Directed Dehydration of Na4Sn2S6 ⋅ 5H2O Generates the New Compound Na4Sn2S6: Crystal Structure and Selected Properties

The new thiostannate Na₄Sn₂S₆ was prepared by directed crystal water removal from the hydrate Na₄Sn₂S₆ ⋅ 5H₂O at moderate temperatures. While the structure of the hydrate comprises isolated [Sn₂S₆]⁴⁻ anions, that of the anhydrate contains linear chains composed of corner-sharing SnS₄ tetrahedra, a structural motif not known in thiostannate chemistry. This structural rearrangement requires bond-breakage in the [Sn₂S₆]⁴⁻ anion, movements of the fragments of the opened [Sn₂S₆]⁴⁻ anion and Sn−S−Sn bond formation. Simultaneously, the coordination environment of the Na⁺ cations is significantly altered and the in situ formed NaS₅ polyhedra are joined by corner- and edge-sharing to form a six-membered ring. Time-dependent in situ X-ray powder diffraction evidences very fast rehydration into Na₄Sn₂S₆ ⋅ 5H₂O during storage in air atmosphere, but recovery of the initial crystallinity requires several days. Impedance spectroscopy demonstrates a mediocre room-temperature Na⁺ ion conductivity of 0.31 μS cm⁻¹ and an activation energy for ionic transport of E_a=0.75 eV.     

Studies of Copper(II) Thiosemicarbazide Complexes and their Reactivities. X-Ray Structure of Two Unusual Reaction Products, [Cu(bpy)(H2O)2SO4] and [(bpy)2Cu2(C2O4)Cl2]·H2O

A number of ternary complexes of Cu²⁺ with thiosemicarbazide (TSC) including [Cu(bpy)(TSC)₂]Cl₂, [Cu(o-phen)(TSC)₂]Cl₂ and [Cu(bpy)(TSC)₂][CuCl₄] [Cu(o-phen)(TSC)₂] [CuCl₄] have been synthesised and characterized. Their reactivities in aqueous and DMF solutions were studied. It was observed that while on coordination to Cu²⁺ thiosemicarbazide is converted to thiocyanate in aqueous solution, in DMF solution the thiocyanate is further aerially oxidised to sulfate. In the presence of hydrogen peroxide, oxidation to sulfate is rapid and from the mother liquor we could isolate [(bpy)₂Cu₂(C₂O₄)Cl₂]·H₂O whose structure was determined by X-ray crystallography. X-ray crystal structure of [Cu(bpy)(H₂O)₂SO₄] is also discussed.*     

Synthesis, Reaction and Structures of Functionally Substituted η~5-Cyclopentadienyl Compounds With Cr≡S Triple Bond [η~5-RC_5H_4Cr(CO)_2]_2S (R=CH_3C(O),CH_3O_2C,C-2H_5O_2C,CH_3CH(OH),CO_2H)

[η_5-OH_3C(O)C_5H_4Cr(CO)_2]_2S 1, [η~5-CH_3O_2CC_5H_4Cr(CO)_2]_2S 2 and [η~5-C_2H_5O_2CC_5H_4Cr(CO)_2]_2S 3 were prepared by the reactions of corresponding sodium salts of functional η~5-cyclopentadienyl-tricarbonylchromium anions with SOCl_2. Reduction of 1 with NaBH_4 prdouced [η~5-CH_3CH(OH)C_5H_4Cr(CO)_2]_2S 4, while saponification of 2 followed by acidification and recrystallization from acetone afforded [η~5-HO_2CC_5H_4Cr(CO)_2]_2S·nCH_3C·(O)CH_3 5. 1—5 are a new class of Cr≡S triple bond compounds containing functional organic group on the cyclopentadienyl ring. A single-crystal X-ray diffraction analysis of 1 revealed that it consists of two identical organometallic fragments η~5-CH_3C(O)C_5H_4Cr(CO)_2 joined together by a sulfur atom via triple bonds. The geometry of structural unit Cr≡S≡Cr belongs to linearity and the average triple bond length of Cr≡S is 2.072(?).