B12 and Related Organocobalt Chemistry: Formation and Cleavage of Cobalt Carbon Bonds

Synthesis and characterization of aquo[N,N′-ethylenebis(3-ethoxysalicylideneaminato)]dioxouranium(VI)

Ten copper(II) complexes of tetradentate Schiff bases obtained by condensing two moles of an o-hydroxyphenylcarbonyl compound with a diamine have been prepared and characterized by elemental analyses, melting points, IR and electronic spectra. The IR and electronic spectra of the free ligand and the complexes are compared and discussed. The deconvolution of the visible spectra of the complexes in CHCl3, approximately C2V or C1, yielded four peaks at ca. 15000, 17000, 18000-19000, and 20000-22000 cm−l, assigned to the four d-d transitions.

Tetradentate Schiff Base Copper(II) Complexes

The use of metal complexes fac-tris(1-phenylpyrazolato-N,C2‘)cobalt(III) [fac-Co(ppz)3], fac-tris(2-phenylpyridinato-N,C2‘)cobalt(III) [fac-Co(ppy)3], and {tris[2-((pyrrole-2-ylmethylidene)amino)ethyl]amine}gallium(III) [Ga(pma)] as materials for hole-transporting layers (HTL) in organic light-emitting diodes (OLEDs) is reported. Co(ppz)3 and Co(ppy)3 were prepared by following literature procedures and isolated as mixtures of facial (fac) and meridional (mer) isomers. The more stable fac isomers were separated from the unstable mer forms via column chromatography and thermal gradient sublimation. Crystals of fac-Co(ppz)3 are monoclinic, space group P21/c, with a = 13.6121(12) A, b = 15.5600(12) A, c = 22.9603(17) A, β = 100.5°, V = 4781.3(7) A3, and Z = 8. {Tris[2-((pyrrol-2-ylmethylidene)amino)ethyl]amine}gallium [Ga(pma)] was prepared by the reaction of gallium(III) nitrate with the pmaH3 ligand precursor in methanol. Ga(pma) crystallizes in the cubic space group I43d with cell parameters a = 20.2377(...

Organometallic complexes as hole-transporting materials in organic light-emitting diodes

CoIII(S2CNR2)3 (R = Et, cyclohexyl) complexes were electrochemically oxidised by one-electron in CH2Cl2 containing Bu4NPF6 as the supporting electrolyte. Voltammetric, EPR and UV-VIS-NIR spectroscopic data indicated that the cation complexes, [CoIV(S2CNR2)3]+, formed by oxidation of the parent CoIII compounds were stable for at least several hours at low temperatures (T
 = 233 K), although instability was evident at higher temperatures and/or longer times. EPR spectroscopic data obtained by in situ electrogeneration of the oxidised species at low temperatures indicated that the unpaired electron largely resided on the metal centre, thereby confirming a formally CoIV state. The UV-VIS-NIR spectra of the [CoIV(S2CNR2)3]+
complexes showed a new set of low energy and moderate intensity series of bands at ν
 = 9600, 13300 and 15500 cm−1 (e
 = 700–1500 L cm−1 mol−1) which were interpreted as ligand-to-metal charge transfer excitations to the unfilled t2g orbital. The EPR spectra of [CoIV(S2CNR2)3]+ (g//
≈ 2.65 and g⊥
≈ 1.90) required low temperatures to be detected (T < ca. 50 K) and displayed a high degree of anisotropy consistent with a distorted octahedral structure.

Voltammetric, EPR and UV-VIS-NIR spectroscopic studies associated with the characterisation of electrochemically generated tris(dithiocarbamato)cobalt(IV) complexes in dichloromethane

Electrochemistry of organometallic compounds. Part IV. Oxidations of benzylic derivatives and p-substituted benzylic derivatives of bis(dimethylglyoximato) and bis(salicylaldehyde)o-phenylenediimine cobalt(III) in dimethylformamide

E.R. Dockal

Papers

Electrochemistry of organometallic compounds. Part IV. Oxidations of benzylic derivatives and p-substituted benzylic derivatives of bis(dimethylglyoximato) and bis(salicylaldehyde)o-phenylenediimine cobalt(III) in dimethylformamide