A series of 3d–4f heterometallic MOFs: syntheses,structures, optical,and electrochemical properties

Abstract

A series of heterometallic metal-organic frameworks (MOFs) employing pyridine-2,6-dicarboxylate and 1,10-phenanthroline as ligands have been synthesized hydrothermally. In isostructural compounds 1–3 [Ln(pydc)₃Cu₂(phen)₄]·I·× H₂O (Ln?=?La (1), Nd (2), Dy (3); x?=?6, 5, 5), the metalloligand [Ln(pydc)₃] assembles with [Cu(phen)₂] units to construct a dodecanuclear cluster via Cu–O bonds and π–π interactions. The clusters are further stacked into three-dimensional supramolecular frameworks with nano-sized cavities. In [La(Hpydc)(pydc)₂Zn(phen)₃]·3H₂O (4), the metalloligand [Ln(Hpydc)(pydc)₂] assembles with [Zn(phen)₃] units to construct a tetranuclear cluster via electrostatic interaction and π–π interaction. This work reveals that the changes of lanthanide metalloligands and the coordination pattern of 3d transition centers would result in significant variation in the final structures. The thermal, optical, and electrochemical properties have been well investigated.     

Four tri-spin lanthanide–nitronyl nitroxide (LnIII = GdIII,DyIII, ErIII,and HoIII) complexes: syntheses,structures, and magnetic properties

Four radical–Ln(III)–radical complexes, [Ln(hfac)₃(NITPhSCH₃)₂] (Ln?=?Gd (1), Dy (2), Er (3), Ho (4); hfac?=?hexafluoroacetylacetonate; NITPhSCH₃?=?4′-thiomethylphenyl-4,4,5,5tetramethyl-imidazoline-1-oxyl-3-oxide), have been synthesized, and structurally and magnetically characterized. The X-ray crystal structures show that the structures of the four complexes are similar, consisting of isolated molecules in which Ln(III) ions are coordinated by six oxygen atoms from three hfac and two oxygen atoms from nitronyl radicals. The temperature dependencies of magnetic susceptibilities for the four complexes show that in the Gd(III) complex, ferromagnetic interactions between Gd(III)–radical and antiferromagnetic interactions between the radicals coexist with J _Rad–Gd?=?1.09?cm^?1, J _Rad–Rad?=??1.85?cm^?1.     

Energetics, structures, bonding, and kinetics of the HSCl–HClS system

The [H,S,Cl] potential-energy surface has been investigated at the self-consistent field (SCF), complete active space self-consistent field (CASSCF), second-order M?ller–Plesset, coupled-cluster single-double and perturbative triple excitation, [CCSD(T)]/6-31G(d,p), 6-31G(2df,2pd), and correlation-consistent polarized valence triple zeta (cc-pVTZ) levels of theory. CCSD(T)/ cc-pVTZ results predict a very stable HSCl species, an isomer HClS, 51.84 kcal/mol higher in energy, and a transition state 57.68 kcal/mol above HSCl. Independent of the level of theory, results with the smaller 6-31G(d,p) basis set turned out to be poor, especially for HClS. Vibrational analysis indicates that both species can be easily differentiated if isolated. Bonding differences between these molecules are illustrated by contour plots of valence orbitals. Viewed classically, bonding in HClS involves a dative bond. Transition-state rate constants, and equilibrium constants for the HSCl ↔ HClS isomerization have been estimated for various temperatures (200–1000 K). At 298.15 K, the forward rate is predicted to be 7.95 × 10⁻²⁹ s⁻¹, and the equilibrium constant to be 2.31 × 10⁻³⁸. Tunneling corrections vary from 1.57 at 298.15 K to 1.05 at 1000 K. Activation energies have been obtained by a two-points linear fit to the Arrhenius equation. Received: 7 May 1999 / Accepted: 22 July 1999 / Published online: 4 October 1999     

A series of (6,6)-connected porous lanthanide−organic framework enantiomers with high thermostability and exposed metal sites: scalable syntheses, structures, and sorption properties

A series of microporous lanthanide-organic framework enantiomers, Ln(BTC)(H(2)O)·(DMF)(1.1) (Ln = Y 1a, 1b; Tb 2a, 2b; Dy 3a, 3b; Er 4a, 4b; Yb 5a, 5b, BTC = 1,3,5-benzenetricarboxylate; DMF = N,N-dimethylformamide) with unprecedented (6,6)-connected topology have been prepared and characterized. All these compounds exhibit very high thermal stability of over 450 °C. The pore characteristics and gas sorption properties of these compounds were investigated at cryogenic temperatures by experimentally measuring nitrogen, argon, and hydrogen adsorption/desorption isotherms. The studies show that all these compounds are highly porous with surface areas of 1080 (1), 786 (2), 757 (3), 676 (4), and 774 m(2)/g (5). The amounts of the hydrogen uptakes, 1.79 (1), 1.45 (2), 1.40 (3), 1.51 (4), and 1.41 wt % (5) at 77 K (1 atm), show their promising H(2) storage performances. These porous materials with considerable surface areas, high voids of 44.5% (1), 44.8% (2), 47.7% (3), 44.2% (4), and 45.7% (5), free windows of 6-7 ?, available exposed metal sites and very high thermal stability can be easily prepared on a large scale, which make them excellent candidates in many functional applications, such as, gas storage, catalysis, and so on.     

Oligomeric allyl-palladium(II) complexes of β-substituted ethylselenolates: syntheses, structures and thermal decomposition

Tri-nuclear allyl-palladium complexes, [Pd(μ-SeCH(2)CH(2)COOR)(η(3)-C(3)H(4)R')](3) (R = H, Me, Et and R' = H, Me), have been synthesized by the reaction of [Pd(2)(μ-Cl)(2)(η(3)-C(3)H(4)R')(2)] with NaSeCH(2)CH(2)COOR. These complexes exist in a dynamic equilibrium with a dimeric form in solution and are fluxional at room temperature as shown by variable temperature (1)H NMR spectroscopy. The DFT calculations indicate that there is a negligible energy difference between the dimer and the trimer, and suggest that the delicate balance between the steric factors and angular strain decides the reaction products. These complexes (with R' = H) on treatment with [Pd(2)(μ-Cl)(2)(η(3)-C(3)H(5))(2)] afforded hetero-bridged complexes [Pd(2)(μ-Cl)(μ-SeCH(2)CH(2)COOR)(η(3)-C(3)H(5))(2)] (R = Me, Et). All the complexes have been characterized by NMR ((1)H, (13)C, (77)Se) spectroscopy. The molecular structure of [Pd(μ-SeCH(2)CH(2)COOEt)(η(3)-C(3)H(5))](3) revealed a chair conformation of the six-membered Pd(3)Se(3) ring, in which all the allyl groups lie at one side of the ring (similar to three axial 1,3,5-hydrogens of cyclohexane). Thermolysis of [Pd(μ-SeCH(2)CH(2)COOEt)(η(3)-C(3)H(5))](n) in diphenyl ether or hexadecylamine (HDA) yielded Pd(7)Se(4) as characterized by powder XRD.     

Six lanthanide(III) coordination polymers with 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole: syntheses,structures, and photoluminescence

Six 3-D lanthanide(III)-metal-organic frameworks (MOFs) through multidentate 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole (H₂BCPT); acetic acid (HOAc); and corresponding trivalent rare earth chloride, {[Ln(BCPT)(OAc)(H₂O)]·(H₂O)}_n (Ln = Nd³⁺ (1); Sm³⁺ (2), Gd³⁺ (3), Tb³⁺ (4), Ho³⁺ (5), Yb³⁺ (6)), have been synthesized. MOFs 1–6 were characterized via FT-IR spectroscopy, elemental analysis, X-ray single-crystal diffraction, thermal analysis, and fluorescence. MOFs 1–6 are isomorphous, which can be described as a 3-D construction containing a dinuclear cluster [Tb₂(CO₂)₂(O)₂]. The 3-D structure with (4,4) topologies have been extended through BCPT^2? using μ₄-kO;kO;kO;kO coordination modes. Solid-state luminescence of 1–4 and 6 shows the characteristic bands of Nd³⁺, Sm³⁺, Tb³⁺, and Yb³⁺ from visible to near-infrared spectral regions.     

Syntheses,structures, and luminescent properties of lanthanide complexes with N,N′-bis(p-methoxyphenyl)-3-oxapentanediamide

An amide-type acyclic polyether, N,N′-bis(p-methoxyphenyl)-3-oxapentanediamide (L), and its three lanthanide coordination compounds, [Ln(NO₃)(L)₂(H₂O)₂]?·?(NO₃)₂ [Ln?=?Pr (1), Nd (2), and Dy (3)], have been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis, and X-ray diffraction. Single crystal X-ray structure analyses reveal that 1 and 2 have the same structure and crystallize in the monoclinic crystal system with C2/c space group. The coordination geometry around the central atom is a distorted bicapped square antiprism. Extensive intermolecular hydrogen bonds in 1 and 2 result in 3-D supramolecular networks. Complex 3 exhibits luminescence in the visible region upon excitation with UV-rays.     

Organoboron compounds: XXIX. A comparison of pπ-pπ, bonding in alkoxy and alkylthiopiperidinophenylboranes

The results of a VT ¹³C NMR study of alkoxy and alkylthio derivatives of 2- and 3-methylpiperidinophenylboranes demonstrate that the p_π-p_π bonding between boron and oxygen is some 3 kcal mol⁻¹ stronger than that between sulphur and boron.     

From 2-D layer to 2-D → 3-D parallel interpenetration: syntheses,structures and luminescent properties

Two new coordination polymers based on 1,1′-(1,4-butanediyl)bis(imidazole) (bbi) and 5-hydroxyisophthalic acid (OH-BDC), [Co₂(HO-BDC)₂(bbi)₂]·H₂O (1) and [Zn(HO-BDC)(bbi)] (2), have been hydrothermally synthesized. The complexes were characterized by single-crystal X-ray diffraction, IR, and elemental analysis. The structure determination reveals that 1 manifests a deeply corrugated 2-D layer with a (4,4) lattice. For 2, there is a highly undulating 2-D (4,4) layer structure. The layers penetrate by each other to give a 2-D → 3-D parallel interpenetrating network. Fluorescence properties and thermal stabilities of 1 and 2 in the solid state have been studied.     

The chemistry of Group 13/15 compounds (III–V compounds) with the higher homologues of Group 15, Sb and Bi

Sb(SiMe₃)₃ reacts with R₃M (R=Alkyl, M=Al, Ga, In) to form simple Lewis acid–base adducts R₃M←SbR′₃. Reactions with R₂MCl (R=Me, Et, t-Bu) do not give uniform reaction products. Ga and In derivatives react under dehalosilylation to give heterocyclic compounds of the type [R₂MSb(SiMe₃)₂]_x (x=2, 3). In contrast, Me₂AlCl leads to the formation of the six-membered heterocycle [Me(Cl)AlSb(SiMe₃)₂]₃. Sterically more demanding diorgano aluminum halides Et₂AlCl and t-Bu₂AlCl form simple adducts R₂AlCl←Sb(SiMe₃)₃ (R=Et, t-Bu). Heterocycles of the type [R₂AlSbR′₂]_x (x=2, 3) are obtained by dehydrosilylation reactions between dialkyl aluminum hydrides R₂AlH (R=Me, Et, i-Bu) and R′₂SbSiMe₃ (R′=SiMe₃, t-Bu). This reaction pathway also leads to the first synthesis of an organometallic bismuthide of Group 13 elements, Al, Ga and In. [Me₂AlBi(SiMe₃)₂]₃ is formed by reaction of Me₂AlH with Bi(SiMe₃)₃ and its structure, as determined by X-ray crystallography, clearly reveals the formation of a six-membered heterocycle in the solid state. Monomeric aluminum stibides R₂AlSbR′₂←dimethylaminopyridine (dmap) are synthesized by reaction of the corresponding heterocycles [R₂AlSbR′₂]_x with dmap. Pyrolyses of Ga and In adducts, as well as Ga and In heterocycles, yield nanocrystalline GaSb and InSb through a β-hydride elimination pathway. Detailed metalorganic chemical vapor deposition investigations also demonstrate the potential of AlSb heterocycles [R₂AlSb(SiMe₃)₂]₂ (R=Et, i-Bu) to produce AlSb thin films. In addition, GaSb can be prepared in solution by a dehalosilylation reaction between GaCl₃ and Sb(SiMe₃)₃. Depending on the solvent and its boiling point, nanoscale GaSb crystallites are obtained. Both the particle size and the composition can be controlled by the solvent.     

Synthesis,crystal structures,luminescence and thermal properties of lanthanide complexes containing 2,5-dichlorobenzoic acid and 2,2:6′,2″-terpyridine

Journal of Thermal Analysis and Calorimetry - Three novel ternary lanthanide complexes [Ln(2,5-DClBA)3(terpy)(H2O)] (Ln = Eu (1), Tb (2), Ho (3),...     

Volatile iridium(I) complexes with β-diketones and cyclooctadiene: syntheses,structures and thermal properties

A series of volatile mixed-ligand iridium(I) complexes [Ir(cod)(L)] (cod = cyclooctadiene-1,5, L = R¹C(O)CHC(O)R², R¹ = CF₃, R² = CF₃ – hfac 1, Me – tfac 2; ^tBu – ptac 3, Ph – btfac 4, R¹ = R² = Me – acac 5; ^tBu – thd 6) was synthesized and investigated in terms of usage in metal-organic chemical vapor deposition processes. Compounds 3 and 4 were obtained for the first time. All compounds were investigated by elemental analysis, NMR spectroscopy, thermogravimetry, and mass spectrometry. Crystal structures of 2–4 and 6 were determined by single-crystal XRD. The influence of β-diketonate ligand on the thermal properties of complexes in condensed and gas phase was revealed. The following volatility order was arranged: L = hfac 1 > tfac 2 ≈ ptac 3 > acac 5 > thd 6 > btfac 4. Complexes 1 and 6 vapors demonstrated the lowest and the highest thermostability, respectively.     

Syntheses and structures of metal–metal triply bonded M2R6 compounds: consideration of starting materials,stability, and structural parameters

The syntheses and structures of four homoleptic metal–metal triply-bonded M₂R₆ compounds [Mo₂(CH₂CMe₂Ph)₆, 1; Mo₂(CH₂SiMe₂Ph)₆, 2; W₂(CH₂SiMe₂Ph)₆, 3; and W₂(CH₂Ph)₆, 4] are reported. The synthetic effort suggests that ditungsten compounds are inherently more difficult to prepare and more thermally sensitive than dimolybdenum compounds, probably as a result of the larger dimetal core the ligands must protect. The structural data confirm that dimetal hexaalkyls exhibit shorter M≡M distances than do dimetal hexaalkoxides, even in a matched pair case where steric differences are minimal.     

pH-Controlled assembly of two polyoxometalate chains based on [α-GeW11O39]8− and Eu3+: syntheses,crystal structures,and properties

Utilizing reactions of [α-GeW₁₁O₃₉]^8? and Eu³⁺ under different pH conditions, two types of polymer chains, Cs₃K[Eu₄(H₂O)₁₈Ge₂W₂₂O₇₈]?·?16.5H₂O (1) and Cs₃K₂[Eu(H₂O)₂GeW₁₁O₃₉]?·?10H₂O (2), have been isolated and characterized by elemental analysis, IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. The Eu/[α-GeW₁₁O₃₉]^8? ratio is 1?:?1 in polyanion 2a and is an infrequent 2?:?1 in polyanion 1a. The Ln?:?POM ratio can be increased by controlling the reaction conditions. The solid photoluminescence spectra of 1 and 2 have been investigated at room temperature. The luminescence of 1 and 2 are distinctly different owing to their different Eu coordination geometries. UV spectra and electrochemical properties of 1 and 2 have been investigated. Compound 1 displays good electrocatalytic activity toward the reduction of nitrite.     

Synthesis and properties of β,β-sp3-hybridized subphthalocyanine analogues

A β,β-sp(3)-hybridized subphthalocyanine analogue, dibenzosubtriazachlorin, was synthesized, and its significantly split Q band absorptions in longer and shorter wavelength regions relative to those of subphthalocyanines were revealed. The effect of benzo-annulation to a subtriazachlorin structure on the position of the split Q bands as well as the electronic structures was also investigated.     

Oxidation and coupling of β-diketiminate ligand in lanthanide complexes: novel eight-nuclear lanthanide clusters with μ-, μ3-Cl, and μ4-O bridge

Two novel eight-nuclear lanthanide oxide and chloride clusters Ln(8)(μ-η(2)-L(4))(2)(μ(3)-Cl)(4)(μ-Cl)(10)(μ(4)-O)(3)(THF)(8) (Ln = Er(3), Dy(4); L(4) = [OC{(Me)CN-2,6-(i)PrC(6)H(3)}(2)](2-)) have been synthesized by the reaction of β-diketiminate rare-earth metal chlorides with oxygen, providing a new oxidation and coupling reaction of the β-diketiminate ligand.     

New poly-iron(II) complexes of N4O dinucleating Schiff bases and pseudohalides: syntheses, structures, and magnetic and Mössbauer properties

Six dinuclear ferrous complexes including [Fe2(acpypentO)(O2CMe)(NCS)2] (1), [Fe2(acpypentO)(O2CMe)(NCSe)2] (2), [Fe2(acpypentO)(NCO)3] (3), ([Fe2(acpybutO)(O2CMe)(NCS)2] (5), [Fe2(acpybutO)(O2CMe)(NCO)2] (6), and [Fe2(acpybutO)(O2CMe)(N3)2] (7), one tetranuclear (bis-dinuclear) ferrous compound, [Fe4(acpypentO)2(N3)6] (4), and one mononuclear ferrous compound, [Fe(acpybutOH)(NCS)2] (8), have been prepared, and their structures and magnetic and M?ssbauer properties have been studied (acpybutOH = 1,4-bis[[2-pyridyl(1-ethyl]imino)]butane-2-ol and acpypentOH = 1,5-bis[[2-pyridyl(1-ethyl]imino)]pentane-3-ol). The X-ray diffraction analyses yielded the following results: 1 (C23H26Fe2N6O3S2, monoclinic, P2(1)/n, a = 8.0380(7) A, b = 12.4495(8) A, c = 27.358(2) A, beta = 92.180(10) degrees, V = 2735.7(4) A(3), Z = 4) is a dinuclear species in which the unequivalent high-spin (HS) Fe(II) sites are bridged by the alkoxo oxygen atom of the symmetrical acpypentO- Schiff base and one syn-syn acetato anion; 3 (C22H23Fe2N7O4, triclinic, Ponemacr;, a = 8.4152(10) A, b = 9.1350(10) A, c = 17.666(2) A, alpha = 97.486(14) degrees, beta = 100.026(14) degrees, gamma = 113.510(13) degrees, V = 1195.9(2) A3, Z = 2) is a dinuclear species in which the unequivalent HS Fe(II) sites are bridged by the alkoxo oxygen atom of the symmetrical acpypentO- Schiff base and one end-on NCO anion; 4-MeOH (C39H50Fe4N26O3, triclinic, Ponemacr;, a = 9.1246(11) A, b = 10.2466(11) A, c = 14.928(2) A, alpha = 91.529(15) degrees, beta = 101.078(16) degrees, gamma = 106.341(14) degrees, V = 1309.6(3) A3, Z = 1) is a bis-dinuclear species in which the unequivalent HS Fe(II) sites are bridged by the alkoxo oxygen atom of the symmetrical acpypentO- Schiff base and one end-on N(3)(-) anion, and the symmetry related Fe(II) sites are bridged by two end-on N3- anions; 8-MeOH (C21H26FeN6O2S2, triclinic, Ponemacr;, a = 8.7674(9) A, b = 12.0938(13) A, c = 12.2634(14) A, alpha = 106.685(14) degrees, beta = 93.689(14) degrees, gamma = 108.508(13) degrees, V = 1163.7(2) A3, Z = 2) is a mononuclear species in which the octahedral low-spin (LS) Fe(II) site is in an N6 environment provided by the four N atoms of the protonated asymmetrical acpybutOH Schiff base and two thiocyanato anions. The M?ssbauer spectra of all dinuclear species (1-3 and 5-7), and of the bis-dinuclear compound 4, evidence two distinct HS Fe(II) sites while the M?ssbauer spectra of the mononuclear compound 8 evidence a LS Fe(II) site over the 80-300 K temperature range. The temperature dependence of the magnetic susceptibility was fitted with J = -13.7 cm(-1), D = -1.8 cm(-1), and g = 2.096 for 1; J = 3.0 cm(-1), D(1) = 1.6 cm(-1), E(1) = -0.35 cm(-1) (lambda(1) = 0.22), D2 = - 12.2 cm(-1), E2 = 1.1 cm(-1) (lambda2 = 0.09), and g = 2.136 for 3; and J(1) = - 0.09 cm(-1), J(2) = 15.9 cm(-1), D(1) = 5.7 cm(-1), D(2) = 12.1 cm(-1), and g = 1.915 for 4. The nature of the ground state in 3 and 4 was confirmed by simulation of the magnetization curves at 2 and 5 K. The intradinuclear interaction through the central O(alkoxo) of the acpypentO- ligand and one pseudohalide bridges is ferromagnetic in 3 (end-on cyanato) while it is very weakly antiferromagnetic in 4 (end-on azido). The interdinuclear interaction through two end-on azido bridges (4) is ferromagnetic as expected. In agreement with the symmetry of the two iron sites of complexes 3 and 4, the fits show that D2 (tetragonal pyramid) is larger than D1 (distorted trigonal bipyramid (3) or distorted octahedron (4)).     

Studies on solid state reactions of coordination compounds——XLⅦ.Solid state syntheses and crystal structures of cluster compounds {Cu_3MoS_3I}(PPh_3)_3S and {Cu_3WS_3Br} (PPh_3)_3S

Reactions of [NH_4]_2[MS_4](M=Mo,W),CuX(X=Br,I)and PPh_3 in the solid state producedfour mixed-metal sulfur containing clusters{Cu_3MS_3X}(PPh_3)_3S(M=Mo,W;X=Br,I),two of which(1:M=Mo,X=I;2:M=W,X=Br)were structurally determined.Crystals of 1 and 2 are triclinic,space group P(1:a=11.895(3),b=13.107(1),c=20.473(2),α=74.95(6),β=84.87(8),γ=64.27(7)°,Z=2,V=2776.1 ,Rw=0.064 for 6443 observed reflections.2:α=11.876 (1),b=13.065 (2),c=20.325(2),α=74.95(1),β=85.39(1),γ=64.09(1)°,Z=2,V=2737.3,R_w=0.055 for 5303 observedreflections).The results of the structure determination showed that the central units of the two cubane-like cluster compounds are composed of four metal atoms and four non-metal atoms situated at alter-nate comers.The differences of cubane-like cluster compounds obtained from solid state reactions andfrom solution reactions are discussed.