- Highly Selective Colorimetric and Luminescence Response of a Square-Planar Platinum(II) Terpyridyl Complex to Aqueous TcO4
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Molecular recognition of an aqueous pertechnetate (TcO4-) anion is fundamentally challenging partly due to the charge-diffuse nature of this anion, which hampers design of new technologies for its separation and detection. To address this gap, simple salts of transition metal complexes that undergo a distinct spectroscopic change upon exposure to aqueous anions were explored. The Pt(II) complex [Pt(tpy)Br]SbF6 (tpy = 2,2′;6′,2″-terpyridine) undergoes a dramatic color change and intense luminescence response upon TcO4- uptake due to concomitant enhancement of Pt···Pt interactions. The spectroscopic response was highly selective and quantitative for aqueous TcO4- among other competing anions. Complementary Raman spectroscopy and microscopy techniques, structural determination, and theoretical methods were employed to elucidate the mechanism of this response at the molecular level.
- Chatterjee, Sayandev,Norton, Amie E.,Edwards, Matthew K.,Peterson, James M.,Taylor, Stephen D.,Bryan, Samuel A.,Andersen, Amity,Govind, Niranjan,Albrecht-Schmitt, Thomas E.,Connick, William B.,Levitskaia, Tatiana G.
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- LIGATING PROPERTIES OF THIONITROSOAMINES. II. CRYSTAL AND MOLECULAR STRUCTURE OF cis-DICHLORO-(N-THIONITROSODIMETHYLAMINE)(TRIPHENYLARSINE)PALLADIUM(II) COMPLEX. SYNTHESIS AND CHARACTERIZATION OF NEUTRAL BINUCLEAR COMPLEXES OF PALLADIUM(II) AND CATIONIC COMPLEXES OF PALLADIUM(II) AND ...
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The crystal and molecular structure of Pd(SNNMe2)(AsPh3)Cl2 was determined from single-crystal X-ray diffraction data.In agreement with the structure previously proposed on the basis of IR data, the complex has the cis-configuration with the Me2NNS ligand S-bonded to the metal.It crystallizes in the space group P with a 9.407(2), b 10.540(2), c 12.265(4) Angstroem; α 68.1(1), β 78.3(1), γ 86.3(1) deg and Z = 2.The structure was refined to R = 0.029 for 2664 diffractometer data with I 3?(I).The palladium atom is in a nearly square planar coordination geometry with Pd-S 2.249(1), Pd-As 2.362(1), Pd-Cl(1) 2.313(1), Pd-Cl(2) 2.359(1) Angtroem.The very short Pd-S bond length may indicate a strong ? + ? synergistic interaction of the Pd atom with the N-thionitrosodimethylamine ligand.Me2NNS reacts with Pd(PhCN)2Cl2 to give, besides the known cis-Pd(SNNMe2)2Cl2, the complex 2> (IIIa), and an unstable compound which is probably Cl2.The stable salts (BPh4)2 (IVa) and HgCl4 (IVd) were obtained from this unstable compound and NaBPh4 or HgCl2.Alternatively the stable salts (PF6)2 (IVb) and PdCl4 (IVc) were obtained from Me2NNS and (PF6)2 (diene = 1,5-cyclooctadiene, norbornadiene) or Na2PdCl4.Me2NNS reacts with Pt(PhCN)2Cl2 to form an unstable compound probably Cl2 which was obtained in the stable form as Y2 (Y = BPh4 (Va), PF6 (Vb); Y2 = PtCl4 (Vc)).The complexes 2> (X = Cl (IIIa), Br (IIIb), SCN (IIIc), SeCN (IIId)) were prepared by reaction of Pd(PhCN)2Cl2 with Pd(SNNMe2)2X2.
- Tresoldi, Giuseppe,Bruno, Giuseppe,Piraino, Pasquale,Faraone, Giovanni,Bombieri, Gabriella
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- On the mechanistic behavior of highly efficient palladium-tetraphosphine catalytic systems for cross-coupling reactions: First spectroscopic and electrochemical studies of oxidative addition on Pd(0)/multidentate ferrocenylpolyphosphine complexes
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Electrochemical studies carried out in conjunction with 31P NMR spectroscopy on the palladium(II)/ palladium(O) halogeno complexes of the tetraphosphine 1,1′,2,2′-tetrakis(diphenylphosphino)-4,4′-di- tert-butylferrocene, termed Fc(P4)tBu, are reported. Fc(P4)1Bu was chosen with regard to its good performances in pallado-catalyzed cross-coupling reactions, which resulted in catalytic turnover numbers (TONs) up to 1 000 000 [Organometallics 2003, 22, 4490-4499]. The complexes [PdX2(Fc(P)4tBu}] (X = Cl, Br, I) are described with their X-ray molecular characterization in the solid state and multinuclear NMR in solution. The electrochemical behavior of Fc(P 4)tBu and [PdX2{Fc(P)4 tBu}] complexes was investigated by cyclic voltammetry and electrolysis: a formulation of the corresponding electro-generated Pd 0 species formed is proposed on the basis of their NMR characterization. The oxidative addition reaction of phenyl iodide on these zerovalent palladium/ferrocenyltetraphosphine complexes was also studied by combining electrochemistry and 31P NMR. The Pd(II) species that result from phenyl iodide oxidative addition are described, and their rate of formation under standard conditions is given; the halogeno phenyl products obtained are identified and characterized. These results are discussed in light of the knowledge existing for more classical systems combining Pd(II) halides or zerovalent palladium with n monodentate tertiary phosphines (n = 2-4). In this respect, me system using Fc(P4)tBu is relevant since its four triarylphosphine groups (Ph2PCp) are formally similar to a 4-fold excess of the triarylphosphine triphenylphosphine (PPh3) as ligand. However, the phosphorus atoms of the tetraphosphine ligand present a mutual spatial proximity that is absent in monophosphines, due to their implantation on the ferrocene platform. Therefore, the possible effects of multidentarity are discussed. Finally, the importance of palladium anionic species is confirmed in this study, and the rate value of Ph-I oxidative addition (130 ± 10 ms) on Pd(0) confirmed both the good reactivity and the enhanced stability provided to palladium species by the ferrocenyltet- raphosphine ligand.
- Evrard,Lucas,Mugnier,Meunier,Hierso
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p. 2643 - 2653
(2009/02/02)
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