12427-42-8Relevant articles and documents
Kolodsick, Kevin J.,Schrier, Paul W.,Walton, Richard A.
, p. 457 - 462 (1994)
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.
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.
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.
