mercaptide bridges (Pd…Pd 2.95–3.23 Å, Pd…Pd angles 87.15°–92.85°). In cluster II, the Pd atoms form a planar six-membered cycle with Pd···Pd distances of 3.09–3.14 Å, the PdPdPd angles being 118.95°–120.80°. The Pd atoms are linked in pairs by two mercaptide bridges. The formation of clusters I and II in solution is proved by IR spectroscopy and calorimetry. Analogous clusters are formed in solution upon the reaction of palladium(II) diacetate with thiophenol.     

Crystal structures of <Emphasis Type="Italic">trans</Emphasis>-[Re<Subscript>6</Subscript>S<Subscript>8</Subscript>(CN)<Subscript>2</Subscript>L<Subscript>4</Subscript>] complexes,L = pyridine or 4-methylpyridine

The structures of three novel octahedral rhenium cluster compounds [Re₆S₈(CN)₂(py)₄]·H₂O (1), [Re₆S₈(CN)₂(4-Mepy)₄] (2), [Re₆S₈(CN)₂(4-Mepy)₄]·4-Mepy (3) (py = pyridine, 4-Mepy = 4-methylpyridine) are determined by X-ray crystallography. Crystal data are: C2/m space group, a = 14.813(1) Å, b = 14.772(1) Å, c = 9.2122(6) Å, β = 119.085(2)°, V = 1761.7(2) ų, d _x = 3.318 g/cm³, R = 0.0585 (1); I4₁/amd space group, a = 16.0018(3) Å, c = 14.7186(5) Å, V = 3768.81(16) ų, d _x = 3.169 g/cm³, R = 0.0489 (2); P2₁/c space group, a = 9.0452(4) Å, b = 15.8065(7) Å, c = 15.2951(6) Å, β = 103.700(2)°, V = 2124.57(16) ų, d _x = 2.957 g/cm³, R = 0.0245 (3). Molecular cluster complexes interact via π-π stacking affording 3D frameworks in 1 and 2 and chains in 3.     

Hexa(isothiocyanato)chromates(III) of Some Yttrium Group Lanthanide(III) and Europium Complexes with Nicotinic Acid: Synthesis and Crystal Structures

Double ionic complexes [M(C₅H₅NCOO)₃(H₂O)₂][Cr(NCS)₆] · nH₂O, where M = Eu (I), n = 1.15; Dy (II), Er (III), n = 1.5; M = Yb (IV), n = 2, have been synthesized by the reaction between M(NO₃)₃, M = Eu, Dy, Er, Yb, K₃[Cr(NCS)₆], and nicotinic acid (C₅H₅NCOO) in an aqueous solution and studied by chemical analysis, IR spectroscopy, and X-ray diffraction. Crystals of complexes I–IV are monoclinic, space group P2₁/n, Z = 4; a = 9.5358(2) Å, b = 25.4871(5) Å, c = 15.4303(4) Å, β = 105.513(1)°, V = 3613.6(1) ų, ρ_calcd = 1.799 g/cm³ for I, a = 9.5901(5) Å, b = 25.8599(15) Å, c = 15.6316(9) Å, β = 106.829(2)°, V = 3710.6(4) ų, ρ_calcd = 1.782 g/cm³ for II, a = 9.5640(3) Å, b = 25.8936(11) Å, c = 15.6498(7) Å, β = 106.895(2)°, V = 3708.3(3) ų, ρ_calcd = 1.791 g/cm³ for III, and a = 9.5049(2) Å, b = 25.6378(4) Å, c = 15.5120(3) Å, β = 106.934(1)°, V = 3616.1(1) ų, ρ_calcd = 1.864 g/cm³ for IV.     

Synthesis and structural investigation of hafnium(IV) complexes with acetylacetone and trifluoroacetylacetone

Two volatile hafnium(IV) complexes with acetylacetone and trifluoroacetylacetone (HL) have been prepared and their structures have been studied at ?30°C. Crystal data for C₂₀H₂₈HfO₈: a = 21.5493(4) Å, b = 8.36720(10) Å, c = 13.9905(3) Å; β = 116.5550(10)°, space group C2/c, Z = 4, d _calc = 1.692 g/cm³, R = 0.015. Crystal data for C₂₀H₁₆F₁₂HfO₈: a = 8.1039(12) Å, b = 11.4499(14) Å, c = 15.790(2) Å; α = 99.341(4)°, β = 103.175(4)°, γ = 108.185(4)°, space group P?1, Z = 2, d _calc = 2.003 g/cm³, R = 0.074. Both structures are molecular and comprise isolated complex molecules HfL₄. The hafnium atom is coordinated with eight oxygen atoms of four β-diketonate ligands, Hf-O distances varying from 2.153 Å to 2.191 Å. The molecules make van der Waals contacts in the structures.