Diamagnetic Singlet Research Articles

Se2NCl3 and [Se2NCl2]+ [GaCl4]−, Chloride Nitrides of Trivalent Selenium

The planar structure with C2v symmetry resembles a compass in the case of Se2NCl3 (1), a chlorine nitride, which is readily soluble and stable, but at the same time very reactive. The chlorine atom in 1 bridging the selenium atoms can be readily removed with GaCl3 to form [Se2NCl2][GaCl4] in which the cation is U-shaped. Both compounds have a diamagnetic singlet ground state.

A molecular structure study of partially deuterated succinic acid by 1H and 2H distant ENDOR

Distant ENDOR was used as a sensitive spectroscopic method for the determination of molecular structure parameters of C 2H 4(COOD) 2 and C 2D 4(COOH) 2 in their diamagnetic singlet ground state. The structural information was obtained by measuring the quadrupole coupling tensors of the deuterium atoms in the CD 2 positions and in the intermolecular hydrogen bonds OD … O and by measuring the dipolar coupling tensors between the protons in the CH 2 group and between the carboxylic protons in adjacent hydrogen bonds. The distant ENDOR results agree very well with crystallographic data.

Mössbauer spectroscopy on oxygenated sperm whale myoglobin: evidence for an Fe3+-O2- coupling at the active center.

57Fe Mössbauer spectra of oxygenated sperm whale myoglobin (MbO2) show a well resolved quadrupole doublet with a temperature dependent splitting. The temperature dependence of the corresponding electric field gradient tensor (EFG) can be calculated from a Fe3+ term scheme for the iron at the active center. The Mössbauer spectra as well as the diamagnetc character of the MbO2-complex are then understood by an exchange coupling of the Fe3+-ion with O2- oxygen molecule ion. The resulting groundstate is a diamagnetic singlet. In order to keep the whole complex diamagnetic at room temperature, an exchange coupling with [J] greater than or equal to 300cm-1 is necessary. As the whole model is in fair agreement with many other spectroscopic data, it is believed to be a good starting point for further detailed calculations.

Observation of deuterium quadrupole splittings of aromatic free radicals in liquid crystals by ENDOR and TRIPLE resonance

First measurements of deuterium quadrupole coupling constants of a polyatomic doublet state radical are reported. The quadrupole couplings were determined by ENDOR and electron–nuclear–nuclear TRIPLE resonance in liquid crystals. For the partially deuterated perinaphthenyl radical the out-of-plane component of the deuterium quadrupole coupling was measured to be e2q33Q/h =−(94±3) kHz for both molecular sites. Within experimental error these values are equal to those measured earlier for deuterated alternant hydrocarbons in the diamagnetic singlet ground state.

The Magnetic Properties of Cu3Cl6(C6H7NO)2·2H2O

Abstract From magnetic susceptibility and ESR measurements, it has been confirmed that polybis(μ-(2-picoline N-oxide)-chlorocopper(II)di-μ-chloro)diaquocopper, Cu3Cl6(C6H7NO)2·2H2O, consists of alternating linear chains with diamagnetic Cu2Cl4(C6H7NO)2 units and paramagnetic CuCl2·2H2O units joined by long Cu–Cl bonds. The two copper ions in the Cu2Cl4(C6H7NO)2 unit are coupled together very strongly by antiferromagnetic exchange interaction and occupy almost entirely the diamagnetic singlet state below room temperature. This interpretation is appropriately supported by the observation of a half-field resonance near 1600 Oe in the ESR spectrum of the powdered sample. On the other hand, the copper ion in the CuCl2·2H2O unit isolated magnetically can account for the ESR spectrum due to ΔM=±1 transition and magnetic susceptibility, following the Curie law. The magnetic susceptibility of the dehydrate compound, Cu3Cl6(C6H7NO)2, has also been measured.