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1.
Five novel lanthanoid-containing silicotungstates with polymeric crystal structures [Ln(2)(H(2)O)(7)Si(2)W(18)O(66)](n)(10n-) [Ln = Gd(III) (Gd-1 and Gd-2), Tb(III), Ho(III)] and [Dy(2)(H(2)O)(6.5)(C(2)H(4)O(2))(0.5)Si(2)W(18)O(66)](n)(10n-) were obtained from the one-step reaction of Na(10)[SiW(9)O(34)]·nH(2)O with Ln(NO(3))(3)·nH(2)O in a sodium acetate buffer. The compounds were characterized by single-crystal X-ray diffraction and a wide range of analytical methods, including FT-IR, UV/vis, and photoluminescence spectroscopy as well as electrochemistry and thermogravimetric analysis. This new polyoxotungstate series is the first example of lanthanoids embedded in the open Wells-Dawson silicotungstate anion [α-Si(2)W(18)O(66)](16-). The lanthanoid-containing Wells-Dawson-type polyoxoanions [Ln(2)(H(2)O)(7)Si(2)W(18)O(66)](10-) [Ln = Gd(III) (Gd-1 and Gd-2), Tb(III), Ho(III)] and [Dy(2)(H(2)O)(6.5)(C(2)H(4)O(2))(0.5)Si(2)W(18)O(66)](10-) are linked by Ln(3+) cations to form 3D architectures for Gd-1 or 2D frameworks for the isostructural compounds Tb-2, Dy-2, Ho-2, and Gd-2. The structure-directing influence of the lanthanoid cation on the local structure of the dimeric building blocks and on the crystal packing motifs is investigated in detail. The photoluminescence properties of Tb-2 and Dy-2 were investigated at room temperature, and Ho-2 exhibits an interesting photochromic behavior. The magnetic susceptibility of Gd-1 and Gd-2 was studied in the temperature range between 2 and 300 K for its effective magnetic moment. 相似文献
2.
The dimeric, pentacopper(II) substituted tungstosilicate [Cu(5)(OH)(4)(H(2)O)(2)(A-alpha-SiW(9)O(33))(2)](10-) (1) has been synthesized in good yield using a one-pot procedure by reaction of Cu(2+) ions with the trilacunary precursor salt K(10)[A-alpha-SiW(9)O(34)]. The title polyanion represents the first polyoxotungstate substituted by 5 copper centers and the central copper-hydroxo-aqua fragment is completely unprecedented. In the course of the reaction, two [A-alpha-SiW(9)O(34)](10-) Keggin half-units have fused in an asymmetrical fashion resulting in the lacunary polyoxotungstate [Si(2)W(18)O(66)](16-). The vacancy in this species is stabilized by a magnetic cluster of five octahedrally coordinated Cu(2+) ions resulting in polyanion 1 with C(2v) symmetry. 相似文献
3.
By reacting Keggin-type polyoxometalate cluster anions H(2)W(12)O(40)(6)(-) (metatungstate) or Co(II)W(12)O(40)(6)(-) (tungstocobaltate) with the large aluminum cluster polycation [Al(30)O(8)(OH)(56)(H(2)O)(26)](18+), Keggin ion based molecular ionic compounds [delta-Al(13)O(4)(OH)(24)(H(2)O)(12)][XW(12)O(40)](OH).nH(2)O (X = H(2) (1) and Co (2); n congruent with 20) and [W(2)Al(28)O(18)(OH)(48)(H(2)O)(24)][H(2)W(12)O(40)](2).55H(2)O (3) were obtained. The polygon-shaped cluster ions are packed alternately through intercluster hydrogen bonds as well as electrostatic interactions, leaving large pores, which result from the packing of large clusters. The clusters are arranged in square pyramidal geometries, showing face-to-face interactions between them. The isolation of metastable [delta-Al(13)O(4)(OH)(24)(H(2)O)(12)](7+) and the formation of a new transition metal substituted aluminum heteropolycation [W(2)Al(28)O(18)(OH)(48)(H(2)O)(24)](12+) in 1-3 result from the slow fragmentation and recombination of Al(30) in the presence of suitable counter cluster anions with similar shape and charge. 相似文献
4.
The potentiometric titration of a γ-Keggin tetra-protonated silicodecatungstate, [γ-SiW(10)O(34)(H(2)O)(2)](4-) (H(4)·I), with TBAOH (TBA = [(n-C(4)H(9))(4)N](+)) showed inflection points at 2 and 3 equiv of TBAOH. The (1)H, (29)Si, and (183)W NMR data suggested that the in situ formation of tri-, doubly-, and monoprotonated silicodecatungstates, [γ-SiW(10)O(34)(OH)(OH(2))](5-) (H(3)·I), [γ-SiW(10)O(34)(OH)(2)](6-) (H(2)·I), and [γ-SiW(10)O(35)(OH)](7-) (H·I), with C(1), C(2v), and C(2) symmetries, respectively. Single crystals of TBA(6)·H(2)·I suitable for the X-ray structure analysis were successfully obtained and the anion part was a monomeric γ-Keggin divacant silicodecatungstate with two protonated bridging oxygen atoms. Compounds H(3)·I, H(2)·I, and H·I were reversibly monoprotonated to form H(4)·I, H(3)·I, and H(2)·I, respectively. 相似文献
5.
Two new barium borogermanates with two types of novel structures, namely, Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) and Ba(3)Ge(2)B(6)O(16), have been synthesized by hydrothermal or high-temperature solid-state reactions. They represent the first examples of alkaline-earth borogermanates. Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) crystallized in a polar space group Cc. Its structure features a novel three-dimensional anionic framework composed of [B(7)O(16)(OH)(2)](13-) polyanions that are bridged by Ge atoms with one-dimensional (1D) 10-membered-ring (MR) tunnels along the b axis. The Ba(II) cations, hydroxide ions, and water molecules are located at the above tunnels. Ba(3)Ge(2)B(6)O(16) crystallizes in centrosymmetric space group P1. Its structure exhibits a thick layer composed of circular B(6)O(16) units connected by GeO(4) tetrahedra via corner sharing, forming 1D 4- and 6-MR tunnels along the c axis. Ba1 ions reside in the tunnels of the 6-MRs, whereas Ba2 ions are located at the interlayer space. Both compounds feature new types of topological structures. Second-harmonic-generation (SHG) measurements indicate that Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) displays a weak SHG response of about 0.3 times that of KH(2)PO(4). Optical, thermal stability, and ferroelectric properties as well as theoretical calculations have also been performed. 相似文献
6.
Four Th(IV) hydroxide/oxide clusters have been synthesized from aqueous solution. The structures of [Th(8)(μ(3)-O)(4)(μ(2)-OH)(8)(H(2)O)(15)(SeO(4))(8)·7.5H(2)O] (1), [Th(8)(μ(3)-O)(4)(μ(2)-OH)(8)(H(2)O)(17)(SeO(4))(8)·nH(2)O] (2), [Th(9)(μ(3)-O)(4)(μ(2)-OH)(8)(H(2)O)(21)(SeO(4))(10)] (3), and Th(9)(μ(3)-O)(4)(μ(2)-OH)(8)(H(2)O)(21)(SeO(4))(10)·nH(2)O (4) were determined using single crystal X-ray diffraction. Each structure consists of an octanuclear core, [Th(8)O(4)(OH)(8)](16+), that is built from eight Th(IV) atoms (four Th in a plane and two up and two down) linked by four "inner" μ(3)-O and eight "outer" μ(2)-OH groups. Compounds 3 and 4 additionally contain mononuclear [Th(H(2)O)(5)(SeO(4))(4)](4-) units that link the octamers into an extended structure. The octanuclear units are invariably complexed by two selenate anions that sit in two cavities formed by four planar Th(IV) and four extra-planar Th(IV) atoms, thus making [Th(8)O(4)(OH)(8)(SeO(4))(2)](12+) a common building block in 1-4. However, changes in hydration as well selenate coordination give rise to structural differences that are observed in the extended structures of 1-4. The compounds were also characterized by Raman spectroscopy. Density functional theory calculations were performed to predict the geometries, vibrational frequencies, and relative energies of different structures. Details of the calculated structures are in good agreement with experimental results, and the calculated frequencies were used to assign the experimental Raman spectra. On the basis of an analysis of the DFT results, the compound Th(8)O(8)(OH)(4)(SeO(4))(6) was predicted to be a strong gas phase acid but is reduced to a weak acid in aqueous solution. Of the species studied computationally, the dication Th(8)O(6)(OH)(6)(SeO(6))(6)(2+) is predicted to be the most stable in aqueous solution at 298 K followed by the monocation Th(8)O(7)(OH)(5)(SeO(6))(6)(+). 相似文献
7.
Zhou J Zhang J Fang WH Yang GY 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(44):13253-13261
Three novel extended vanadogermanates, {[(en)(2)Cd(2)Ge(8)V(12)O(40)(OH)(8)(H(2)O)][Cd(en)(2)](2)}·6H(2)O (1), {[Zn(2)(dap)(3)][Zn(dap)](2)Ge(6)V(15)O(48)(H(2)O)}[Zn(dap)(2)(H(2)O)](2)·3H(2)O (2), and {[Cd(3)(μ-dien)(2)(Hdien)(2)(H(2)O)(2)]Ge(4)V(16)O(42)(OH)(4)(H(2)O)}·2H(2)O (3; en=ethylenediamine, dap=1,2-diaminopropane, dien=diethylenetriamine), have been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectroscopy, powder XRD, thermogravimetric analysis, and single-crystal XRD. Their Ge-V-O cluster anions are derived from the V(18)O(42) cluster shell by replacing VO(5) square pyramids with Ge(2)O(7) groups. Compound 1 exhibits a 1D sinusoidal chain built up from rare inorganic-organic hybrid dicadmium-substituted vanadogermanate {[Cd(en)](2)V(12)O(40)(GeOH)(8)(H(2)O)} clusters and [Cd(en)(2)] complexes. Compound 2 is the first example of a 2D network based on linkage of the unusual {Ge(6)V(15)O(48)(H(2)O)} clusters and two types of Zn complex fragments. Compound 3 is an unprecedented 3D framework built by {Ge(4)V(16)O(42)(OH)(4)(H(2)O)} clusters and rare trinuclear bridging complex cations [Cd(3)(μ-dien)(2)(Hdien)(2)(H(2)O)(2)](8+). Magnetic measurements illustrate that both 1 and 2 have antiferromagnetic exchange interactions between metal centers, whereas 3 exhibits ferrimagnetic behavior, which is rare in polyoxovanadate complexes. 相似文献
8.
ZL Lang W Guan LK Yan SZ Wen ZM Su LZ Hao 《Dalton transactions (Cambridge, England : 2003)》2012,41(37):11361-11368
The formation mechanism is always a fundamental and confused issue for polyoxometalate chemistry. Two formation mechanisms (M1 and M2) of the Lindqvist anion [W(6)O(19)](2-) have been adopted to investigate it's self-assembly reaction pathways at a density functional theory (DFT) level. The potential energy surfaces reveal that both the mechanisms are thermodynamically favorable and overall barrierless at room temperature, but M2 is slightly dominant to M1. The formation of the pentanuclear species [W(5)O(16)](2-) and [W(5)O(15)(OH)](-) are recognized as the rate-determining steps in the whole assembly polymerization processes. These two steps involve the highest energy barriers with 30.48 kcal mol(-1) and 28.90 kcal mol(-1), respectively, for M1 and M2. [W(4)O(13)](2-) and [W(4)O(12)(OH)](-) are proved to be the most stable building blocks. In addition, DFT results reveal that the formation of [W(3)O(10)](2-) experiences a lower barrier along the chain channel. 相似文献
9.
The reaction of [Mo(3)S(4)(H(2)O)(9)](4+) (1) with [(CpRhCl(2))(2)] afforded a novel rhodium-molybdenum cluster, [{Mo(3)RhCpS(4)(H(2)O)(7)(O)}(2)](8+) (2). X-ray structure analysis of [2](pts)(8).14H(2)O (pts(-) = CH(3)C(6)H(4)SO(3)(-)) has revealed the existence of a new oxo-bridged twin cubane-type core, (Mo(3)RhCpS(4))(2)(O)(2). The high affinity of the CpRh group for sulfur atoms in 1 seems to be the main driving force for this reaction. The strong Lewis acidity of the CpRh group in intermediate A, [Mo(3)RhCpS(4)(H(2)O)(9)](6+), caused a release of proton from one of the water molecules attached to the molybdenum atoms to give intermediate B, [Mo(3)RhCpS(4)(H(2)O)(8)(OH)](5+). The elimination of two water molecules from two intermediate B molecules, followed by the deprotonation reaction of hydroxo bridges, generated the twin cubane-type cluster 2. The formal oxidation states of rhodium and molybdenum atoms are the same before and after the reaction (i.e., Mo(IV)(3), Rh(III)). The Mo-O-Mo moieties in [2](pts)(8).14H(2)O are nearly linear with a bond angle of 164.3(3) degrees, and the basicity of the bridging oxygen atoms seems to be weak. For this reason, protonation at the bridging oxygen atoms does not occur even in a strongly acidic aqueous solution. The binding energy values of Mo 3d(5/2), Rh 3d(5/2), and C 1s obtained from X-ray photoelectron spectroscopy measurements for [2](pts)(8).14H(2)O are 229.8, 309.3, and 285 eV, respectively. The XPS measurements on the Rh 3d(5/2) binding energy indicate that the oxidation state of Rh is 3+. The binding energy of Mo 3d(5/2) (229.8 eV) compares with that observed for [1](pts)(4).7H(2)O (230.7 eV, Mo 3d(5/2)). A lower energy shift (0.9 eV) is observed in the binding energy of Mo 3d(5/2) for [2](pts)(8).14H(2)O. This energy shift may correspond to the coordination of an oxygen atom having a negative charge to the molybdenum atom. 相似文献
10.
A novel 1D chain organic-inorganic hybrid polyoxovanadium borate Na[V(12)B(16)O(50)(OH)(7)(en)](2)(enH(2))(6)(enH)(2)(OH)(H(2)O)(19) (1, en = ethylenediamine), based on a [V(12)B(16)O(50)(OH)(7)(en)](7-) cluster unit, has been hydrothermally synthesized and characterized. Interestingly, organic amine is incorporating into the V(12)B(16) clusters. 相似文献
11.
The reaction of [Sb(2)W(22)O(74)(OH)(2)](12-) and [Fe(4)(H(2)O)(10)(β-TeW(9)O(33))(2)](4-) with (NH(4))(2)[RuCl(6)] in aqueous solution resulted in the novel ruthenium(IV)-containing polyanions [{Ru(IV)(4)O(6)(H(2)O)(9)}(2)Sb(2)W(20)O(68)(OH)(2)](4-) and [{Ru(IV)(4)O(6)(H(2)O)(9)}(2){Fe(H(2)O)(2)}(2){β-TeW(9)O(33)}(2)H](-), exhibiting two cationic, adamantane-like, tetraruthenium(IV) units {Ru(4)O(6)(H(2)O)(9)}(4+) bound to the respective polyanion in an external, highly accessible fashion. 相似文献
12.
J Zhao D Shi L Chen Y Li P Ma J Wang J Niu 《Dalton transactions (Cambridge, England : 2003)》2012,41(35):10740-10751
Three organic-inorganic hybrid copper-lanthanide heterometallic germanotungstates, {[Cu(en)(2)(H(2)O)] [Cu(3)Eu(en)(3)(OH)(3)(H(2)O)(2)](α-GeW(11)O(39))}(2)·11H(2)O (1), {[Cu(en)(2)(H(2)O)][Cu(3)Tb(en)(3)(OH)(3)(H(2)O)(2)](α-GeW(11)O(39))}(2)·11H(2)O (2) and {[Cu(en)(2)(H(2)O)][Cu(3)Dy(en)(3)(OH)(3)(H(2)O)(2)](α-GeW(11)O(39))}(2)·10H(2)O (3) and three polyoxometalate hybrids built by lanthanide-containing germanotungstates and copper-ethylendiamine complexes, Na(2)H(6)[Cu(en)(2)(H(2)O)](8){Cu(en)(2)[La(α-GeW(11)O(39))(2)](2)}·18H(2)O (4), K(4)H(2)[Cu(en)(2)(H(2)O)(2)](5)[Cu(en)(2)(H(2)O)](2)[Cu(en)(2)](2){Cu(en)(2)[Pr(α-GeW(11)O(39))(2)](2)}·16H(2)O (5) and KNa(2)H(7)[enH(2)](3)[Cu(en)(2)(H(2)O)](2)[Cu(en)(2)](2){Cu(en)(2)[Er(α-GeW(11)O(39))(2)](2)}·15H(2)O (6) (en = ethylenediamine) have been hydrothermally synthesized and structurally characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP-AES) analyses, IR spectra, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. 1-3 are essentially isomorphous and their main skeletons display the interesting dimeric motif {[Cu(3)Ln(en)(3)(OH)(3)(H(2)O)(2)](α-GeW(11)O(39))}(2)(4-), which is constructed from two {Cu(3)LnO(4)} cubane anchored monovacant [α-GeW(11)O(39)](8-) fragments through two W-O-Ln-O-W linkers. The primary backbones of 4-6 exhibit the tetrameric architecture {Cu(en)(2)[Ln(α-GeW(11)O(39))(2)](2)}(24-) built by two 1?:?2-type [Ln(α-GeW(11)O(39))(2)](13-) moieties and one [Cu(en)(2)](2+) bridge, albeit they are not isostructural. To our knowledge, 1-6 are rare polyoxometalate derivatives consisting of copper-lanthanide heterometallic/lanthanide germanotungstate fragments. 1 exhibits antiferromagnetic coupling interactions within the {Cu(3)EuO(4)} cubane units, while 2 and 3 display dominant ferromagnetic interactions between the Tb(III)/Dy(III) and Cu(II) cations. The room-temperature solid-state photoluminescence properties of 1-3 have been investigated. 相似文献
13.
We present (29)Si, (27)Al, and (67)Zn NMR evidence to show that silicate ions in alkaline solution form complexes with zinc(II) (present as zincate, Zn(OH)(3)(-) or Zn(OH)(4)(2-)) and, concomitantly, with aluminate (Al(OH)(4)(-)). Zincate reacts with monomeric silicate at pH 14-15 to form [(HO)O(2)Si-O-Zn(OH)(3)](4-) and with dimeric silicate to produce [HO-SiO(2)-O-SiO(2)-O-Zn(OH)(3)](6-). The exchange of Si between these free and Zn-bound sites is immeasurably fast on the (29)Si NMR time scale. The cyclic silicate trimer reacts relatively slowly and incompletely with zincate to form [(HO)(3)Zn{(SiO(3))(3)}](7-). The concentration of the cyclic trimer becomes further depleted because zincate scavenges the silicate monomer and dimer, with which the cyclic trimer is in equilibrium on the time scale of sample preparation. Identification of these zincate-silicate complexes is supported by quantum chemical theoretical calculations. Aluminate and zincate, when present together, compete roughly equally for a deficiency of silicate to form [(HO)(3)ZnOSiO(2)OH](4-) and [(HO)(3)AlOSiO(2)OH](3-) which exchange (29)Si at a fast but measurable rate. 相似文献
14.
Mal SS Dickman MH Kortz U Todea AM Merca A Bögge H Glaser T Müller A Nellutla S Kaur N van Tol J Dalal NS Keita B Nadjo L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(4):1186-1195
The 16-Fe(III)-containing 48-tungsto-8-phosphate [P(8)W(48)O(184)Fe(16)(OH)(28)(H(2)O)(4)](20-) (1) has been synthesised and characterised by IR and ESR spectroscopy, TGA, elemental analyses, electrochemistry and susceptibility measurements. Single-crystal X-ray analyses were carried out on Li(4)K(16)[P(8)W(48)O(184)Fe(16)(OH)(28)(H(2)O)(4)]66 H(2)O2 KCl (LiK-1, orthorhombic space group Pnnm, a=36.3777(9) A, b=13.9708(3) A, c=26.9140(7) A, and Z=2) and on the corresponding mixed sodium-potassium salt Na(9)K(11)[P(8)W(48)O(184)Fe(16)(OH)(28)(H(2)O)(4)].100 H(2)O (NaK-1, monoclinic space group C2/c, a=46.552(4) A, b=20.8239(18) A, c=27.826(2) A, beta=97.141(2) degrees and Z=4). Polyanion 1 contains--in the form of a cyclic arrangement--the unprecedented {Fe(16)(OH)(28)(H(2)O)(4)}(20+) nanocluster, with 16 edge- and corner-sharing FeO(6) octahedra, grafted on the inner surface of the crown-shaped [H(7)P(8)W(48)O(184)](33-) (P(8)W(48)) precursor. The synthesis of 1 was accomplished by reaction of different iron species containing Fe(II) (in presence of O(2)) or Fe(III) ions with the P(8)W(48) anion in aqueous, acidic medium (pH approximately 4), which can be regarded as an assembly process under confined geometries. One fascinating aspect is the possibility to model the uptake and release of iron in ferritin. The electrochemical study of 1, which is stable from pH 1 through 7, offers an interesting example of a highly iron-rich cluster. The reduction wave associated with the Fe(III) centres could not be split in distinct steps independent of the potential scan rate from 2 to 1000 mV s(-1); this is in full agreement with the structure showing that all 16 iron centres are equivalent. Polyanion 1 proved to be efficient for the electrocatalytic reduction of NO(x), including nitrate. Magnetic and variable frequency EPR measurements on 1 suggest that the Fe(III) ions are strongly antiferromagnetically coupled and that the ground state is tentatively spin S=2. 相似文献
15.
Wang GM Li JH Wang P Li ZX Wang YX Wang ZM Lin JH 《Dalton transactions (Cambridge, England : 2003)》2012,41(3):734-736
A novel aluminoborate (NH(4))(6)[C(5)NH(12)](6)[Al(12)B(65)O(105)(OH)(33)]·(H(2)O)(15) (QD-6), has been synthesized under mild hydrothermal conditions and characterized by IR, elemental analysis, TGA, powder and single-crystal X-ray diffractions. This compound crystallizes in the rhombohedral space group R3 (No. 148) with the lattice constants a = 23.7421(2) ?, c = 24.7699(3) ?, V = 12091.9(2) ?(3), and Z = 3. QD-6 consists of two unprecedented aluminoborate clusters, [Al(6)B(34)O(54)(OH)(18)](6-) and [Al(6)B(31)O(51)(OH)(15)](6-), which are built from the same hexagon-like [B@Al(6)O(24)] clusters and [B(11)O(17)(OH)(6)] or [B(10)O(16)(OH)(5)] polyborates. 相似文献
16.
Reaction of acidified (pH approximately 7) sodium tungstate solutions with transition metal cations (Fe(3+), Ni(2+), Zn(2+), Co(2+)) leads to the formation of transition-metal-disubstituted Keggin-type heteropolytungstates with 3d-metal ions distributed over three different positions. A detailed investigation of the synthesis conditions confirmed that the complexes could equally be obtained using aqueous solutions of either Na(2)WO(4).2H(2)O (sodium monotungstate) at pH approximately 7, Na(6)[W(7)O(24)]. approximately 14H(2)O (sodium paratungstate A), or Na(10)[H(2)W(12)O(42)].27H(2)O (sodium paratungstate B) as starting materials. Three complexes, (NH(4))(6)Ni(II)(0.5)[alpha-Fe(III)O(4)W(11)O(30)Ni(II)O(5)(OH(2))].18H(2)O, (NH(4))(7)Zn(0.5)[alpha-ZnO(4)W(11)O(30) ZnO(5)(OH(2))].18H(2)O, and (NH(4))(7)Ni(II)(0.5)[alpha-ZnO(4)W(11)O(30)Ni(II)O(5)(OH(2))].18H(2)O were isolated in crystalline form. X-ray single-crystal structure analysis revealed that the solid-state structures of the three compounds consist of four main structural fragments, namely [MO(4)W(11)O(30)M'O(5)(OH(2))](n-) (Keggin-type, alpha-isomer) heteropolytungstates, hexaquo metal cations, [M'(OH(2))(6)](2+), ammonium-water cluster ions, [(NH(4)(+))(8)(OH(2))(12)], and additional ammonium cations and water molecules. The 3d metals occupy the central (tetrahedral, M) and the peripheral (octahedral, M') positions of the Keggin anion, as well as cationic sites (M') outside of the polyoxotungstate framework. UV-vis spectroscopy, solution ((1)H, (183)W) and solid-state ((1)H) NMR, and also chemical analysis data provided evidence that the 3d-metal-disubstituted Keggin anions do not exist in solution but are being formed only during the crystallization process. Investigations in the solid state and in solution were completed by ESR, IR, and Raman measurements. 相似文献
17.
McClintock LF Cavigliasso G Stranger R Blackman AG 《Dalton transactions (Cambridge, England : 2003)》2008,(37):4984-4992
The syntheses and X-ray structures of [Co(Me-tpa)O(2)COZnCl(3)], [Co(pmea)O(2)COZnCl(3)].H(2)O [Co(trpyn)O(2)COZn(OH(2))(4)OCO(2)Co(trpyn)](ZnCl(4))(2).H(2)O, [Co(trpyn)(O(2)COH)]ZnCl(4).3H(2)O and [Co(trpyn)(O(2)CO)]ClO(4) are reported (Me-tpa = [(6-methyl-2-pyridyl)methyl]bis(2-pyridylmethyl)amine, pmea = bis(2-pyridylmethyl)-2-(2-pyridylethyl)amine, trpyn = tris(2-(1-pyrazolyl)ethyl)amine). The chelated bicarbonate complex [Co(trpyn)(O(2)COH)]ZnCl(4).3H(2)O is isolated as a crystalline solid from an acidic solution of the parent carbonate [Co(trpyn)(O(2)CO)]ClO(4), and X-ray structural analysis shows that lengthening of the C[double bond, length as m-dash]O(exo) bond and shortening of the C-O(endo) bond accompanies protonation. The bimetallic complex [Co(Me-tpa)O(2)COZnCl(3)] results from the unexpected coordination of ZnCl(3)(-) to the exo O atom of a chelated carbonate ligand. This complex is obtained from both acidic and neutral solutions in which [Zn(2+)] = 1.0 M, while the structurally similar complex [Co(pmea)O(2)COZnCl(3)].H(2)O is isolated from an analogous neutral solution. The trimetallic complex [Co(trpyn)O(2)COZn(OH(2))(4)OCO(2)Co(trpyn)](ZnCl(4))(2).H(2)O crystallises on prolonged standing of [Co(trpyn)(O(2)CO)]ClO(4) in a neutral solution having [Zn(2+)] = 1.0 M. The Zn-O bond lengths in all three complexes are indicative of bonds of significant strength. DFT calculations show that the nature of the bonding interaction between the Co(iii) ion and the endo O atoms of the carbonate ligand remain essentially unaffected by coordination of Zn(2+) to the exo O atom. They also show that such coordination of Zn(2+) decreases the C-O(exo) bond order. 相似文献
18.
Planas N Vigara L Cady C Miró P Huang P Hammarström L Styring S Leidel N Dau H Haumann M Gagliardi L Cramer CJ Llobet A 《Inorganic chemistry》2011,50(21):11134-11142
The geometry and electronic structure of cis-[Ru(II)(bpy)(2)(H(2)O)(2)](2+) and its higher oxidation state species up formally to Ru(VI) have been studied by means of UV-vis, EPR, XAS, and DFT and CASSCF/CASPT2 calculations. DFT calculations of the molecular structures of these species show that, as the oxidation state increases, the Ru-O bond distance decreases, indicating increased degrees of Ru-O multiple bonding. In addition, the O-Ru-O valence bond angle increases as the oxidation state increases. EPR spectroscopy and quantum chemical calculations indicate that low-spin configurations are favored for all oxidation states. Thus, cis-[Ru(IV)(bpy)(2)(OH)(2)](2+) (d(4)) has a singlet ground state and is EPR-silent at low temperatures, while cis-[Ru(V)(bpy)(2)(O)(OH)](2+) (d(3)) has a doublet ground state. XAS spectroscopy of higher oxidation state species and DFT calculations further illuminate the electronic structures of these complexes, particularly with respect to the covalent character of the O-Ru-O fragment. In addition, the photochemical isomerization of cis-[Ru(II)(bpy)(2)(H(2)O)(2)](2+) to its trans-[Ru(II)(bpy)(2)(H(2)O)(2)](2+) isomer has been fully characterized through quantum chemical calculations. The excited-state process is predicted to involve decoordination of one aqua ligand, which leads to a coordinatively unsaturated complex that undergoes structural rearrangement followed by recoordination of water to yield the trans isomer. 相似文献
19.
The reaction of Hg(OAc)(2) with 1,4-benzenedithiol in ethylenediamine at 80 °C yields [Hg(SC(6)H(4)S)(en)](n), while the reaction of Pb(OAc)(2) with 1,4-benzenedithiol in diethylenetriamine at 130 °C yields [Pb(SC(6)H(4)S)(dien)](n). Both products are crystalline materials, and structure determination by synchrotron X-ray powder diffraction revealed that both are essentially one-dimensional metal-organic polymers with -M-SC(6)H(4)S- repeat units. Diffuse reflectance UV-visible spectroscopy indicates band gaps of 2.89 eV for [Hg(SC(6)H(4)S)(en)](n) and 2.54 eV for [Pb(SC(6)H(4)S)(dien)](n), while density functional theory (DFT) band structure calculations yielded band gaps of 2.24 and 2.10 eV, respectively. The two compounds are both infinite polymers of metal atoms linked by 1,4-benzenedithiolate, the prototypical molecule for single-molecule conductivity studies, yet neither compound has significant electrical conductivity as a pressed pellet. In the case of [Pb(SC(6)H(4)S)(dien)](n) calculations indicate fairly flat bands and therefore low carrier mobilities, while the conduction band of [Hg(SC(6)H(4)S)(en)](n) does have moderate dispersion and a calculated electron effective mass of 0.29·m(e). Hybridization of the empty Hg 6s orbital with SC(6)H(4)S orbitals in the conduction band leads to the band dispersion, and suggests that similar hybrid materials with smaller band gaps will be good semiconductors. 相似文献
20.
Jancik V Rascón-Cruz F Cea-Olivares R Toscano RA 《Chemical communications (Cambridge, England)》2007,(43):4528-4530
The heterobimetallic aluminosilicate [LAl(SLi)(micro-O)Si(OLi.2thf)(O(t)Bu)(2)](2) was prepared from the LAl(SH)(micro-O)Si(OH)(O(t)Bu)(2) (L = [HC{C(Me)N(Ar)}(2)](-), Ar = 2,6-di-(i)Pr(2)C(6)H(3)) ligand, which can also be hydrolyzed to LAl(OH.thf)(micro-O)Si(OH)(O(t)Bu)(2)- leading to the first aluminosilicate-dihydroxide soluble in organic solvents. 相似文献