Michael Daub

Synthesis, Single‐Crystal Structure and Characterization of (CH3NH3)2Pb(SCN)2I2

The perovskite phase (CH3 NH3 )2 Pb(SCN)2 I2 with a structure closely related to the K2 NiF4 -type was identified as the product of the reaction of CH3 NH3 I and Pb(SCN)2 by single-crystal X-ray analysis. This extends the range of suitable dyes for solar cell applications to a class of perovskite-related structures of the general composition (AMX3 )n (AX)m .

The First Borosulfate K5[B(SO4)4]

Sulfate anions SO4 2 do not show a strong tendency to form condensed oligoanions owing to the high formal charge of sulfur. A recent very interesting example for an oligosulfate is ReO2Cl(S2O7). [1] Disulfate tetrahedra share common corners with an adjacent ReO6 octahedron forming a cyclic moiety. Regarding oligosulfates, only chainlike anions, typically S3O10 2 or even S5O16 2 , were described. In K5[B(SO4)4], sulfate tetrahedra avoid direct condensation but form the unprecedented anion [B(SO4)4] 5 shown in Figure 1. In

Exploring a New Structure Family: Alkali Borosulfates Na5[B(SO4)4], A3[B(SO4)3] (A = K, Rb), Li[B(SO4)2], and Li[B(S2O7)2]

New alkali borosulfates were obtained by precipitation from oleum, solid-state reactions, or thermal decomposition. The crystal structures were characterized with single-crystal data. They are all based on corner-linked BO4 and SO4 tetrahedra with varying coordination of the alkali cations. According to the ratio of BO4 and SO4 tetrahedra, different frameworks are observed, i.e., noncondensed complex anions (1:4), one-dimensional chains (1:3), or three-dimensional (3D) networks (1:2). This is in analogy to silicates, where the ratio Si/O relates to the dimensionality also. For Na5[B(SO4)4], which exists in two different polymorphs, there are noncondensed pentameric units. Na5[B(SO4)4]-I: space group Pca21, a = 10.730(2) Å, b = 13.891(3) Å, c = 18.197(4) Å. Na5[B(SO4)4]-II: space group P212121, a = 8.624(2) Å, b = 9.275(2) Å, c = 16.671(3) Å. A3[B(SO4)3] (A = K, Rb) are isotypic with Ba3[B(PO4)3] adopting space group Ibca [K3[B(SO4)3], a = 7.074(4) Å, b = 14.266(9) Å, c = 22.578(14) Å; Rb3[B(SO4)3], a = 7.2759(5) Å, b = 14.7936(11) Å, c = 22.637(2) Å] with vierer chains of BO4tetrahedra based on two bridging and two terminal SO4 tetrahedra. Li[B(SO4)2] [space group Pc, a = 7.6353(15) Å, b = 9.342(2) Å, c = 8.432(2) Å, and β = 92.55(2)°] comprises a 3D network that is closely related to β-tridymite. Li[B(S2O7)2] [space group P212121, a = 10.862(2) Å, b = 10.877(2) Å, c = 17.769(4) Å] represents the first example of a disulfate complex with noncondensed [B(S2O7)2](-) units. Vibrational spectra were recorded from all compounds, and the thermal behavior was also investigated.

The Borosulfate Story Goes on—From Alkali and Oxonium Salts to Polyacids

The structural principles of borosulfates derived from the B/S ratio are confirmed and extended to new representatives of this class showing novel motifs. According to the composition, Na[B(S2O7)2] (P2(1)/c; a=10.949(6), b=8.491(14), c=12.701(8) Å; β=110.227(1)°; Z=4) and K[B(S2O7)2] (Cc; a=11.3368(6), b=14.662(14), c=13.6650(8) Å; β=94.235(1)°; Z=8) contain isolated [B(S2O7)2](-) ions, in which the central BO4 tetrahedron is coordinated by two disulfate units. The alkali cations have coordination numbers of 7 (Na) and 8 (K), respectively. The structure of Cs[B(S2O7)(SO4)] (P2(1)/c; a=10.4525(6), b=11.3191(14), c=8.2760(8) Å; β=103.206(1); Z=4) combines, for the first time, sulfate and disulfate units into a chain structure. Cs has a coordination number of 12. The same structural units were found in H[B(S2O7)(SO4)] (P2(1)/c; a=15.6974(6), b=11.4362(14), c=8.5557(8) Å; β=90.334(3)°; Z=8). This compound represents the first example of a polyacid. The hydrogen atoms were located and connect the chains to form layers through hydrogen-bonding bridges. H3O[B(SO4)2] (P4/ncc; a=9.1377(6), c=7.3423(8) Å; Z=4) is the first oxonium compound of this type to be found. The BO4 tetrahedra are linked by SO4 tetrahedra to form linear chains similar to those in SiS2. The chains form a tetragonal rod packing structure with H3O(+) between the rods. The structures of borosulfates can be classified following the concept described by Liebau for silicates, which was extended to borophosphates by Kniep et al. In contrast to these structures, borosulfates do not comprise B-O-B bonds but instead contain S-O-S connections. All compounds were obtained as colourless, moisture-sensitive single crystals by reaction of B2O3 and the appropriate alkali salt in oleum.

The First Boroselenates as new Silicate Analogues

The first boroselenates were obtained as single crystals by the reaction of selenic acid with boron acid and the corresponding alkali carbonates. The structure determinations showed a far-reaching analogy to very recently described borosulfates and the borophosphates, that is, tetrahedral BO4 and SeO4 units linked by common corners. In each case, the BO4 tetrahedra are surrounded by SeO4 tetrahedra. As a function of the B/Se ratio, this results in chains (1:3; Cs3 [B(SeO4)3], Rb3 [B(SeO4)3]), isolated pentamers (1:4; HK4 [(B(SeO4)4]), or pentamers with additional isolated SeO4 tetrahedra (1:5; (H3 O)Na6 [B(SeO4 )4 ](SeO4). Compound Rb3 [B(SeO4)3] (orthorhombic, Ibca, Z=8, a=7.508(2), b=15.249(3), c=23.454(5) Å) is isotypic to Rb3 [B(SO4)3]) and Ba3 [B(PO4)3]. Compound Cs3 [B(SeO4)3] (monoclinic, P21 /c, Z=4, a=11.3552(4), b=7.9893(3), c=15.7692(6) Å, β=101.013(1)°) represents a distorted variant of Rb3 [B(SeO4)3]. The isolated pentamers in HK4 [(B(SeO4)4]) (triclinic, P

Synthesis, Crystal Structure, and Properties of Bi3TeBO9 or Bi3(TeO6)(BO3): A Non-Centrosymmetric Borate-Tellurate(VI) of Bismuth

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Synthesis, Crystal Structure, and Spectroscopy of the Mixed-Valent Boroseleniteselenate B2Se3O10

, Z=6, a=7.5303(1), b=7.5380(1), c=42.3659(4) Å, α=88.740(1), β=89.971(1), γ=89.971(1)°) were also found in K5 [(B(SO4)4] and Na5 [(B(SO4)4]. Compound (H3 O)Na6 [B(SeO4)4](SeO4) (tetragonal, I

First representatives of (210)-oriented perovskite variants−Synthesis, crystal structures and properties of the new 2D hybrid perovskites A[HC(NH2)2]PbI4; A=[C(NH2)3], [HSC(NH2)2]

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Tailoring the Band Gap in 3D Hybrid Perovskites by Substitution of the Organic Cations: (CH3NH3)1−2y (NH3(CH2)2NH3)2y Pb1−y I3 (0≤y≤0.25)

, a=9.9796(1), c=18.2614(2) Å) is a super structure of the borophosphates Sr6 [B(PO4)4](PO4) and Pb6 [B(PO4)4](PO4). Because the tetrahedra are only connected through apices, there are topological analogies to silicates. Therefore, boroselenates may have a similar variability of crystal structures, such as borosulfates and borophosphates.

Coactivation of α-Sr(PO3)2 and SrM(P2O7) (M = Zn, Sr) with Eu2+ and Mn2+

Pale-yellow single crystals of the new borate tellurate(VI) Bi3 TeBO9 were obtained by reaction of stoichiometric amounts of Bi2 O3 , B2 O3 , and Te(OH)6 at 780 °C. The non-centrosymmetric crystal structure (P63 , Z=2, a=8.7454(16), c=5.8911(11) Å, 738 refl., 43 param, R1=0.037, wR2=0.093) contains isolated trigonal-planar BO3 units and nearly undistorted TeO6 octahedra. The Bi3+ cations are located in between in octahedral voids. The BiO6 octahedra are significantly distorted to a [3+3] pattern (2.25/2.50 Å) due to the ns2 configuration. According to the structural features, the formula can be written as Bi3 (TeO6 )(BO3 ). Alternatively, the structure can also be described as hcp of oxygen with TeVI and BiIII in octahedral voids and BIII in trigonal- planar voids. The vibrational spectra show the typical features of BO3 and TeO6 units with a significant 10 B/11 B isotopic splitting of the IR-active B-O valence mode (1248 and 1282 cm-1 ). The UV/Vis spectrum shows an optical band edge with an onset around 480 nm (2.6 eV). MAS-NMR spectra of 11 B show an anisotropic signal with a quadrupole coupling constant of CQ =2.55 MHz. and a very small deviation from rotational symmetry (η=0.2). The isotropic chemical shift is 20.1 ppm. The second harmonic generation (SHG) test was positive with an activity comparable to potassium dihydrogen phosphate (KDP). Bi3 TeBO9 decomposes in air at 825 °C to Bi2 TeO5 .