Syntheses And Properties Of New Functional Metal Complexes With Nitrogen Containing Conjugated Multi-Sulfur Ligands

With the rapid development of electronics, information science and material science, one of the current challenges in chemistry is the synthesis and investigation of molecule-based materials involving interplay and synergy between multiple physical properties. Tetrathiafulvalene (TTF) and its derivatives have been seen as the gateway to organic metals, superconductors, and semiconductors due to its strong electron-donor ability, outstanding thermal and photochemical tabilities and attractive redox properties. In addition to work on electrical conductivity, TTF derivatives are also extensivly researched as building blocks in magnetic conductor/ semiconductor, organic field-effect transistors (OFETs), intramolecular donor-acceptor (D-A) systems of nonlinear optic (NLO) materials, liquid crystalline materials and Langmuir-Blodgett (LB) films. One of the current challenges in new TTF derivatives for functional materials is to search for molecules with more ?-extended systems. It has been demonstrated that the extension of the TTF core not only leads to stabilized oxidized states and can enhance the dimensionality in materials by increasing ?…? or S…S interactions. In order to obtain multi-functional molecular materials, much attention has been devoted to association of the electrochemically active TTF core with optical or magnetic properties of the metal ions bridged by various functional groups, such as pyridine, bipyridine, carboxylic groups, dithiolate, phosphine and acetylacetonate. In this dissertation, we report the syntheses and characterization of new nitrogen containing ?-conjugated multi-sulfur ligands and related metal complexes. The physical and chemical properties of the new compounds are also discussed.1. Four new metal complexes based on the multi-sulfur dithiolene ligand L1 (L1= [4,5:5,6] [1,4] dithiino[2,3-b] quinoxaline-1,3-dithiolate), [n-Bu4N]n[Ni(L1)2] (n =1,1; n= 0,2) and [R4N][Au(L1)2] (R=n-Bu,3; R= Et,4), are synthesized and characterized. The solid and frozen glass ESR spectra of complex 1 at 110 K have been measured. The NIR spectra of complexes 1 and 2 have also been studied. The nickel complex 1 is of special interest since it shows remarkable absorption in the near-IR region (?=1082 nm,?=15000 dm3mol-cm-1), which is very close to 1064 nm (Nd-YAG lasers) and 1079 nm (Nd-YAP lasers). More importantly, it is well soluble in most organic solvents and exhibits high thermal and photochemical stabilities. Complex 1 can be an excellent candidate as a near-IR dye for Q-switching neodymium lasers and optical limiting (OL) materials. The crystal structures of 1 and 3 have been determined by X-ray crystallography. Their third-order non-linear optical properties have been studied by using the Z-scan method.2. We have firstly synthesized the novel ligand L2 that TTF is directly linked to the terpy moiety (L2=4-tetrathiafulvalene-2,2:6,2-terpyridine). Two novel iron(II) complexes [Fe?(L2)2][ClO4]2(5) and [Feu(L2·+)2][ClO4]4(6) have been obtained by reactions of L2 with Fe(ClO4)2·xH2O or Fe(C104)3-xH20, respectively. The crystal structure of 5 has been determined by X-ray crystallography. The electrochemical properties of organic ligand L2 and complex 5 have been investigated.The results suggest the first two oxidation waves correspond to two-electron oxidation of the TTF moieties in complex 5. The absorption spectra of L2,5 and 6 have also been measured, the oxidation of complex 5 by NOPF6 leads to the appearance of new bands characteristic for cation radical (440 and 665 nm), which are in good agreement with the absorption spectra of complex 6. Spectroelectrochemical measurements were also carried out in order to study the charge-transfer of L2 and 5. the EPR spectrum of powdered complex 6 displays signal at g=2.012 at room temperature, which suggests the existence of L2·+ spins. No signal at around 1500 G shows that there is no Fe3+ in 6. The electrical resistivity of 6 is 1.3×10-7S cm-1 at 290 K, which is almost 2 order of magnitude greater than that of 5. XPS valence spectra imply the Fe in 6 is totally at the+? oxidation state. The ground state structures and spin-allowed electronic transitions of 5 has been studied by using density functional theory (DFT) and time-dependent DFT (TDDFT), and the calculated transitions (???*, ILCT, LLCT and MLCT) agree well with the experimental ones.3. We report here the design and preparation of new ligand L3 (L3= 6,6"-Dimethyl-4-tetrathiafulvalene-2,2:6,2-terpyridine), five TTF-based complexes, [Ru(L2)(terpy)][PF6]2 (7), [Ru(L2)2][PF6]2 (8), [Fe?(L2)2][CF3SO3]2 (9), [Nin(L2)2][C104]2 (10) and [Fe?(L3)2][ClO4]2 (11), are successfully obtained based on the ligand L2 and L3. The crystal structures of 7,9-11 have been determined by X-ray crystallography. The electrochemistry measurements suggested that all the compounds display rich redox processes. Spectroscopic behaviors of these compounds and spectroelectrochemical measurements of L2 and 7-8 have been studied. Magnetic susceptibility measurements of 11 suggest that high spin Fe? has been obtained based on the ligand L3. The results show that the two ligands are useful for the design of multifunctional materials.4. A series of ex-TTF derivatives 10-[4,5-Di(methoxycarbonyl)-1,3-dithiol-2-ylidene]-9-(4,5-Di(methylthio)-1,3-dithiol-2-ylidene)-9,10-dihydroanthracene (Pi), 9,10-bis(4,5-dimethoxycarbonyl-1,3-dithiol-2-ylidene)-9,10-dihydroanthracene (P2), 10-[4,5] [1',10']phenanthroline-1,3-dithiol-2-ylidene]-9-(4,5-Di(methylthio)-1,3-dith-iol-2-ylidene)-9,10-dihydroanthracene (L4),10-[4,5][1',10']phenanthroline-1,3-dithiol-2-ylidene]-9-(4,5-Di(methoxycarbonyl)-1,3-dithiol-2-ylidene)-9,10-dih-ydro-anthracene (L5), have been synthesized and characterized. Reactions of Re(CO)5Cl with the ligand L4 and L5 afford rhenium tricarbonyl complexes 12 and 13 in high yields, respectively. X-ray crystal structure determinations on P1 and P2 reveal that both molecules adopt saddle-like conformations. The electrochemical and spectroscopic behavior of all compounds has been studied. Meanwhile, the chemical oxidative titration of these compounds by NOPF6 leads to a decrease of the characteristic absorption of the neutral compounds and the appearance of dication bands, and addition of NOPF6 led to fluorescence enhancement.