Alcohol Solvates of Lanthanoid(III) Trifluoromethanesulfonates

After vacuum dehydration, a number of hydrated trivalent lanthanoid trifluoromethanesulfonates (“triflate”, “OTf” = F₃CSO₃), when recrystallized from various alcohol (ROH) solutions, yield solvates Ln(OTf)₃ · xROH, x = 3, 5 or 6. The following have been defined crystallographically (R/Ln/x): Me/La/3;Me/Gd/6; Et/Sm/3; Et/Gd/5 iPr/Nd,Sm/3. The Me/Gd/6complex, Gd(OTf)₃ · 6MeOH is a mononuclear/ionic form [(MeOH)₆Gd(O–OTf)₂](OTf), the gadolinium environment being octacoordinate, square‐antiprismatic with the O–OTf donors quasi‐trans on different faces of the coordination polyhedron; the Et/Gd/5 complex is neutral, molecular, mononuclear [(EtOH)₅Gd(O–OTf)₃], also with an octacoordinate, square‐antiprismatic coordination sphere, derivative of that of the methanol solvate. The remainder form one‐dimensional polymeric arrays, successive lanthanoid atoms linked by (μ‐O–OTf–O′)₃ triads, at either end of a tricapped trigonal prismatic array, the ROH molecules contributing the capping atoms. A (“baseline”) (re‐)determination of the “parent” Sm(OTf)₃ · 9H₂O is also recorded.     

Structural Systematics for Lanthanide(III) Systems: Lattice Interactions in Salts [CoL3][Ln(dipic)3]·nH2O (L = N,N′‐Aromatic Bidentate Ligand; dipic = Dipicolinate = pyridine‐2,6‐dicarboxylate) Containing Complex Ions of D3 Symmetry

Structural characterisation of a number of hydrated solids containing chiral, kinetically inert [Co(A–A)₃]³⁺ cations (A–A = 2,2′‐bipyridine, 1,10‐phenanthroline, 4,4′‐dimethyl‐2,2′‐bipyridine) and chiral, kinetically labile [Ln(dipic)₃]^3– anions (Ln = La, Eu, Tb, Ho, Er, Lu, Y, though not for all cobalt cations; dipic = dipicolinate = pyridine‐2,6‐dicarboxylate) show a remarkable range of associations between the lattice components, though all are racemic arrays. Analysis of the structures in terms of short interatomic contacts between the components shows that, whereas numerous contacts of the heteroaromatic ligands do occur, very few define an arrangement which could be truly termed “π‐stacking” where the rings are closely parallel and atom overlaps in projection are substantial. Water is important in the highly hydrated lattice structures, not only because of hydrogen‐bonding interactions with itself and carboxylate‐O atoms but also because of its interactions with the aromatic units. The family [Co(bipy)₃][Ln(dipic)₃]·~13H₂O are essentially isomorphous for the full range of Ln plus Y (triclinic, Pbar{1} , a = 12.3, b = 14.3, c = 16.5 Å, α = 94, β = 94, γ = 108 ?, Z = 2). Among the heavier lanthanides, the potential symmetry of the anion/cation combination is realised in the trigonal space group Pbar{3} , both species lying together as an ion‐pair, disposed on the trigonal axis for [Co(phen)₃][Ln(dipic)₃]·22H₂O (Ln = Eu, Er; a = 15.2, c = 16.8 Å, Z = 2).     

Novel Lanthanide(III) Ternary Complexes with Naphthoyltrifluoroacetone: A Synthetic and Spectroscopic Study

A series of lanthanide complexes with general formula [Ln(NTA)₃X] were prapared [Ln = Y ( a ), Er ( b ), Eu ( c ), NTA = naphthoyltrifluoroacetone, X = H₂O ( 1 ), phen = phenanthroline ( 2 ), bpyO1 = 2, 2′‐bipyridine N‐oxide ( 3 ), and bpyO2 = 2, 2′‐bipyridine‐N,N′‐dioxide ( 4 )]. The crystal structures of [Eu(NTA)₃bpyO2] ( 4b ), [Er(NTA)₃bpyO1] ( 3c ), and [Er(NTA)₃phen] ( 2c ) were determined. X‐ray crystallographic analysis reveals that the complexes are of mononuclear structure with three NTA and one ancillary ligand. The photoluminescence spectra of 3c and 4b exhibit strong characteristic emissions arising from Eu³⁺ central ion due to the efficient sensitization of bpyO1 and bpyO2, respectively.     

One‐dimensional Salen‐type Chain‐like Lanthanide(III) Coordination Polymers: Syntheses,Crystal Structures,and Fluorescence Properties

Four salen‐type lanthanide(III) coordination polymers [LnH₂L(NO₃)₃(MeOH)_x]_n [Ln = La ( 1 ), Ce ( 2 ), Sm ( 3 ), Gd ( 4 )] were prepared by reaction of Ln(NO₃)₃ · 6H₂O with H₂L [H₂L = N,N′‐bis(salicylidene)‐1,2‐cyclohexanediamine]. Single‐crystal X‐ray diffraction analysis revealed that H₂L effectively functions as a bridging ligand forming a series of 1D chain‐like polymers. The solid‐state fluorescence spectra of polymers 1 and 2 emit single ligand‐centered green fluorescence, whereas 3 exhibits typical red fluorescence of Sm^III ions. The lowest triplet level of ligand H₂L was calculated on the basis of the phosphorescence spectrum of Gd^III complex 4 . The energy transfer mechanisms in the lanthanide polymers were described and discussed.     

Synthesis and Properties of Lanthanide Ruthenium(III) Oxide Perovskites

An extensive series of new LnRuO₃ perovskites has been synthesized at high pressure. These ruthenium(III)‐based oxides are ruthenium deficient, and high‐pressure samples have compositions close to LnRu_0.9O₃. These phases stabilize ruthenium(III) which is very unusual in oxides. X‐ray and neutron powder diffraction studies show that the materials adopt orthorhombic perovskite superstructures in which the RuO₆ octahedra are tetragonally compressed. These distortions, and the Mott insulator properties of the materials, are driven by strong spin‐orbit coupling.     

Cobalt(III) Complexes of D‐Galactosylamine

The β‐pyranose isomer of D ‐galactosylamine ( 1 ) formed complexes with three different cobalt(III) fragments. Crystals containing the dication [Co(tren)(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 3 ) showed coordination through the anomeric amino group (N1) and the deprotonated hydroxy group (O2) of the ⁴C₁ β‐pyranose form, which is also the major isomer of free galactosylamine. The cationic complexes [Co(fac‐dien)(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 4 ) and [Co(phen)₂(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 5 ) were analysed by NMR spectroscopy and showed the same coordination mode as 3 . In terms of available ligand isomers it was shown that 1 exhibits an anomeric equilibrium in solution of both pyranose and both furanose forms as is typical for the parent glycose, galactose.     

Self‐Assembly of Organic Chromosphere Cations with Inorganic Lanthanide(III) Complex Counterions

Hybrid complexes based on a D‐π‐A type dye p‐aminostyryl‐pyridinum cation and a lanthanide(III) complex anion were synthesized by ionic exchange reaction. Different alkyl‐substituted amino groups were used as electron donors in organic dye cations. The synthesized complexes were characterized by elemental analysis. In addition, the structural features of them were studied by single‐crystal X‐ray diffraction analysis. Their optical properties were systematically investigated by absorption and fluorescence spectroscopy.     

Triphenylarsane Oxide Complexes of Lanthanide Nitrates: Polymorphs and Photophysics

trans‐[Ln(NO₃)₂(Ph₃AsO)₄](NO₃)₂ ( 1 ) and mer‐[Ln(NO₃)₃(Ph₃AsO)₃] ( 2 ) complexes were prepared from Ln(NO₃)₃ · xH₂O and Ph₃AsO in chloroform (Ln = Y, Sm, Eu, Tb, and Dy). Production of complexes 1 vs. 2 and solvent content was found to be highly dependent on crystallization solvent choice. Tb and Eu produced only 1 , while the other Ln metals produced both 1 and 2 . Solvent‐free, acetone‐, and methanol‐containing polymorph series were identified for complexes 1 . Acetone/ether‐ and CH₂Cl₂‐containing polymorph series were identified for complexes 2 . Luminescence measurements were performed on solvent‐free 1 (Ln = Y, Eu, Tb, and Dy) and 2 (Ln = Sm) at 78 K. Sensitized lanthanide emission bands via resonance energy transfer were observed in all cases, except the control (Ln = Y). The efficiency of this energy transfer process varies amongst the lanthanide metals studied and was rationalized using Latva's empirical rule and Density Functional Theory calculations.     

Nickel(II)–Lanthanide(III) Magnetic Exchange Coupling Influencing Single‐Molecule Magnetic Features in {Ni2Ln2} Complexes

Four isostructural [Ni₂Ln₂(CH₃CO₂)₃(HL)₄(H₂O)₂]³⁺(Ln³⁺=Dy ( 1 ), Tb ( 2 ), Ho ( 3 ) or Lu ( 4 )) complexes and a dinuclear [NiGd(HL)₂(NO₃)₃] ( 5 ) complex are reported (where HL=2‐methoxy‐6‐[(E)‐2′‐hydroxymethyl‐phenyliminomethyl]‐phenolate). For compounds 1 – 3 and 5 , the Ni²⁺ ions are ferromagnetically coupled to the respective lanthanide ions. The ferromagnetic coupling in 1 suppresses the quantum tunnelling of magnetisation (QTM), resulting in a rare zero dc field Ni–Dy single‐molecule magnet, with an anisotropy barrier U_eff of 19 K.     

Triphenylphosphane Oxide Complexes of Lanthanide Nitrates: Polymorphs and Photophysics

A series of mer‐[Ln(NO₃)₃(Ph₃PO)₃] complexes were prepared from Ln(NO₃)₃ · xH₂O and Ph₃PO in chloroform (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, and Er). The La and Nd complexes were 0.25 CHCl₃ solvates, whereas the others were solvent‐free. The identical reaction using Yb(NO₃)₃ · xH₂O produced the unique salt trans‐[Yb(NO₃)₂(Ph₃PO)₄][Yb(NO₃)₄(Ph₃PO)] · Et₂O. All nitrate ions in all complexes are η²‐chelating. A comparison of the various [Ln(NO₃)₃(Ph₃PO)₃] structures, including those in the literature, reveals at least four common polymorphs, each of which is represented by isomorphic structures of multiple Ln ions. Luminescence of mer‐[Ln(NO₃)₃(Ph₃PO)₃] (Ln = Y, La, Nd, Sm, Eu, Gd, Tb, and Dy), trans‐[Yb(NO₃)₂(Ph₃PO)₄][Yb(NO₃)₄(Ph₃PO)] and Ph₃PO assignments are reported. Latva's empirical rule allows for the antenna effect, in which energy is transferred from the triplet state of the Ph₃PO ligand, to occur only for Tb³⁺. Excitation via Ph₃PO results in strong green luminescence for Tb³⁺ having twice the intensity as that which results from direct excitation of the f‐f transitions.     

Synthesis,Crystal Structures,and Photoluminescence of Lanthanide Coordination Polymers with 4‐Acetamidobenzoate

The reactions of Ln(NO₃)₃ · 6H₂O and 4‐acetamidobenzoic acid (Haba) with 4,4′‐bipyridine (4,4′‐bpy) in ethanol solution resulted in three new lanthanide coordination polymers, namely {[Ln(aba)₃(H₂O)₂] · 0.5(4,4′‐bpy) · 2H₂O}_∞ [Ln = Sm ( 1 ), Gd ( 2 ), and Er ( 3 ), aba = 4‐acetamidobenzoate]. Compounds 1 – 3 are isomorphous and have one‐dimensional chains bridged by four aba anions. 4,4′‐Bipyridine molecules don’t take part in the coordination with Ln^III ions and occur in the lattice as guest molecules. Moreover, the adjacent 1D chains in the complex are further linked through numerous N–H ··· O and O–H ··· O hydrogen bonds to form a 3D supramolecular network. In addition, complex 1 in the solid state shows characteristic emission in the visible region at room temperature.     

Two Hexagonal Series of Lanthanoid(III) Oxide Fluoride Selenides: M6O2F8Se3 (M = La – Nd) and M2OF2Se (M = Nd,Sm, Gd – Ho)

Two hexagonal series of lanthanoid(III) oxide fluoride selenides with similar structure types can be obtained by the reaction of the components MF₃, M₂O₃, M, and Se in sealed niobium tubes at 850 °C using CsI as fluxing agent. The compounds with the lighter and larger representatives (M = La – Nd) occur with the formula M₆O₂F₈Se₃, whereas with the heavier and smaller ones (M = Nd, Sm, Gd – Ho) their composition is M₂OF₂Se. For both systems single‐crystal determinations were used in all cases. The compounds crystallize in the hexagonal crystal system (space group: P6₃/m) with lattice parameters of a = 1394–1331 pm and c = 403–372 pm (Z = 2 for M₆O₂F₈Se₃ and Z = 6 for M₂OF₂Se). The (M1)³⁺ cations show different square antiprismatic coordination spheres with or without an extra capping fluoride anion. All (M2)³⁺ cations exhibit a ninefold coordination environment shaped as tricapped trigonal prism. In both structure types the Se^2– anions are sixfold coordinated as trigonal prisms of M³⁺ cations, being first condensed by edges to generate trimeric units and then via faces to form strands running along [001]. The light anions reside either in threefold triangular or in fourfold tetrahedral cationic coordination. For charge compensation, both structures have to contain a certain amount of oxide besides fluoride anions. Since F^– and O^2– can not be distinguished by X‐ray diffraction, bond‐valence calculations were used to address the problem of their adjunction to the available crystallographic sites.     

Cyclopentadienyl Ruthenium(II) Complexes with Bridging Alkynylphosphine Ligands: Synthesis and Electrochemical Studies

The reaction of [CpRuCl(PPh₃)₂] (Cp=cyclopentadienyl) and [CpRuCl(dppe)] (dppe=Ph₂PCH₂CH₂PPh₂) with bis‐ and tris‐phosphine ligands 1,4‐(Ph₂PC≡C)₂C₆H₄ ( 1 ) and 1,3,5‐(Ph₂PC≡C)₃C₆H₃ ( 2 ), prepared by Ni‐catalysed cross‐coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal‐directed self‐assembly methodologies, two linear bimetallic complexes, [{CpRuCl(PPh₃)}₂(μ‐dppab)] ( 3 ) and [{CpRu(dppe)}₂(μ‐dppab)](PF₆)₂ ( 4 ), and the mononuclear complex [CpRuCl(PPh₃)(η¹‐dppab)] ( 6 ), which contains a “dangling arm” ligand, were prepared (dppab=1,4‐bis[(diphenylphosphino)ethynyl]benzene). Moreover, by using the triphosphine 1,3,5‐tris[(diphenylphosphino)ethynyl]benzene (tppab), the trimetallic [{CpRuCl(PPh₃)}₃(μ₃‐tppab)] ( 5 ) species was synthesised, which is the first example of a chiral‐at‐ruthenium complex containing three different stereogenic centres. Besides these open‐chain complexes, the neutral cyclic species [{CpRuCl(μ‐dppab)}₂] ( 7 ) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2 . Two rigid macrocycles based on cis coordination of dppab to [CpRu(PPh₃)] were obtained, that is, the dinuclear complex [{CpRu(PPh₃)(μ‐dppab)}₂](PF₆)₂ ( 8 ) and the tetranuclear square [{CpRu(PPh₃)(μ‐dppab)}₄](PF₆)₄ ( 9 ). The solid‐state structures of 7 and 8 have been determined by X‐ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X‐band ESR spectroscopy in the case of the electrogenerated paramagnetic species.     

Lanthanide Contraction within a Series of Asymmetric Dinuclear [Ln2] Complexes

A complete isostructural series of dinuclear asymmetric lanthanide complexes has been synthesized by using the ligand 6‐[3‐oxo‐3‐(2‐hydroxyphenyl)propionyl]pyridine‐2‐carboxylic acid (H₃ L ). All complexes have the formula [Ln₂(H L )₂(H₂ L )(NO₃)(py)(H₂O)] (Ln=La ( 1 ), Ce ( 2 ), Pr ( 3 ), Nd ( 4 ), Sm ( 5 ), Eu ( 6 ), Gd ( 7 ), Tb ( 8 ), Dy ( 9 ), Ho ( 10 ), Er ( 11 ), Tm ( 12 ), Yb ( 13 ), Lu ( 14 ), Y ( 15 ); py=pyridine). Complexes of La to Yb and Y have been crystallographically characterized to reveal that the two metal ions are encapsulated within two distinct coordination environments of differing size. Whereas one site maintains the coordination number (nine) through the whole series, the other one increases from nine to ten owing to a change in the coordination mode of an NO₃^? ligand. This series offers a unique opportunity to study in detail the lanthanide contraction within complexes of more than one metal. This analysis shows that various representative parameters proportional to this contraction follow a quadratic decay as a function of the number n of f electrons. Slater’s model for the atomic radii has been used to extract, from these decays, the shielding constant of 4f electrons. The average of O???O distances within the coordination polyhedra shared by both metals and of the Ln???Ln separations follow also a quadratic decay, therefore showing that such dependence holds also for parameters that receive the contribution of two lanthanide ions simultaneously. The magnetic behavior has been studied for all nondiamagnetic complexes. It reveals the effect of the spin–orbit coupling and a weak antiferromagnetic interaction between both metals. Photoluminescent studies of all the complexes in the series reveal a single broad emission band in the visible region, which is related to the coordinated ligand. On the other hand, the Nd, Er, and Yb complexes show features in the near‐IR region due to metal‐based transitions.     

Synthesis of Five Coordinate Spirocyclic Germanium(IV) Complexes Containing Diethanol Amine

Reaction of dihydroxo(2,2′-iminodiethanolato-AWO′) germanium(IV) (A) or dihydroxo(2,2′-methyliminodiethanolato-N,O.O′) germanium(IV) (B) with bidentate ligands, e.g. diol, α-hydroxy acid, oxalic acid, 2,6-pyridinedicarboxylic acid, or 2-aminophenol in a mixture of ethanol and xylene mixture yielded a series of unsymmetrical spiro-germanium complexes 1-6. These complexes were characterized by NMR, IR, mass spectra and elementary analysis. The ¹H NMR spectrums of all these compounds show the existence of an intramolecular N – Ge bond. X-ray analysis of compound 6 shows a short N–Ge bond (2.08 Å).     

A Series of [Mn6] Complexes with Terminal Functional Groups

A series of [Mn₆O₂(R¹OH)₄(sao)₆(R²COO)₂] complexes with terminal functional groups ( 1 : R¹ = CH₃, R² = HO‐C₆H₄, 2 : R¹ = C₂H₅, R² = H₂N‐C₆H₄, 3 : R¹ = CH₃, R² = Cl‐C₆H₄, 4 : R¹ = CH₃, R² = CH₃S‐C₆H₄, 5 : R¹ = CH₃, R² = I‐C₆H₄, 6 : R¹ = CH₃, R² = pymSCH₂, 7 : R¹ = CH₃, R² = ortho‐pyr‐SCH₃, 8 : R¹ = C₂H₅, R² = (CH₃)₃OOCNHCH₂C₆H₄; sao = doubly deprotonated salicylaldoxime ligand, pym = pyrimidyl, pyr = pyridyl) have been obtained in a reaction of a ligand R²C₆H₄COOH, salicylaldoxime, manganese(II) perchlorate and [NEt₄](OH) in methanol or a 1:1 mixture of ethanol and dichloromethane. In this report, structural aspects as well as preliminary studies of magnetic and thermal properties are presented. Compounds 1 , 3 , 6 , 8 exhibit an antiferromagnetic coupling of the Mn²⁺ ions, whereas 4 and 7 show ferromagnetic interactions. The title compounds may act as starting materials for further derivatization addressing the functional groups.     

Synthesis and Characterization of Terminal [Re(XCO)(CO)2(triphos)] (X=N,P): Isocyanate versus Phosphaethynolate Complexes

The terminal rhenium(I) phosphaethynolate complex [Re(PCO)(CO)₂(triphos)] has been prepared in a salt metathesis reaction from Na(OCP) and [Re(OTf)(CO)₂(triphos)]. The analogous isocyanato complex [Re(NCO)(CO)₂(triphos)] has been likewise prepared for comparison. The structure of both complexes was elucidated by X‐ray diffraction studies. While the isocyanato complex is linear, the phosphaethynolate complex is strongly bent around the pnictogen center. Computations including natural bond orbital (NBO) theory, natural resonance theory (NRT), and natural population analysis (NPA) indicate that the isocyanato complex can be viewed as a classic Werner‐type complex, that is, with an electrostatic interaction between the Re^I and the NCO group. The phosphaethynolate complex [Re(P?C?O)(CO)₂(triphos)] is best described as a metallaphosphaketene with a Re^I–phosphorus bond of highly covalent character.     

Syntheses,Crystal Structures,and Photophysical Properties of Heteronuclear Zinc(II)/Cadmium(II)‐Lanthanide(III) Coordination Complexes based on Benzoic Acid

The heteronuclear d‐f coordination complexes [Er₂Zn₂(C₆H₅COO)₁₀(phen)₂] (1), [Ho₂Zn₂(C₆H₅COO)₁₀(phen)₂] ( 2 ), [Pr₃Zn₆(C₆H₅COO)₂₁(phen)₃] ( 3 ), [ErCd(C₆H₅COO)₅(phen)·H₂O] ( 4 ), [Ho₂Cd₃(C₆H₅COO)₁₂(phen)₂] ( 5 ), [EuCd₂(C₆H₅COO)₇(phen)₂] ( 6 ) (C₆H₅COOH = benzoic acid;phen = 1,10‐phenanthroline) were synthesized by hydrothermal methods, and their structures were studied by single‐crystal X‐ray diffraction. Complexes 1 , 2 , 4 , and 5 crystallize in the triclinic space group P$\bar{1}$ and complexes 3 and 6 in the monoclinic space group C2/c. The room temperature IR, UV/Vis/NIR absorption, and emission spectra of the six complexes were determined and assigned. In the visible and NIR regions, the emission spectra of complexes show characteristic bands of corresponding Ln^III ions, which are attributed to the sensitization from the d block (Zn/Cd‐ligand section) and ligands. In comparison with isolated Ln^III ions, the NIR emission bands of complexes 1 – 5 exhibit shifting, broadening and splitting, which are also present in their UV/Vis/NIR absorption spectra. Thus, the two spectra of complexes can evidence each other.     

Hexacoordinate Nickel(II)/(III) Complexes that Mimic the Catalytic Cycle of Nickel Superoxide Dismutase

A functional model complex of nickel superoxide dismutase (NiSOD) with a non‐peptide ligand which mimics the full catalytic cycle of NiSOD is unknown. Similarly, it has not been fully elucidated whether NiSOD activity is a result of an outer‐ or inner‐sphere electron‐transfer mechanism. With this in mind, two octahedral nickel(II)/(III) complexes of a bis‐tridentate N₂S donor carboxamide ligand, N‐2‐phenylthiophenyl‐2′‐pyridinecarboxamide (HL^Ph), have been synthesized, structurally characterized, and their SOD activities examined. These complexes mimic the full catalytic cycle of NiSOD. Electrochemical experiments support an outer‐sphere electron‐transfer mechanism for their SOD activity.     

Structural Investigation of Homoleptic Lanthanide(III) Tris(pivalamidinates), [tBuC(NiPr)2]3Ln (Ln = Ce,Eu, Tb)

Three new homoleptic lanthanide(III) tris(pivalamidinates), [tBuC(NiPr)₂]₃Ln (Ln = Ce ( 1 ), Eu ( 2 ), Tb ( 3 )) were synthesized by reaction of anhydrous LnCl₃ with 3 equivalents of in situ prepared Li[tBuC(NiPr)₂] in THF. X‐ray structural analyses confirmed the presence of homoleptic, unsolvated tris(amidinates) in which the central Ln³⁺ ions are coordinated by three chelating pivalamidinate anions in a distorted all‐nitrogen trigonal prismatic arrangement. Compounds 1 – 3 all crystallize in the monoclinic system, with 1 and 3 containing solvent of crystallization ( 1 : toluene, 3 : n‐pentane) whereas the europium derivative 2 is unsolvated.