Synthesis of new ethynylbipyridine-linked mono- and bis-tetrathiafulvalenes: electrochemical, spectroscopic, and Ru(II)-binding studies (original) (raw)
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HETEROCYCLES, 2010
Novel NCN-pincer carbene complexes of Ru(II), 1,3-bis(2-pyridylmethyl)benzimidazolineruthenium(II) bishexafluorophosphate (2), and Pt(II), 1,3-bis(2-pyridylmethyl)benzimidazolinechloroplatinum(II) hexafluorophosphate , complexes based on 1,3-bis(2-pyridylmethyl)-1H-benzimidazolium chloride (1) were synthesized and characterized by different spectroscopic methods. Complex 2 shows an absorption maximum at 386 nm, blue-shifted in comparison to Ru(bpy) 3 2+ and Ru(tpy) 2 2+ , probably due to the strong s-donor and weak p-acceptor properties of the electron-rich NHC ligand. Electrochemical studies show Ru(II)/Ru(III) and Pt(II)/Pt(IV) reversible couples at 0.67 and 0.58 eV, respectively, lower than those for the analogous complexes of ligands like bipyridine (bpy), terpyridine (tpy) and phenylbipyridine (pbpy). The solid state structure of 2 was solved by X-ray diffraction. Theoretical studies (B3LYP/LANL2DZ) of the complex show a HOMO (À0.38594 au) mainly centered on the ruthenium and benzimidazole, whereas the LUMO (À0.25130 au) is populated by pyridines. Therefore, it is assumed that the charge transfer from HOMO -LUMO is mixed ILCT (interligand charge transfer)/MLCT (metal to ligand charge transfer). The observed lower redox potentials of the Pt(II) complex compared to the Ru(II) complex is supported by theoretically calculated ionisation potentials and also electron affinity values. To the best of our knowledge, 2 is the first example of a six-membered metallacycle homoleptic chelate pincer NCN-Ru(II) N-heterocyclic carbene complex.
European Journal of Inorganic Chemistry, 2009
The synthesis and characterisation of a group of vinylenedithio-TTFs bearing two or four 2-or 4-pyridyl groups are described, along with related nickel and gold bidithiolene, as potential substrates for preparing multifunctional materials. In spite of the pyridyl groups not being coplanar with the vinylenedithio-TTF cores and the significant chair-type distortions of the cores, because of the flexing of the dithiin rings, these substituted donors preserve the stacking ability of the unsub-[a] Schoolyielded a [4a-H](ReO 4 ) 2 salt, which is discussed. Furthermore, we describe the synthesis and characterisation of two new nickel and gold dithiolene complexes 6 and 7.
Synthesis and properties of new metal complexes involving unsymmetrical tetrathiafulvalenes
Journal of Chemical and Pharmaceutical Research, 2014
A new unsymmetrical tetrathiafulvalenes (TTF) containing nitrophenyl or aminophenyl rings were prepared by using a cross-coupling method of the respective 4,5-dialkyl-1,3-dithiole-2-one 1a-e with 4-(p-nitrophenyl)-1,3dithiole-2-thione 2. The conversion of the nitro moiety 3a-e to amino groups' 4a-e used reduction reaction. The reducing power of each new precursor was determined by cyclic voltammetry. Charge transfer complexes of the donors with tetracyanoquino-dimethane (TCNQ) were prepared and characterized. The electrical conductivity of these materials was measured and discussed.
Novel π-conjugated donor-acceptor chromophores, based on the strong electron-donating tetrathiafulvalene moiety and different electron-withdrawing acceptors, exhibit large second-order optical nonlinearities. The effect of increasing the length of the polyenic spacer and the influence of the nature of the acceptor moiety on the NLO properties have been studied by using the electric fieldinduced second-harmonic generation (EFISH) technique as well as by semiempirical and ab initio theoretical calculations. A charge-transfer band has been observed in the absorption spectra of these D-π-A compounds that undergoes an hypsochromic shift when increasing the number of vinylenic spacer units connecting both donor and acceptor moieties. The degree of the intramolecular charge transfer from the donor to the acceptor has also been analyzed by means of Raman spectroscopy.
The Journal of Organic Chemistry, 1998
Syntheses of the bis(heterocycle)-fused bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives 7 and 8, the heterocycle-fused BEDT-TTF, methylenedithio(ethylenedithio)tetrathiafulvalene (MET), and ethylenedithiotetrathiafulvalene derivatives 9-11, and the 1,3-dioxolane derivative of MET 12a and its analogues 12b-d are described. The heterocycle-fused ketones 17 and 19 with cis ring fusions could be prepared by the BF 3 -promoted reaction of tin dithiolate 13 with dihaloheterocycles 15 and 16 in good yields, respectively, and served as key intermediates for the (RO) 3 Pand/or Me 3 Al-promoted coupling syntheses of these new tetrathiafulvalene donors 7-12. Further, the electrochemical properties of new donors 8-12 by the use of cyclic voltammetry and the molecular structures of 9a, 10a, 11, and 12a by X-ray crystallographic analyses are also reported. Figure 2. Molecular structure of 17. Scheme 1 Scheme 2 New TTF Donors with Extended Peripheral Substituents
Synthetic Metals, 2005
The HR 2 Si-functionalized tetrathiafulvalene (TTF) ligand TTF(SiR 2 H) 4 (R = Me 2a; R = Ph 2b) have been synthesized and the molecular structure of 2a determined. The reactivity of the four Si-H bonds for oxidative addition reactions has been exploited. Thus, the bimetallic platinum-silicon complex [(PPh 3) 2 Pt{(Me 2 Si) 2 TTF(SiMe 2) 2 }Pt(PPh 3) 2 ] 3 incorporating TTF(SiMe 2 H) 4 as bridging unit has been assembled by oxidative addition across [Pt(PPh 3) 2 (CH 2 CH 2)]. Electrochemical investigations by means of cyclic voltammetry reveals, for the complex 3, a strong cathodic shift of the two redox processes of the TTF core compared with those of 2a.
Synthesis and Electroconductive Properties of Radical Salts Derived from Tetrathiafulvalene Dimers
Journal of Solid State Chemistry, 2002
Palladium(II)-or copper(II)-catalyzed homo-coupling reaction of either trimethylstannyltetrathiafulvalene or tetrathiafulvalenylzinc chloride produces symmetrical bitetrathiafulvalenes (bi-TTFs) in good yields, whereas palladium(0)catalyzed cross-coupling reaction of tetrathiafulvalenylzinc chloride with 4-iodotetrathiafulvalenes leads to the corresponding unsymmetrically substituted bi-TTFs in moderate-to-high yields. The X-ray analysis of bi-TTF derivatives showed planar structures, and the cyclic voltammetry suggested that bi-TTFs have good donor ability comparable to that of BEDT-TTF. The symmetrical bi-TTFs formed the corresponding CT-complexes and cation radical salts. These CT-complexes and radical salts were found to be metallic or semiconducting, reflecting the effect of stoichiometry control in the dimeric TTF system. The X-ray structures of two cation radical salts revealed a unique stacking, and the precise conducting path in BEDO-bi-TTF . ClO 4 was discussed on the basis of MO calculations. # 2002 Elsevier Science (USA)