Synthesis and Characterization of Methylzinc Tri(tert‐butyl)silylphosphanide as well as Related Sodium and Potassium Phosphanylzincates

The reaction of dimethylzinc and tri(tert‐butyl)silylphosphane in toluene yielded dimeric methylzinc tri(tert‐butyl)silylphosphanide ( 1 ) which crystallized tetrameric. Compound 1 was deprotonated with sodium in DME and the solvent‐separated dimeric ion pair [(dme)₃Na]⁺ [(dme)Na(MeZn)₂(μ‐PSitBu₃)₂]^? ( 2 ) was isolated. The reaction of 1 in THF with two equivalents of potassium and one equivalent of tri(tert‐butyl)silylphosphane gave dimeric [{tBu₃Si(H)P}{(thf)₂K}₂(MeZn)(PSitBu₃)]₂ ( 3 ). Both of these phosphanylzincates contain Zn₂P₂ cycles with Zn‐P bond lengths of approximately 237 pm, whereas in 1 larger Zn‐P bond lengths of 248.5 pm were found due to the larger coordination numbers of the phosphorus and zinc atoms.     

Ammonothermal Synthesis and Characterization of Cs2[Zn(NH2)4]

Cs₂[Zn(NH₂)₄] was synthesized under ammonothermal conditions (sc‐NH₃, 523 K, 155 MPa) from CsNH₂ and Zn. Growth of cm‐sized crystals succeeded upon application of a temperature gradient. The crystal structure is based on the motif of a hexagonal closed packing of [Zn(NH₂)₄]^2– ions with occurrence of no significant hydrogen bridges according to distances and vibrational spectroscopy. Cs⁺ ions are located within octahedral and tetrahedral holes of the packing.     

Synthese und Kristallstrukturen der Tetrachlorozinkate SrZnCl4 und BaZnCl4

Synthesis and Crystal Structures of the Tetrachlorozincates SrZnCl₄ and BaZnCl₄ The tetrachlorozincates SrZnCl₄ and BaZnCl₄ are obtained from the respective binary chlorides at 550 °C in silica ampoules. SrZnCl₄ (tetragonal, I4₁/a, Z = 4, a = 650.40(7), c = 1437.0(2) pm) crystallizes with the scheelite type of structure, BaZnCl₄ (orthorhombic, Pnna, Z = 4, a = 724.15(6), b = 986.2(2), c = 947.71(8) pm) belongs to the GaCl₂ type of structure. The coordination polyhedra of the cations are the same in both compounds: Sr²⁺ and Ba²⁺ are surrounded by eight Cl^– (trigon‐dodecahedron), Zn²⁺ is tetrahedrally coordinated. For both compounds no phase transitions could be detected between 140 and 620 K.     

Metallierung von Triisopropylsilylarsan durch Bis(tetrahydrofuran)calcium‐bis[tris(trimethylsilylmethyl)zinkat]

Metalation of Triisopropylsilylarsane with Bis(tetrahydrofuran)calcium‐bis[tris(trimethylsilylmethyl)zincate] The transmetalation of bis(trimethylsilylmethyl)zinc with distilled calcium in THF yields bis(tetrahydrofuran)calcium bis[tris‐(trimethylsilylmethyl)zincate] ( 1 ). The trialkylzincate anion appears as a bidentate ligand with Ca‐C‐Zn three‐center‐bonds. The CaC bond lengths show values of 265.5(2) and 271.7(2) pm. The metalation of triisopropylsilylarsane gives tetrakis(tetrahydrofuran)calcium [1, 3‐bis(triisopropylsilylarsanyl)‐2, 4‐bis(triisopropylsilyl)‐1, 3‐dizinca‐2, 4‐diarsacyclobutane‐2, 4‐diide] ( 2 ). The central moiety is a sligthly distorted trigonal As₂CaZn₂ bipyramid with the arsenic atoms in apical positions. The mean Ca‐As bond lengths lie with a mean value of 291.4 pm in the charakteristic region for calcium bis‐(arsanides).