"A" cation polarity control in ACuTe2O7 (A = Sr2+, Ba2+, or Pb2+)

The synthesis and characterization of ACuTe(2)O(7) (A = Sr(2+), Ba(2+), or Pb(2+)) have been carried out. Interestingly, SrCuTe(2)O(7) and PbCuTe(2)O(7) are centrosymmetric and isostructural, whereas BaCuTe(2)O(7) is noncentrosymmetric and polar. All of the materials contain [CuTe(2)O(7)](2-) layers stacked along the b-axis direction that are separated by the "A" cations. The layers are composed of corner-shared CuO(5), TeO(6), and TeO(4) polyhedra. The influence of the "A" cation on the polarity is described by bond valence concepts, including the bond strain index and global instability index. Infrared, UV-vis, thermogravimetric, differential thermal analysis, and magnetic measurements were performed on all three materials. For BaCuTe(2)O(7), second-harmonic generation (SHG), piezoelectric, and polarization measurements were performed. A moderate SHG efficiency of approximately 70 × α-SiO(2) was measured. In addition, we determined that BaCuTe(2)O(7) is not ferroelectric; that is, the macroscopic polarization is not reversible. For BaCuTe(2)O(7), a pyroelectric coefficient of -9.5 μC/m(2)·K at 90 °C and a piezoelectric charge coefficient of 49 pm/V were determined. Crystal data are the following: SrCuTe(2)O(7), orthorhombic, space group Pbcm (No. 57), a = 7.1464(7) ?, b = 15.0609(15) ?, c = 5.4380(5) ?, V = 585.30(10) ?(3), and Z = 4; PbCuTe(2)O(7), orthorhombic, space group Pbcm (No. 57), a = 7.2033(5) ?, b = 15.0468(10) ?, c = 5.4691(4) ?, V = 592.78(7) ?(3), and Z = 4.     

New vanadium selenites: centrosymmetric Ca2(VO2)2(SeO3)3(H2O)2, Sr2(VO2)2(SeO3)3, and Ba(V2O5)(SeO3), and noncentrosymmetric and polar A4(VO2)2(SeO3)4(Se2O5) (A = Sr2+ or Pb2+)

Five new vanadium selenites, Ca(2)(VO(2))(2)(SeO(3))(3)(H(2)O)(2), Sr(2)(VO(2))(2)(SeO(3))(3), Ba(V(2)O(5))(SeO(3)), Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), have been synthesized and characterized. Their crystal structures were determined by single crystal X-ray diffraction. The compounds exhibit one- or two-dimensional structures consisting of corner- and edge-shared VO(4), VO(5), VO(6), and SeO(3) polyhedra. Of the reported materials, A(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) (A = Sr(2+) or Pb(2+)) are noncentrosymmetric (NCS) and polar. Powder second-harmonic generation (SHG) measurements revealed SHG efficiencies of approximately 130 and 150 × α-SiO(2) for Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), respectively. Piezoelectric charge constants of 43 and 53 pm/V, and pyroelectric coefficients of -27 and -42 μC/m(2)·K at 70 °C were obtained for Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), respectively. Frequency dependent polarization measurements confirmed that the materials are not ferroelectric, that is, the observed polarization cannot be reversed. In addition, the lone-pair on the Se(4+) cation may be considered as stereo-active consistent with calculations. For all of the reported materials, infrared, UV-vis, thermogravimetric, and differential thermal analysis measurements were performed. Crystal data: Ca(2)(VO(2))(2)(SeO(3))(3)(H(2)O)(2), orthorhombic, space group Pnma (No. 62), a = 7.827(4) ?, b = 16.764(5) ?, c = 9.679(5) ?, V = 1270.1(9) ?(3), and Z = 4; Sr(2)(VO(2))(2)(SeO(3))(3), monoclinic, space group P2(1)/c (No. 12), a = 14.739(13) ?, b = 9.788(8) ?, c = 8.440(7) ?, β = 96.881(11)°, V = 1208.8(18) ?(3), and Z = 4; Ba(V(2)O(5))(SeO(3)), orthorhombic, space group Pnma (No. 62), a = 13.9287(7) ?, b = 5.3787(3) ?, c = 8.9853(5) ?, V = 673.16(6) ?(3), and Z = 4; Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), orthorhombic, space group Fdd2 (No. 43), a = 25.161(3) ?, b = 12.1579(15) ?, c = 12.8592(16) ?, V = 3933.7(8) ?(3), and Z = 8; Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), orthorhombic, space group Fdd2 (No. 43), a = 25.029(2) ?, b = 12.2147(10) ?, c = 13.0154(10) ?, V = 3979.1(6) ?(3), and Z = 8.     

Synthesis, characterization, and structure-property relationships in two new polar oxides: Zn2(MoO4)(SeO3) and Zn2(MoO4)(TeO3)

Two new noncentrosymmetric (NCS) polar oxide materials, Zn(2)(MoO(4))(AO(3)) (A = Se(4+) or Te(4+)), have been synthesized by hydrothermal and solid-state techniques. Their crystal structures have been determined, and characterization of their functional properties (second-harmonic generation, piezoelectricity, and polarization) has been performed. The isostructural materials exhibit a three-dimensional network consisting of ZnO(4), ZnO(6), MoO(4), and AO(3) polyhedra that share edges and corners. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicate the materials exhibit moderate SHG efficiencies of 100 × and 80 × α-SiO(2) for Zn(2)(MoO(4))(SeO(3)) and Zn(2)(MoO(4))(TeO(3)), respectively. Particle size vs SHG efficiency measurements indicate the materials are type 1 non-phase-matchable. Converse piezoelectric measurements resulted in d(33) values of ～14 and ～30 pm/V for Zn(2)(MoO(4))(SeO(3)) and Zn(2)(MoO(4))(TeO(3)), respectively, whereas pyroelectric measurements revealed coefficients of -0.31 and -0.64 μC/m(2) K at 55 °C for Zn(2)(MoO(4))(SeO(3)) and Zn(2)(MoO(4))(TeO(3)), respectively. Frequency-dependent polarization measurements confirmed that all of the materials are nonferroelectric; that is, the macroscopic polarization is not reversible, or "switchable". Infrared, UV-vis, thermogravimetric, and differential thermal analysis measurements were also performed. First-principles density functional theory (DFT) electronic structure calculations were also done. Crystal data: Zn(2)(MoO(4))(SeO(3)), monoclinic, space group P2(1) (No. 4), a = 5.1809(4) ?, b = 8.3238(7) ?, c = 7.1541(6) ?, β = 99.413(1)°, V = 305.2(1) ?(3), Z = 2; Zn(2)(MoO(4))(TeO(3)), monoclinic, space group P2(1) (No. 4), a = 5.178(4) ?, b = 8.409(6) ?, c = 7.241(5) ?, β = 99.351(8)°, V = 311.1(4) ?(3), Z = 2.     

Synthesis and structure of A4V6[Te2(4+)Te6+]O24 (A = K, Rb)-two new quaternary mixed-valent tellurium oxides

Two new mixed-valent tellurium oxides with vanadium(V), A(4)V(6)[Te(2)(4+)Te(6+)]O(24) (A = K and Rb), have been synthesized by hydrothermal and conventional solid state techniques. Their structures were determined by single-crystal X-ray diffraction analysis. These two iso-structural compounds exhibit layered structural topologies consisting of [V(6)Te(3)O(24)](4-) anionic units. In these anionic structural units, a Te(6+)O(6) octahedron is connected to six VO(4) tetrahedra by corner-sharing to generate a [V(6)TeO(24)] unit, and each of these [V(6)TeO(24)] units are interconnected by sharing two Te(4+)O(3) polyhedra to complete the infinite [V(6)Te(3)O(24)](4-) sheets. Infrared spectroscopy, UV-Visible diffuse reflectance spectroscopy, and thermogravimetric analysis were also performed on these two compounds. Crystal data: K(4)V(6)Te(3)O(24), trigonal, space group R ?3c (No. 167) with a = b = 9.7075(6) ?, c = 42.701(3) ?, V = 3484.9(4) ?(3), and Z = 6; Rb(4)V(6)Te(3)O(24), trigonal, space group R ?3c (No. 167) with a = b = 9.8399(9) ?, c = 43.012(4) ?, V = 3606.6(6) ?(3), and Z = 6.     

Sulfates of the refractory metals: crystal structure and thermal behavior of Nb2O2(SO4)3, MoO2(SO4), WO(SO4)2, and two modifications of Re2O5(SO4)2

The sulfates Nb(2)O(2)(SO(4))(3), MoO(2)(SO(4)), WO(SO(4))(2,) and two modifications of Re(2)O(5)(SO(4))(2) have been synthesized by the solvothermal reaction of NbCl(5), WOCl(4), Re(2)O(7)(H(2)O)(2), and MoO(3) with sulfuric acid/SO(3) mixtures at temperatures between 200 and 300 °C. Besides the X-ray crystal structure determination of all compounds, the thermal behavior was investigated using thermogravimetric studies. WO(SO(4))(2) (monoclinic, P2(1)/n, a = 7.453(1) ?, b = 11.8232(8) ?, c = 7.881(1) ?, β = 107.92(2)°, V = 660.7(1) ?(3), Z = 4) and both modifications of Re(2)O(5)(SO(4))(2) (I: orthorhombic, Pba2, a = 9.649(1) ?, b = 8.4260(8) ?, c = 5.9075(7) ?, V = 480.27(9) ?(3), Z = 2; II: orthorhombic, Pbcm, a = 7.1544(3) ?, b = 7.1619(3) ?, c = 16.8551(7) ?, V = 863.64(6) ?(3), Z = 4) are the first structurally characterized examples of tungsten and rhenium oxide sulfates. Their crystal structure contains layers of sulfate connected [W═O] moieties or [Re(2)O(5)] units, respectively. The cohesion between layers is realized through weak M-O contacts (343-380 pm). Nb(2)O(2)(SO(4))(3) (orthorhombic, Pna2(1), a = 9.9589(7) ?, b = 11.7983(7) ?, c = 8.6065(5) ?, V = 1011.3(1) ?(3), Z = 4) represents a new sulfate-richer niobium oxide sulfate. The crystal structure contains a three-dimensional network of sulfate connected [Nb═O] moieties. In MoO(2)(SO(4)) (monoclinic, I2/a, a = 8.5922(6) ?, b = 12.2951(6) ?, c = 25.671(2) ?, β = 94.567(9)°, V = 2703.4(3) ?(3), Z = 24) [MoO(2)] units are connected through sulfate ions to a three-dimensional network, which is pervaded by channels along [100] accommodating the terminal oxide ligands. In all compounds except WO(SO(4))(2), the metal ions are octahedrally coordinated by monodentate sulfate ions and oxide ligands forming short M═O bonds. In WO(SO(4))(2), the oxide ligand and two monodentate and two bidentate sulfate ions build a pentagonal bipyramid around W. The thermal stability of the sulfates decreases in the order Nb > Mo > W > Re; the residues formed during the decomposition are the corresponding oxides.     

Synthesis, Structure, and Characterization of New Li(+) - d(0) -Lone-Pair - Oxides: Noncentrosymmetric Polar Li(6)(Mo(2)O(5))(3)(SeO(3))(6) and Centrosymmetric Li(2)(MO(3))(TeO(3)) (M = Mo(6+) or W(6+))

New quaternary lithium - d(0) cation - lone-pair oxides, Li(6)(Mo(2)O(5))(3)(SeO(3))(6) (Pmn2(1)) and Li(2)(MO(3))(TeO(3)) (P2(1)/n) (M = Mo(6+) or W(6+)), have been synthesized and characterized. The former is noncentrosymmetric and polar, whereas the latter is centrosymmetric. Their crystal structures exhibit zigzag anionic layers composed of distorted MO(6) and asymmetric AO(3) (A = Se(4+) or Te(4+)) polyhedra. The anionic layers stack along a 2-fold screw axis and are separated by Li(+) cations. Powder SHG measurements on Li(6)(Mo(2)O(5))(3)(SeO(3))(6) using 1064 nm radiation reveal a SHG efficiency of approximately 170 × α-SiO(2). Particle size vs SHG efficiency measurements indicate Li(6)(Mo(2)O(5))(3)(SeO(3))(6) is type 1 nonphase-matchable. Converse piezoelectric measurements result in a d(33) value of ～28 pm/V and pyroelectric measurements reveal a pyroelectric coefficient of -0.43 μC/m(2)K at 50 °C for Li(6)(Mo(2)O(5))(3)(SeO(3))(6). Frequency-dependent polarization measurements confirm that Li(6)(Mo(2)O(5))(3)(SeO(3))(6) is nonferroelectric, i.e., the macroscopic polarization is not reversible, or 'switchable'. Infrared, UV-vis, thermogravimetric, and differential thermal analysis measurements and electron localization function calculations were also done for all materials.     

Synthesis, structure, and characterization of two new layered mixed-metal phosphates, BaTeMO4(PO4) (M = Nb5+ or Ta5+

Two new isostructural mixed-metal phosphates, BaTeMO(4)(PO(4)) (M = Nb(5+) or Ta(5+)), have been synthesized as bulk phase powders and single crystals by standard solid-state techniques using BaCO(3), TeO(2), Nb(2)O(5) (or Ta(2)O(5)), and NH(4)H(2)PO(4) as reagents. The materials have novel layered crystal structures consisting of [M(5+)O(6/2)](-) corner-sharing octahedral chains that are connected to [Te(4+)O(4/2)](0) polyhedra and [P(5+)O(2/1)O(2/2)](-) tetrahedra. The Ba(2+) cations reside between the layers and maintain charge balance. The Te(4+) cations are in asymmetric coordination environments attributable to their lone pairs. The Nb(5+) distorts along the local C(4) direction of its octahedron resulting in a "short-long-short-long" Nb-O-Nb bond motif. The Nb(5+) cation displaces away from the oxide ligands that are bonded to Te(4+) or P(5+) cations, attributable to the structural rigidity of the TeO(4) and PO(4) polyhedra. Thus, the TeO(4) and PO(4) polyhedra support and reinforce the intraoctahedral distortion observed within the NbO(6) octahedra. Infrared and Raman spectroscopy, thermogravimetric analysis, and ion-exchange experiments are also presented. Crystal data: BaTeNbO(4)(PO(4)), orthorhombic, space group Pbca (No. 61), with a = 6.7351(9) A, b = 7.5540(10) A, c = 27.455(4) A, V = 1396.8(3) A(3), and Z = 8; BaTeTaO(4)(PO(4)), orthorhombic, space group Pbca (No. 61), with a = 6.734(2) A, b = 7.565(3) A, c = 27.435(9) A, V = 1372.6(8) A(3), and Z = 8.     

BiO(IO3): a new polar iodate that exhibits an aurivillius-type (Bi2O2)2+ layer and a large SHG response

A new noncentrosymmetric (NCS) and polar material containing two lone-pair cations, Bi(3+) and I(5+), and exhibiting an Aurivillius-type (Bi(2)O(2))(2+) layer has been synthesized and structurally characterized. The material, BiO(IO(3)), exhibits strong second-harmonic generation (SHG), ～12.5 × KDP (or ～500 × α-SiO(2)), using 1064 nm radiation, and is found in the NCS polar orthorhombic space group Pca2(1) (No. 29). The structure consists of (Bi(2)O(2))(2+) cationic layers that are connected to (IO(3))(-) anions. The macroscopic polarity, observed along the c-axis direction, may be attributed to the alignment of the IO(3) polyhedra. In addition to the crystal structure and SHG measurements, polarization and piezoelectric measurements were performed, as well as electronic structure analysis.     

Polar hexagonal tungsten bronze-type oxides: KNbW2O9, RbNbW2O9, and KTaW2O9

The synthesis, crystal structures, second-harmonic generation (SHG), piezoelectric, pyroelectric, and ferroelectric properties of three polar noncentrosymmetric (NCS) hexagonal tungsten bronze-type oxides are reported. The materials KNbW 2O 9, RbNbW 2O 9, and KTaW 2O 9 were synthesized by standard solid-state techniques and structurally characterized by laboratory powder X-ray diffraction. The compounds are isostructural, crystallizing in the polar NCS space group Cmm2. The materials exhibit a corner-shared MO 6 (M = Nb (5+)/W (6+) or Ta (5+)/W (6+)) octahedral framework, with K (+) or Rb (+) occupying the "hexagonal" tunnels. The d (0) transition metals, Nb (5+), Ta (5+), and W (6+), are displaced from the center of their oxide octahedra attributable to second-order Jahn-Teller effects. SHG measurements using 1064 nm radiation revealed frequency-doubling efficiencies ranging from 180 to 220 x alpha-SiO 2. Converse piezoelectric measurements resulted in d 33 values ranging from 10 to 41 pm V (-1). The total pyroelectric coefficient, p, at 50 degrees C ranged from -6.5 to -34.5 muC K (-1) m (-2). The reported materials are also ferroelectric, as demonstrated by hysteresis loops (polarization vs electric field). Spontaneous polarization values, P s, ranging from 2.1 to 8.4 muC cm (-2) were measured. The magnitudes of the SHG efficiency, piezoelectric response, pyroelectric coefficient, and ferroelectric polarization are strongly dependent on the out-of-center distortion of the d (0) transition metals. Structure-property relationships are discussed and explored. Crystal data: KNbW 2O 9, orthorhombic, space group Cmm2 (No. 35), a = 21.9554(2) A, b = 12.60725(15) A, c = 3.87748(3) A, V = 1073.273(13) A (3), and Z = 6; RbNbW 2O 9, orthorhombic, space group Cmm2 (No. 35), a = 22.00985(12) A, b = 12.66916(7) A, c = 3.8989(2) A, V = 1086.182(10) A (3), and Z = 6; KTaW 2O 9, orthorhombic, space group Cmm2 (No. 35), a = 22.0025(2) A, b = 12.68532(14) A, c = 3.84456(4) A, V = 1073.05(2) A (3), and Z = 6.     

Preparation and Characterization of Halogen-Boron-Phosphorus Compounds. X-ray Crystal Structures of X(3)B.P(SiMe(3))(3) and [X(2)BP(SiMe(3))(2)](2) (X = Cl, Br)

The 1:1 mole ratio reactions of boron trihalides (BX(3)) with tris(trimethylsilyl)phosphine [P(SiMe(3))(3)] produced 1:1 Lewis acid/base adducts [X(3)B.P(SiMe(3))(3), X = Cl (1), Br (2), I (5)]. Analogous 1:1 mole ratio reactions of these boron trihalides with lithium bis(trimethylsilyl)phosphide [LiP(SiMe(3))(2)] produced dimeric boron-phosphorus ring compounds {[X(2)BP(SiMe(3))(2)](2), X = Br (3), Cl (4)}. X-ray crystallographic studies were successfully conducted on compounds 1-4. Compound 1 crystallized in the orthorhombic space group Pbca, with a = 13.420(3) ?, b = 17.044(5) ?, c = 21.731(7) ?, V = 4970.6(25) ?(3), and D(calc) = 1.229 g cm(-3) for Z = 8; the B-P bond length was 2.022(9) ?, Compound 2 crystallized in the orthorhombic space group Pbca, with a = 13.581(6) ?, b = 17.106(7) ?, c = 22.021(9) ?, V = 5116(4) ?(3), and D(calc) = 1.540 g cm(-3) for Z = 8; the B-P bond length was 2.00(2) ?. Compound 3 crystallized in the monoclinic space group P2(1)/n, with a = 9.063(5) ?, b = 16.391(8) ?, c = 9.331(4) ?, V = 1379.2(12) ?(3), and D(calc) = 1.676 g cm(-3) for Z = 2; the B-P bond length was 2.023(10) ?. Compound 4 crystallized in the monoclinic space group P2(1)/n, with a = 9.143(5) ?, b = 16.021(8) ?, c = 9.170(4) ?, V = 1342.2(11) ?(3), and D(calc) = 1.282 g cm(-3) for Z = 2; the B-P bond length was 2.025(3) ?. Thermal decomposition studies were performed on compounds 1-4, yielding colored powders with boron:phosphorus ratios greater than 1:1 and significant C and H contamination indicated by elemental analyses.     

Assembly of Carbohydrates on a Nickel(II) Center by Utilizing N-Glycosidic Bond Formation with Tris(2-aminoethyl)amine (tren). Syntheses and Characterization of [Ni{N-(aldosyl)-tren}(H(2)O)](2+), [Ni{N,N'-bis(aldosyl)-tren}](2+) and [Ni{N,N',N"-tris(aldosyl)-tren}](2+)

Reactions of [Ni(tren)(H(2)O)(2)]X(2) (tren = tris(2-aminoethyl)amine; X = Cl (1a), Br (1b); X(2) = SO(4) (1c)) with mannose-type aldoses, having a 2,3-cis configuration (D-mannose and L-rhamnose), afforded {bis(N-aldosyl-2-aminoethyl)(2-aminoethyl)amine}nickel(II) complexes, [Ni(N,N'-(aldosyl)(2)-tren)]X(2) (aldosyl = D-mannosyl, X = Cl (2a), Br (2b), X(2) = SO(4) (2c); aldosyl = L-rhamnosyl, X(2) = SO(4) (3c)). The structure of 1c was confirmed by X-ray crystallography to be a mononuclear [Ni(II)N(4)O(2)] complex with the tren acting as a tetradentate ligand (1c.2H(2)O: orthorhombic, Pbca, a = 15.988(2) ?, b = 18.826(4) ?, c = 10.359(4) ?, V = 3118 ?(3), Z = 8, R = 0.047, and R(w) = 0.042). Complexes 2a,c and 3c were characterized by X-ray analyses to have a mononuclear octahedral Ni(II) structure ligated by a hexadentate N-glycoside ligand, bis(N-aldosyl-2-aminoethyl)(2-aminoethyl)amine (2a.CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 16.005(3) ?, b = 20.095(4) ?, c = 8.361(1) ?, V = 2689 ?(3), Z = 4, R = 0.040, and R(w) = 0.027. 2c.3CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 14.93(2) ?, b = 21.823(8) ?, c = 9.746(2) ?, V = 3176 ?(3), Z = 4, R = 0.075, and R(w) = 0.080. 3c.3CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 14.560(4) ?, b = 21.694(5) ?, c = 9.786(2) ?, V = 3091 ?(3), Z = 4, R = 0.072, and R(w) = 0.079). The sugar part of the complex involves novel intramolecular sugar-sugar hydrogen bondings around the metal center. The similar reaction with D-glucose, D-glucosamine, and D-galactosamine, having a 2,3-trans configuration, resulted in the formation of a mono(sugar) complex, [Ni(N-(aldosyl)-tren)(H(2)O)(2)]Cl(2) (aldosyl = D-glucosyl (4b), 2-amino-2-deoxy-D-glucosyl (5a), and 2-amino-2-deoxy-D-galactosyl (5b)), instead of a bis(sugar) complex. The hydrogen bondings between the sugar moieties as observed in 2 and 3 should be responsible for the assembly of two sugar molecules on the metal center. Reactions of tris(N-aldosyl-2-aminoethyl)amine with nickel(II) salts gave the tris(sugar) complexes, [Ni(N,N',N"-(aldosyl)(3)-tren)]X(2) (aldosyl = D-mannosyl, X = Cl (6a), Br (6b); L-rhamnosyl, X = Cl (7a), Br (7b); D-glucosyl, X = Cl (9); maltosyl, X = Br (10); and melibiosyl, X = Br (11)), which were assumed to have a shuttle-type C(3) symmetrical structure with Delta helical configuration for D-type aldoses on the basis of circular dichroism and (13)C NMR spectra. When tris(N-rhamnosyl)-tren was reacted with NiSO(4).6H(2)O at low temperature, a labile neutral complex, [Ni(N,N',N"-(L-rhamnosyl)(3)-tren)(SO(4))] (8), was successfully isolated and characterized by X-ray crystallography, in which three sugar moieties are anchored only at the N atom of the C-1 position (8.3CH(3)OH.H(2)O: orthorhombic, P2(1)2(1)2(1), a = 16.035(4) ?, b = 16.670(7) ?, c = 15.38(1) ?, V = 4111 ?(3), Z = 4, R = 0.084, and R(w) = 0.068). Complex 8 could be regarded as an intermediate species toward the C(3) symmetrical tris(sugar) complexes 7, and in fact, it was readily transformed to 7b by an action of BaBr(2).     

Synthesis, characterization and magnetic properties of four new organically templated metal sulfates [C5H14N2][M(II)(H2O)6](SO4)2, (M(II) = Mn, Fe, Co, Ni)

A series of novel organically templated metal sulfates, [C(5)H(14)N(2)][M(II)(H(2)O)(6)](SO(4))(2) with (M(II) = Mn (1), Fe (2), Co (3) and Ni (4)), have been successfully synthesized by slow evaporation and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, thermogravimetric analysis and magnetic measurements. All compounds were prepared using a racemic source of the 2-methylpiperazine and they crystallized in the monoclinic systems, P2(1)/n for (1, 3) and P2(1)/c for (2,4). Crystal data are as follows: [C(5)H(14)N(2)][Mn(H(2)O)(6)](SO(4))(2), a = 6.6385(10) ?, b = 11.0448(2) ?, c = 12.6418(2) ?, β = 101.903(10)°, V = 906.98(3) ?(3), Z = 2; [C(5)H(14)N(2)][Fe(H(2)O)(6)](SO(4))(2), a = 10.9273(2) ?, b = 7.8620(10) ?, c = 11.7845(3) ?, β = 116.733(10)°, V = 904.20(3) ?(3), Z = 2; [C(5)H(14)N(2)][Co(H(2)O)(6)](SO(4))(2), a = 6.5710(2) ?, b = 10.9078(3) ?, c = 12.5518(3) ?, β = 101.547(2)°, V = 881.44(4) ?(3), Z = 2; [C(5)H(14)N(2)][Ni(H(2)O)(6)](SO(4))(2), a = 10.8328(2) ?, b = 7.8443(10) ?, c = 11.6790(2) ?, β = 116.826(10)°, V = 885.63(2) ?(3), Z = 2. The three-dimensional structure networks for these compounds consist of isolated [M(II)(H(2)O)(6)](2+) and [C(5)H(14)N(2)](2+) cations and (SO(4))(2-) anions linked by hydrogen-bonds only. The use of racemic 2-methylpiperazine results in crystallographic disorder of the amines and creation of inversion centers. The magnetic measurements indicate that the Mn complex (1) is paramagnetic, while compounds 2, 3 and 4, (M(II) = Fe, Co, Ni respectively) exhibit single ion anisotropy.     

New quaternary tellurite and selenite: synthesis, structure, and characterization of centrosymmetric InVTe2O8 and noncentrosymmetric InVSe2O8

Two new quaternary mixed metal oxide materials--InVTe(2)O(8) and InVSe(2)O(8)--have been synthesized, as crystals and pure bulk powders by standard solid-state reactions using In(2)O(3), V(2)O(5), and TeO(2) (or SeO(2)) as reagents. The crystal structures of the reported materials were determined using single-crystal X-ray diffraction. InVTe(2)O(8) crystallizes in the monoclinic centrosymmetric space group P2(1)/n (No. 14), with unit-cell parameters of a = 7.8967(16) ?, b = 5.1388(10) ?, c = 16.711(3) ?, β = 94.22(3)°, and Z = 4, and InVSe(2)O(8) crystallizes in the noncentrosymmetric space group Pm (No. 6) with unit-cell parameters of a = 4.6348(9) ?, b = 6.9111(14) ?, c = 10.507(2) ?, β = 97.77(3)°, and Z = 2. While the centrosymmetric InVTe(2)O(8) shows a two-dimensional (2D) layered structure composed of InO(6) octahedra, VO(4) tetrahedra, and TeO(4) polyhedra, the noncentrosymmetric InVSe(2)O(8) exhibits a three-dimensional (3D) framework structure with distorted InO(6) octahedra, VO(5) square pyramids, and SeO(3) polyhedra. Powder second-harmonic generation (SHG) measurements on InVSe(2)O(8), using 1064-nm radiation, indicate that the material has a SHG efficiency ~30 times that of α-SiO(2). Additional SHG measurements reveal that the material is not phase-matchable (Type 1). Infrared, ultraviolet-visible light (UV-vis) diffuse reflectance, and thermogravimetric analyses for the two compounds are also presented, as are dipole moment calculations.     

Linear Trinuclear Pt.Mo-Mo Complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CR)(2)](2) (X = Cl, Br, I; R = CH(3), C(CH(3))(3); pyphos = 6-(Diphenylphosphino)-2-pyridonate) with an Axial Interaction between the Quadruply Bonded Mo(2) Moiety and the Platinum Atom

An example of a direct axial interaction of a platinum(II) atom with a Mo(2) core through a uniquely designed tridentate ligand 6-(diphenylphosphino)-2-pyridonate (abbreviated as pyphos) is described. Treatment of PtX(2)(pyphosH)(2) (2a, X = Cl; 2b, X = Br; 2c, X = I) with a 1:1 mixture of Mo(2)(O(2)CCH(3))(4) and [Mo(2)(O(2)CCH(3))(2)(NCCH(3))(6)](2+) (3a) in dichloromethane afforded the linear trinuclear complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CCH(3))(2)](2) (4a, X = Cl; 4b, X = Br; 4c, X = I). The reaction of [Mo(2)(O(2)CCMe(3))(2)(NCCH(3))(4)](2+) (3b) with 2a-c in dichloromethane afforded the corresponding pivalato complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CCMe(3))(2)](2) (5a, X = Cl; 5b, X = Br; 5c, X = I), whose bonding nature is discussed on the basis of the data from Raman and electronic spectra as well as cyclic voltammograms. The linear trinuclear structures in 4b and 5a-c were confirmed by NMR studies and X-ray analyses: 4b, monoclinic, space group C2/c, a = 34.733(4) ?, b = 17.81(1) ?, c = 22.530(5) ?, beta = 124.444(8) degrees, V = 11498(5) ?(3), Z = 8, R = 0.060 for 8659 reflections with I > 3sigma(I) and 588 parameters; 5a, triclinic, space group P&onemacr;, a = 13.541(3) ?, b = 17.029(3) ?, c = 12.896(3) ?, alpha = 101.20(2) degrees, beta = 117.00(1) degrees, gamma = 85.47(2) degrees, V = 2599(1) ?(3), Z = 2, R = 0.050 for 8148 reflections with I > 3sigma(I) and 604 parameters; 5b, triclinic, space group P&onemacr;, a = 12.211(2) ?, b = 20.859(3) ?, c = 10.478(2) ?, alpha = 98.88(1) degrees, beta = 112.55(2) degrees, gamma = 84.56(1) degrees, V = 2433.3(8) ?(3), Z = 2, R = 0.042 for 8935 reflections with I > 3sigma(I) and 560 parameters; 5c, monoclinic, space group P2(1)/n, a = 13.359(4) ?, b = 19.686(3) ?, c = 20.392(4) ?, beta = 107.92(2) degrees, V = 5101(2) ?(3), Z = 4, R = 0.039 for 8432 reflections with I > 3sigma(I) and 560 parameters.     

Syntheses,structures, and characterization of new lead(II)-tellurium(IV)-oxide halides: Pb3Te2O6X2 and Pb3TeO4X2 (X = Cl or Br)

The syntheses, structures, and characterization of four new lead(II)-tellurium(IV)-oxide halides, Pb(3)Te(2)O(6)X(2) and Pb(3)TeO(4)X(2) (X = Cl or Br) are reported. The materials are synthesized by solid-state techniques, using Pb(3)O(2)Cl(2) or Pb(3)O(2)Br(2) and TeO(2) as reagents. The compounds have three-dimensional structural topologies consisting of lead-oxide halide polyhedra connected to tellurium oxide groups. In addition, the Pb(2+) and Te(4+) cations are in asymmetric coordination environments attributable to their stereoactive lone pair. We also demonstrate that Pb(3)Te(2)O(6)X(2) and Pb(2)TeO(4)X(2) can be interconverted reversibly through the loss or addition of TeO(2). X-ray data: Pb(3)Te(2)O(6)Cl(2), monoclinic, space group C2/m (No. 12), a = 16.4417(11) A, b = 5.6295(4) A, c = 10.8894(7) A, beta = 103.0130(10) degrees, Z = 4; Pb(3)Te(2)O(6)Br(2), monoclinic, space group C2/m (No. 12), a = 16.8911(8) A, b = 5.6804(2) A, c = 11.0418(5) A, beta = 104.253(2) degrees, Z = 4; Pb(3)TeO(4)Cl(2), orthorhombic, space group Bmmb (No. 63), a = 5.576(1) A, b = 5.559(1) A, c = 12.4929(6) A, Z = 4; Pb(3)TeO(4)Br(2), orthorhombic, space group Bmmb (No. 63), a = 5.6434(4) A, b = 5.6434(5) A, c = 12.9172(6) A, Z = 4.     

Asymmetric cationic coordination environments in new oxide materials: synthesis and characterization of Pb(4)Te(6)M(10)O(41) (M = Nb(5+) or Ta(5+))

Two new isostructural tellurites, Pb(4)Te(6)M(10)O(41) (M = Nb(5+) or Ta(5+)), have been synthesized by standard solid-state techniques using PbO, Nb(2)O(5) (or Ta(2)O(5)), and TeO(2) as reagents. The structures of Pb(4)Te(6)Nb(10)O(41) and Pb(4)Te(6)Ta(10)O(41) were determined by single-crystal and powder X-ray diffraction. The materials exhibit a three-dimensional framework consisting of layers of corner-shared NbO(6) octahedra connected by TeO(3) and PbO(6) polyhedra. The Nb(5+), Te(4+), and Pb(2+) cations are in asymmetric coordination environments attributable to second-order Jahn-Teller effects. The Nb(5+) cations undergo an intraoctahedral distortion either toward a face or a corner, whereas the Te(4+) and Pb(2+) cations are in distorted environments attributable to their lone pair. In addition, the TeO(3) polyhedra strongly influence the direction of the Nb(5+) intraoctahedral distortion. Infrared and Raman spectroscopy, thermogravimetric analysis, and dielectric measurements are also presented. Crystal data: Pb(4)Te(6)Nb(10)O(41), monoclinic, space group C2/m (No. 12), with a = 23.412(3) A, b = 20.114(3) A, c = 7.5008(10) A, beta = 99.630(4) degrees, V = 3482.4(8) A(3), and Z = 4; Pb(4)Te(6)Ta(10)O(41), monoclinic, space group C2/m (No. 12), with a = 23.340(8) A, b = 20.068(5) A, c = 7.472(2) A, beta = 99.27(3) degrees, V = 3453.8(2) A(3), and Z = 4.     

Synthesis, Structure, and Magnetic Properties of Transition Metal Complexes of the Nitroxide 2,5-Dihydro-4,5,5-trimethyl-2,2-bis(2-pyridyl)imidazole-1-oxyl

With the radical 2,5-dihydro-4,5,5-trimethyl-2,2-bis(2-pyridyl)imidazole-1-oxyl (L) a series of transition metal complexes have been prepared: [ML(2)](SbF(6))(2) with M(2+) = Mn(2+) (1), Fe(2+) (2), Co(2+) (3), Ni(2+) (4), Cu(2+) (5), and Zn(2+) (6), Cu(L)(Cl)(2)(MeOH) (7), and Cu(L)SO(4).H(2)O (8). The structures of 1, 3, and 6 were determined by X-ray structural analyses. In these compounds the tridendate L is coordinated to the metal ion by the two pyridine nitrogen donors and by the oxygen atom of the nitroxide group. The N-O bond distances are 1.25(2) ? (1), 1.267(13) ? (3), and 1.260(11) ? (6). The M-O-N angles are 117.0(10) degrees (1), 114.5(8) degrees (3), and 114.2(7) degrees (6). Crystal data: space group P2(1)/n, for 1, 3, and 6; compound 1, a = 10.806(3) ?, b = 14.101(6) ?, c = 14.253(4) ?, beta = 108.82(2) degrees, V = 2055.7(12) ?(3), Z = 2, R(1) = 0.0677, wR(2) = 0.1512. Compound 3, a = 10.761(4) ?, b = 14.253(6) ?, c = 14.108(5) ?, beta = 111.16(3) degrees, V = 2017.9(13) ?(3), Z = 2, R(1) = 0.0702, wR(2) = 0.1460; compound 6, a = 10.788(2) ?, b = 14.147(3) ?, c = 14.196(3) ?, beta = 109.93(3) degrees, V = 2036.8(7) ?(3), Z = 2, R(1) = 0.0573, wR(2) = 0.1194. Magnetic measurements of 1, 2, 5, and 8 show strong antiferromagnetic interaction between the spin of the metal ion and the spin of the radical which increases at lower temperatures. For 6 the magnetic moment corresponds to two noninteracting spins in the temperature range 60-300 K.     

In-phase alignments of asymmetric building units in Ln4GaSbS9 (Ln = Pr, Nd, Sm, Gd-Ho) and their strong nonlinear optical responses in middle IR

New noncentrosymmetric rare-earth metal gallium thioantimonates, Ln(4)GaSbS(9) were synthesized from stoichiometric element mixtures at 950 °C by high-temperature solid-state reactions. These compounds crystallize in orthorhombic space group Aba2 (no.41) with a = 13.799(3)-13.427(5) ?, b = 14.187(3)-13.756(5) ?, c = 14.323(3)-13.954(5) ?, V = 2804(2)-2577 (2) ?(3), and Z = 8 on going from Ln = Pr to Ho. The asymmetric building units, bimetallic polar (Sb(2)S(5)) units, and dimeric (GaS(4))(2) tetrahedra are in-phase aligned as an infinite single anionic chain of {[(Ga(2)S(6))(Sb(2)S(5))](10-)}(∞) that is further packed in a noncentrosymmetric pseudolayer motif perpendicular to the c axis. Three of the title compounds show large powder second harmonic generation (SHG) effects at 2.05 μm, and two of them also exhibit large transparency ranges (1.75 or 0.75 to 25 μm) in the middle-IR region. Significantly, the Sm-member exhibits the strongest SHG response among sulfides to date with intensity approximately 3.8 times that of the benchmark AgGaS(2). The band structures, indirect band gap nature, bonding strengths, and lone pair effects around Sb have also been studied by Vienna ab initio simulation package calculations.     

PbMSeO6 (M = Mo and W): new quaternary mixed metal selenites with asymmetric cationic coordination environments

Two new isostructural mixed metal selenites, PbMSeO(6) (M = Mo(6+) or W(6+)), that are only composed of second-order Jahn-Teller (SOJT) distortive cations have been synthesized by standard solid-state reaction techniques using PbO, SeO(2), and MoO(3) (or WO(3)) as reagents. The structures of the reported materials were determined by single-crystal and powder X-ray diffraction. The materials show a three-dimensional framework structure consisting of chains of corner-shared MO(6) octahedra connected by SeO(3) and PbO(8) polyhedra. All of the constituent cations (M(6+), Se(4+), and Pb(2+)) are in distorted environments attributable to second-order Jahn-Teller (SOJT) effects. While the Mo(6+) cations undergo a C(2)-type intraoctahedral distortion toward an edge, the Se(4+) and Pb(2+) cations are in asymmetric coordination environments attributable to their lone pairs. The SeO(3) polyhedra strongly influence the direction of the Mo(6+) intraoctahedral distortion. Infrared spectroscopy, thermogravimetric analysis, the magnitudes of out-of-center distortions, and dipole moment calculations are also presented. Crystal data: PbMoSeO(6), triclinic, space group P-1 (No. 2), with a = 6.8944(6) ?, b = 7.2219(6) ?, c = 10.8294(9) ?, α = 99.751(2)°, β = 99.996(2)°, γ = 90.041(2)°, V = 523.09(8) ?(3), and Z = 2; PbWSeO(6), triclinic, space group P-1 (No. 2), with a = 6.8689(2) ?, b = 7.2398(2) ?, c = 10.9037(3) ?, α = 99.699(4)°, β = 100.348(3)°, γ = 90.139(4)°, V = 525.50(3) ?(3), and Z = 2.     

Quaternary tellurides with different valent Ge centers: Cs2Ge3M6Te14 (M = Ga, In)

New quaternary tellurides, Cs(2)Ge(3)M(6)Te(14) (M = Ga, In), were discovered by solid-state reactions. These compounds crystallize in space group P3ml (No. 164), with a = b = 8.2475(2) ?, c = 14.2734(8) ?, and V = 840.82(6) ?(3) (Z = 1) for Cs(2)Ge(3)Ga(6)Te(14) (1) and a = b = 8.5404(2) ?, c = 14.6766(8) ?, and V = 927.07(6) ?(3) (Z = 1) for Cs(2)Ge(3)In(6)Te(14) (2). The remarkable structural feature is the novel three-dimensional [Ge(3)M(6)Te(14)](2-) anionic framework made by condensed In(6)Te(14) (or Ga(6)Te(14)) layers that are connected alternately by dimeric Ge(3+)(2)Te(6) units and Ge(2+)Te(6) octahedra along the c direction. The presence of Ge centers with different oxidation states is also supported by the results of the electron localization function calculation and X-ray photoelectron spectroscopy measurement.