Syntheses, structure, and magnetic properties of hexanuclear Mn(III)(2)M(III)(4) (M = Y, Gd, Tb, Dy) complexes

The synthesis and characterizations of a family of isomorphous [Mn(III)(2)M(III)(4)L(2)(μ(4)-O)(2)(N(3))(2)(CH(3)O)(2)(CH(3)OH)(4)(NO(3))(2)]·2H(2)O (M = Y(1), Gd(2), Tb(3), Dy(4)) are reported, where H(4)L = N,N'-dihydroxyethyl-N,N'-(2-hydroxy-4,5-dimethylbenzyl)ethylenediamine. They were obtained from the reactions of H(4)L with M(NO(3))(3)·6H(2)O, Mn(ClO(4))(2)·6H(2)O, NaN(3) and NEt(3) in a 1?:?1?:?1?:?2?:?2 molar ratio. The core structure consists of a Mn(2)M(4) unit. The four M(III) ions that are held together by two μ(4)-bridging oxygen atoms form a butterfly M(4) moiety. The M(4) core is further connected to the two five-coordinate trigonal-bipyramidal Mn(III) ions via one μ(4)-O(2-), two alkyloxo and one methoxo triple bridges. Magnetic susceptibility measurements indicate the presence of intramolecular antiferromagnetic interactions in complex 2, and overall intramolecular ferromagnetic interactions in complexes 3 and 4. The alternating current (AC) magnetic susceptibility studies revealed that complexes 3 and 4 showed frequency-dependent out-of-phase signals, which indicates that they exhibit slow relaxation of the magnetization.     

A family of 3d-4f octa-nuclear [Mn(III)(4)Ln(III)(4)] wheels (Ln = Sm, Gd, Tb, Dy, Ho, Er, and Y): synthesis, structure, and magnetism

We present the syntheses, crystal structures, and magnetochemical characterizations for a family of isostructural [Mn(4)Ln(4)] compounds (Ln = Sm, Gd, Tb, Dy, Ho, Er, and Y). They were prepared from the reactions of formic acid, propionic acid, N-n-butyl-diethanolamine, manganese perchlorate, and lanthanide nitrates under the addition of triethylamine in MeOH. The compounds possess an intriguing hetero-octanuclear wheel structure with four Mn(III) and four Ln(III) ions alternatively arranged in a saddle-like ring, where formate ions act as key carboxylate bridges. In the lattice, the molecules stack into columns in a quasi-hexagonal arrangement. Direct current (dc) magnetic susceptibility measurements indicated the depopulation of the Stark components at low temperature and/or very weak antiferromagnetic interactions between magnetic centers. The zero-field alternating current (ac) susceptibility studies revealed that the compounds containing Sm, Tb, and Dy showed frequency-dependent out-of-phase signals, indicating they are single-molecule magnets (SMMs). Magnetization versus applied dc field sweeps on a single crystal of the Dy compound down to 40 mK exhibited hysteresis depending on temperatures and field sweeping rates, further confirming that the Dy compound is a SMM. The magnetization dynamics of the Sm and Y compounds investigated under dc fields revealed that the relaxation of the Sm compound is considered to be dominated by the two-phonon (Orbach) process while the Y compound displays a multiple relaxation process.     

Ln(III)(2)Mn(III)(2) heterobimetallic "butterfly" complexes displaying antiferromagnetic coupling (Ln = Eu, Gd, Tb, Er)

The isostructural heterometallic complexes [Ln(III)(2)Mn(III)(2)O(2)(ccnm)(6)(dcnm)(2)(H(2)O)(2)] (Ln = Eu (1Eu), Gd (1Gd), Tb (1Tb), Er (1Er); ccnm = carbamoylcyanonitrosomethanide; dcnm = dicyanonitrosomethanide) have been synthesised and structurally characterised. The in situ transition metal promoted nucleophilic addition of water to dcnm, forming the derivative ligand ccnm, plays an essential role in cluster formation. The central [Ln(III)(2)Mn(III)(2)(O)(2)] moiety has a "butterfly" topology. The coordinated aqua ligands and the NH(2) group of the ccnm ligands facilitate the formation of a range of hydrogen bonds with the lattice solvent and neighbouring clusters. Magnetic measurements generally reveal weak intracluster antiferromagnetic coupling, except for the large J(MnMn) value in 1Gd. There is some evidence for single molecule magnetic (SMM) behaviour in 1Er. Comparisons of the magnetic properties are made with other recently reported butterfly-type {Ln(III)(x)M(III)(4-x) (d-block)} clusters, x = 1, 2; M = Mn, Fe.     

A convenient route to lanthanide triiodide THF solvates. Crystal structures of LnI(3)(THF)(4) [Ln = Pr] and LnI(3)(THF)(3.5) [Ln = Nd, Gd, Y

The reaction between 1.5 equiv of elemental iodine and rare earth metals in powder form in THF at room temperature gives the rare earth triiodides LnI(3)(THF)(n)() in good yields. Purification by Soxhlet extraction of the crude solids with THF reliably gives the THF adducts LnI(3)(THF)(4) [Ln = La, Pr] and LnI(3)(THF)(3.5) [Ln = Nd, Sm, Gd, Dy, Er, Tm, Y] as microcrystalline solids. X-ray crystallography reveals that the early, larger lanthanide iodide PrI(3)(THF)(4) crystallizes as discrete molecules having a pentagonal bipyramidal structure, whereas the later, smaller lanthanide iodides LnI(3)(THF)(3.5) [Ln = Nd, Gd, Y] crystallize as solvent-separated ion pairs [LnI(2)(THF)(5)][LnI(4)(THF)(2)] in which the cations adopt a pentagonal bipyramidal geometry and the anions adopt an octahedral geometry in the solid state.     

Syntheses, structures and properties of seven isomorphous 1D Ln3+complexes Ln(BTA)(HCOO)(H2O)3 (H2BTA = bis(tetrazoly)amine, Ln = Pr, Gd, Eu, Tb, Dy, Er, Yb) and two 3D Ln3+ complexes Ln(HCOO)3 (Ln = Pr, Nd)

Seven isomorphous 1D chain Ln3+ complexes Ln(BTA)(HCOO)(H2O)3 (Ln = Pr (1), Gd (2), Eu (3), Tb (4) Dy (5), Er (6) and Yb (7)), and two formate coordinating and bridging 3D Ln3+ complexes Ln(HCOO)3 (Ln = Pr (8) and Nd (9)) have been synthesized and characterized by single crystal X-ray diffraction analysis. Although the Ln3+ ions in 1-7 have different radius, the trivalent lanthanide ions in 1-7 show the same coordinated environment. The well-defined single crystal structures of 8 and 9 are first samples for formate-bridged Ln3+ metallic complexes. The luminescent properties of solid samples of 2-5 at room temperature and the magnetic property of 2 have been also reported and discussed in this paper.     

Family of double-cubane Mn4Ln2 (Ln = Gd, Tb, Dy, Ho) and Mn4Y2 complexes: a new Mn4Tb2 single-molecule magnet

The synthesis and characterization of a family of Mn(2)(III)Mn(2)(II)Ln(III)(2) complexes (Ln = Gd (1), Tb (2), Dy (3), and Ho (4)) of formula [Mn(4)Ln(2)O(2)(O(2)CBu(t))(6)(edteH(2))(2)(NO(3))(2)] are reported, where edteH(4) is N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine. The analogous Mn(4)Y(2) (5) complex has also been prepared. They were obtained from reaction of Ln(NO(3))(3) or Y(NO(3))(3) with Mn(O(2)CBu(t))(2), edteH(4), and NEt(3) in a 2:3:1:2 molar ratio. The crystal structures of representative 1 and 2 were obtained, and their core consists of a face-fused double-cubane [Mn(4)Ln(2)(μ(4)-O(2-))(2)(μ(3)-OR)(4)] unit. Such double-cubane units are extremely rare in 3d metal chemistry and unprecedented in 3d-4f chemistry. Variable-temperature, solid-state dc and ac magnetic susceptibility studies on 1-5 were carried out. Fitting of dc χ(M)T vs T data for 5 gave J(bb) (Mn(III)···Mn(III)) = -32.6(9) cm(-1), J(wb) (Mn(II)···Mn(III)) = +0.5(2) cm(-1), and g = 1.96(1), indicating a |n, 0, n> (n = 0-5) 6-fold-degenerate ground state. The data for 1 indicate an S = 12 ground state, confirmed by fitting of magnetization data, which gave S = 12, D = 0.00(1) cm(-1), and g = 1.93(1) (D is the axial zero-field splitting parameter). This ground state identifies the Mn(II)···Gd(III) interactions to be ferromagnetic. The ac susceptibility data independently confirmed the conclusions about 1 and 5 and revealed that 2 displays slow relaxation of the magnetization vector for the Mn(4)Tb(2) analogue 2. The latter was confirmed as a single-molecule magnet by observation of hysteresis below 0.9 K in magnetization vs dc field scans on a single crystal of 2·MeCN on a micro-SQUID apparatus. The hysteresis loops also displayed well-resolved quantum tunneling of magnetization steps, only the second 3d-4f SMM to do so.     

高温高压法提取金属富勒烯Lnm@C2nLn=Y, Gd, Tb)

笼内金属富勒烯以其独特的结构性质和潜在的应用价值而引起了人们极大的注意 [1～ 3] ,但因制备技术复杂、产率低以及将其从伴生的空心富勒烯中分离出来比较困难而使其研究受到很大的限制 .笼内金属富勒烯的分离提取始终是金属富勒烯研究的一个重要分支 .通常的方法是将放电得到的烟炱采用甲苯索氏提取的方法粗提 ,然后用高压液相色谱法分离得到纯品 ,笼内金属富勒烯的产率仅为烟炱的 0 .1 % [4～ 6] .我们改进了常规的提取方法 ,建立了一种新的提取方法—高温高压提取法 .具体的做法是采用甲苯索氏提取法从烟炱中提取出空心富勒烯和少量金…     

Heterometallic thiacalix[4]arene-supported Na2Ni(II)12Ln(III)2 clusters with vertex-fused tricubane cores (Ln = Dy and Tb)

Two heterometallic thiacalix[4]arene-supported complexes possess a trinary-cubane core composed of one [Ni(2)Ln(2)] cubane unit and two [NaNi(2)Ln] cubane units sharing one Ln(III) ion (Ln = Dy and Tb). Only the Dy(III) complex exhibits slow magnetic relaxation behaviour of single molecule magnet nature.     

Synthesis, Structure, and Reactivities of [eta(2)-P(7)M(CO)(4)](3)(-), [eta(2)-HP(7)M(CO)(4)](2)(-), and [eta(2)-RP(7)M(CO)(4)](2)(-) Zintl Ion Complexes Where M = Mo, W

Ethylenediamine (en) solutions of [eta(4)-P(7)M(CO)(3)](3)(-) ions [M = W (1a), Mo (1b)] react under one atmosphere of CO to form microcrystalline yellow powders of [eta(2)-P(7)M(CO)(4)](3)(-) complexes [M = W (4a), Mo (4b)]. Compounds 4 are unstable, losing CO to re-form 1, but are highly nucleophilic and basic. They are protonated with methanol in en solvent giving [eta(2)-HP(7)M(CO)(4)](2)(-) ions (5) and are alkylated with R(4)N(+) salts in en solutions to give [eta(2)-RP(7)M(CO)(4)](2)(-) complexes (6) in good yields (R = alkyl). Compounds 5 and 6 can also be prepared by carbonylations of the [eta(4)-HP(7)M(CO)(3)](2)(-) (3) and [eta(4)-RP(7)M(CO)(3)](2)(-) (2) precursors, respectively. The carbonylations of 1-3 to form 4-6 require a change from eta(4)- to eta(2)-coordination of the P(7) cages in order to maintain 18-electron configurations at the metal centers. Comparative protonation/deprotonation studies show 4 to be more basic than 1. The compounds were characterized by IR and (1)H, (13)C, and (31)P NMR spectroscopic studies and microanalysis where appropriate. The [K(2,2,2-crypt)](+) salts of 5 were characterized by single crystal X-ray diffraction. For 5, the M-P bonds are very long (2.71(1) ?, average). The P(7)(3)(-) cages of 5 are not displaced by dppe. The P(7) cages in 4-6 have nortricyclane-like structures in contrast to the norbornadiene-type geometries observed for 1-3. (31)P NMR spectroscopic studies for 5-6 show C(1) symmetry in solution (seven inequivalent phosphorus nuclei), consistent with the structural studies for 5, and C(s)() symmetry for 4 (five phosphorus nuclei in a 2:2:1:1:1 ratio). Crystallographic data for [K(2,2,2-crypt)](2)[eta(2)-HP(7)W(CO)(4)].en: monoclinic, space group C2/c, a = 23.067(20) ?, b = 12.6931(13) ?, c = 21.433(2) ?, beta = 90.758(7) degrees, V = 6274.9(10) ?(3), Z = 4, R(F) = 0.0573, R(w)(F(2)) = 0.1409. For [K(2,2,2-crypt)](2)[eta(2)-HP(7)Mo(CO)(4)].en: monoclinic, space group C2/c, a = 22.848(2) ?, b = 12.528(2) ?, c = 21.460(2) ?, beta = 91.412(12) degrees, V = 6140.9(12) ?(3), Z = 4, R(F) = 0.0681, R(w)(F(2)) = 0.1399.     

Crystal structure and luminescence of lanthanide monodentate complexes [Ln(C(4)N(4)H(6)O)(2)(H(2)O)(6)]Cl(3) and [Ln(C(4)N(4)H(6)O)(2)(H(2)O)(3)(NO(3))(3)] (Ln = Tb or Eu)

New eight- and nine-coordinate luminescent europium(III) and terbium(III) complexes 1-4 with carbonyl group coordination have been prepared using the monodentate ligand (L) 2,4-diamino-6-hydroxy pyrimidine and characterized by X-ray and spectroscopic methods.     

Carboxylate-bridged copper(II)-lanthanide(III) complexes [(Cu(3)Ln(2)(oda)(6)(H(2)O)(6)).12H(2)O](n)(Ln = Dy,Ho, Er,Y; oda = oxydiacetate)

The hydrothermal reaction of Ln(2)O(3) (Ln = Dy and Ho), Cu(OAc)(2).2H(2)O, and oxydiacetic acid in the approximate mole ratio of 1:3:8 resulted in the formation of two new members of the isostructural series of polymers formulated as [(Cu(3)Ln(2)(oda)(6)(H(2)O)(6)).12H(2)O](n), crystallizing in the hexagonal crystal system, space group P6/mcc (No. 192). Temperature-dependent magnetic susceptibilities and EPR spectra are reported for the heterometallic compounds Cu-Dy 1, Cu-Ho 2, Cu-Er 3, and Cu-Y 4. The results are discussed in terms of the structure of the compounds, the electronic properties of the lanthanide ions, and the exchange interactions between the magnetic ions.     

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.     

Defect-dicubane Ni2Ln2 (Ln = Dy, Tb) single molecule magnets

Two pairs of Ni(2)Dy(2) and Ni(2)Tb(2) complexes, [Ni(2)Ln(2)(L)(4)(NO(3))(2)(DMF)(2)] {Ln = Dy (1), Tb (2)} and [Ni(2)Ln(2)(L)(4)(NO(3))(2)(MeOH)(2)]·3MeOH {Ln = Dy (3), Tb (4)} (H(2)L is the Schiff base resulting from the condensation of o-vanillin and 2-aminophenol) possessing a defect-dicubane core topology were synthesized and characterized. All four complexes are ferromagnetically coupled, and the two Dy-analogues are found to be Single Molecule Magnets (SMMs) with energy barriers in the range 18-28 K. Compound 1 displays step-like hysteresis loops, confirming the SMM behavior. Although 1 and 3 show very similar structural topologies, the dynamic properties of 1 and 3 are different with blocking temperatures (3.2 and 4.2 K at a frequency of 1500 Hz) differing by 1 K. This appears to result from a change in orientation of the nitrate ligands on the Dy(III) ions, induced by changes in ligands on Ni(II).     

Syntheses and Crystal Structures of Homleptic Lanthanide Complexes [C_6H_5COCHC(CH_3)N-(p-ClC_6H_4)]_3Ln(THF)_n (Ln =Yb,Y,Nd)

Three homoleptic lanthanide complexes, [C6H5COCHC(CH3)N(p-ClC6H4)]3Ln(THF)n(n = 0, Ln = Yb(1); n = 0, Ln = Y(2); n = 1, Ln = Nd(3)), were synthesized by amine elimination reaction of Ln[N(SiMe3)2]3 with 1-phenyl-3-N-(p-chlorophenylimino)-1-butanone. These complexes crystallize in triclinic, space group P1 with a = 9.805(3), b = 14.831(6), c = 16.075(6) A, α = 111.996(9), β = 91.570(7), γ = 93.744(6)°, V = 2159.4(13) A3, Z = 2, D3 c = 1.515 g/cm, F(000) = 986, μ(MoKα) = 2.396 mm-1, R = 0.0360 and wR = 0.0850 for 9548 observed reflections with I 2σ(I) for complex 1; a = 9.861(5), b = 14.852(9), c = 16.111(9) A, α = 112.362(13), β = 91.949(11), γ = 93.678(14)°, V = 2173(2) A3, Z = 2, Dc = 1.377 g/cm3, F(000) = 924, μ(MoKα) = 1.570 mm-1, R = 0.0735 and wR = 0.1389 for 8015 observed reflections with I 2σ(I) for complex 2; and a = 9.308(3), b = 15.357(3), c = 17.419(4) A, α = 66.493(13), β = 88.61(2), γ = 86.664(19)°, V = 2279.4(9) A3, Z = 2, Dc = 1.499 g/cm3, F(000) = 1046, μ(MoKα) = 1.364 mm-1, R = 0.0843 and wR = 0.2280 for 8433 observed reflections with I 2σ(I) for complex 3. Each central metal in complexes 1 and 2 is six-coordinated by three nitrogen and three oxygen atoms from three β-ketoiminate ligands to give a distorted octahedral geometry, while the central metal in 3 is seven-coordinated by three nitrogen and three oxygen atoms from three β-ketoiminate ligands and one oxygen atom from the solvated THF molecule to complete a distorted monocapped trigonal prism.     

Synthesis,crystal structures and luminescent properties of two new Ln(III)-dicarboxylate (Ln=Eu,Tb) complexes exhibiting three dimensional networks

Two new coordination polymers, {[Eu₂(L₁)₃(H₂O)₂]?·?H₂O} _n (1), (Cu(II)?···?Cu(II), [Tb(H₂O)]₂(L₂)₃?·?4H₂O (2) (H₂L₁?=?succinic acid, H₂L₂?=?glutaric acid) have been hydrothermally synthesized and characterized by elemental analysis, IR, luminescence spectra and single crystal X-ray diffraction. The complexes are constructed by dicarboxylates bridging chains of edge-sharing EuO₈(H₂O) and TbO₈(H₂O) polyhedra to form 3D network structures. Complexes 1 and 2 exhibit intense red and green photoluminescence upon UV excitation in the solid state at room temperature.     

The thermal characteristics of potassium oxalato lanthanates: K3LnOx3 · n H2O (Ln=La−Tb) and K8Ln2Ox7 · 14 H2O (Ln=Tb−Yb,Y)

The title compounds were studied by TG, DTA, DSC, IR and absorption spectroscopy. The complexes go through dehydration (70–200°C), an irreversible exothermic process (in air or N₂ atmosphere, 250–300°C) and decomposition to a mixture of oxides and carbonates (385–700°C). The exothermic process occurs without weight loss and corresponding heats of reaction fall in the range 0–26 kJ/mol. The absorption spectrum of the Nd complex in the range 5000–6000 Å was employed to monitor perturbations in the coordination sphere of Nd³⁺ arising from the exothermic process. Involvement of the Nd³⁺ cation is implied and the heats of reaction show a close relationship to the radii of Ln³⁺. The interpretation of these data was made with the aid of valuable structural information obtained previously.     

Photophysical properties of near-infrared-emitting Ln(III) complexes with 1-(9-Anthryl)-4,4,4-trifluoro-1,3-butandione (Ln = Nd and Er)

We report the synthesis and photophysical properties of Nd(III) and Er(III) complexes with 1-(9-anthryl)-4,4,4-trifluoro-1,3-butandione (9-ATFB). The complexes of [Nd(9-ATFB)4]- and [Er(9-ATFB)4]- produced sensitized near-infrared (NIR) luminescence via the excitation of anthracene. This suggests that the intramolecular energy transfer occurred from the singlet excited state of anthracene to the resonance levels of the metal ions, since the phosphorescence of anthracene is forbidden under normal conditions. The observed quantum yield of the visible luminescence showed that the energy transfer is more efficient for [Nd(9-ATFB)4]- than for [Er(9-ATFB)4]-. The lifetimes of the NIR luminescence of the complexes were in the microsecond range. The quantum yields of the sensitized NIR of the complexes were estimated using the lifetime and the energy-transfer quantum yield.     

Syntheses,structures, and properties of the bis(cyclopentadienyl) rare-earth imidodiphosphinochalocogenido compounds Cp2Ln[N(QPPh2)2] (Ln = La,Gd, Er,or Yb for Q = Se; Ln = Yb for Q = S)

The compounds Cp2Ln[N(QPPh2)2] (Ln = La (1), Gd (2), Er (3), or Yb (4) for Q = Se, Ln = Yb (5) for Q = S) have been synthesized from the corresponding rare-earth tris(cyclopentadienyl) compound and H[N(QPPh2)2]. The structures of compounds 1, 2, 3, and 5, as determined by X-ray crystallography, consist of a Cp2Ln fragment, coordinated eta 3 through two chalcogen atoms and an N atom of the imidodiphosphinochalcogenido ligand [N(QPPh2)2]-. In compound 4, the Cp2Yb moiety is coordinated eta 2 through the two Se atoms of the [N(SePPh2)2]-ligand. 31P and 77Se (for 1) NMR spectroscopies lend insight into the solution nature of these species. Crystal data: 1, C34H30LaNP2Se2, triclinic, P1, a = 9.7959(10) A, b = 12.4134(13) A, c = 13.9077(14) A, alpha = 88.106(2) degrees, beta = 88.327(2) degrees, gamma = 68.481(2) degrees, V = 1572.2(3) A3, T = 153 K, Z = 2, and R1(F) = 0.0257 for the 5947 reflections with I > .2 sigma(I); 2, C34H30GdNP2Se2, triclinic, P1, a = 9.7130(14) A, b = 12.2659(17) A, c = 13.953(2) A, alpha = 88.062(2) degrees, beta = 87.613(2) degrees, gamma = 69.041(2) degrees, V = 1550.7(4) A3, T = 153 K, Z = 2, and R1(F) = 0.0323 for the 5064 reflections with I > 2 sigma(I); 3, C34H30ErNP2Se2, triclinic, P1, a = 9.704(2) A, b = 12.222(3) A, c = 13.980(4) A, alpha = 88.230(4) degrees, beta = 87.487(4) degees, gamma = 69.107(4) degrees, V = 1547.4(7) A3, T = 153 K, Z = 2, and R1(F) = 0.0278 for the 6377 reflections with I > 2 sigma(I); 4, C34H30NP2Se2Yb.C4H8O, triclinic, P1, a = 12.087(4) A, b = 12.429(4) A, c = 23.990(7) A, alpha = 89.406(5) degrees, beta = 86.368(5) degrees, gamma = 81.664(5) degrees, V = 3558.8(18) A3, T = 153 K, Z = 4, and R1(F) = 0.0321 for the 11,883 reflections with I > 2 sigma(I); and 5, C34H30NP2S2Yb, monoclinic, P21/n, a = 13.8799(18) A, b = 12.6747(16) A, c = 17.180(2) A, beta = 91.102(3) degrees, V = 3021.8(7) A3, T = 153 K, Z = 4, and R1(F) = 0.0218 for the 6698 reflections with I > 2 sigma(I).     

Thermochemistry of rare earth complexes [Ln(Ala)2(Im)(H2O)](ClO4)3 (Ln=Pr, Gd)

The two complexes, [Ln(Ala)₂(Im)(H₂O)](ClO₄)₃ (Ln=Pr, Gd), were synthesized and characterized. Using a solution-reaction isoperibol calorimeter, standard enthalpies of reaction of two reactions: LnCl₃⋅6H₂O(s)+2Ala(s)+Im(s)+3NaClO₄(s)=[Ln(Ala)₂(Im)(H₂O)](ClO₄)₃(s)+3NaCl(s)+5H₂O(l) (Ln=Pr, Gd), at T=298.15 K, were determined to be (39.26±0.10) and (5.33±0.12) kJ mol^–1 , respectively. Standard enthalpies of formation of the two complexes at T=298.15 K, Δ_fH^Θ_m {[Ln(Ala)₂(Im)(H₂O)](ClO₄)₃(s)} (Ln=Pr, Gd), were calculated as –(2424.2±3.3) and –(2443.4±3.3) kJ mol^–1 , respectively.