NO-Na+ complex

The and the Na hyperfine interactions were finally employed to obtain the spin densities in the molecular orbitals of the NO-Na" complex to give insight into the electronic structure of the adsorption complex. An isotropic /r/coupling of Aiso( Na) = 7.8 MHz was evaluated from the above principal values of the A( Na) tensor. From the Aiso( Na) value an unpaired electron spin density in the Na 3s orbital is evaluated to be /03s(Na) = 0.9% [34]. In addition, judging from the small anisotropic values of the A( Na) tensor, Bzz( Na) = A - Aiso = 3.1 0.2 MHz, the spin density in Na 3p orbitals is negligible. Thus, the unpaired electron in the Na" -NO complex is concluded to be mainly localized at the NO molecule. 

Kasai et al. [4c] have first reported that the CW X-band ESR spectrum of NO adsorbed on Na-LTA zeolite consists of two signals, one due to the NO-Na" complex (NO mono-radical) as described in the above section and the other due to an unusual... 

The X-band spectrum of the NO/Na-LTA zeolite system is mainly due to the NO mono-radical when the pressure is low (Pno <0.1 kPa), while the (NO)2 bi-radical becomes dominant at higher NO pressure (Pno > 10 kPa) [24, 36]. The ESR signals due to the NO mono-radical (NO-Na" complex) and the (NO)2 bi-radical are superimposed at intermediate pressures. The 2-band ESR spectrum helped very much to resolve the individual spectrum and to evaluate the accurate ESR parameters of the (N0)2 bi-radical. As shown in Fig. 6.5, the Q-band spectral line-shape is well simulated using the following g tensor and the D and E parameters of the zero field splitting (ZFS) tensor for the (N0)2 bi-radical (gxx, gyy, gzz) = (1.9120, 2.0042,... 

The interaction of nitric oxide (NO) with metal ions in zeolites has been one of the major subjects in catalysis and environmental science and the first topic was concerned with NO adsorbed on zeolites. NO is an odd-electron molecule with one unpaired electron and can be used here as a paramagnetic probe to characterize the catalytic activity. In the first topic focus was on a mono NO-Na" complex formed in a Na -LTA type zeolite. The experimental ESR spectrum was characterized by a large -tensor anisotropy. By means of multi-frequency ESR spectroscopies the g tensor components could be well resolved. The N and Na hyperfine tensor components were accurately evaluated by ENDOR spectroscopy. Based on these experimentally obtained ESR parameters the electronic and geometrical structures of the NO-Na complex were discussed. In addition to the mono NO-Na complex the triplet state (NO)2 bi-radical is formed in the zeolite and dominates the ESR spectrum at higher NO concentration. The structure of the bi-radicai was discussed based on the ESR parameters derived from the X- and Q-band spectra. Furthermore the dynamical ESR studies on nitrogen dioxides (NO2) on various zeolites were briefly presented. 

This two-wave behaviour [which has been described previously (Chariot et al., 1962 Saji, 1986)] has been rationalized in terms of the high stability constant of [25] Na+ complex. Kinetic effects (i.e. slow decomplexation kinetics) were discounted on the basis that no change in the CV of a solution of [25] in the presence of 0.5 equiv Na+ cations was observed when the scan rate was varied between 0.02 and 5 V s 1. 

In the fit associated with consideration of specific sorption, the formation =Sp-Na° and =Sp-Ca reduces the negative surface potential relative to he no-surface-complexation case by about 25 mV over the entire isotherm. The result is a decrease in the predicted surface concentrations of sodium <4 M) and calcium (<1.5 M) and their accumulation in the diffuse layer. 

The fit model reproduces the mean activity coefficients for all of the C104 salts considered. The fit model included C104 complexes for the following ions Ba, H" ", Na" ", and Sr. Stability constants for these complexes were -0.16, -0.5, -0.35, and 0.2, respectively. However, it is uncertain whether these C104 complexes have any physical reality. No C104 complexes were included in the WATEQ or amended WATEQ models. 

Dark-violet K3[Co(CN)3(NO)] results from the action of KCN on [Co(CO)3(NO)] in liquid ammonia and the intermediate compounds K[Co(CN)(CO)2 (NO)] and K2[Co(CN)2(CO)(NO)] may be obtained when the reaction is carried out using stoichiometric ratios of the reactants. The conversion of [Co(NO)2Br2] to brown Na[Co(CN)2(NO)2] by treatment with ethanolic NaCN has been described, and similar preparations using [Co(NO)2BrL] reactants (L = PPhj, AsPh3, SPPhj, SePPhj) give the corresponding Na2[Co(CN)(NO)2L] complexes. 

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