σ-Bonded organotransition-metal ions. Part IX. Strong hyperconjugative and inductive electron donation by some alkyl-manganese, -molybdenum, -tungsten, and -iron carbonyl groups in substituted pyridinium ions

1970 ◽  
Vol 0 (0) ◽  
pp. 507-511 ◽  
Author(s):  
M. D. Johnson ◽  
N. Winterton
Keyword(s):  
Metal Ions ◽  
Iron Carbonyl ◽  
Carbonyl Groups ◽  
Electron Donation ◽  
Pyridinium Ions

scholarly journals Crystal structure of bis{μ2-2,2′-[(4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-diyl)bis(methylene)]bis(4-oxo-4H-pyran-3-olato)}dicobaltcalcium bis(perchlorate) 1.36-hydrate

2017 ◽  
Vol 73 (12) ◽  
pp. 1959-1965
Author(s):  
Patrizia Rossi ◽  
Eleonora Macedi ◽  
Paola Paoli ◽  
Luca Giorgi ◽  
Mauro Formica ◽  
...  
Keyword(s):  
Metal Ions ◽  
Rotation Axis ◽  
Hard Metal ◽  
Three Dimensions ◽  
Trinuclear Complex ◽  
Water Molecules ◽  
Carbonyl Groups ◽  
Asymmetric Unit ◽  
Perchlorate Ion ◽  
Trigonal Prismatic

The title compound, [CaCo2(C22H30N4O6)2](ClO4)2·1.36H2O or {Ca[Co(H–2L1)]2}·2ClO4·1.36H2O {whereL1is 4,10-bis[(3-hydroxy-4-pyron-2-yl)methyl]-1,7-dimethyl-1,4,7,10-tetraazacyclododecane}, is a trinuclear complex whose asymmetric unit comprises a quarter of the {Ca[Co(H–2L1)]2}2+trinuclear complex, half of a perchlorate ion and 0.34-water molecules. In the neutral [Co(H–2L1)] moiety, the cobalt ion is hexacoordinated in a trigonal–prismatic fashion by the surrounding N4O2donor set. A Ca2+cation holds together two neutral [Co(H–2L1)] moieties and is octacoordinated in a distorted trigonal–dodecahedral fashion by the surrounding O atoms belonging to the deprotonated oxide and carbonyl groups of two [Co(H–2L1)] units. The coordination of the CoIIcation preorganizesL1and an electron-rich area forms, which is able to host hard metal ions. The comparison between the present structure and the previously published ones suggests a high versatility of this ligand; indeed, hard metal ions with different nature and dimensions lead to complexes having different stoichiometry (mono- and dinuclear monomers and trinuclear dimers) or even a polymeric structure. The heterotrinuclear CoII–CaII–CoIIcomplexes are connected in three dimensionsviaweak C—H...O hydrogen bonds, which are also responsible for the interactions with the perchlorate anions and the lattice water molecules. The perchlorate anion is disordered about a twofold rotation axis and was refined giving the two positions a fixed occupancy factor of 0.5. The crystal studied was refined as a two-component inversion twin [BASF parameter = 0.14 (4)].

scholarly journals N-Alkyl pyrrolidone ether podands as versatile alkali metal ion chelants

2014 ◽  
Vol 43 (8) ◽  
pp. 3153-3161 ◽  
Author(s):  
Andrea Perrin ◽  
Dominic Myers ◽  
Katharina Fucke ◽  
Osama M. Musa ◽  
Jonathan W. Steed
Keyword(s):  
Alkali Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Alkali Metal Ions ◽  
Carbonyl Groups ◽  
Alkali Metal Ion ◽  
Lactam Carbonyl

The highly polar nature of lactam carbonyl groups makes them potent chelators of alkali metal ions as part of a flexible podand ligand.

scholarly journals Carbonyl-to-Alkyne Electron Donation Effects in up to 10-nm-Long, Unimolecular Oligo(p-phenylene ethynylenes)

2021 ◽  
Vol 03 (02) ◽  
pp. 337-345
Author(s):  
Sinu C. Rajappan ◽  
Olav Vestrheim ◽  
Mona Sharafi ◽  
Jianing Li ◽  
Severin T. Schneebeli
Keyword(s):  
Absorption Spectrum ◽  
Exponential Growth ◽  
Photophysical Properties ◽  
Rotational Barrier ◽  
Carbonyl Groups ◽  
Conformational Disorder ◽  
Triple Bonds ◽  
Phenylene Ethynylenes ◽  
Electron Donation

We synthesized some of the longest unimolecular oligo(p-phenylene ethynylenes) (OPEs), which are fully substituted with electron-withdrawing ester groups. An iterative convergent/divergent (a.k.a. iterative exponential growth – IEG) strategy based on Sonogashira couplings was utilized to access these sequence-defined macromolecules with up to 16 repeating units and 32 ester substituents. The carbonyl groups of the ester substituents interact with the triple bonds of the OPEs, leading to (i) unusual, angled triple bonds with increased rotational barrier, (ii) enhanced conformational disorder, and (iii) associated broadening of the UV/Vis absorption spectrum. Our results demonstrate that fully air-stable, unimolecular OPEs with ester groups can readily be accessed with IEG chemistry, providing new macromolecular backbones with unique geometrical, conformational, and photophysical properties.

Solid-state 13 C NMR spectra of iron carbonyl complexes: shielding tensor and error analyses

1989 ◽  
Vol 424 (1866) ◽  
pp. 93-111 ◽  
Keyword(s):  
Solid State ◽  
Magic Angle Spinning ◽  
Iron Carbonyl ◽  
Magic Angle ◽  
Carbonyl Groups ◽  
Carbonyl Complexes ◽  
Side Band ◽  
Shielding Tensor ◽  
Angle Spinning ◽  
C Nmr

The high-resolution solid-state 13 C NMR (nuclear magnetic resonance) spectra are reported of the iron carbonyl complexes Fe 3 (CO) 8 (PhCCPh) 2 (I) and Fe 3 (CO) 12 (II), 13 C-enriched at the carbonyl carbons. The spectra were recorded with slow magic-angle spinning, and the intensities of the spinning side bands analysed by a computerized adaptation of the method of Herzfeld & Berger to give values for the principal components of the carbonyl carbon shielding tensors. Complex (I) includes two asymmetric double-bridging carbonyl groups, and the 13 C shielding-tensor components assigned to the C—O bond axis (σ 33 ) are intermediate between the values obtained for symmetric double-bridging carbonyl groups and linear M—C≡0 terminal carbonyls. It is proposed that the σ 33 shielding component may therefore be used to monitor the degree of asymmetric bridging of a carbonyl group. All 13 C resonances of complex (II) exhibit a degree of asymmetry in the shielding tensor and possible reasons for this are discussed. Three methods of estimating errors in the derived shielding-tensor components are considered. One method use calculated variances based upon differences between the experimental and calculated side-band intensities; this gives unreasonably large errors in the cases of axial symmetry in the shielding tensor. A second method explores different shielding components for values of ɸ 2 (the sum of the squares of the differences between the experimental and calculated side-band intensity ratios) which exceed the best minimum by an arbitrary percentage. The third method considers errors due to the signal: noise ratios in the experimental spectra. The relative merits of these three approaches of error estimation are examined.

Use of solid-state carbon-13 NMR spectroscopy to quantify the degree of asymmetry of bonding for semibridging carbonyl groups in iron carbonyl complexes

1991 ◽  
Vol 30 (7) ◽  
pp. 1489-1493 ◽  
Author(s):  
Geoffrey E. Hawkes ◽  
Keith D. Sales ◽  
Silvio. Aime ◽  
Roberto. Gobetto ◽  
Lu Yun. Lian
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Iron Carbonyl ◽  
Carbonyl Groups ◽  
Carbonyl Complexes

Übergangsmetallkomplexe von Diazenen, XVI [1] Struktur und Mößbauerdaten von (2.3-Diazanorbornen)Fe3(CO)9 / Transition Metal Complexes of Diazenes, XVI [1] Structure and Mössbauer Data of (2,3-Diazanorbornene)Fe3(CO)9

1981 ◽  
Vol 36 (2) ◽  
pp. 205-207 ◽  
Author(s):  
H. Kisch ◽  
C. Krüger ◽  
A. Trautwein
Keyword(s):  
Molecular Structure ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Iron Carbonyl ◽  
Mossbauer Spectrum ◽  
Carbonyl Groups ◽  
Mössbauer Spectrum ◽  
Mössbauer Data ◽  
Single Bonds

Abstract The molecular structure of (2,3-diazanorbornene)Fe3(CO)9 consists of a triangular Fe3(CO)9 group bound to the diazene unit. The seven-coordinated Fe(CO)3 group forms two Fe-N bonds with lengths of 1.974 and 1.965 Å, each of the two six-coordinated Fe(CO)3 groups has slightly shorter Fe-N-bonds of 1.898 and 1.903 Å. One Fe-Fe distance, 2.612Å, is longer than the two other ones, 2.572 and 2.582 Å, which are in the range of typical single bonds. The presence of seven-and six-coordinated iron carbonyl groups is also demonstrated by the Mössbauer spectrum showing signals with quadrupole splittings of 1.23 and 0.78, 0.62 ± 0.01 mm/s, respectively.

Controllable photophysical properties and self-assembly of siloxane-poly(amidoamine) dendrimers

2015 ◽  
Vol 17 (40) ◽  
pp. 26783-26789 ◽  
Author(s):  
Hang Lu ◽  
Jie Zhang ◽  
Shengyu Feng
Keyword(s):  
Metal Ions ◽  
Self Assembly ◽  
Photophysical Properties ◽  
The Self ◽  
Carbonyl Groups ◽  
Strong Luminescence ◽  
Coordination Bonds

Siloxane–poly(amidoamine) dendrimers (Si–PAMAM) can emit strong luminescence due to the aggregation of carbonyl groups, induced by N → Si coordination bonds. So the fluorescence of Si–PAMAM could be adjusted by solvents, H+, metal ions, and dendrimer structures. Micron-sized tube were observed in water–methanol due to the self-assembly of Si–PAMAM.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

Sign in / Sign up

Export Citation Format

Share Document