A new class of eight-membered Sn2P2O4 heterocycles. Crystal structure and electrolytic dissociation in solution of cyclo-[R2Sn(OPPh2O)2SnR2](O3SCF3)2(R=Me, t-Bu)

The syntheses of cyclo-[R₂Sn(OPPh₂O)₂SnR₂](O₃SCF₃)₂ (R = Me (1), t-Bu (2)) by the consecutive reaction of R₂SnO (R = Me, t-Bu) with triflic acid and diphenylphosphinic acid are presented. In the solid state, 1 and 2 were investigated by ¹¹⁹Sn MAS and ³¹P MAS NMR spectroscopy as well as X-ray crystallography and appear to exist as ion pairs of cyclo-[R₂Sn(OPPh₂O)₂SnR₂]²⁺ dications and triflate anions. In solution, 1 and 2 are involved in extensive equilibria processes featuring cationic diorganotin(IV) species with Sn-O-P linkages, as evidenced by ¹¹⁹Sn and ³¹P NMR spectroscopy, electrospray mass spectrometry, and conductivity measurements.

Synthesis and reactivity of para-substituted benzoylmethyltellurium(II and IV) compounds: observation of intermolecular C-H-O hydrogen bonding in the crystal structure of (p-MeOC6H4COCH2)2TeBr2

Bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC₆H₄COCH₂)₂TeBr₂, (y=H (1a), Me (1b), MeO (1c)) can be prepared
either by direct insertion of elemental Te across CRf-Br bonds (where C_Rf refers to α-carbon of a functionalized organic moiety) or by the oxidative addition of bromine to (p-YC₆H₄COCH₂)₂Te (y = H (2a), Me (2b), MeO (2c)). Bis(p-substituted benzoylmethyl)tellurium dichlorides, (p-YC₆H₄COCH₂)₂TeCh (y = H (3a), Me (3b), MeO (3c)), are prepared by the reaction of the bis(p-substituted benzoylmethyl)tellurides 2a--c with S0₂Cl₂, whereas the corresponding diiodides (p-YC₆H₄COCH₂)₂Teh (y = H
(4a), Me (4b), MeO (4c)) can be obtained by the metathetical reaction of la--c with KI, or alternatively, by the oxidative addition of
iodine to 2a--c. The reaction of 2a--c with allyl bromide affords the diorganotellurium dibrornides la--c, rather than the expected
triorganotelluronium bromides. Compounds 1-4 were characterized by elemental analyses, IR spectroscopy, ¹H, ^l3C and ¹²⁵Te
NMR spectroscopy (solution and solid-state) and in case of Ie also by X-ray crystallography. (p-MeOC₆H₄COCH₂)₂TeBr₂ (1c) provides, a rare example, among organotellurium compounds, of a supramolecular architecture, where C-H-O hydrogen bonds appear to be the non-covalent intermolecular associative force that dominates the crystal packing.

Synthesis, x-ray structure of ferrocene bearing Bis(Zn-cyclen) complexes and the selective electrochemical sensing of TpT

The new ligand, [Fc(cyclen)₂] (5) (Fc=ferrocene, cyclen=1,4,7,10-tetraazacyclododecane), and corresponding Zn^II complex receptor, [Fc{Zn(cyclen)(CH₃OH)}₂](ClO₄)₄ (1), consisting of a ferrocene moiety bearing one Zn^II-cyclen complex on each cyclopentadienyl ring, have been designed and prepared through a multi-step synthesis. Significant shifts in the ¹H NMR signals of the ferrocenyl group, cf. ferrocene and a previously reported [Fc{Zn(cyclen)}]²⁺ derivative, indicated that the two Zn^II-cyclen units in 1 significantly affect the electronic properties of the cyclopentadienyl rings. The X-ray crystal structure shows that the two positively charged Zn^II-cyclen complexes are arranged in a trans like configuration, with respect to the ferrocene bridging unit, presumably to minimise electrostatic repulsion. Both 5 and 1 can be oxidized in 1:4 CH₂Cl₂/CH₃CN and Tris-HCl aqueous buffer solution under conditions of cyclic voltammetry to give a well defined ferrocene-centred (Fc⁰/+) process. Importantly, 1 is a highly selective electrochemical sensor of thymidilyl(3′-5′)thymidine (TpT) relative to other nucleobases and nucleotides in Tris-HCl buffer solution (pH 7.4). The electrochemical selectivity, detected as a shift in reversible potential of the Fc⁰/+ component, is postulated to result from a change in the configuration of bis(Zn^II-cyclen) units from a trans to a cis state. This is caused by the strong 1:1 binding of the two deprotonated thymine groups in TpT to different Zn^II centres of receptor 1. UV-visible spectrophotometric titrations confirmed the 1:1 stoichiometry for the 1:TpT adduct and allowed the determination of the apparent formation constant of 0.89±0.10×10⁶ M⁻¹ at pH 7.4.

Protonated melonate Ca[HC6N7(NCN)3]·7H2O – synthesis, crystal structure, and thermal properties

Calcium hydrogenmelonate heptahydrate Ca[HC6N7(NCN)3]·7H2O was obtained by metathesis reaction in aqueous solution. The structure of the molecular salt was elucidated by single-crystal X-ray diffraction. The crystal structure consists of alternating layers of planar monopronated melonate ions, Ca2+ and crystal water molecules. The anions of adjacent layers are staggered so that no π–π stacking occurs. The melonate entities are interconnected by hydrogen bonds within and between the layers. Ca[HC6N7(NCN)3]·7H2O was investigated by solid-state NMR and FTIR spectroscopy, TG and DTA measurements.

Crystal structure of (4-bromonaphthalen-2-yl) acetonitrile, C12H8BrN

C_I2H₈BrN, monoclinic, Pl2₁/cl (No. 14), a = 7.555(6) Å, b =7.727(3) Å, c =16.643(2) Å, β =98.95(2)°, V =959.8 ų , Z =4, R_gt(F) =0.033, wRref(F²) =0.097, T =173 K.

Crystal structure of (13S*,13aR*)-2,3-dimethoxy-13-hydroxy-13a-methyl-8-oxo-5,6,13,13a-tetrahydro-8H-dibenzo[a,g]quinolizine, C20H21NO4

C₂₀H₂₁N0_4, monoclinic, P12₁/cl (No. 14), a = 7.521(2) Å,
b = 23.257(2) Å c = 9.784(2) Å, ß= 95.57(2)°, V = 1703.3 ų,
Z = 4, R_gt(F) = 0.060, wR_ref(F²) = 0.183, T = 293 K.

Crystal structure of (3S*,4S*)-4-hydroxy-2-(2`-methoxyethyl)-3-phenyl-3,4-dihydroisoquinol-1(2H)-one,C18H19NO3

C₁₈H₁₉N0₃, monoclinic, P12₁/n1 (No. 14), a =8.454(6) Å,
b =13.123(3) Å, c =14.698(3) Å, ß =104.85(3)^o, V =1576.2ų,
Z =4, R_gt(F) =0.062, wR_ref(F²) =0.184, T =293 K.

Crystal structure of a ceIII/feIII heterobimetallic complex

A central μ₃—O moiety linking two Fe^III and one Ce^III sites supported by two distinct heterometallic carboxylate bridging modes features in self-assembled [CeFe₂(bpy)₂(μ₃—O)(μ—L)₂(μ—LH)₂(LH)(H₂O)₂]·0.5(bpy)·7H₂O (1) (LH₂ = glycolic acid), and the structure models potential bonding modes of the Rare Earth corrosion inhibitor Ce(glycolate)₃ to iron or iron oxide.

Determination of crystal structure and crystallographic characteristics in Ni-Mn-Ga ferromagnetic shape memory alloys

Ni-Mn-Ga ferromagnetic shape memory alloys (FSMAs) have received great attention during the past decade due to their giant magnetic shape memory effect and fast dynamic response. The crystal structure and crystallographic features of two Ni-Mn-Ga alloys were precisely determined in this study. Neutron diffraction measurements show that Ni48Mn30Ga22 has a Heusler austenitic structure at room temperature; its crystal structure changes into a seven-layered martensitic structure when cooled to 243K. Ni53Mn25Ga22 has an I4/mmm martensitic structure at room temperature. Electron backscattered diffraction (EBSD) analyses reveal that there are only two martensitic variants with a misorientation of ~82° around <110> axis in each initial austenite grain in Ni53Mn25Ga22. The investigation on crystal structure and crystallographic features will shed light on the development of high-performance FSMAs with optimal properties.