Cobaltoceniumselenolate is an unusual, highly air‐sensitive, mesoionic compound containing a very soft anionic selenium donor atom. Here we explore its coordination chemistry with Au(I) metal centers and show that its hetero‐ and homoleptic gold complexes are highly colored, air‐stable compounds, which were characterized by
1
H/
13
C/
31
P/
77
Se NMR, IR, UV‐Vis, HR‐MS and single crystal XRD. Cytotoxicity of these polar, water‐soluble complexes was studied against various standard cancer cell lines (A549MDA‐MB‐231, HT‐29) revealing good anticancer activity of all three complexes.
Cobaltocenium carbaldehyde (formylcobaltocenium) hexafluoridophosphate,
a long sought-after functionalized cobaltocenium salt, is accessible
from cobaltocenium carboxylic acid by a three-step synthetic sequence
involving (i) chlorination to the acid chloride, (ii) copper-borohydride
reduction to the hydroxymethyl derivative, and (iii) Dess–Martin
oxidation to the title compound. Due to the strongly electron-withdrawing
cationic cobaltocenium moiety, no standard aldehyde reactivity is
observed. Instead, nucleophilic addition followed by haloform-type
cleavage prevails, thereby ruling out common useful aldehyde derivatization.
One-electron reduction of cobaltocenium carbaldehyde hexafluoridophosphate
affords the deep-blue, isolable cobaltocene carbaldehyde 19-valence-electron
radical whose spin density is located fully at cobalt and not at the
formyl carbon atom. 1H/13C NMR, IR, EPR spectroscopy,
high-resolution mass spectrometry, cyclic voltammetry, single crystal
structure analysis (XRD), and density functional theory are applied
to characterize these unusual formyl-cobaltocenium/cobaltocene compounds.
The title compound, [Co(C5H5)(C10H9N2)]PF6, was synthesized from deprotonated 1-aminopyridinium iodide, followed by microwave-assisted nucleophilic aromatic substitution of iodo-cobaltocenium iodide. After anion exchange with potassium hexafluoridophosphate, the title compound crystallizes as orange prisms in the space group Pc. This very stable pyridine nitrene adduct is the first example of a cobaltocenium derivative, formally containing a nitrene nitrogen species.
The title compound, [Co6Hg2(C5H5)6(C5H4Se)6](PF6)4·2CH3CN or [Hg2(CcSe)6][PF6]4·2CH3CN (Cc = C10H9Co), was obtained as bright-orange needle-shaped crystals. It is a salt containing a tetracationic dimercury species with six cobaltoceniumselenolate ligands, four hexafluoridophosphate counter-ions and two acetonitrile solvent molecules. The cation (point group \overline{1}) has a bitetrahedral {Hg2Se6} core with two bridging Se atoms and four terminal Se atoms.
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