12427-42-8Relevant academic research and scientific papers
Rational Synthesis of Metallo-Cations Toward Redox- A nd Alkaline-Stable Metallo-Polyelectrolytes
Zhu, Tianyu,Sha, Ye,Firouzjaie, Horie Adabi,Peng, Xiong,Cha, Yujin,Dissanayake, D. M. M. Mevan,Smith, Mark D.,Vannucci, Aaron K.,Mustain, William E.,Tang, Chuanbing
, p. 1083 - 1089 (2020)
Cations are crucial components in emerging functional polyelectrolytes for a myriad of applications. Rapid development in this area necessitates the exploration of new cations with advanced properties. Herein we describe a combination of computational and experimental design of cobaltocene metallo-cations that have distinct electronic and redox properties. One of the direct outcomes on the first synthesis of a complete set of cation derivatives is to discover highly stable cations, which are further integrated to construct metallo-polyelectrolytes as anion-exchange membranes in solid-state alkaline fuel cells. The device performance of these polyelectrolytes under highly basic and oxidative environments is competitive with many organo-polyelectrolytes.
Mobile metal-metal bonds: Studies on mixed valence Ir3 and Ir4 clusters
Venturelli, Anne,Rauchfuss, Thomas B.
, p. 4824 - 4831 (1994)
The dicationic clusters [(C5Me5)4Ir4S4] 2+ ([1]2+) and [(C5Me5)3Ir3S2] 2+ ([2]2+) were prepared by treatment of [(C5Me5)IrCl2]2 with (Me3Si)2S followed by ion exchange chromatography. Crystallographic characterization of the tetrairidium cluster [1]2+ reveals a cubane motif consisting of interpenetrated Ir4 and S4 tetrahedra. The Ir4 core is distorted from idealized tetrahedral symmetry by virtue of a single IrIV-IrIV bonding contact of 2.764(1) ?. The four IrIV-IrIII contacts are nearly equivalent at 3.5 ?, while the IrIII?IrIII distance is 3.683(1) ?. Variable-temperature 1H NMR studies indicate that [I]2+ is fluxional with a coalescence temperature of 13 °C (400 MHz), corresponding to ΔG? = 57 kJ/mol. This dynamic process is attributed to migration of the metal-metal bond arising from internal IrIV/IrIII self-exchange. Cyclic voltammetry studies of [1]2+ reveal a pair of reversible one-electron reductions at -218 and -487 mV vs Ag/AgCl. Chemical reduction of [1]2+ was effected with cobaltocene while the neutral cluster could be reoxidized with HC1/O2. In the solid state [1]2+ features a trigonal-bipyramidal Ir3S2 core with average Ir-Ir contacts of 2.82 ? and Ir-S distances of 2.28 ?. Cyclic voltammetry studies indicate that this closo dication undergoes two single electron reductions at -712 and -993 mV. Cobaltocene reduction of [2]2+ afforded dark blue crystals of neutral [2]0. Variable-temperature 1H NMR spectra of [2]0 reveal dynamic behavior, with coalescence at 60 °C (400 MHz), corresponding to ΔG? = 64 kJ/mol. These structural dynamics suggest migration of the nonbonding Ir?Ir interaction among the three edges of the Ir3 triangle.
Unprecedented tris-phosphido-bridged triangular clusters with 42 valence electrons. chemical, electrochemical and computational studies of their formation and stability
Funaioli, Tiziana,Leoni, Piero,Marchetti, Lorella,Albinati, Alberto,Rizzato, Silvia,Fabrizi De Biani, Fabrizia,Ienco, Andrea,Manca, Gabriele,Mealli, Carlo
, p. 4635 - 4647 (2013)
This paper presents the synthesis and structural characterization of the unprecedented tris-phosphido-bridged compounds Pt3(μ-PBu t2)3X3 (X = Cl, Br, I), having only 42 valence electrons, while up to now analogous clusters typically have 44e -. The new species were obtained by an apparent bielectronic oxidation of the 44e- monohalides Pt3(μ-PBu t2)3(CO)2X with the corresponding dihalogen X2. Their X-ray structures are close to the D3h symmetry, similarly to the 44e- analogues with three terminal carbonyl ligands. The products were also obtained by electrochemical oxidation of the same monohalides in the presence of the corresponding halide. In a detailed study on the formation of Pt3(μ-PBut 2)3I3, the redox potentials indicated that I2 can only perform the first monoelectronic oxidation but is unsuited for the second one. Accordingly, the 43e- intermediate [Pt3(μ-PBut2)3(CO) 2I]+ was ascertained to play a key role. Another piece of information is that, together with the fully oxidized product Pt 3(μ-PBut2)3I3, the transient 44e- species [Pt3(μ-PBut 2)3(CO)3]+ is formed in the early steps of the reaction. In order to extract detailed information on the formation pathway, involving both terminal ligand substitutions and electron transfer processes, a DFT investigation has been performed and all the possible intermediates have been defined together with their associated energy costs. The profile highlights many important aspects, such as the formation of an appropriate couple of 43e- intermediates having different sets of terminal coligands, and suitable redox potentials for the transfer of one electron. Optimizations of 45e- associative intermediates in the ligand substitution reactions indicate their possible involvement in the redox process with reduction of the overall energy cost. Finally, according to MO arguments, the unique stability of the 42e- phosphido-bridged Pt 3 clusters can be attributed to the simultaneous presence of three terminal halides.
Biolabeling with cobaltocinium tags
Müller-Bomke, Susanne,Sperling, Michael,Hayen, Heiko,Karst, Uwe
, p. 781 - 791 (2018)
A label for amino and thiol functionalities of peptides and proteins based on the activated cobaltocinium hexafluorophosphate succinimide ester (CoS) is presented. Despite the known selectivity of a succinimide ester towards amines, CoS also modifies cysteine residues under the same reaction conditions. The derivatized biomolecules were investigated using liquid chromatography with subsequent electrospray-mass spectrometric detection (LC/ESI-MS). In combination with their remarkable stability under physiological conditions, easy handling and good spectroscopic properties, cobaltocinium ions provide all requirements for a powerful labeling reagent. Furthermore, in direct comparison to the isoelectronic well-established ferrocene reagents, the higher redox potential and the chemical stability of the cobaltocinium moiety add to the benefits as a derivatizing agent for bioanalysis.
Synthesis and solution self-assembly of side-chain cobaltocenium-containing block copolymers
Ren, Lixia,Hardy, Christopher G.,Tang, Chuanbing
, p. 8874 - 8875 (2010)
The synthesis of side-chain cobaltocenium-containing block copolymers and their self-assembly in solution was studied. Highly pure monocarboxycobaltocenium was prepared and subsequently attached to side chains of poly(tert-butyl acrylate)-block-poly(2-hyd
Crystal forms of hexafluorophosphate organometallic salts and the importance of charge-assisted C-H - F hydrogen bonds
Grepioni, Fabrizia,Cojazzi, Gianna,Draper, Sylvia M.,Scully, Noelle,Braga, Dario
, p. 296 - 307 (1998)
Architecture, stability, and behavior with temperature of the hexafluorophosphate salts [(C5H5)2Co][PF6] (1), [(C5H5)2Fe][PF6] (2), [(C6H6)2Cr][PF6] (3), and [(C6H5Me)2Cr][PF6] (4) have been investigated. Crystals 1 and 2 have been measured by variable-temperature X-ray diffraction and differential scanning calorimetry. The phase-transitional behavior of [(C5H5)2Co][PF6], which undergoes two fully reversible crystal-to-crystal phase transitions, has been compared with the known behavior of [(C5H5)2Fe][PF6]. The room- and low-temperature phases (form I and form II) of [(C5H5)2Fe][PF6] and [(C5H5)2Co][PF6] are isostructural and isomorphous. The basic packing features of crystalline 1 and 2 are maintained on substituting the metallocene system with the bisbenzenechromium cation in 3. The architecture common to the three salts is otherwise disrupted by substituting toluene for benzene in 4. It has been shown that, when assisted by the difference in charge between anions and cations, the C-H - F interactions play a significant role. The structural parameters obtained for C-H - F interactions in 1-4 have been compared with data retrieved from the Cambridge Crystallographic Database on interactions of the X-H - F(δ-) type (X - C, N, O) in organometallic salts of the PF6- anion.
Synthesis, crystal structure and comparative electrochemistry of metallocenyldiphenylphosphines of ruthenocene, osmocene, ferrocene and cobaltocenium hexafluorophosphate
Fourie, Eleanor,Van Rensburg, J. Marthinus Janse,Swarts, Jannie C.
, p. 80 - 87 (2014/02/14)
The metallocenyldiphenylphosphines [M(C5H5)(C 5H4PPh2)] with M = Fe(II) (ferrocenyl = Fc), 1, Ru(II) (ruthenocenyl = Rc), 2, Os(II) (osmocenyl = Oc), 3, and Co(III) +PF6- (cobaltocenium hexafluorophosphate = [Cc][PF6]), 4, were synthesized and the crystal structure of RcPPh2, 2, (Z = 4, monoclinic, space group P21/c) was determined. The differences in reactivity of each metallocenyl derivative were such that 1 could be obtained from a Friedel Crafts reaction between ferrocene and PPh2Cl in the presence of AlCl3 as catalyst. Both the ruthenocene and osmocene derivatives 2 and 3 were obtained by reacting the monolithiated metallocene precursor with PPh2Cl. However, monolithiation of ruthenocene had to be achieved via a stoichiometric amount of tBuLi. For osmocene, monolithiation was achieved by a 20% excess of nBuLi. This was evidenced by the failure to isolate any bisphosphine, Oc(PPh2)2, during workup. Complex 4 could not be obtained via phosphination of free cobaltocenium hexafluorophosphate. Phosphine derivatisation of free cyclopentadiene prior to complexation with Co III was required to form [CcPPh2][PF6], 4. The electrochemistry of all phosphines was studied by voltammetric techniques in CH2Cl2/0.1 mol dm-3 [N(nBu) 4][B(C6F5)4]. A reversible one-electron transfer process for the ferrocenyl group of 1 was observed at 0.078 V vs. FcH/FcH+. The osmocenyl and ruthenocenyl derivatives exhibited irreversible metallocenyl oxidations at 0.355 and 0.476 V respectively. The cobaltocenium complex, 4, exhibited two reversible one-electron transfer reductions to liberate first a neutral CoII cobaltocene species at -1.062 V and then an anionic CoI cobaltocene species at -2.122 V. A single electrochemical irreversible, one-electron oxidation at the phosphorus centre which forms a quickly-decomposing phosphorus radical cation, Mc+Ph2P+, was also observed at Epa > 0.754 V. The newly-formed Mc+Ph2P + species or its chemical decomposition products can be oxidized at Epa > 1.090 V vs. FcH/FcH+.
Synthesis, electrochemistry, and reactivity of half-sandwich ruthenium complexes bearing metallocene-based bisphosphines
Shaw, Anthony P.,Norton, Jack R.,Buccella, Daniela,Sites, Lauren A.,Kleinbach, Shannon S.,Jarem, Daniel A.,Bocage, Katherine M.,Nataro, Chip
, p. 3804 - 3814 (2009/12/04)
The bimetallic complexes CpRu(P-P)X [Cp = n5-C5H 5; X = Cl, H; P-P = dppf (1,1′-bis(diphenylphosphino)ferrocene) , dppr (1,1′-bis(diphenylphosphino)ruthenocene), dppo (1,1′- bis(diphenylphosphino)-osmocene), dippf (1,1′-bi
Molecular and electronic structure of square planar complexes [Pd II(tbpy)(LN,OIP)]0, [PdII(tbpy)(LN,OISQ](PF 6), and [PdII(tbpy)(LN,O IBQ](PF6)(BF4)·2CH2Cl 2
Kokatam, Swarna-Latha,Chaudhuri, Phalguni,Weyhermueller, Thomas,Wieghardt, Karl
, p. 373 - 378 (2008/02/06)
Three PdII complexes which are members of the same electron-transfer series have been synthesized. Refluxing of the reaction mixture containing equimolar amounts of PdCl2, 2-(2-trifluoromethyl) anilino-4,6-di-tert-butylphenol (H2LN,O), 4,4′-di-tert-butyl-2,2′-dipyridyl (tbpy), and 3 equiv of triethylamine in MeOH under an argon atmosphere followed by exposure to air and addition of KPF6 after cooling to room temperature yields reddish brown crystals of paramagnetic (S = 1/2) [Pd(LISQN,O)(tbpy)](PF 6) (2). Reaction of 2 with one equiv of [CoCp2] in dry and degassed CH2Cl2 using anaerobic conditions gives diamagnetic [Pd(LIPN,O)(tbpy)] (1), which is the one-electron reduced form of 2. One-electron oxidation of 2 in CH2Cl2 under argon with one equiv of NOBF4 affords diamagnetic [Pd(LIBQN,O)( tbpy)](PF6)(BF4)·2CH2Cl 2 (3). Complexes 1, 2, and 3 constitute three members of the same electron-transfer series. They are ideally suited to distinctly distinguish the geometrical and spectroscopic features of the N,O-coordinated, closed-shell, diamagnetic o-iminophenolate (LIPN,O)2-, the corresponding open-shell π-radical o-iminobenzosemiquinonate (LISQN,O)1- (Srad = 1/2), and the closed-shell o-iminobenzoquinone (LIBQN,O)0 forms. All complexes were characterized by X-ray crystallography (100 K), cyclic voltammetry, EPR, and UV-vis spectroscopy. Complex 2 exhibits three reversible electron transfer waves in the cyclic voltammogram. Structural characterization of complex 3 reveals an interesting strong ion pairing between the BF 4 anion and the complex dication with a short C-F distance of 2.7 A. The Royal Society of Chemistry.
Synthesis and characterization of a bimetallic boratabenzene cobalt complex
Hascall, Tony,Beck, Victoria,Barlow, Stephen,Cowley, Andrew R.,O'Hare, Dermot
, p. 3808 - 3813 (2008/10/09)
Reaction of 1,4-(BBr2)2C6H4 with cobaltocene gives a bimetallic cobalt complex with cyclopentadienyl and boratabenzene ligands. Oxidation allows the dicationic dicobalt(III) complex to be isolated; the bis(hexafluorophosphate) salt has been structurally characterized. Variable-temperature magnetic susceptibility measurements on the neutral dicobalt(II) complex showed substantial deviation from the Curie -Weiss law; a fit to the Bleaney-Bowers equation for a singlet ground state and a triplet excited state gave an exchange interaction of J = ca. -28 cm -1. Electrochemical studies, as well as near-infrared data on the mixed-valence species, suggest that the interaction between the metal centers is weak.
