Supramolecular structures and properties models of macrocyclic polymer complexes

Abstract

Two novel supramolecular complexes of types [Ru(L)(H 2 L)Cl·OH 2 ] and [Ru(HL n )Cl 3 ] (where H2L is a potential tetradentate ligand derived from hydrazine hydrate and diethyl malonate, and HL n is a potential bidentate ligand derived from coupling of allyl azo-β-diketone) have been synthesized and characterized by elemental analysis, conductance and magnetic measurements, followed by 1 H NMR, to determine the effect of substituents on the intramolecular hydrogen bond. The electronic properties and models of the bonding of ligands and complexes were investigated by UV-Vis and IR spectroscopies. The first type of complex contains terminal hydrazinic nitrogen atoms with an unshared electron pair and may take part in nucleophilic condensations. Therefore, the reactions of allyl-β-diketone complexes with malonic dihydrazide have also been studied, as these cause ring closure and formation of supramolecular macrocyclic ligand complexes. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory, and various parameters have been evaluated. On the basis of the electronic spectra, an octahedral geometry has been established for the polymer complexes C. The macrocyclic polymer complexes D are pentacoordinate, and a trigonal-bipyramidal environment (D 3h ) is suggested for the ruthenium(III) ion. The effect of the Hammett constant on the ligand field parameters is also discussed.

Role of a Novel Mixed-Valence-Ligand on the Structures of Supramolecular Polymeric Complexes

“…Steric factors prevent the coordination of all the donors to a single metal ion. This mode of complexation is confirmed by the appearance of new bands due to ν(C=N) and ν(C=O) [12,13,20] with respect to other bands due to ν(C=O) and ν(C=S). The non-ligand bands appearing in the 480-325 and 365-330 cm −1 regions may tentatively be assigned to ν(M-O) and ν(M-S) vibrations, respectively [21].…”

“…The ground term for Ru(III) (t 5 2g configuration) is 2 T 2g and the first excited levels in order of increasing energy are 4 T 1g and 2 A 2g , which arise from t 4 2g e 1 g configurations. In most of the Ru(III) complexes the electronic spectra show only charge-transfer bands [20]. It has been observed that charge-transfer bands of the type L xy → t 2g are prominent in the low-energy region, which obscures the weaker d-d transitions.…”

“…The B-value obtained for the Rh(III) complex suggests a considerable orbital overlap with a strong covalence in the metal-ligand σ -bond. Here the reduced values of B are also associated with the reduction in the effective cationic charge (Z * ; 1.8) [3,20], evaluated Table 3. Electronic spectral band assignments, ligand field parameters and proposed geometries for polymer complexes (1)-(8) * (for molecular structures see Fig.…”

“…The electronic spectra of Ru(III) polymer complexes show bands in the 15 290-15 260, 19 040-17 700 and 24 090-21 500 cm −1 regions (Table 3) which may be assigned to 2 T 2g → 4 T 1g , 2 T 2g → 4 T 2g and 2 T 2g → 2 A 2g , 2 T 1g transitions, respectively [20,24].…”

Polymer complexes: supramolecular modeling for determination and identification of the bond lengths in novel polymer complexes from their infrared spectra

“…Consequently, in the UO 2 2+ case, the uranyl atom should be a six-coordinate octahedron with the oxygen atom in the apical position. 8 Bis(allyl propenyl-2-(4-derivative phenylazo)butan-3-one uranyl has a low solubility in water and in common organic solvents. Therefore, in order to improve solubility, we have synthesized the azoallyl acetoacetate ( Fig.…”