Structures, Bonding Analyses and Reactivity of a Dicationic Digallene and Diindene Mimicking trans-bent Ditetrylenes.

The reaction of bisdicyclohexylphosphinoethane (dcpe) and the subvalent MI sources [MI (PhF)2 ][pf] (M=Ga+ , In+ ; [pf]- =[Al(ORF )4 ]- ; RF =C(CF3 )3 ) yielded the salts [{M(dcpe)}2 ][pf]2 , containing the first dicationic, trans-bent digallene and diindene structures reported so far. The non-classical MI ⇆MI double bonds are surprisingly short and display a ditetrylene-like structure. The bonding situation was extensively analyzed by quantum chemical calculations, QTAIM (Quantum Theory of Atoms in Molecules) and EDA-NOCV (Energy Decomposition Analysis with the combination of Natural Orbitals for Chemical Valence) analyses and is compared to that in the isoelectronic and isostructural, but neutral digermenes and distannenes. The dissolved [{Ga(dcpe)}2 ]2+ ([pf]- )2 readily reacts with 1-hexene, cyclooctyne, diphenyldisulfide, diphenylphosphine and under mild conditions at room temperature. This reactivity is analyzed and rationalized.

Synthesis and Characterization of Stable Iron Pentacarbonyl Radical Cation Salts.

The open-shell iron pentacarbonyl cation [Fe(CO)5 ].+ was isolated by deelectronation, i.e., the single-electron oxidation of the parent neutral Fe(CO)5 using [phenazineF ].+ as the [Al(ORF )4 ]- and [F-{Al(ORF )3 }2 ]- salt (RF =C(CF3 )3 ; phenazineF =perfluoro-5,10-bis(perfluorophenyl)-5,10-dihydrophenazine). [Fe(CO)5 ].+ [Al(ORF )4 ]- was fully characterized (scXRD analysis, IR, NMR, EPR, 57 Fe spectroscopy, CV and SQUID magnetization study) and, apart from being a compound of fundamental interest, may serve as a precursor for low-valent iron coordination chemistry.

From 1D to 3D: Perovskites within the System HSC(NH2)2I/CH3NH3I/PbI2 with Maintenance of the Cubic Closest Packing.

This work describes crystalline phases of the system [HSC(NH2)2]I/(CH3NH3)I/PbI2 and discusses the crystal structures in the context of a common cubic closest packing of organic cations and iodide anions with Pb2+ in all anionic octahedral voids. Ternary boundary phases were (CH3NH3)PbI3 (3D perovskite), [HSC(NH2)2]3PbI5 (1D perovskite), [HSC(NH2)2]PbI3 (NH4CdCl3 type), and [HSC(NH2)2]Pb2I5, with strands of edge-sharing octahedra of the NH4CdCl3 type, which are connected to 2D layers via common corners. Within the system, we identified ribbonlike structures of the general composition [HSC(NH2)2]m+1(CH3NH3)mPbmI4m+1 with m = 2 and 3, representing the transition from 1D to 2D structures. Layered structures with variable thickness were found for the series [HSC(NH2)2](CH3NH3)nPbnI3n+1 with n = 1-3. The color and band gap correlate directly with the pattern of how the PbI6 octahedra are linked. 1D structures are colorless or pale yellow to orange. Layered structures are red to black, depending on the layer thickness. A first laboratory-scale solar cell yielded an efficiency of ∼6% based on the compound with n = 3.

Borosulfates-Synthesis and Structural Chemistry of Silicate Analogue Compounds.

Borosulfates are oxoanionic compounds consisting of condensed sulfur- and boron-centered tetrahedra. Hitherto, they were mostly achieved from solvothermal syntheses in SO3 -enriched sulfuric acid, or from reactions with the superacid H[B(HSO4 )4 ]. The crystal structures are very similar to those of the corresponding class of silicates and their substitution variants, especially regarding the typical structural motif of corner-sharing tetrahedra. However, the borosulfates are supposed to be even more versatile, because (BO3 ) units might also be part of the anionic network. The following article deals with detailed reports on the different synthesis strategies, the crystal chemistry of borosulfates in comparison to silicates, and their hitherto identified properties.

Going Homoleptic: Synthesis and Full Characterization of Stable Manganese Tetranitrosyl Cation Salts.

Although similar to carbon monoxide, the chemistry of homoleptic nitrogen monoxide complexes is fundamentally unexplored compared to their carbonyl analogues. Herein we report the synthesis of the first truly homoleptic transition-metal nitrosyl cation as the salt of the weakly coordinating anions (WCAs) [Al(ORF )4 ]- and [F{Al(ORF )3 }2 ]- (RF =C(CF3 )3 ). These salts are easily accessible in good yields, phase pure, and were fully characterized by IR/Raman, NMR and UV/Vis spectroscopy as well as single-crystal and powder X-ray diffraction. They may serve as unprecedented simple model systems for theoretical and experimental studies of nitrosyl complexes.

Tailoring the Band Gap in 3D Hybrid Perovskites by Substitution of the Organic Cations: (CH3 NH3 )1-2y (NH3 (CH2 )2 NH3 )2y Pb1-y I3 (0≤y≤0.25).

Tuning the optical properties of MAPbI3 (MA=methylammonium) is a key requirement to increase the efficiency of perovskite solar cells (PSCs). Simple precipitation from solution allows the partial substitution of MA in MAPbI3 by H3 NCH2 CH2 NH3 (H2 en). Surprisingly, there is 1:1 exchange of the monovalent cation MA by the dication H2 en. The charge compensation results from a deficit of Pb2+ , leading to a series MA1-2y (H2 en)2y Pb1-y I3 with 0≤y≤0.25. This model has been supported by single-crystal measurements and NMR investigations. The substitution results in a continuous shift of the band gap from 1.51 to 2.1 eV and a color change from black to orange-red. The H2 en content stabilizes the cubic high-temperature (HT) form of MAPbI3 . There is a linear correlation between band gap and unit cell volume. The substitution enables controlled band gap tuning because the extent of substitution is closely related to the applied MA:H2 en ratio in solution.

Synthesis, Crystal Structure, and Properties of Bi3 TeBO9 or Bi3 (TeO6 )(BO3 ): A Non-Centrosymmetric Borate-Tellurate(VI) of Bismuth.

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 .

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, ß=101.013(1)°) represents a distorted variant of Rb3 [B(SeO4)3]. The isolated pentamers in HK4 [(B(SeO4)4]) (triclinic, P$\bar 1$, Z=6, a=7.5303(1), b=7.5380(1), c=42.3659(4) Å, α=88.740(1), ß=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$\bar 4$, 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.

Synthesis, crystal structure, and spectroscopy of the mixed-valent boroseleniteselenate B2Se3O10.

The first mixed-valent boroseleniteselenate B2Se3O10 was obtained as a colorless, hygroscopic compound from the reaction of boric acid (H3BO3) in concentrated selenic acid (H2SeO4) at 265 °C. H2SeO4 can be replaced by appropriate amounts of SeO2 and H2O2. The crystal structure was determined from single-crystal data (P21/c, Z = 4, a = 4.3466(2) Å, b = 7.0237(4) Å, c = 22.1460(9) Å, ß = 94.922(2)°, R1 = 0.036, wR2 = 0.096). It represents a new structure type that is characterized by a 3D net of BO4 tetrahedra, Se(VI)O4 tetrahedra, and trigonal-pyramidal Se(IV)O3 in a ratio of 2:1:2. (77)Se magic-angle-spinning NMR investigations confirm the mixed-valent character because the chemical shifts are found in the typical regions, i.e., 1278 and 1202 ppm for Se(IV) and 972 ppm for Se(VI). The vibrational spectra show the typical modes according to the present polyhedra. In addition, NMR and vibrational spectra of the closely related B2Se2O7 are presented.

Synthesis, single-crystal structure and characterization of (CH3 NH3 )2 Pb(SCN)2 I2.

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 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; ß=110.227(1)°; Z=4) and K[B(S2O7)2] (Cc; a=11.3368(6), b=14.662(14), c=13.6650(8) Å; ß=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; ß=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; ß=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.

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 ß = 92.55(2)°] comprises a 3D network that is closely related to ß-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 tin sulfates Sn(SO4)2 and Sn2(SO4)3: crystal structures, optical and thermal properties.

We report the crystal structures of two tin(IV) sulfate polymorphs Sn(SO4)2-I (P21/c (no. 14), a = 504.34(3), b = 1065.43(6), c = 1065.47(6) pm, ß = 91.991(2)°, 4617 independent reflections, 104 refined parameters, wR2 = 0.096) and Sn(SO4)2-II (P21/n (no. 14), a = 753.90(3), b = 802.39(3), c = 914.47(3) pm, ß = 92.496(2)°, 3970 independent reflections, 101 refined parameters, wR2 = 0.033). Moreover, the first heterovalent tin sulfate Sn2(SO4)3 is reported which adopts space group P1̄ (no. 2) (a = 483.78(9), b = 809.9(2), c = 1210.7(2) pm, α = 89.007(7)°, ß = 86.381(7)°, γ = 73.344(7)°, 1602 independent reflections, 152 refined parameters, wR2 = 0.059). Finally, SnSO4 - the only tin sulfate with known crystal structure - was revised and information complemented. The optical and thermal properties of all tin sulfates are investigated by FTIR, UV-vis, luminescence and 119Sn Mössbauer spectroscopy as well as thermogravimetry and compared.

Stable salts of the hexacarbonyl chromium(I) cation and its pentacarbonyl-nitrosyl chromium(I) analogue.

Homoleptic carbonyl radical cations are a textbook family of complexes hitherto unknown in the condensed phase, leaving their properties and applications fundamentally unexplored. Here we report on two stable 17-electron [Cr(CO)6]•+ salts that were synthesized by oxidation of Cr(CO)6 with [NO]+[Al(ORF)4]- (RF = C(CF3)3)) in CH2Cl2 and with removal of NO gas. Longer reaction times led to NO/CO ligand exchange and formation of the thermodynamically more stable 18-electron species [Cr(CO)5(NO)]+, which belongs to the family of heteroleptic chromium carbonyl/nitrosyl cations. All salts were fully characterized (IR, Raman, EPR, NMR, scXRD, pXRD, magnetics) and are stable at room temperature under inert conditions over months. The facile synthesis of these species enables the thorough investigation of their properties and applications to a broad scientific community.

Synthesis, crystal structure and optical properties of Na2RE(PO4)(WO4) (RE = Y, Tb-Lu).

Phase-pure samples of sodium rare-earth phosphate tungstates Na(2)RE(PO(4))(WO(4)) (RE = Y, Dy-Lu) and Na(2)Y(PO(4))(WO(4)):Ln(3+) (Ln = Eu, Tb) were obtained by reaction of the respective rare-earth oxide with ammonium hydrogen phosphate with sodium tungstate Na(2)WO(4)·2H(2)O as a flux at 1220 K. According to X-ray single-crystal investigations Na(2)RE(PO(4))(WO(4)) (RE = Y, Tb-Lu) crystallise orthorhombically in space group Ibca (no. 73) (RE = Y, Z = 8, a = 1799.7(4), b = 1210.2(2), c = 683.82(14) pm, wR(2) = 0.040, R(1) = 0.037, 661 reflections, 62 parameters). The crystal structure contains non-condensed phosphate and tungstate tetrahedra with the (3 + 3)-coordinate sodium and eight-coordinate rare-earth ions in the voids. Relevant absorption and infrared spectra as well as the fluorescence spectra of Na(2)Y(PO(4))(WO(4)):Ln(3+) (Ln = Eu, Tb) are presented. An FP-LAPW band-structure calculation confirms the assignment of the main absorption as well as the optical band-gap (ε(calc) = 5.1 eV; ε(meas) = 5.2(1) eV) of Na(2)Y(PO(4))(WO(4)).