Search results for "Lone pair"
showing 10 items of 53 documents
Antimony-121 mössbauer and infrared spectral study on halophenylantimonate(III) Compounds
1981
Abstract The synthesis and the 121 Sb Mossbauer and infrared spectra of halophenylantimonates(III) M[PhSbX 3 ] (M Me 4 N, Ph 4 As;X Cl, Br, I) are reported, and the spectral data are discussed and compared with those of SbX 4 and other related systems. The results are in accord with the participation of the antimony 5s electrons in the SbPh bond. In the interpretation of the electric field gradient, the contributions to V zz from both the lone pair and the SbPh bond electron densities are assumed to be dominant.
Die kopplungskonstanten nJ(SnC) und n+1J(SnH) ineinigen verbindungen mit der tetramethyldizinngruppe
1977
Abstract Comparison of data on seven compounds containing the group tetramethylditin shows a variation in the coupling constants depending on the lone pair electrons of the substituents.
Modeling the properties of lanthanoid single-ion magnets using an effective point-charge approach
2012
Herein, we present two geometrical models based on an effective point-charge approach to provide a full description of the lowest sublevels in lanthanoid single ion magnets (SIMs). The first one, named as the Radial Effective Charge (REC) model, evaluates the crystal field effect of spherical ligands, e.g. F(-), Cl(-) or Br(-), by placing the effective charge along the Ln-ligand axes. In this case the REC parameters are obtained fitting high-resolution spectroscopic data for lanthanoid halides. The second model, named as the Lone Pair Effective Charge (LPEC) model, has been developed in order to provide a realistic description of systems in which the lone pairs are not pointing directly tow…
Molecular anisotropy analysis of single-ion magnets using an effective electrostatic model.
2014
Simple electrostatic models have been shown to successfully rationalize the magnetic properties of mononuclear single molecule magnets based on f-elements and even to predict the direction of the magnetic anisotropy axis in these nanomagnets. In this Article, we go a step forward by showing that these models, conveniently modified to account for the covalency effects, are able to predict not only the easy axis direction but also the three components of the magnetic anisotropy. Thus, by using a lone pair effective charge (LPEC) model we can fully reproduce the angular dependence of the magnetic susceptibility in single crystals of pentamethylcyclopentadienyl-Er-cyclooctatetraene single-ion m…
Pressure-dependent modifications in the optical and electronic properties of Fe(IO3)3: the role of Fe 3d and I 5p lone–pair electrons
2021
We have determined by means of optical-absorption experiments that Fe(IO3)3 is an indirect band-gap material with a band-gap energy of 2.1 eV. This makes this compound the iodate with the smallest band gap. We also found that under compression the band-gap energy has an unusual non-linear pressure dependence, which is followed by an abrupt and discontinuous decrease of the band gap at 24 GPa. The observed behavior is explained by means of density-functional calculations, which show that the behavior of the band gap is governed by the combined influence of Fe 4d and I 5p lone pair electrons. In addition, the abrupt decrease of the band-gap energy at 24 GPa is a consequence of a first-order s…
Trapping Molecular SnBr 2 (OH) 2 by Tin Alkoxide Coordination: Syntheses and Molecular Structures of [MeN(CH 2 CMe 2 O) 2 SnBr 2 ] 2 ·SnBr 2 (OH) 2 a…
2012
The synthesis of the intramolecularly coordinated stannylenes and their transition-metal complexes of the type RN(CH2CMe2O)2SnL [1: L = lone pair, R = Me; 2: L = lone pair, R = n-octyl; 5: L =W(CO)5, R = Me; 6: L = Cr(CO)5, R = Me; 7: L =W(CO)5, R = n-octyl; 8: L = Fe(CO)4, R = Me], and of the tin(IV) compounds RN(CH2CMe2O)2SnBr2 (9: R = Me), [MeN(CH2CMe2O)2SnBr2]2·SnBr2(OH)2 (10) and spiro-[RN(CH2CMe2O)2]2Sn (3: R = Me; 4: R = n-octyl) is reported. The compounds were characterized by elemental analyses, 1H, 13C, 119Sn, and 119Sn magic-angle spinning (5, 6) NMR spectroscopy, electrospray mass spectrometry, and single-crystal X-ray diffraction analysis.
[1,2,3]Triazolo[1,5-a]pyridyl phosphines reflecting the influence of phosphorus lone pair orientation on spectroscopic properties
2010
A series of new triazolopyridine-based phosphines has been prepared. These compounds revealed unexpected spectroscopic patterns. In particular, the NMR spectra are highly dependent on the relative conformational preference of the phosphine substituent at C7. Here, we report on their complete NMR analysis, X-ray structures and DFT calculations that confirm the particular arrangement of the phosphorus lone pair orbital related to the substituent pattern of the chosen phosphine.
Aminoallenylidene complexes of ruthenium(II) from the regioselective addition of secondary amines to butatrienylidene intermediates: a combined exper…
2003
Aminoallenylidene complexes trans-[Cl(dppm)2RuC3(NRR )(CH3)] are obtained from the regioselective addition of secondary amines to trans-[Cl(dppm)2Ru C C C CH2] . Unsymmetrically substituted amines give rise to Z/E isomeric mixtures. Dynamic 31P NMR spectroscopy gave an energy barrier of about 85 kJ mol 1 for rotation around the CN-bond pointing to a large contribution of the iminium alkynyl resonance form trans-[Cl(dppm)2Ru–C C– C( NRR )(CH3)] . This is also indicated by the pronounced bond length alternation within the RuC3N-chain as is revealed by X-ray structure analysis of the Z isomer of the (benzylmethyl)methylamine derivative 2d. The issue of NR2 rotation was also addressed by DFT ca…
Specific orientation of dipole moments in azocrown cetocyanine dyes determined by electrooptical absorption measurements (EOAM)
2019
Abstract From electrooptical absorption measurements (EOAM) follows that the dipole moments of azacrown ketocyanine dyes 2,5-di{(E)-1-[4-(4,7,10,13-tetraoxa-1-azacyclopentadecyl)phenyl]methylidene}-1-cyclopentanone (Compound 1) and (E)-1-(2-hydroxy-4methoxyphenyl)-3-[4-(4,7,10,13-tetraoxa-1-azacyclopentadecyl)phenyl]-2-propen-1-one (Compound 2) in the equilibrium ground state μg and the change of dipole moments upon transition to the excited Franck–Condon state Δaμ are large. This alteration causes a significant long-wavelength shift of the absorption and emission spectra, as well as large fluorescence Stokes shift with increasing polarity of the solvent. From the DFT calculations follows t…
Synthesis of and structural studies on lead(II) cysteamin complexes.
2004
The novel compounds PbCl(2).(SCH(2)CH(2)NH(3)) (1), Pb(SCH(2)CH(2)NH(2))(2).2PbCl(SCH(2)CH(2)NH(2)) (2), and Pb(SCH(2)CH(2)NH(2))(2) (3) were synthesized by reaction of PbO or PbCl(2) with [HSCH(2)CH(2)NH(3)]Cl and NaOH, and were characterized by elemental analysis, IR-, and UV/vis-spectroscopy. Single-crystal X-ray diffraction revealed different coordination modes for the two Pb atoms in 2. The Pb atom in the Pb(SCH(2)CH(2)NH(2))(2) unit forms two covalent Pb-S and two intramolecular dative Pb...N bonds, leading to a pseudo trigonal bipyramidal configuration with a stereochemically active lone pair. The Pb atom in the PbCl(SCH(2)CH(2)NH(2)) unit, the first moiety structurally characterized…