Thallium(I) Coordination Polymers Based on Monosubstituted Arylcyanoximes

Date of Graduation

Spring 2006

Degree

Master of Science in Chemistry

Department

Chemistry and Biochemistry

Committee Chair

Nikolay Gerasimchuk

Abstract

Design of new types of metal-organic networks and search for unusual crystal architecture represents an important task for modern inorganic and materials chemistry research. A group of new monosubstituted phenylcyanoximes, containing F, Cl and Br atoms at 2-, 3- or 4- positions, were synthesized using the high yield nitrosation reaction with CH3-ONO, spectroscopically (1H, 13C, UV-visible, IR, mass-spectrometry) and structurally characterized. Results of x-ray analysis revealed non-planar trans-anti geometry for 2-chlorophenyl(oximino)acetonitrile, H(2Cl-PhCO), non-planar anti-configuration for 4-chlorophenyl(oximino)acetonitrile, H(4Cl-PhCO), and planar cis-syn geometry for 3-fluorophenyl(oximino)acetonitrile, H(3F-PhCO). All arylcyanoximes undergo deprotonation in solutions with the formation of colored anions exhibiting pronounced negative solvatochromism in a series of polar protic and aprotic solvents. Nine thallium(I) cyanoximates were obtained using the reaction between hot (̃95oC) aqueous solutions of Tl2CO3 and solid powdery monohalogenated arylcyanoximes HL. Crystal structures of two Tl(I) cyanoximates (Tl(2Cl-PhCO) and Tl(4Br-PhCO)) contained centrosymmetric dimeric units (TlL)2 that are connected to one-dimensional coordination polymer by means of an oxygen atom of the oxime group of the neighboring molecule. Cyanoxime anions act as bridging ligands in both structures where the polymeric motif consists of double-stranded Tl-O chains interconnected with the formation of zigzagging Tl2O2 planar rhombes. Thallium atoms form infinite linear arrays with close intermetallic separations. The nearest Tl(I)---Tl(I) distances are 3.838 Å and 4.058 Å in the Tl(2Cl-PhCO) and Tl(4Br-PhCO) structures respectively, close to that in metallic thallium (3.456 Å).

Keywords

Cyanoximes, Thallium (I), one-dimensional coordination polymers, x-ray crystallography, NMR, infrared spectroscopy

Subject Categories

Chemistry

Copyright

© Daniel Robertson

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