Chemical trends of Mn4+ emission in solids

2014 ◽  
Vol 2 (14) ◽  
pp. 2475-2481 ◽  
Author(s):  
M. H. Du

Calculated Mn4+ emission energies for various oxides as functions of Mn–O bond length. The experimental values are shown (in red) wherever available. There are three groups of materials: the ones with small O–Mn–O bond angle distortion (black squares), the ones with large O–Mn–O bond angle distortion (blue circles), and phosphates (green triangles). Weak Mn4+-ligand hybridization as a result of long Mn–O bond lengths and/or large O–Mn–O bond angle distortion generally leads to higher emission energies.

An extremely careful inquiry is made into the possibility of predicting bond lengths in condensed aromatic hydrocarbon molecules. Agreement with the best experimental values, such as those of Robertson, Abrahams, White, Mathieson and Sinclair, is fairly easily obtained to an accuracy of about 0.02Å. This shows that the concept of fractional bond order may quite properly be used to infer bond lengths. Both the molecular-orbital and resonance methods are equally good for this purpose. Predictions to within less than 0.02Å require the introduction of new factors usually neglected. No less than five such factors are discussed: ( а ) electrostatic forces, arising from possible differences in electronegativity of the various carbon atoms, ( b ) changes of bond orders due to electronegativity differences, ( c ) variation of resonance integrals with bond length, ( d ) obtaining a self-consistent set of resonance integrals, ( e ) inclusion of configuration interaction. Correction terms which result from these improvements lie between 0 and 0.015Å, and are not all of the same sign. It is unlikely therefore that this type of analysis will be able to give confident predictions of bond lengths to less than 0.01Å.


1963 ◽  
Vol 41 (8) ◽  
pp. 2074-2085 ◽  
Author(s):  
R. J. Gillespie ◽  
E. A. Robinson

It is shown that the bond length of an SO bond and the bond angle of an SO2 group may be very satisfactorily correlated with the SO stretching frequency. The bond-length – stretching-frequency relationship is used to predict some bond lengths that have not been measured and the OSO angles in some sulphuryl compounds are also calculated. The problem of defining and measuring the bond order of sulphur–oxygen bonds is discussed. It is shown that there is a linear relationship between the force constant and the bond order and a non-linear relationship between the bond length and the bond order.


Author(s):  
Varsha Rani ◽  
Harkesh B. Singh ◽  
Ray J. Butcher

In the title salt, (C34H41N4Te)[HgI3(C4H8O2)], the aryltellurenium [C34H41N4Te]+cations and [HgI3(dioxane)]−anions are linked by a short interaction between the Te atom and one of the I-atom donors of the anion, as well as through weak C—H...I interactions. The geometry around the Te atom is T-shaped with the coordination comprising a C atom of the central aromatic ring and two N atom donors of the benzimidazolyl moiety. The Te—N bond lengths are almost equal [2.232 (3) and 2.244 (3) Å], while the Te—C bond length is 2.071 (4) Å. The N—Te—N bond angle is 150.68 (11)°. The HgIIatom of the anion is coordinated by iodide ions from three sides and the fourth coordination site is occupied by an O atom of the solvent molecule (dioxane). Thus, it attains a trigonal–pyrimidal geometry, with O—Hg—I angles ranging of 90.76 (8) and 96.76 (7)° and I—Hg—I angles ranging from 112.41 (1) to 125.10 (1)°. The cations and anions are involved in numerous weak π–π stacking interactions involving both the central phenyl ring and two inversion-related benzimidazole moieties, which propagate in thea-axis direction. In addition, there are numerous C—H...I interactions between the cations and anions, which link them into a complex three-dimensional array.


2015 ◽  
Vol 51 (56) ◽  
pp. 11248-11251 ◽  
Author(s):  
T. D. Humphries ◽  
D. A. Sheppard ◽  
C. E. Buckley

For homoleptic 18-electron complex hydrides, an inverse linear correlation has been established between the T–deuterium bond length and the average electronegativity of the metal countercations.


1972 ◽  
Vol 94 (13) ◽  
pp. 4743-4744 ◽  
Author(s):  
Philip E. Stevenson ◽  
Warren G. Anderson ◽  
C. Hackett Bushweller ◽  
Geetha U. Rao

2021 ◽  
Vol 874 ◽  
pp. 171-181
Author(s):  
Nurdeni ◽  
Atje Setiawan Abdullah ◽  
Budi Nurani Ruchjana ◽  
Anni Anggraeni ◽  
Annisa Nur Falah ◽  
...  

A study of the quantitative relationship of structure and property (Quantitative Structure Property Relationship (QSPR) has been carried out on complex compounds formed between gadolinium (Gd) and dibutyldithiophosphate (DBDTP) derivative ligands. This study is a part of our laboratory research program on the development of extractant ligands, including DBDTP in extraction for the separation and purification of rare-earth elements (REEs), specifically Gd. Gadolinium has also been a part of the research program about its use in the synthesis of magnetic resonance imaging (MRI) contrast agents, for the diagnosis of various diseases. This chemical calculation research aims to analyze the effect of descriptors in the form of parameters of the physical-chemical properties of bond lengths, bond angles, and bond energies on the stability of Gd complex compounds with DBDTP derivative ligands. To get descriptors PM7 semi-empirical method was used, while for data analysis, Multiple Linear Regression Analysis was used, assuming the model error is normally distributed with zero mean and constant variance. Furthermore, data processing was done using SPSS software. This research was conducted by involving 28 DBDTP derivative ligands and using multiple linear regression analysis. The regression equation is Y ̂ = - 0.966 + 0.586 V1 - 0.014 V2 + 0.000 V3. From the resulted research data it was found that there are three findings, namely: (1) bond length and bond angle have a significant simultaneous effect on stability of Gd complex compounds with DBDTP derivative ligands; (2) bond length and bond angle have a partially significant effect on stability of Gd complex compounds with DBDTP derivative ligands; (3) bond length proved to have a significant dominant effect on stability of Gd complex compounds with DBDTP derivative ligands.


1980 ◽  
Vol 35 (5) ◽  
pp. 522-525 ◽  
Author(s):  
Gisela Beindorf ◽  
Joachim Strähle ◽  
Wolfgang Liebelt ◽  
Kurt Dehnicke

The complexes AsPh4[Cl4V = N-Cl] and AsPh4[VOCl4] are prepared by the reaction of AsPh4Cl with Cl3VNCl and VOCl3, respectively. The IR spectra indicate C4v symmetry for the complex anions with multiple VN and VO bonds and a linear arrangement for the VNCl-group. AsPh4[VOCl4] crystallizes in the tetragonal space group P4/n with two formula units in the unit cell. The crystal structure was solved by X-ray diffraction methods (R = 0,062, 1096 observed, independent reflexions). The structure consists of AsPh4+ cations and [VOCl4]- anions with symmetry C4v. The extremely short VO bond length corresponds with a VO triple; its steric requirements cause the relatively large bond angle OVCl of 103.4°.


2020 ◽  
Vol 860 ◽  
pp. 106-111
Author(s):  
Dhawud Sabilur Razaq ◽  
Budhy Kurniawan ◽  
Ikhwan Nur Rahman ◽  
Dicky Rezky Munazat

Nanosized La0.75K0.05Ba0.05Sr0.15MnO3 manganite have been synthesized using sol-gel method. Afterwards, the samples were sintered at eight different temperature ranging from 650 to 1000 °C. Phase purity, crystal structure and the morphology of the sample have been examined using X-Ray Diffractometer (XRD) and Scanning Electron Microscope. It has been found that different higher sintering temperature greatly affect the phase purity and crystallite size of the sample. Regardless of the sintering temperature, all the samples crystallized in rhombohedral structure with R-3c space group. The crystallite size of the samples is found to increase from 41.59 nm up to 73.42 nm as the sintering temperature increases. Further analysis from XRD result shows that sintering temperature also affect the average Mn-O bond length and Mn-O-Mn bond angle of the sample. The average Mn-O bond length is found to increase while the average Mn-O-Mn bond angle tends to decrease as sintering temperature increases. SEM measurement shows that various grain size ranging from ~100 nm up to ~ 350 nm exists in all the sample regardless the sintering temperature.


1997 ◽  
Vol 52 (7) ◽  
pp. 847-850 ◽  
Author(s):  
Joachim Pickardt ◽  
Sven Wiese

The reactions of diaza-15-crown-5 (“2.1”), and diaza-18-crown-6 (“2.2”), resp., with HgI2 in methanol afford the compounds [Hg(2.1)I][Hg2I6] (1) and [Hg(2.2)I][Hg2I6] (2), the crystal structures of which were determined. 1 consists of isolated cations [Hg(2.1)I]+ and anions [Hg2I6]2-. In the cations Hg is coordinated by one iodine atom, the two N atoms and the three O atoms of the ligand; the Hg-I distance is 262.1(3) pm, the Hg-N bond lengths are 221(2) and 238(2) pm; they are significantly shorter than the Hg-O distances, which are in the range between 262 and 271 pm. 2 consists of cations [Hg(2.2)I]+, which are bridged by the anions. In the cations of 2 Hg is coordinated by an iodine atom and by the two N atoms of the ligand, but by only three of the four O atoms. The Hg-I distance is 275.8(5) pm, the mean Hg-N bond length 234(4) pm, and the Hg-O distances vary between 285 and 304 pm. The Hg-I distance to the bridging I atom of the anion is 388.6(6) pm. The Hg-I bond lengths within the anions are slightly widened by this coordination.


1987 ◽  
Vol 65 (7) ◽  
pp. 739-752 ◽  
Author(s):  
H. Lew ◽  
R. Groleau

An analysis of 15 bands of the [Formula: see text] system of D2O+ is given. All assigned lines are tabulated. The rotational structures of the [Formula: see text], 1, and 3 levels of the ground state are fitted to the Watson asymmetric rotor Hamiltonian with added spin-rotation terms. For the upper state, the rotational structures of various substates are expressed: for [Formula: see text], in terms of a simple formula for linear molecules; and for [Formula: see text], 2, and 3, in terms of a modified Hill – Van Vleck formula given by Jungen, Hallin, and Merer. From the rotational constants of the ground state, term values are calculated and a small portion of a Type-B infrared band is derived. Some predicted microwave lines are also given. The bond length and bond angle of the molecule in the ground state (ν = 0) are r0 = 0.9987 ± 0.0002 Å and θ0 = 110.17 ± 0.02 deg.


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