Electrochemical investigation of the kinetics of chloride substitution upon reduction of [Ru(porphyrin)(NO)Cl] complexes in THF.

The electrochemistry of several ruthenium porphyrin nitrosyl chloride complexes [Ru(por)(NO)Cl] have been examined in tetrahydrofuran. The complexes undergo 1-electron irreversible reductions which result in the diffusion-limited substitutions of the chloride ligands for THF. This chloride metathesis is reversible in the presence of added NBu4Cl, and equilibrium constants and rate constants for chloride loss have been estimated. These parameters correlate with the NO stretching frequencies of the parent complexes, with more electron-donating porphyrin ligands favouring chloride loss from the reduced complexes. The [Ru(por)(NO)(THF)] products of the reductions can be detected by IR, EPR and visible spectroscopies. These species undergo three further reductions, with good reversibility at scan rates \u3e0.40 V s-1. The [Ru(por)(NO)(THF)]+/0 couples have also been determined, and the rate constants and equilibrium constants for recombination with chloride have been estimated. One-electron reductions of the [Ru(por)(NO)Cl] complexes result in ~1018 enhancement of the rates of chloride loss

Over or Under: Hydride Attack at the Metal versus the Coordinated Nitrosyl Ligand in Ferric Nitrosyl Porphyrins.

Hydride attack at a ferric heme–NO to give an Fe–HNO intermediate is a key step in the global N--‐cycle. We demonstrate differential reactivity when six--‐ and five--‐coordinate ferric heme--‐NO models react with hydride. Although Fe–HNO formation is thermodynamically favored from this reaction, Fe–H formation is kinetically favored for the 5C case

Bis(cobaltocenium) tetrachloridocobaltate(II) dichloromethane 1.2-solvate

The structure of bis(cobaltocenium) tetrachloridocobaltate(II) dichloromethane 1.2-solvate, [Co(C5H5)2]2[CoCl4]1.2CH2Cl2, has been determined at 100 K. The title compound crystallizes in the space group P1 and is an example of an unusual Z0 = 5 structure. The asymmetric unit contains ten cobaltocenium ions, five tetrachloridocobaltate(II) ions and six molecules of dichloromethane, i.e. 5{[Cp2Co]2[CoCl4]}6CH2Cl2. All the cobaltocenium ions are determined to be in the eclipsed conformation with respect to the cyclopentadienyl rings

Bis(cobaltocenium) tetrachloridocobaltate(II) dichloromethane 1.2-solvate

The structure of bis(cobaltocenium) tetrachloridocobaltate(II) dichloromethane 1.2-solvate, [Co(C5H5)2]2[CoCl4]·1.2CH2Cl2, has been determined at 100 K. The title compound crystallizes in the space group P\overline{1} and is an example of an unusual Z′ = 5 structure. The asymmetric unit contains ten cobaltocenium ions, five tetrachloridocobaltate(II) ions and six molecules of dichloromethane, i.e. 5{[Cp2Co]2[CoCl4]}·6CH2Cl2. All the cobaltocenium ions are determined to be in the eclipsed conformation with respect to the cyclopentadienyl rings