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1. Studied and Forgotten. A Fresh Look at the Li–Mn–Ge System

   https://doi.org/10.1002/zaac.202000133  

   Ovchinnikov, Alexander; Bobev, Svilen (May 2020, Zeitschrift für anorganische und allgemeine Chemie)

   The crystal structure of the ternary germanide Li₂MnGe has been re‐evaluated from single‐crystal X‐ray diffraction data. This compound crystallizes in a non‐centrosymmetric superstructure of the ZrCuSiAs type (space groupP4bm, Pearson codetP16), with the lattice parametersa= 6.088(4) Å,c= 6.323(4) Å. First‐principle calculations for the idealized structure predict antiferromagnetic exchange in the square Mn nets and semimetallic ground state. In addition, a new ternary phase with the composition Li_2–xMn_4+xGe₅(x≈ 1.2) was discovered. It adopts the V₆Si₅structure type (space groupIbam, Pearson codeoI44), with the lattice parametersa= 7.570(2) Å,b= 16.323(3) Å,c= 5.057(1) Å. DSC/TG measurements show that this compound is thermally stable below 995 K. 

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2. A new family of liquid and solid guanidine-based n-type dopants for solution-processed perovskite solar cells

   https://doi.org/10.1039/D0QM00437E  

   Nakayama, Hidenori; Schneider, Julia A.; Faust, Mina; Wang, Hengbin; Read de Alaniz, Javier; Chabinyc, Michael L. (January 2020, Materials Chemistry Frontiers)

   We present a series of new dopants based on a bicyclcic guanidine-type structure, 1,5,7-triazabicyclo[4.4.0]dec-5-ene ( TBD ), for organic semiconductors. A series of TBD derivatives that were alkylated at the 7-position were synthesized and their physical properties were determined. These stable dopants were shown to be effective n-type dopants for [6,6]-phenyl- C 61 -butyric acid methyl ester (PC 61 BM), poly{[ N , N ′-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]- alt -5,5′-(2,2′-bithiophene)} (P(NDI2OD-T2)) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3- d :2′,3′- d ′]- s -indaceno[1,2- b :5,6- b ′]dithiophene (ITIC). Films of PC 61 BM doped with 10 mol% of a dimeric derivative of TBD had electrical conductivities of 0.065 S cm −1 . The utility of the dopants was further shown by doping electron transport layers of PC 61 BM with 2TBD-C10 for methyl ammonium lead iodide (MAPbI 3 ) solar cells leading to improved fill factors and PCEs relative to undoped ETLs. 

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3. Crystal structures of 2-bromo-1,1,1,3,3,3-hexamethyl-2-(trimethylsilyl)trisilane and 2-bromo-1,1,1,3,3,3-hexaisopropyl-2-(triisopropylsilyl)trisilane

   https://doi.org/10.1107/S2056989018009696  

   Gulotty, Eva M.; Staples, Richard J.; Biros, Shannon M.; Gaspar, Peter P.; Rath, Nigam P.; Winchester, William R. (August 2018, Acta Crystallographica Section E Crystallographic Communications)

   The synthesis and crystal structures of two tris(trialkylsilyl)silyl bromide compounds, C 9 H 27 BrSi 4 ( I , HypSiBr) and C 27 H 63 BrSi 4 ( II , TipSiBr), are described. Compound I was prepared in 85% yield by free-radical bromination of 1,1,1,3,3,3-hexamethyl-2-(trimethylsilyl)trisilane using bromobutane and 2,2′-azobis(2-methylpropionitrile) as a radical initiator at 333 K. The molecule possesses threefold rotational symmetry, with the central Si atom and the Br atom being located on the threefold rotation axis. The Si—Br bond distance is 2.2990 (12) Å and the Si—Si bond lengths are 2.3477 (8) Å. The Br—Si—Si bond angles are 104.83 (3)° and the Si—Si—Si bond angles are 113.69 (2)°, reflecting the steric hindrance inherent in the three trimethylsilyl groups attached to the central Si atom. Compound II was prepared in 55% yield by free-radical bromination of 1,1,1,3,3,3-hexaisopropyl-2-(triisopropylsilyl)trisilane using N -bromosuccinimide and 2,2′-azobis(2-methylpropionitrile) as a radical initiator at 353 K. Here the Si—Br bond length is 2.3185 (7) Å and the Si—Si bond lengths range from 2.443 (1) to 2.4628 (9) Å. The Br—Si—Si bond angles range from 98.44 (3) to 103.77 (3)°, indicating steric hindrance between the three triisopropylsilyl groups. 

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4. Structural characterization and Hirshfeld surface analysis of 2-iodo-4-(pentafluoro-λ ⁶ -sulfanyl)benzonitrile

   https://doi.org/10.1107/S2056989020000365  

   González Espiet, Jean C.; Cintrón Cruz, Juan A.; Piñero Cruz, Dalice M. (February 2020, Acta Crystallographica Section E Crystallographic Communications)

   null (Ed.)

   The title compound, C 7 H 3 F 5 INS, a pentafluorosulfanyl (SF 5 ) containing arene, was synthesized from 4-(pentafluorosulfanyl)benzonitrile and lithium tetramethylpiperidide following a variation to the standard approach, which features simple and mild conditions that allow direct access to tri-substituted SF 5 intermediates that have not been demonstrated using previous methods. The molecule displays a planar geometry with the benzene ring in the same plane as its three substituents. It lies on a mirror plane perpendicular to [010] with the iodo, cyano, and the sulfur and axial fluorine atoms of the pentafluorosulfanyl substituent in the plane of the molecule. The equatorial F atoms have symmetry-related counterparts generated by the mirror plane. The pentafluorosulfanyl group exhibits a staggered fashion relative to the ring and the two hydrogen atoms ortho to the substituent. S—F bond lengths of the pentafluorosulfanyl group are unequal: the equatorial bond facing the iodo moiety has a longer distance [1.572 (3) Å] and wider angle compared to that facing the side of the molecules with two hydrogen atoms [1.561 (4) Å]. As expected, the axial S—F bond is the longest [1.582 (5) Å]. In the crystal, in-plane C—H...F and N...I interactions as well as out-of-plane F...C interactions are observed. According to the Hirshfeld analysis, the principal intermolecular contacts for the title compound are F...H (29.4%), F...I (15.8%), F...N (11.4%), F...F (6.0%), N...I (5.6%) and F...C (4.5%). 

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5. Crystal structures of two bis-carbamoylmethylphosphine oxide (CMPO) compounds

   https://doi.org/10.1107/S205698901900820X  

   VanderWeide, Andrew I.; Staples, Richard J.; Biros, Shannon M. (July 2019, Acta Crystallographica Section E Crystallographic Communications)

   Two bis-carbamoylmethylphosphine oxide compounds, namely {[(3-{[2-(diphenylphosphinoyl)ethanamido]methyl}benzyl)carbamoyl]methyl}diphenylphosphine oxide, C 36 H 34 N 2 O 4 P 2 , (I), and diethyl [({2-[2-(diethoxyphosphinoyl)ethanamido]ethyl}carbamoyl)methyl]phosphonate, C 14 H 30 N 2 O 8 P 2 , (II), were synthesized via nucleophilic acyl substitution reactions between an ester and a primary amine. Hydrogen-bonding interactions are present in both crystals, but these interactions are intramolecular in the case of compound (I) and intermolecular in compound (II). Intramolecular π–π stacking interactions are also present in the crystal of compound (I) with a centroid–centroid distance of 3.9479 (12) Å and a dihedral angle of 9.56 (12)°. Intermolecular C—H...π interactions [C...centroid distance of 3.622 (2) Å, C—H...centroid angle of 146°] give rise to supramolecular sheets that lie in the ab plane. Key geometric features for compound (I) involve a nearly planar, trans- amide group with a C—N—C—C torsion angle of 169.12 (17)°, and a torsion angle of −108.39 (15)° between the phosphine oxide phosphorus atom and the amide nitrogen atom. For compound (II), the electron density corresponding to the phosphoryl group was disordered, and was modeled as two parts with a 0.7387 (19):0.2613 (19) occupancy ratio. Compound (II) also boasts a trans -amide group that approaches planarity with a C—N—C—C torsion angle of −176.50 (16)°. The hydrogen bonds in this structure are intermolecular, with a D ... A distance of 2.883 (2) Å and a D —H... A angle of 175.0 (18)° between the amide hydrogen atom and the P=O oxygen atom. These non-covalent interactions create ribbons that run along the b -axis direction. 

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