Dong-Youn Noh

Syntheses and characterization of heterobimetallic complexes (dppf)Pt(dithiolate) (dppf: bis(diphenylphosphino)ferrocene); X-ray crystal structures of (dppf)PtL where L=dmit, phdt and i-mnt

Abstract Heterobimetallic complexes of the type (dppf)PtL (dppf=1,1′-bis(diphenylphosphino)ferrocene; L=dmit (1,3-dithiole-2-thione-4,5-dithiolate), dddt (5,6-dihydro-1,4-dithiin-2,3-dithiolate), phdt (6-hydro-5-phenyl-1,4-dithiin-2,3-dithiolate), dphdt (5,6-diphenyl-1,4-dithiin-2,3-dithiolate), mtdt (1,2-bis(methylthio)ethylene-1,2-dithiolate), i-mnt (2,2-dicyano-1,1-ethylenedithiolate)) have been synthesized and studied by a high-resolution FAB-MS, cyclic voltammetry and 31P NMR. (Dppf)Pt(i-mnt) exhibits one reversible redox peak at E1/2=1.225 V and a strong Pt–P coupling constant (JPt–P=3237 Hz) due to the electron-accepting property of i-mnt ligand. On the contrary, (dppf)Pt(mtdt) shows three reversible redox peaks corresponding to [dppf]0/+ (E1/21=0.470 V), [Pt(mtdt)]0/+ (E1/22=1.050 V) and [Pt(mtdt)]+/2+ (E1/23=1.405 V) processes and a weak Pt–P coupling constant (JPt–P=2962 Hz) due to relatively strong electron-donor property of mtdt ligand. X-ray structural analyses were performed for the three complexes: (dppf)PtL where L=dmit, phdt and i-mnt. The P2PtS2 core shows a distorted square planar geometry for the three complexes with P(1)–Pt–P(2) bite angle being larger than 96°. The S(1)–Pt–S(2) bite angle of the i-mnt complex is the smallest (74.42°) because of the formation of the four-membered ring.

New synthesis of phenyl-substituted 2,3-dihydro-1,3-dithiolo[4,5-e][1,4]dithiin-6-thione

Abstract The facile synthesis of 4 and (±)- 6 was carried out via a Diels-Alder type [2+4] cycloaddition reaction of oligomeric dien 8 with styrene or t -stilbene, respectively, as a dienophile by a thermal reaction and/or photoreaction. (±)- 6 crystallized as a racemic compound composed of ( 2R,3R ) and ( 2S,3S ) enantiomers.

Redox Multifunctionality in a Series of PtII Dithiolene Complexes of a Tetrathiafulvalene-Based Diphosphine Ligand

The redox-active and chelating diphosphine, 3,4-dimethyl-3,4-bis(diphenylphosphino)-tetrathiafulvalene, denoted as P2, is engaged in a series of platinum complexes, [(P2)Pt(dithiolene)], with different dithiolate ligands, such as 1,2-benzenedithiolate (bdt), 1,3-dithiole-2-thione-4,5-dithiolate (dmit), and 5,6-dihydro-1,4-dithiin-2,3-dithiolate (dddt). The complexes are structurally characterized by X-ray diffraction, together with a model compound derived from bis(diphenylphosphino)ethane, namely, [(dppe)Pt(dddt)]. Four successive reversible electron-transfer processes are found for the [(P2)Pt(dddt)] complex, associated with the two covalently linked but electronically uncoupled electrophores, that is, the TTF core and the platinum dithiolene moiety. The assignments of the different redox processes to either one or the other electrophore is made thanks to the electrochemical properties of the model compound [(dppe)Pt(dddt)] lacking the TTF redox core, and with the help of theoretical calculations (DFT) to understand the nature and energy of the frontier orbitals of the [(P2)Pt(dithiolene)] complexes in their different oxidation states. The first oxidation of the highly electron-rich [(P2)Pt(dddt)] complex can be unambiguously assigned to the redox process affecting the Pt(dddt) moiety rather than the TTF core, a rare example in the coordination chemistry of tetrathiafulvalenes acting as ligands.

Electrochemistry and strong near-IR absorption of the [Ni(dphdt)2]n complexes (n=−1, 0; dphdt=5,6-diphenyl-1,4-dithiin-2,3-dithiolate); X-ray crystal structure of (Ph4P)[Ni(dphdt)2](CH2Cl2)

Abstract Nickel bisdithiolene complexes Cx[Ni(dphdt)2] (x=1 or 0.1, C=tetrabutylammonium (n-Bu4N+); x=1, C=tetraphenylphosphonium (Ph4P+); dphdt=5,6-diphenyl-1,4-dithiin-2,3-dithiolate) have been synthesized and characterized. The molecular structure of (Ph4P)[Ni(dphdt)2](CH2Cl2) was determined by X-ray analysis. Ni(S2C2S2)2 core is planar and stacking along the c-axis and the shortest intra-stack S⋯S distance is 4.529 A. According to the cyclic voltammetry of (n-Bu4N)[Ni(dphdt)2], two phenyl groups on the dphdt ligand decrease the electron density on the Ni(S2C2S2)2 core and increase the oxidation potentials compared to those of the (n-Bu4N)[Ni(dddt)2] complex (dddt=5,6-dihydro-1,4-dithiin-2,3-dithiolate). Near-IR spectra of the complexes show that phenyl substitution on the ligand does not give rise to the evident change in transition energy due to the lack of coplanarity with the Ni(S2C2S2)2 core.

Synthesis, structure and properties of new nickel-bis(ferrocenyldithiolene)

Tetra-n-butylammonium bis(2,3-diferrocenyl-1,4-dithiin-5,6-dithiolato) nickel(III) complex, TBA[Ni(dfcvdt) 2 ], is prepared and obtained as crystals (orthorhombic, Pnma, a = 20.457, b = 39.220, c = 8.496A, V = 6817A 3 and Z = 4), in which ferrocenes are covalently connected to dithiolene ligand. It shows strong near-IR absorption (λ max = 1155nm, log∈ = 4.06dm 3 /mol cm). Upon treatment of iodine, TBA complex is oxidized to neutral one, [Ni(dfcvdt) 2 ] 0 , as Ni(dddt) 2 complexes are. Pressed pellet conductivity of neutral complex is measured as 10 -5 S/cm at room temp.

Ferrocene-containing vt compound as a new molecular donor#

Abstract New VT compound containing directly bonded ferrocenes (Bis(ferrocenylvinylenedithio)tetrathiafulvalene : BFcVDT-TTF or FcVT) is synthesized by the standard coupling method using neat P(OEt) 3 and confirmed by spectroscopic methods. It shows one reversible cyclic voltammogram at Epa=0.66V and Epc= 0.56V ( vs . Ag/AgCl). Radical cation salts of FcVT are prepared by using iodine and HBF 4 , of which pressed pellet conductivities are in the range of 10 −2 –10 −3 S/cm at room temp.

Multifunctional Nickel-Bisdithiolate Complexes with trans -4-[2-(1-Ferrocenyl)Vinyl]-1-Methylpyridinium Cation

Nickel-bisdithiolate complexes with a ferrocene-containing 2nd order nonlinear optical chromophore as a cation, (FcCH=CHPyMe)[NiL 2 ] where L=dmit (1a), dddt (1b) and debt (1c) were synthesized by the cation exchange reaction. In the X-ray crystal structure of complex (1a), no intrastack but interstack S…S interactions less than 3.7 A are observed. This complex was revealed to be an insulator at room temperature. However, (FcCH=CHPyMe) x [Ni(dmit) 2 ] (0<x<1) (3) needle grown in an H-type electrochemical cell shows semiconductor behavior ( E a =106 meV) over the temperature range measured (30∼300 K) with σ RT =1 Ω −1 cm −1 . The electronic transition at UV-vis-NIR region was measured for the nickel complexes and discussed.

Synthesis and crystal structure of an unusual bimetallic mercury–dithiolene complex

A bimetallic mercury(II) dithiolene complex in which the ligand exhibits three different modes of coordination to the mercury atoms within the same molecular species is reported.

Electronic Structure of (NiS4) - Investigated by Single-Crystal EPR and Density Functional Theory

To understand the electronic structure of (NiS4) - complex ions, two complexes with such (NiS4) - core, FcCH〓CHPymCH3(Ni(dmit)2) (Pym = pyridinium, dmit 2- = 2-thioxo-1,3-dithiole-4,5-dithiolate) and FcCH〓CHPymCH3(Ni(dddt)2)•½H2O (dddt 2- = 5,6-dihydro-1,4-dithiin-2,3- dithiolato), were synthesized to be characterized by X-ray crystallography, single crystal electron paramagnetic resonance (EPR) and density functional theory (DFT) calculation. Powder EPR spectra show narrow g-anisotropy but the anisotropy is bigger in (Ni(dmit)2) - than in (Ni(dddt)2) - , indicating bigger spin density in Ni(III) d- orbital of (Ni(dmit)2) - than in (Ni(dddt)2) - , which is consistent to DFT results. EPR studies of the crystals of the complexes surprisingly suggest that the gy-axis of (Ni(dddt)2) - is approximately on or perpendicular to the (NiS4) - plane while the gy- axis of (Ni(dmit)2) - is on the plane, though DFT study of the complexes of this study and previously reported (NiS4) - complexes indicate that the gy-axis is on the (NiS4) -

Selective landing of semiconducting single-wall carbon nanotubes onto tetrathiafulvalene moiety self-assembled on ITO substrate

Semiconducting single-wall carbon nanotubes (SWCNTs) were selectively interacted with tetrathiafulvalene (TTF) moiety self-assembled on indium tin oxide (ITO) substrate by charge-transfer interaction. The charge-transfer phenomena between two molecules were elucidated by cyclic voltammetry (CV) and Raman spectroscopy. CV measurement of TTF-modified ITO substrate as a working electrode presented the difference between heat-treated system and untreated one. The two redox potentials, which are typically related to redox behavior of TTF, were shown in the unheated system during both oxidation and reduction cycles, while the two oxidation peaks were disappeared in the heated system. Raman spectra indicated that the intensities of RBM originated from metallic SWCNTs were much reduced in the heat-treated system, while there were little change in the unheated one. These results revealed that only semiconducting SWNTs were selectively adsorbed on the TTF moiety self-assembled on ITO when the system with heat treatment.