Solvent-free mechanochemical synthesis of dithiophosphonic acids and corresponding nickel(II) complexes

<p>We report a green chemistry route for dithiophosphonic acids of the type [HS₂P(OR)(4-MeOC₆H₄)] [R = H, (<b>1</b>); Me (<b>2</b>); Et (<b>3</b>); <i>ⁱ</i>Pr (<b>4</b>)]. The different dithiophosphonic acids formed through the stoichiometric addition of water or alcohols to Lawesson's Reagent (molar ratio 2:1), followed by an intimate grinding of the mixture (mechanochemistry). The products formed without the use of solvent or external heat in less than 5 minutes. The acids are formed with 100% atom economy, and because they form in essentially quantitative yield, are also formed with >98% atom efficiency and an E-factor = 0, because no waste is produced. Of importance is that this methodology is different from conventional methods in forming dithiophosphonic acids where the use of organic solvents, added heat, long reaction times and lower yields are commonplace. We further demonstrate that nickel(II) complexes can form directly from the <i>in situ</i> generated acids. Thus, the reaction between <b>1–4</b> and NiCl₂ ‧ 6 H₂O (molar ratio 2:1) lead to complexes of the type [Ni{S₂P(OR)(4-MeOC₆H₄)}₂] [R = H, (<b>5</b>); Me (<b>6</b>); Et (<b>7</b>); ⁱPr (<b>8</b>)] with no use of organic solvent. All compounds were characterized or verified by a combination of ¹H, ³¹P NMR, elemental analysis (solids), and FT-IR.</p

Heterodimetallic Ferrocenyl Dithiophosphonate Complexes of Nickel(II), Zinc(II) and Cadmium(II) as Sensitizers for TiO 2

The formation, characterization, and dye sensitized solar cell application of nickel(II), zinc(II) and cadmium(II) ferrocenyl dithiophosphonate complexes were investigated. The multidentate monoanionic ligand [S2PFc(OH)]− (L1) was synthesized. The reaction between metal salt precursors and L1 produced Ni(II) complexes of the type [Ni{S2P(Fc)(OH)}2] (1) (molar ratio 1:2), and a tetranickel(II) complex of the type [Ni2{S2OP(Fc)}2]2 (2) (molar ratio (1:1). It also produced a Zn(II) complex [Zn{S2P(Fc)(OH)}2]2 (3), and a Cd(II) complex [Cd{S2P(Fc)(OH)}2]2 (4). Complexes 1–4 were characterized by 1H and 31P NMR, FTIR and elemental analysis, and complexes 1 and 2 were additionally analyzed by X-ray crystallography. The first examples of dye-sensitized solar cells (DSSCs) co-sensitized with ferrocenyl dithiophosphonate complexes 1–4 are reported. Co-sensitization with the ruthenium dye N719, produced the dye materials (3)-N719 (η=8.30%) and (4)-N719 (η=7.78%), and they were found to have a better overall conversion efficiency than the pure Ru N719 dye standard (η=7.14%) under the same experimental conditions. The DSSCs were characterized using UV/vis, cyclic voltammetry, electrochemical impedance spectroscopy (EIS), photovoltaic- (I−V curves), and performing incident photon-to-current efficiency (IPCE) measurements

Heterodimetallic Ferrocenyl Dithiophosphonate Complexes of Nickel(II), Zinc(II) and Cadmium(II) as Sensitizers for TiO2-Based Dye-Sensitized Solar Cells

The formation, characterization, and dye sensitized solar cell application of nickel(II), zinc(II) and cadmium(II) ferrocenyl dithiophosphonate complexes were investigated. The multidentate monoanionic ligand [S2PFc(OH)]− (L1) was synthesized. The reaction between metal salt precursors and L1 produced Ni(II) complexes of the type [Ni{S2P(Fc)(OH)}2] (1) (molar ratio 1:2), and a tetranickel(II) complex of the type [Ni2{S2OP(Fc)}2]2 (2) (molar ratio (1:1). It also produced a Zn(II) complex [Zn{S2P(Fc)(OH)}2]2 (3), and a Cd(II) complex [Cd{S2P(Fc)(OH)}2]2 (4). Complexes 1–4 were characterized by 1H and 31P NMR, FTIR and elemental analysis, and complexes 1 and 2 were additionally analyzed by X-ray crystallography. The first examples of dye-sensitized solar cells (DSSCs) co-sensitized with ferrocenyl dithiophosphonate complexes 1–4 are reported. Co-sensitization with the ruthenium dye N719, produced the dye materials (3)-N719 (η=8.30%) and (4)-N719 (η=7.78%), and they were found to have a better overall conversion efficiency than the pure Ru N719 dye standard (η=7.14%) under the same experimental conditions. The DSSCs were characterized using UV/vis, cyclic voltammetry, electrochemical impedance spectroscopy (EIS), photovoltaic- (I−V curves), and performing incident photon-to-current efficiency (IPCE) measurements