Syntheses And Propertities Of New Molecular Wires Based On Trtrathiafulvalen-acetylide Ligands

Tetrathiafulvalene (TTF) and its derivatives have a largely delocalized configuration, and display strong electron-donor ability, outstanding thermal and photochemical stabilities and attractive redox properties, which can be used as versatile building blocks in the field of molecular, supermolecular and materials chemistry. Transitional metal alkynyl complexes, especially diruthenium alknyl complexes, contribute to the growing field of molecular electronics. Interesting characteristics of these complexes include intense charge-transfer absorption, tunable bridging ligands and so on. At the same time, since the electronic active molecule-tetrathiafulvalene(TTF) has grown so fast in the last decade, a plenty of ligands, to which a metal-binding functionality is attached, have been synthesized and used for the preparation of metal complexes. Developing methods for joining materials that have different electronic properties is an essential step towards building nanometre-scale electronic devices such as diodes and transistors. In this short communication, we focus on the cooperation of both the the transitional unit and the functional TTF unit in order to build up the novel molecular wires.1. Synthesis and Characterization of TTF-acetylide ligands(Z)-5-iodo-2-(5-iodobenzo[d][1,3]dithiol-2-ylidene)benzo[d][1,3]dithiole (2a) was synthesized by homo-coupling of5-iodobenzo[d][1,3]dithiole-2-thione (1a) under the refluxing condition of P(OEt)3and toluene.2-(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)-5-iodobenzo[d][1,3]dithiole (2b) and2-(5-iodobenzo[d][1,3]dithiol-2-ylidene)benzo[d][1,3]dithiole (2c) were both synthesized under the same conditions by using4,5-bis(methylthio)-1,3-dithiol-2-one (1b) and benzo[d][1,3]dithiol-2-one (1c) instead of1a.(Z)-5-(2-(trimethylsilyl)ethynyl)-2-(5-(2-(trimethylsilyl)ethynyl)benzo[d][1,3]dithiol-2-ylidene)benzo[d][1,3]dithiole (L1),(2-(2-(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)benzo[d][1,3]dithiol-5-yl)ethynyl)tri methylsilane (3b) and (2-(2-(benzo[d][1,3]dithiol-2-ylidene)benzo[d][1,3]dithiol-5-yl)ethynyl)trimethylsilan e (3c) were synthesized by using trimethylsilyl acetylene(TMS-C≡CH) and2a,2b and2c, respectively, through Sonagashira reaction, the last two of which were desilylated to give rise to the ligands:L2and L3. IR, MS and1H NMR were conducted to determine the structure of all the ligands. The structure of complex3b has been determined by X-ray crystallography, the acetylenic bond length of which is within the normal ranges.2. Synthesis and Structure Characterization of Gold(Ⅰ)/Platinum(Ⅱ) Complexes with Tetrathiafulvalene-acetylide LigandsCoordination reactions of L2and L3with Au(PPh3)Cl afford new complexes Au(PPh3)(L2)(4) and Au(PPh3)(L3)(5) respectively, which were both purified by recrystallization. IR, MS and1H NMR were used to determine the structures of both these cmpounds. The crystal structures of complex4and5were determined by X-ray crystallography. Through the comparison of the bond length in both compounds4and5, we consider that the bond lengths in complex4are out of the normal ranges. The vibration frequency of acetenyl unit evidences the formation of weak feedback π bond. Cyclic Voltammetry experiments show sequential oxidation of the neutral compound with two one-electron processes that are assigned to the TTF unit.Efficient coordination reactions of L2and L3with [Pt(tBu3tpy)Cl](ClO4/PF6) give rise to the new complexes Pt(tBu3tpy)(L2/L3)(ClO4/PF6)(6/7/8/9) respectively, which were purified using silica gel column. IR, MS and1H NMR were used to determine the structures of all these cmpounds. The analyses of both the vibration frequency of acetenyl unit and CV experiments are according to complexes4and5.3. Synthesis and Characterization of Monoruthenium Compounds with Tetrathiafulvalene-acetylide LigandsCompounds RuCp(PPh3)2(L2/L3)(10/11) were efficiently synthesized by using RuCp(PPh3)2Cl and L2/L3under mild conditions, which were purified by silica gel column under N2. The identification of compounds10and11were conducted using IR, MS and1H NMR. The crystal structure of compound10was determined by X-ray crystallography, which showed all the typical bond lengths are within the normal ranges. Electrochemical behaviors were studied by cyclic voltammetry and the redox peaks of TTF unit shifted anodically by about350mv, while the Ru unit shifted cathodically by about1OOmv, which means the interaction between the two units.4. Synthesis, Characterization, and Property of Diruthenium Compound with Tetrathiafulvalene-acetylide Ligand L2Facile organometallic reaction between Ru2(DMBA)4(NO3)2and L2was conducted under the mild condition using Schelenk technique. The diamagnetic product Ru2(DMBA)4(L2)2(12) was purified using silica gel column under N2due to the moisture sensitive property. IR, MS and1H NMR were used to identify the structure of compound12. The crystal structure was determined by X-ray crystallography and the Ru-Ru bond length is2.4274A, which is obviously longer than Ru2(DMBA)4(NO3)2(2.2865A). Cyclic Voltammetry experiments show sequential oxidation of the neutral compound with two one-electron processes and two two-electron processes that are assigned to the Ru2and TTF unit, respectively. From the aspect of UV-Vis spectrum, the absorption spectrum features peaks at505and700-900nm. The low-energy transition is attributed to the dipole-allowed HOMO[πyz*(Ru-Ru)]—LUMO[δ*(Ru-Ru)] transition, while the high-energy is likely due to the ligand-to-metal charge chansfer from the amidinate π(N)—δ*(Ru-Ru).