Molecular packing modes. Part V. Crystal and molecular structures of fumaramic acid

The crystal and molecular structures of two triphenyltin dithiocarbamate compounds, viz. [Sn(C6H5)3(C8H16NS2)], (I), and [Sn(C6H5)3(C10H12NS2)], (II), are described. The dithiocarbamate ligand in each molecule coordinates in an asymmetric fashion resulting in heavily distorted tetrahedral C3S coordination geometries for the Sn atoms, with the distortions traced to the close approach of the non-coordinating thione-S atom. The molecular packing in both compounds features C—H...π(Sn-phenyl) interactions. In (I), the donors are Sn-phenyl-C—H groups leading to centrosymmetric aggregates, while in (II), the donors are both Sn-phenyl-C—H and methyl-C—H groups leading to supramolecular chains propagating along the b axis. The identified aggregates assemble into their respective crystals with no directional interactions between them. An analysis of the Hirshfeld surfaces show distinctive patterns, but an overwhelming predominance (>99% in each case) of H...H, C...H/H...C and S...H/H...S contacts on the respective Hirshfeld surface.

Download Full-text

A Solvent-Dependent and Electrochemically Controlled Self-Assembling/Disassembling System

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20031647 ◽

2003 ◽

Vol 68 (9) ◽

pp. 1647-1662 ◽

Cited By ~ 2

Author(s):

Valeria Amendola ◽

Massimo Boiocchi ◽

Yuri Diaz Fernandez ◽

Carlo Mangano ◽

Piersandro Pallavicini

Keyword(s):

Equilibrium Mixture ◽

Bidentate Ligand ◽

Molecular Structures ◽

The Self ◽

Molar Ratio ◽

Crystal And Molecular Structures ◽

Self Assembling ◽

Irreversible Oxidation ◽

Irreversible Reduction ◽

Metal Ligand

The bis-bidentate ligand R,S-1,2-diphenyl-N,N'-bis(2-quinolinemethylidene)ethane-1,2-diamine (ligand 4), containing two (iminomethyl)quinoline moieties separated by a cis-1,2-diphenylethylene spacer, forms stable complexes with both CuI and CuII. With CuII, the monomeric 1:1 complex [CuII(4)]2+ is obtained both in CH3CN and CH2Cl2. With CuI and overall 1:1 metal/ligand molar ratio, an equilibrium mixture is obtained in CH3CN, consisting of [CuI(4)2]+, [CuI2(4)2]2+ and [CuI2(4)(CH3CN)4]2+. The preponderant species is the two-metal one-ligand "open" complex [CuI2(4)(CH3CN)4]2+, in which each Cu+ cation is coordinated in a tetrahedral fashion by one (iminomethyl)quinoline unit and by two CH3CN molecules. Precipitation from the equilibrium mixture yields only crystals of [CuI2(4)(CH3CN)4](ClO4)2·2CH3CN, whose crystal and molecular structures have been determined. On the other hand, in the poorly coordinating CH2Cl2 solvent, only the dimeric helical [CuI2(4)2]2+ complex is obtained, when the overall metal/ligand 1:1 molar ratio is chosen. Addition of large quantities of acetonitrile to solutions of [CuI2(4)2]2+ in dichlorometane results in the formation of [CuI2(4)(CH3CN)4]2+, i.e. in the solvent-driven disassembling of the CuI helicate. While electrochemistry in CH3CN is poorly defined due to the presence of more than one CuI species, cyclic voltammetry experiments carried out in CH2Cl2 revealed a well defined behavior, with irreversible oxidation of [CuI2(4)2]2+ and irreversible reduction of [CuII(4)]2+ taking place at separate potentials (∆E ≈ 700 mV). Irreversibility and separation of the redox events are due to the self-assembling and disassembling processes following the reduction and oxidation, respectively.

Download Full-text