Cluster-type basic lanthanide iodides [M6(mu6-O)(mu3-OH)8(H2O)24]I8(H2O)8 (M = Nd, Eu, Tb, Dy)

Ln6(mu6-O)(mu3-OH)8(H2O)24]I8(H2O)(8) (Ln = Nd, Eu, Tb, Dy) compounds are obtained as the final hydrolysis products of lanthanide triiodides in an aqueous solution. Their X-ray crystal structure features a body-centered arrangement of oxygen-centered {Ln6X8}8+ cluster cores: [Nd6(mu6-O)(mu3-OH)8(H2O)24]I8(H2O)8 [Pearson code oP156, orthorhombic, Pnnm (No. 58), Z = 2, a = 1310.4(3) pm, b = 1502.1(3) pm, c = 1514.9(3) pm, 3384 reflections with I0 > 2sigma(I0), R1 = 0.0340, wR2 = 0.0764, GOF = 1.022, T = 298(2) K], [Eu6(mu6-O)(mu3-OH)8(H2O)24]I8(H2O)8 [Pearson code oP156, orthorhombic, Pnnm (No. 58), Z = 2, a = 1306.6(2) pm, b = 1498.15(19) pm, c = 1499.41(18) pm, 4262 reflections with I0 > 2sigma(I0), R1 = 0.0540, wR2 = 0.0860, GOF = 0.910, T = 298(2) K], [Tb6(mu6-O)(mu3-OH)8(H2O)24]I8(H2O)8 [Pearson code oP156, orthorhombic, Pnnm (No. 58), Z = 2, a = 1296.34(5) pm, b = 1486.13(7) pm, c = 1491.88(6) pm, 4182 reflections with I0 > 2sigma(I0), R1 = 0.0395, wR2 = 0.0924, GOF = 1.000, T = 298(2) K], and [Dy6(mu6-O)(mu3-OH)8(H2O)24]I8(H2O)8 [Pearson code oP156, orthorhombic, Pnnm (No. 58), Z = 2, a = 1296.34(5) pm, b = 1486.13(7) pm, c = 1491.88(6) pm, 3329 reflections with I0 > 2sigma(I0), R1 = 0.0389, wR2 = 0.0801, GOF = 0.992, T = 298(2) K.     

Intermediate states on the way to edge-sharing BO4 tetrahedra in M6B22O39·H2O (M=Fe, Co)

The new borates Fe(II)(6)B(22)O(39)·H(2)O (colourless) and Co(II)(6)B(22)O(39)·H(2)O (dichroic: red/bluish) were synthesised under the high-pressure/high-temperature conditions of 6 GPa and 880 °C (Fe)/950 °C (Co) in a Walker-type multi-anvil apparatus. The compounds crystallise in the orthorhombic space group Pmn2(1) (Z=2) with the lattice parameters a=771.9(2), b=823.4(2), c=1768.0(4) pm, V=1.1237(4) nm(3), R(1)=0.0476, wR(2)=0.0902 (all data) for Fe(6)B(22)O(39)·H(2)O and a=770.1(2), b=817.6(2), c=1746.9(4) pm, V=1.0999(4) nm(3), R(1)=0.0513, wR(2)=0.0939 (all data) for Co(6)B(22)O(39)·H(2)O. The new structure type of M(6)B(22)O(39)·H(2)O (M=Fe, Co) is built up from corner-sharing BO(4) tetrahedra and BO(3) groups, the latter being distorted and close to BO(4) tetrahedra if additional oxygen atoms of the neighbouring BO(4) tetrahedra are considered in the coordination sphere. This situation can be regarded as an intermediate state in the formation of edge-sharing tetrahedra. The structure consists of corrugated multiple layers interconnected by BO(3)/BO(4) groups to form Z-shaped channels. Inside these channels, iron and cobalt show octahedral (M1, M3, M4, M5) and strongly distorted tetrahedral (M2, M6) coordination by oxygen atoms. Co(II)(6)B(22)O(39)·H(2)O is dichroic and the low symmetry of the chromophore [Co(II)O(4)] is reflected by the polarised absorption spectra (Δ(t)=4650 cm(-1), B=878 cm(-1)).     

有生物活性的稀土-腺苷三磷酸系列物的合成及其量子化学理论计算的研究

本文首次报道合成了稀土-腺苷三磷酸固态配合物RE(III)-ATP)RE=Y、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu)。运用红外、激光raman、热分析、紫外、顺磁、X射线衍射、元素分析、配位滴定等技术测定了上述配合物的化学组成和分子结构, 其分子式用通式表为[RE(III)(HATP)(H2O)4]。采用量子化学INDO方法计算了系列物的电子结构, 依据计算结果讨论了生物化学中高能磷酸键的本质。     

Two new groups of homoleptic rare earth pyridylbenzimidazolates: (NC12H8(NH)2)[Ln(N3C12H8)4] with Ln = Y,Tb, Yb,and [Ln(N3C12H8)2(N3C12H9)2][Ln(N3C12H8)4](N3C12H9)2 with Ln = La,Sm, Eu

The compounds (NC(12)H(8)(NH)(2))[Ln(N(3)C(12)H(8))(4)], Ln = Y, Tb, Yb, and [Ln(N(3)C(12)H(8))(2)(N(3)C(12)H(9))(2)][Ln(N(3)C(12)H(8))(4)](N(3)C(12)H(9))(2), with Ln = La, Sm, Eu, were obtained by reactions of the group 3 metals yttrium and lanthanum as well as the lanthanides europium, samarium, terbium, and ytterbium with 2-(2-pyridyl)-benzimidazole. The reactions were carried out in melts of the amine without any solvent and led to two new groups of homoleptic rare earth pyridylbenzimidazolates. The trivalent rare earth atoms have an eightfold nitrogen coordination of four chelating pyridylbenzimidazolates giving an ionic structure with either pyridylbenzimidazolium or [Ln(N(3)C(12)H(8))(2)(N(3)C(12)H(9))(2)](+) counterions. With Y, Eu, Sm, and Yb, single crystals were obtained whereas the La- and Tb-containing compounds were identified by powder methods. The products were investigated by X-ray single crystal or powder diffraction and MIR and far-IR spectroscopy, and with DTA/TG regarding their thermal behavior. They are another good proof of the value of solid-state reaction methods for the formation of homoleptic pnicogenides of the lanthanides. Despite their difference in the chemical formula, both types (NC(12)H(8)(NH)(2))[Ln(N(3)C(12)H(8))(4)], Ln = Y (1), Tb (2), Yb (3), and [Ln(N(3)C(12)H(8))(2)(N(3)C(12)H(9))(2)][Ln(N(3)C(12)H(8))(4)](N(3)C(12)H(9))(2), Ln = La (4), Sm (5), Eu (6), crystallize isotypic in the tetragonal space group I4(1). Crystal data for (1): T = 170(2) K, a = 1684.9(1) pm, c = 3735.0(3) pm, V = 10603.5(14) x 10(6) pm(3), R1 for F(o) > 4sigma(F(o)) = 0.053, wR2 = 0.113. Crystal data for (3): T = 170(2) K, a = 1683.03(7) pm, c = 3724.3(2) pm, V = 10549.4(14) x 10(6) pm(3), R1 for F(o) > 4sigma(F(o)) = 0.047, wR2 = 0.129. Crystal data for (5): T = 103(2) K, a = 1690.1(2) pm, c = 3759.5(4) pm, V = 10739(2) x 10(6) pm(3), R1 for F(o) > 4sigma(F(o)) = 0.050, wR2 = 0.117. Crystal data for (6): T = 170(2) K, a = 1685.89(9) pm, c = 3760.0(3) pm, V = 10686.9(11) x 10(6) pm(3), R1 for F(o) > 4sigma(F(o)) = 0.060, wR2 = 0.144.     

Rare-earth tricyanomelaminates [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)H(2)O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy): structural investigation, solid-state NMR spectroscopy, and photoluminescence

The rare-earth tricyanomelaminates, [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)xH(2)O (LnTCM; Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy), have been synthesized through ion-exchange reactions. They have been characterized by powder as well as single-crystal X-ray diffraction analysis, vibrational spectroscopy, and solid-state (1)H, (13)C, and (15)N MAS NMR spectroscopy. The X-ray powder pattern common to all nine rare-earth tricyanomelaminates LnTCM (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) indicates that they are isostructural. The single-crystal X-ray diffraction pattern of LnTCM is indicative of non-merohedral twinning. The crystals are triclinic and separation of the twin domains as well as refinement of the structure were successfully carried out in the space group P1 for LaTCM (LaTCM; P1, Z=2, a=7.1014(14), b=13.194(3), c=13.803(3) A, alpha=90.11(3), beta=77.85(3), gamma=87.23(3) degrees , V=1262.8(4) A(3)). In the crystal structure, each Ln(3+) is surrounded by two nitrogen atoms from two crystallographically independent tricyanomelaminate moieties and seven oxygen atoms from crystal water molecules. The positions of all of the hydrogen atoms of the ammonium ions and water molecules could not be located from difference Fourier syntheses. The presence of [NH(4)](+) ions as well as two NH groups belonging to two crystallographically independent monoprotonated tricyanomelaminate moieties has only been confirmed by subjecting LaTCM to solid-state (1)H, (13)C, and (15)N{(1)H} cross-polarization (CP) MAS NMR and advanced CP experiments such as cross-polarization combined with polarization inversion (CPPI). The (1)H 2D double-quantum single-quantum homonuclear correlation (DQ SQ) spectrum and the (15)N{(1)H} 2D CP heteronuclear-correlation (HETCOR) spectrum have revealed the hydrogen-bonded (N--HN) dimer of monoprotonated tricyanomelaminate moieties as well as H-bonding through [NH(4)](+) ions and H(2)O molecules. The structures of the other eight rare-earth tricyanomelaminates (LnTCM; Ln=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) have been refined from X-ray powder diffraction data by the Rietveld method. Photoluminescence studies of [NH(4)]Eu[HC(6)N(9)](2)[H(2)O](7)xH(2)O have revealed orange-red (lambda(max)=615 nm) emission due to the (5)D(0)-(7)F(2) transition, whereas [NH(4)]Tb[HC(6)N(9)](2)[H(2)O](7)xH(2)O has been found to show green emission with a maximum at 545 nm arising from the (5)D(4)-(7)F(5) transition. DTA/TG studies of [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)xH(2)O have indicated several phase transitions associated with dehydration of the compounds above 150 degrees C and decomposition above 200 degrees C.     

Synthesis and single-crystal x-ray diffraction examination of a structurally homologous series of tetracoordinate heteroleptic anionic lanthanide complexes: Ln[N[Si(CH3)2CH2CH2Si(CH3)2]]3(mu-Cl)Li(L)3 (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb; (L)3 =(THF)3, (Et2O)3, (THF)2(Et2O)

Anhydrous lanthanide(III) chlorides (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) react with 3 equiv of lithium 2,2,5,5-tetramethyl-2,5-disila-1-azacyclopentanide, Li[N[Si(CH3)2CH2Ch2Si(CH3)2]], in THF or Et(2)O to afford the monomeric four-coordinate heteroleptic ate complexes Ln[N[Si(CH3)2CH2CH2Si(CH3)2]]3(mu-Cl)Li(THF/Et2O)3 (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7), Tm (8), Yb (9)), whose solid-state structures were determined by the single-crystal X-ray diffraction technique. All complexes additionally were characterized by melting point determination, elemental analyses, and mass spectrometry.     

Zn[BPO4(OH)2]: a zinc borophosphate with the rare moganite-type topology

A novel zinc borophosphate Zn[BPO(4)(OH)(2)] with moganite-type topology (a rare polymorph of silica) has been prepared from a mixture of ZnO, B(2)O(3), and P(2)O(5) by hydrothermal treatment at 443 K. The crystal structure was determined from single-crystal X-ray data (orthorhombic, Pbcn (no. 60), a=915.07(3), b=897.22(3), c=1059.19(3) pm, V=869.62(5)x10(6) pm(3), Z=8, R1=0.028, wR2=0.075). The crystal structure comprises unbranched vierer-single borophosphate chains running along [010] and interconnected via ZnO(2)(OH)(2)-tetrahedra by sharing common vertices. The resulting topology of the three-dimensional tetrahedral framework structure is described by the Schl?fli symbol (4(2).6(2).8(2))(4.6(4).8)(2). Although showing Zn in a tetrahedral coordination, the title compound does not belong to the group of zincoborophosphates but is a special case of a borophosphate containing vierer single rings of tetrahedra with the sequence Zn-B-Zn-P.     

Hydroxoundecahydro-closo-dodecaborate(2-) as a Nucleophile. Preparation and Structural Characterization of O-Alkyl and O-Acyl Derivatives of Hydroxoundecahydro-closo-dodecaborate(2-)

The syntheses, solid state structures, and spectral properties of O-alkyl and O-acyl derivatives of hydroxoundecahydro-closo-dodecaborate(2-), 1, are described. Alkylation of 1 with ethyl iodide was achieved in dimethyl sulfoxide using potassium hydroxide as a base, leading to [N(n-C(4)H(9))(4)](2)[CH(3)CH(2)O-B(12)H(11)(2-)], 2, bis(tetrabutylammonium) ethoxyundecahydro-closo-dodecaborate(2-) [monoclinic P2(1)/n, a = 1192.4(9) pm, b = 1253.9(4) pm, c = 3049.1(10) pm, beta = 92.69(4) degrees, Z = 4, R1 = 0.0693, wR(2) = 0.1517]. Alkylation with 1,5-dibromopentane afforded the cyclic oxonium salt [PPN][C(5)H(10)O-B(12)H(11)(1-)], 3, (&mgr;-nitrido)bis(triphenylphosphorus)(1+) tetrahydropyrane-undecahydro-closo-dodecaborate(1-) [monoclinic P2(1)/c, a = 1938.1(2) pm, b = 1329.7(10) pm, c = 1944.0(2) pm, beta = 108.82(10) degrees, Z = 4, R1 = 0.0484, wR(2) = 0.0833]. Acylation of 1 in acetonitrile with acyl chlorides in the presence of pyridine yielded [N(n-C(4)H(9))(4)](2)[C(6)H(5)CO(2)-B(12)H(11)(2-)], 4, bis(tetrabutylammonium) undecahydrobenzoyl-closo-dodecaborate(2-) [monoclinic P2(1)/c, a = 1812.0(4) pm, b = 1711.9(3) pm, c = 1685.0(3) pm, beta = 114.03(3) degrees, Z = 4, R1 = 0.0915, wR(2) = 0.2093], and [N(n-C(4)H(9))(4)](2)[CH(3)CO(2)-B(12)H(11)(2-)], 5, bis(tetrabutylammonium) acetoxyundecahydro-closo-dodecaborate(2-) [monoclinic P2(1)/n, a = 1190.5(2) pm, b = 1243.0(10) pm, c = 3078.4(4) pm, beta = 92.76(10) degrees, Z = 4, R1 = 0.0642, wR(2) = 0.1462]. All crystal structures showed distortion of the pseudoicosahedral geometry of the boron cluster. The boron-oxygen distances varied from 144.2(5) pm for 2, 148.5(3) pm for 5, 149.4(12) pm for 4, to 152.8(4) pm for 3. The 3-fold coordinated oxygen of oxonium salt 3 is nearly planar.     

Isolation of the new cubic phases RE4FeGa(12-x)Ge(x) (RE = Sm,Tb; x = 2.5) from molten gallium: single-crystal neutron diffraction study of the Ga/Ge distribution

The compounds RE4FeGa(12-x)Ge(x) (RE = Sm, Tb) were discovered in reactions employing molten Ga as a solvent at 850 degrees C. However, the isostructural Y4FeGa(12-x)Ge(x) was prepared from a direct combination reaction. The crystal structure is cubic with space group Imm, Z = 2, and a = 8.657(4) A and 8.5620(9) A for the Sm and Tb analogues, respectively. Structure refinement based on full-matrix least squares on F(o)2 resulted in R1 = 1.47% and wR2 = 4.13% [I > 2(I)] for RE = Sm and R1 = 2.29% and wR2 = 7.12% [I > 2(I)] for RE = Tb. The compounds crystallize in the U4Re7Si6 structure type, where the RE atoms are located on 8c (1/4, 1/4, 1/4) sites and the Fe atoms on 2a (0, 0, 0) sites. The distribution of Ga and Ge in the structure, investigated with single-crystal neutron diffraction on the Tb analogue, revealed that these atoms are disordered over the 12d (1/4, 0, 1/2) and 12e (x, 0, 0) sites. The amount of Ga/Ge occupying the 12d and 12e sites refined to 89(4)/11 and 70(4)/30%, respectively. Transport property measurements indicate that these compounds are metallic conductors. Magnetic susceptibility measurements and M?ssbauer spectroscopy performed on the Tb analogue show a nonmagnetic state for Fe, while the Tb atoms carry a magnetic moment corresponding to a mu(eff) of 9.25 mu(B).     

Anion-directed self-assembly of lanthanide-notp compounds and their fluorescence, magnetic, and catalytic properties

Reactions of 1,4,7-triazacyclononane-1,4,7-triyl-tris(methylenephosphonic acid) [notpH(6), C(9)H(18)N(3)(PO(3)H(2))3] with different lanthanide salts result in four types of Ln-notp compounds: [Ln{C(9)H(20)N(3)(PO(3)H)(2)(PO(3))}(NO(3))(H(2)O)].4H2O (1), [Ln = Eu (1 Eu), Gd (1 Gd), Tb (1 Tb)], [Ln{C(9)H(20)N(3)(PO(3)H)(2)(PO(3))}(H2O)]Cl.3H2O (2) [Ln = Eu (2 Eu), Gd (2 Gd), Tb (2 Tb)], [Ln{C(9)H(20)N(3)(PO(3)H)(2)(PO(3))}(H2O)]ClO4.8H2O, (3) [Ln = Eu (3 Eu), Gd (3 Gd)], and [Ln{C(9)H(20)N(3)(PO(3)H)(2)(PO(3))}(H2O)]ClO4.3H2O (4), [Ln = Gd (4 Gd), Tb (4 Tb)]. Compounds within each type are isostructural. In compounds 1, dimers of {Ln2(notpH4)2(NO3)2(H2O)2} are found, in which the two lanthanide atoms are connected by two pairs of O-P-O and one pair of mu-O bridges. The NO3- ion serves as a bidentate terminal ligand. Compounds 2 contain similar dimeric units of {Ln2(notpH4)2(H2O)2} that are further connected by a pair of O-P-O bridges into an alternating chain. The Cl- ions are involved in the interchain hydrogen-bonding networks. A similar chain structure is also found in compounds 3; in this case, however, the chains are linked by ClO4- counterions through hydrogen-bonding interactions, forming an undulating layer in the (011) plane. These layers are fused through hydrogen-bonding interactions, leading to a three-dimensional supramolecular network with large channels in the [100] direction. Compounds 4 show an interesting brick-wall-like layer structure in which the neighboring lanthanide atoms are connected by a pair of O-P-O bridges. The ClO4- counterions and the lattice water molecules are between the layers. In all compounds the triazamacrocyclic nitrogen atoms are not coordinated to the Ln(III) ions. The anions and the pH are believed to play key roles in directing the formation of a particular structure. The fluorescence spectroscopic properties of the Eu and Tb compounds, magnetic properties of the Gd compounds, and the catalytic properties of 4 Gd were also studied.     

Synthesis of Tris(1,2-dimethoxyethane-O,O')barium Bis(2,2,5,5-tetramethyl-2,5-disilaphospholanide) and the Monomer-Dimer Equilibrium in Toluene Solution

(1,2-Dimethoxyethane-O,O')lithium phosphanide (dme)LiPH(2) reacts with 1,2-bis(chloro-dimethylsilyl)ethane to give 2,2,5,5-tetramethyl-2,5-disilaphospholane, 1, as well as 1,1,4,4-tetramethyl-1,4-bis(2,2,5,5-tetramethyl-2,5-disilaphospholanyl)-1,4-disilabutane, 2 (P(2)Si(6)C(18)H(48), space group P&onemacr;, a = 943.3(2) pm, b = 1278.3(3) pm, c = 1413.3(2) pm, alpha = 72.45(1) degrees, beta = 78.13(1) degrees, gamma = 70.83(1) degrees, d = 1.081 g cm(-)(3), Z = 2, wR2 = 0.1553 at 6548 F(2) values). The reaction of 2,2,5,5-tetramethyl-2,5-disilaphospholane 1 and barium bis[bis(trimethylsilyl)amide] in 1,2-dimethoxyethane yields nearly quantitatively tris(1,2-dimethoxyethane-O,O')barium bis(2,2,5,5-tetramethyl-2,5-disilaphospholanide), 3A, which crystallizes in the monoclinic space group C2/c (BaP(2)Si(4)O(6)C(24)H(62), a = 2152.3(1) pm, b = 1381.5(1) pm, c = 1459.7(1) pm, beta = 113.73(1) degrees, d(calc) = 1.268 g cm(-)(3), Z = 4, wR2 = 0.0989 at 5220 F(2) values). Due to the high coordination number of eight of the barium center, rather long Ba-P distances of 333 pm are observed. With loss of the complexating ether solvent this compound forms a dimer 3B of the type R(dme)Ba(&mgr;-R)(3)Ba(dme)(2) in toluene or benzene solution as can be proven by (31)P{(1)H}-NMR spectroscopy ((2)J(P-P) = 6.7 Hz) and by X-ray structure analysis (Ba(2)P(4)Si(8)O(6)C(48)H(106), space group P2(1)/n, a = 1256.3(2) pm, b = 2000.0(3) pm, c = 2986.9(2) pm, beta = 98.929(9) degrees, d(calc) = 1.257 g cm(-)(3), Z = 4, wR2 = 0.1334 at 11580 F(2) values). The Ba-P bond lengths vary between 318 and 338 pm.     

Mercury(I) molybdates and tungstates: Hg2WO4 and two modifications of Hg2MoO4

The high-temperature (beta-) modification of Hg2MoO4 was prepared by solid-state reaction of HgO with MoO2 at 400 degrees C. Well-crystallized samples of the low-temperature (alpha-) modification of Hg2MoO4 and isotypic Hg2WO4 were obtained by hydrothermal recrystallization of the microcrystalline powders at 180 degrees C. The crystal structures of these transparent yellow compounds were determined by single-crystal X-ray diffractometry. beta-Hg2MoO4: P2(1)/c, Z = 4, a = 511.31(6) pm, b = 901.83(7) pm, c = 1086.0(1) pm, beta = 101.01(3) degrees. alpha-Hg2MoO4 and Hg2WO4: C2/c, Z = 4, a = 873.52(6) and 873.0(1) pm, b = 1155.19(7) and 1147.6(3) pm, c = 493.05(3) and 493.24(6) pm, beta = 115.196(5) degrees and 114.86(1) degrees, respectively. In beta-Hg2MoO4 the molybdenum atoms are tetrahedrally coordinated by oxygen atoms and the MoO4 tetrahedra are linked via Hg2 dumb-bells, thus forming infinite zigzag chains. The low-temperature (alpha-)modification of Hg2MoO4 contains MoO6 octahedra, which are linked via common edges to form zigzag chains, which are further linked via Hg2 dumb-bells, resulting in puckered two-dimensionally infinite sheets. Bonding between adjacent sheets is achieved only via weak (secondary) Hg-O bonds of 254.8 pm, while the strong Hg-O bonds of the nearly linear O-Hg-Hg-O groups within the sheets have a length of 214.8 pm. The Hg-Hg bond lengths are practically the same in the three compounds with 252.3(1), 253.49(7), and 253.3(1) pm in beta-Hg2MoO4, alpha-Hg2MoO4, and Hg2WO4, respectively. The average Mo-O distances within the MoO4 tetrahedra and the MoO6 octahedra are 176.2, and 196.5 pm, respectively. The structural chemistry of these compounds is discussed together with that of previously reported mercury I and II molybdates and tungstates.     

共沉淀法合成稀土正磷酸盐(La,Gd)PO4:RE3+(RE=Eu,Tb)及其真空紫外光谱特性

采用共沉淀法制备了稀土正磷酸盐荧光粉(La,Gd)PO4:RE3+(RE=Eu,Tb).红外光谱分析发现GdPO4的红外光谱吸收峰与LaPO4一致,只是峰位向高波数方向移动.(La,Gd)PO4:RE3+的真空紫外光谱特性研究表明,Gd3+在能量传递过程中起中间体作用.XPS研究揭示,LaPO4的价带由O2-的2p能级构成,而GdPO4的价带则是由O2-的2p能级和Gd3+的4f能级共同构成.     

Cobalt Centered Trigonal RE6 Prisms and Mg4 Clusters as Basic Structural Units in RE4CoMg (RE = Y,La, Pr,Nd, Sm,Gd–Tm)

The new rare earth metal rich intermetallic compounds RE₄CoMg (RE = Y, La, Pr, Nd, Sm, Gd–Tm) were prepared via melting of the elements in sealed tantalum tubes in a water‐cooled sample chamber of a high‐frequency furnace. The compounds were investigated by X‐ray diffraction of powders and single crystals: Gd₄RhIn type, , a = 1428.38(9) pm, wR2 = 0.0638, 680 F² values, 20 variables for La₄CoMg, a = 1399.5(2) pm, wR2 = 0.0584, 589 F² values, 20 variables for Pr₄CoMg, a = 1390.2(3) pm, wR2 = 0.0513, 634 F² values, 20 variables for Nd_3.90CoMg_1.10, a = 1381.0(3) pm, wR2 = 0.0730, 618 F² values, 22 variables for Sm_3.92Co_0.93Mg_1.08, a = 1373.1(4) pm, wR2 = 0.0586, 611 F² values, 20 variables for Gd_3.92CoMg_1.08, a = 1362.1(3) pm, wR2 = 0.0576, 590 F² values, 20 variables for Tb_3.77CoMg_1.23, a = 1344.8(2) pm, wR2 = 0.0683, 511 F² values, 20 variables for Dy_3.27CoMg_1.73, and a = 1343.3(2) pm, wR2 = 0.0560, 542 F² values, 20 variables for Er_3.72CoMg_1.28. The cobalt atoms have trigonal prismatic rare earth coordination. Condensation of the CoRE₆ prisms leads to a three‐dimensional network which leaves larger voids that are filled by regular Mg₄ tetrahedra at a Mg–Mg distance of 316 pm in La₄CoMg. The magnesium atoms have twelve nearest neighbors (3 Mg + 9 RE) in icosahedral coordination. In the structures with Nd, Sm, Gd, Tb, Dy, and Er, the RE1 positions which are not involved in the trigonal prismatic network reveal some RE1/Mg mixing and the Sm_3.92Co_0.93Mg_1.08 structure shows small cobalt defects. Considering La₄CoMg as representative of all studied systems an analysis of the chemical bonding within density functional theory closely reproduces the crystal chemistry scheme and shows the role played by the valence states of the different constituents in the electronic band structure. Strong bonding interactions were observed between the lanthanum and cobalt atoms within the trigonal prismatic network.     

Heterometallic cubanes: syntheses, structures, and magnetic properties of lanthanide(III)-nickel(II) architectures

Reactions of lanthanide(III) perchlorate (Ln = Dy, Tb, and Gd), nickel(II) acetate, and ditopic ligand 2-(benzothiazol-2-ylhydrazonomethyl)-6-methoxyphenol (H(2)L) in a mixture of methanol and acetone in the presence of NaOH resulted in the successful assembly of novel Ln(2)Ni(2) heterometallic clusters representing a new heterometallic 3d-4f motif. Single-crystal X-ray diffraction reveals that all compounds are isostructural, with the central core composed of distorted [Ln(2)Ni(2)O(4)] cubanes of the general formula [Ln(2)Ni(2)(μ(3)-OH)(2)(OH)(OAc)(4)(HL)(2)(MeOH)(3)](ClO(4))·3MeOH [Ln = Dy (1), Tb (2), and Gd (3)]. The magnetic properties of all compounds have been investigated. Magnetic analysis on compound 3 indicates ferromagnetic Gd···Ni exchange interactions competing with antiferromagnetic Ni···Ni interactions. Compound 1 displays slow relaxation of magnetization, which is largely attributed to the presence of the anisotropic Dy(III) ions, and thus represents a new discrete [Dy(2)Ni(2)] heterometallic cubane exhibiting probable single-molecule magnetic behavior.     

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.     

Hydrothermal preparation,structures, and NLO properties of the rare earth molybdenyl iodates,RE(MoO2)(IO3)4(OH) [RE = Nd,Sm, Eu

The reactions of RE(IO3)3 [RE = Nd, Sm, Eu] with I2O5 and MoO3 in a 1:2:2 molar ratio at 200 degrees C in aqueous media provide access to RE(MoO2)(IO3)4(OH) [RE = Nd (1), Sm (2), Eu (3)] as pure phases as determined from powder X-ray diffraction data. Single crystal X-ray diffraction experiments demonstrate that these compounds are isostructural and crystallize in the chiral and polar space group P2(1). The structures are composed of three-dimensional networks formed from eight-coordinate, square antiprismatic RE3+ cations and MoO2(OH)+ moieties that are bound by bridging iodate anions. The Mo(VI) centers are present in distorted octahedral environments composed of two cis-oxo atoms, a hydroxo group, and three bridging iodate anions arranged in a fac geometry. There are four crystallographically unique iodate anions in the structures of 1-3, one of these is actually present in the form of a IO3+1 polyhedron where a short interaction of 2.285(4) A is formed between the iodate anion and the hydroxo group bound to the Mo(VI) center. This interaction results in significant distortions of the iodate anion similar to those found in tellurites with TeO3+1 units. Two of the four iodate anions are aligned along the polar b-axis, imparting the required polarity to these compounds. Second-harmonic generation (SHG) measurements on sieved powders of 1 show a response of 350 x alpha-quartz. Crystallographic data: 1, monoclinic, space group P2(1), a = 6.9383(5) A, b = 14.0279(9) A, c = 7.0397(5) A, beta = 114.890(1) degrees, Z = 2; 2, monoclinic, space group P2(1), a = 6.9243(6) A, b = 13.963(1) A, c = 7.0229(6) A, beta = 114.681(1) degrees, Z = 2; 3, monoclinic, space group P2(1), a = 6.9169(6) A, b = 13.943(1) A, c = 7.0170(6) A, beta = 114.542(1) degrees, Z = 2.     

Hydrothermal Syntheses and Structural Characterization of Layered Vanadium Oxides Incorporating Organic Cations: alpha-, beta-(H(3)N(CH(2))(2)NH(3))[V(4)O(10)] and alpha-, beta-(H(2)N(C(2)H(4))(2)NH(2))[V(4)O(10)

Four new layered mixed-valence vanadium oxides, which contain interlamellar organic cations, alpha-(H(3)N(CH(2))(2)NH(3))[V(4)O(10)] (1a), beta-(H(3)N(CH(2))(2)NH(3))[V(4)O(10)] (1b), alpha-(H(2)N(C(2)H(4))(2)NH(2))[V(4)O(10)] (2a), and beta-(H(2)N(C(2)H(4))(2)NH(2))[V(4)O(10)] (2b), have been prepared under hydrothermal conditions and their single-crystal structures determined: 1a, triclinic, space group P&onemacr;, a = 6.602(2) ?, b = 7.638(2) ?, c = 5.984(2) ?, alpha = 109.55(3) degrees, beta = 104.749(2) degrees, gamma = 82.31(3) degrees, Z = 1; 1b, triclinic, P&onemacr;, a = 6.387(1) ?, b = 7.456(2) ?, c = 6.244(2) ?, alpha = 99.89(2) degrees, beta = 102.91(2) degrees, gamma = 78.74(2) degrees, Z = 1; 2a, triclinic, P&onemacr;, a = 6.3958(5) ?, b = 8.182(1) ?, c = 6.3715(7) ?, alpha = 105.913(9) degrees, beta = 104.030(8) degrees, gamma = 94.495(8) degrees, Z = 1; 2b, monoclinic, space group P2(1)/n, a = 9.360(2) ?, b = 6.425(3) ?, c = 10.391(2) ?, beta = 105.83(1) degrees, Z = 2. All four of the compounds contain mixed-valence V(5+)/V(4+) vanadium oxide layers constructed from V(5+)O(4) tetrahedra and pairs of edge-sharing V(4+)O(5) square pyramids with protonated organic amines occupying the interlayer space.     

Highly Luminescent and Thermally Stable Lanthanide Coordination Polymers Designed from 4-(Dipyridin-2-yl)aminobenzoate: Efficient Energy Transfer from Tb(3+) to Eu(3+) in a Mixed Lanthanide Coordination Compound

Herein, a new aromatic carboxylate ligand, namely, 4-(dipyridin-2-yl)aminobenzoic acid (HL), has been designed and employed for the construction of a series of lanthanide complexes (Eu(3+) = 1, Tb(3+) = 2, and Gd(3+) = 3). Complexes of 1 and 2 were structurally authenticated by single-crystal X-ray diffraction and were found to exist as infinite 1D coordination polymers with the general formulas {[Eu(L)(3)(H(2)O)(2)]}(n) (1) and {[Tb(L)(3)(H(2)O)].(H(2)O)}(n) (2). Both compounds crystallize in monoclinic space group C2/c. The photophysical properties demonstrated that the developed 4-(dipyridin-2-yl)aminobenzoate ligand is well suited for the sensitization of Tb(3+) emission (Φ(overall) = 64%) thanks to the favorable position of the triplet state ((3)ππ*) of the ligand [the energy difference between the triplet state of the ligand and the excited state of Tb(3+) (ΔE) = (3)ππ* - (5)D(4) = 3197 cm(-1)], as investigated in the Gd(3+) complex. On the other hand, the corresponding Eu(3+) complex shows weak luminescence efficiency (Φ(overall) = 7%) due to poor matching of the triplet state of the ligand with that of the emissive excited states of the metal ion (ΔE = (3)ππ* - (5)D(0) = 6447 cm(-1)). Furthermore, in the present work, a mixed lanthanide system featuring Eu(3+) and Tb(3+) ions with the general formula {[Eu(0.5)Tb(0.5)(L)(3)(H(2)O)(2)]}(n) (4) was also synthesized, and the luminescent properties were evaluated and compared with those of the analogous single-lanthanide-ion systems (1 and 2). The lifetime measurements for 4 strongly support the premise that efficient energy transfer occurs between Tb(3+) and Eu(3+) in a mixed lanthanide system (η = 86%).