Formation of monomeric Sn(ii) and Sn(iv) perfluoropinacolate complexes and their characterization by 119Sn Mössbauer and 119Sn NMR spectroscopies

The synthesis and characterization of a series of Sn(ii) and Sn(iv) complexes supported by the highly electron-withdrawing dianionic perfluoropinacolate (pin^F) ligand are reported herein. Three analogs of [Sn^IV(pin^F)₃]^2- with NEt₃H⁺ (1), K⁺ (2), and {K(18C6)}⁺ (3) counter cations and two analogs of [Sn^II(pin^F)₂]^2- with K⁺ (4) and {K(15C5)₂}⁺ (5) counter cations were prepared and characterized by standard analytical methods, single-crystal X-ray diffraction, and ¹¹⁹Sn Mössbauer and NMR spectroscopies. The six-coordinate Sn^IV(pin^F) complexes display ¹¹⁹Sn NMR resonances and ¹¹⁹Sn Mössbauer spectra similar to SnO₂ (cassiterite). In contrast, the four-coordinate Sn^II(pin^F) complexes, featuring a stereochemically-active lone pair, possess low ¹¹⁹Sn NMR chemical shifts and relatively high quadrupolar splitting. Furthermore, the Sn(ii) complexes are unreactive towards both Lewis bases (pyridine, NEt₃) and acids (BX₃, Et₃NH⁺). Calculations confirm that the Sn(ii) lone pair is localized within the 5s orbital and reveal that the Sn 5p_x LUMO is energetically inaccessible, which effectively abates reactivity.

Crystal structure of bis-(diiso-propyl-ammonium) cis-di-iodido-bis-(oxolato-κ2O1,O2)stannate(IV)

In the title compound, (iPr2NH2)2[SnI2(C2O4)2], which was prepared by reacting ( i Pr2NH2+)2·C2O42- with SnI4 in a 2:1 molar ratio in a mixed ethanol-aceto-nitrile solvent, the Sn atom is coordinated by two chelating oxalate ions and two iodide ions, with the latter in a cis configuration. In the crystal, the cations are linked to the anions by N-H⋯O and bifurcated N-H⋯(O,O) hydrogen bonds, generating [10-1] chains.

Air and moisture stable covalently-bonded tin(ii) coordination polymers

Compounds (1)–(4) display 1D, 2D or 3D coordination networks, in which the Sn(ii) cations exhibit distorted disphenoidal geometries due to the stereochemically active electron lone pairs.

Packing polymorphism in 3-amino-2-pyrazinecarboxylate based tin(ii) complexes and their catalytic activity towards cyanosilylation of aldehydes

3-Amino-2-pyrazinecarboxylic acid is used to synthesize two new mononuclear interconvertible packing polymorphs of tin(ii) which act as heterogeneous catalysts for the cyanosilylation of aldehydes with trimethylsilyl cyanide.

Control of hydroxyapatite crystal growth by gallic acid

The purpose of this study is to detect the effect of gallic acid (GA) on hydroxyapatie crystal growth and find the mechanism of the regulation. We evaluated the morphology of HAP crystals grown under various amounts of GA (0, 0.05, 1, and 4 gL(-1)). Subsequently, the chemical composition, crystal size and the morphology were investigated via the energy-dispersive X-ray spectrometer, attenuated total fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction analysis, transmission electron microscope and scanning electron microscopy. In all groups, the Ca/P ratio was closed to 1.67. In the absence of GA, crystals did not arrange, while in the presence of GA, crystals tended to form spherules. The size of the crystals decreased with the concentration of GA increased. These results indicated the role of GA on the growth and morphology of hydroxyapatite crystals, which might be the key mechanism for gallic acid regulating the mineralization.

catena-Poly[[di-tert-butyl-tin(IV)]-μ-oxalato]

The title compound, [Sn(C₄H₉)₂(C₂O₄)]_n, an unexpected side product in the reaction of di-tert-butyl­tin(IV) oxide with nitric acid, represents the first diorganotin(IV) oxalate to be structurally characterized. The Sn^IV atom of the one-dimensional coordination polymer is located on a mirror plane and is coordinated by two chelating oxalate ions with two rather different Sn—O bond lengths of 2.150 (1) and 2.425 (1) Å, and two t-butyl groups with Sn—C bond lengths of 2.186 (2) and 2.190 (2) Å. The coordination polyhedron around the Sn^IV atom is a distorted tetra­gonal disphenoid. The centrosymmetric oxalate ion also has an asymmetric coordination geometry, as reflected by the two slightly different C—O bond lengths of 1.242 (2) and 1.269 (2) Å. The chains of the polymer propagate along the b-axis direction. Only van der Waals inter­actions are observed between the chains.

S. A, Pratik SM, Datta A, Nath R, Mandal S. Synthesis, structure, photocatalytic and magnetic properties of an oxo-bridged copper dimer

A new paramagnetic and semiconductor copper citrate dimer exhibits photocatalytic behaviour towards organic dye degradation.

Vibrational spectra of tin(II) oxalate

The infrared and Raman spectra of anhydrous tin(II) oxalate, SnC(2)O(4), were recorded and discussed on the basis of its structural peculiarities. Some comparisons with other previously investigated metallic oxalates were made.