Electron transfer and CO addition to polynitrido cobalt carbonyl clusters: Parallel pathways for conversion of the [Co10N2(CO)(19)](4-) anion to the novel [Co11N2(CO)(21)](3-) anion

The redox aptitude of the dinitrido anion [Co10N2(CO)19]4- has been tested from both chemical and electrochemical points of view, together with its reactivity toward CO that induces disproportionation. In any case, through a remarkable overlapping of intermediate steps, the new anion [Co11N2(CO)21]3- (4) is eventually obtained. A detailed study of the pathways to 4 allowed the identification of three labile intermediates by their characteristic IR spectra as well as their electrochemical and paramagnetic properties. The unprecedented structure of trianion 4 has been studied in details in two different crystalline salts

Sphingoid esters from the molecular distillation of squid oil: A preliminary bioactivity determination

A mixture of sphingoid esters was isolated (1.4% w/w) from the molecular distillation of crude squid visceral oil. A preliminary investigation on the bioactivity profile and toxic potential of this residue was carried out by in vitro experiments. No cytotoxicity and a moderate lipase inhibition activity were highlighted

C-H and C-C bonds activation by iridium clusters: Synthesis and solid state structure of [Ir6(CO)14(μ3- η1:η2:η1-C7H 8)]

The reaction between norbornene (C7H10) and Ir 6(CO)16 in refluxing toluene yields the substituted cluster [Ir6(CO)14(C7H8)]. In the solid state, the six iridium atoms define an octahedral metal cage, and one face is capped by the C7H8 ligand, coordinated through a 1,2-vinylidene unit. The loss of two hydrogen atoms from the olefin is, presumably, the result of a double oxidative addition of its C-H bonds, followed by elimination of a hydrogen molecule from the cluster. The bonding parameters of the organic fragment, as well as the architecture of the carbonyl ligands, closely match those found in the alkyne-substituted [Ir6(CO) 14(PhCCPh)] complex. The cluster [Ir6(CO) 14(C7H8)] was characterized through 1H-, 13C- and bidimensional COSY NMR. © 2005 Elsevier B.V. All rights reserved

Periodical trends in [Co6E(CO)16]- clusters: Structural, synthetic and energy changes produced by substitution of P with As

The anionic cluster [Co6As(CO)16]-was synthesized through the reaction of Na[Co(CO)4] and arsenic acid in THF at room temperature. Crystallization from MeOH/2-propanol yielded two polymorphs that feature two slightly different isomers of the anion with the same PPh4+cation. One of the isomers is very similar to the known [Co6P(CO)16]-, formed by four edge fused triangles, partially wrapping the main group atom. The other isomer features a deformed cage, which differs mainly for a non-bonding Co-Co distance. The reasons for this unprecedented stereochemistry, and the factors which may trigger this isomer, have been investigated by DFT calculations

From Small Metal Clusters to Molecular Nanoarchitectures with a Core-Shell Structure: The Synthesis, Redox Fingerprint, Theoretical Analysis, and Solid-State Structure of [Co38As12(CO)50]4

The cluster [Co38As12(CO)50]4- was obtained by pyrolysis of [Co6As(CO)16]-. The metal cage features a closed-packed core inside a Co/As shell that progressively deforms from a cubic face-centered symmetry. The redox and acid-base reactivities were determined by cyclic voltammetry and spectrophotometric titrations. The calculated electron density revealed the shell-constrained distribution of the atomic charges, induced by the presence of arsenic

Mixed Co-Rh nitrido-encapsulated carbonyl clusters. Synthesis, Solid-State Structure, and Electrochemical/EPR Characterization of the anions [Co10Rh(N)2(CO)21]3 , [Co10Rh2(N)2(CO)24]2- and [Co11Rh(N)2(CO)24]2-

The nitrido-encapsulated heterometallic cluster anions [Co10Rh(N)2(CO)21]3- (1), [Co10Rh2(N)2(CO)24]2- (2), and [Co11Rh(N)2(CO)24]2- (3), have been obtained by tailored redox-condensation reactions. These three anions are rare high-nuclearity mixed-metal clusters containing two interstitial nitrogen atoms. Their structures have been determined by single-crystal X-ray diffraction on their [NR4]+ salts (R = Me for 1 and 3, R = Et for 2) and their electrochemical and ESR properties have been studied in detail. Noteworthy, 1 has an unprecedented stereochemistry, that does not exhibits a close geometrical resemblance with the isoelectronic homometallic anion [Co11N2(CO)11(\u3bc2-CO)10]3-; and 2, despite its even number of electrons, is a paramagnetic species

Mixed Co-Rh nitrido-encapsulated carbonyl clusters. Synthesis, solid-state structure, and electrochemical/EPR characterization of the anions [Co10Rh(N)2(CO)21]3-, [Co10Rh2(N)2(CO)24]2-, and [Co11Rh(N)2(CO)24]2-

The nitrido-encapsulated heterometallic cluster anions [Co10Rh(N)2(CO)21]3-(1), [Co10Rh2(N)2(CO)24]2-(2), and [Co11Rh(N)2(CO)24]2-(3) have been obtained by tailored redox-condensation reactions. These three anions are rare high-nuclearity mixed-metal clusters containing two interstitial nitrogen atoms. Their structures have been determined by single-crystal X-ray diffraction on their [NR4]+salts (R = Me for 1 and 3, R = Et for 2), and their electrochemical and ESR properties have been studied in detail. It is noteworthy that 1 has an unprecedented stereochemistry that does not exhibit a close geometrical resemblance with the isoelectronic homometallic anion [Co11N2(CO)11(μ2-CO)10]3-, and 2, despite its even number of electrons, is a paramagnetic species. © 2007 American Chemical Society