Electron holography of thin amorphous carbon films: measurement of the mean inner potential and a thickness-independent phase shift.

The phase shift induced by thin amorphous carbon films with thicknesses between 1 and 16 nm was measured by electron holography in a transmission electron microscope. Large phase shifts Delta phi are observed as the thickness of the amorphous C films decreases which cannot be described by the well-known equation Delta phi = CE V0t (V0: mean inner Coulomb potential of the material, t: sample thickness). Data plotted in a Delta phi vs.

Geometrical and electronic structures of dinuclear complex ions {(mu-bpym)[Cu(EAr3)2]2}2+ with intramolecular "organic sandwich" formation (E = P or As; Ar = Aryl; bpym = 2,2'-bipyrimidine).

The compound {(mu-bpym)[Cu(AsPh3)2]2}(BF4)2 (1) has been prepared and studied in comparison with the triphenylphosphine analogue 2. Qualitatively, the structure of 1 with characteristically distorted copper(I) coordination caused by Ph/bpym/Ph sandwich interactions is similar to that of 2 and is approximately reproduced by DFT calculations for the model complex ions {(mu-bpym)[Cu(EMe2Ph)2]2}2+, E = P or As. In contrast, the dinuclear {(mu-bpym)[Cu(P(3-Me-C6H4)3)2]2}(BF4)2 (3) displays a distinctly less distorted metal coordination geometry due to the steric requirements of the methyl groups in the meta-tolyl substituents.

Proof of innocence for the quintessential noninnocent ligand TCNQ in its tetranuclear complex with four [fac-Re(CO)3(bpy)]+ groups: unusually different reactivity of the TCNX ligands (TCNX = TCNE, TCNQ, TCNB).

The reactions of [fac-Re(CO)(3)(bpy)(MeOH)](PF(6)), bpy = 2.2'-bipyridine, with the TCNX ligands (TCNE = tetracyanoethene, TCNQ = 7,7,8,8-tetracyano-p-quinodimethane, and TCNB = 1,2,4,5-tetracyanobenzene) in CH(2)Cl(2) gave very different results. No reaction was observed with TCNB whereas TCNE produced very labile intermediates which converted under mild conditions to structurally characterized [(mu-CN)[fac-Re(CO)(3)(bpy)](2)](PF(6)) with an eclipsed conformation relative to the almost linear Re-CN-Re axis (Re-N(NC) 2.

Low-valent cobalt complexes with three different pi acceptor ligands: experimental and DFT studies of the reduced and the low-lying excited states of (R-DAB)Co(NO)(CO), R-DAB = substituted 1,4-diaza-1,4-butadiene.

The complexes (RN=CH-CH=NR)Co(NO)(CO) with R = isopropyl, 2,6-diisopropylphenyl, or p-tolyl are chemically and electrochemically reducible to radical anions at potentials which strongly depend on R. The DFT calculated structure for the neutral compound with R = iPr agrees with the experiment, and the computed structure of the anion radical reveals changes according to a reduction of the R-DAB ligand. EPR results confirm an (R-DAB)-based singly occupied molecular orbital in [(RNCHCHNR)Co(NO)(CO)](.

Multifrequency EPR study and density functional g-tensor calculations of persistent organorhenium radical complexes.

The dinuclear radical anion complexes [(mu-L)[Re(CO)(3)Cl](2)](*)(-), L = 2,2'-azobispyridine (abpy) and 2,2'-azobis(5-chloropyrimidine) (abcp), were investigated by EPR at 9.5, 94, 230, and 285 GHz (abpy complex) and at 9.5 and 285 GHz (abcp complex).

Reduced and excited states of (bpym)[PtCl(2)](n)() (bpym = 2,2'-bipyrimidine; n = 1, 2): experiments and DFT calculations.

The complexes (bpym)PtCl(2) (1) and the new (micro-bpym)[PtCl(2)](2) (2), bpym = 2,2'-bipyrimidine, were synthesized and, in the case of 1, crystallized in solvent-free form for X-ray diffraction. The molecules 1 exhibit two different kinds of stacking motifs in the crystal with an interstack CH--N interaction. Complexes 1 and 2 were found to be sufficiently soluble for cyclic voltammetry, spectroscopy (absorption and emission), and spectroelectrochemical studies (UV-vis, EPR).

A Fully Characterized Complex Ion with Unreduced TCNQ as Fourfold Bridging Ligand: [(μ -TCNQ){fac-Re(CO) (bpy)} ].

Innocent behavior of a typical non-innocent ligand has been observed for the first structurally characterized discrete metal complex with tetranucleating TCNQ. The coordination of four [Re(CO) (bpy)] units (see picture: C: black, N: green, O: blue, Re: red) facilitates the reduction of the already excellent π-acceptor molecule TCNQ by a further 0.74 V! TCNQ=7,7,8,8-tetracyano-p-quinodimethane, bpy=2,2'-bipyridine.

Ga (CMe ) , an Important New Building Block in the Structural Chemistry of the Alkylelement(I) Compounds E R (E=B-In).

A simple preparative method has been employed for the synthesis of the novel cluster compound Ga (CMe ) , which contains a tricapped trigonal prism of monovalent gallium atoms. Electron transfer processes were observed similar to those of polyboranes, leading to the the reversible formation of the corresponding radical anion.