Adsorbate interactions of Cu(II) in Cu(II)-exchanged K-L gallosilicate studied by CW and Pulsed electron spin resonance

Abstract

The interactions of Cu(II) in Cu(II)-exchanged K-L gallosilicate with adsorbates containing coordinative nitrogens in ammonia, pyridine, aniline, acetonitrile and hydrazine, and with the adsorbates carbon monoxide, benzene, propanol and dimethyl sulfoxide ate investigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. These results are compared with those in Cu(II)-exchanged K-L aluminosilicate and the differences are discussed. Adsorption of ammonia produces a complex comaining four molecules of ammonia based on resolved nitrogen superhyperfine imeraction. Upon equilibrium with pyridine, Cu(II) forms a complex containing four molecules of pyridine in CuK-L gallosilicate and a complex containing only three molecules of pyridine in CuK-L aluminosilicate based on resolved nitrogen superhyperfine. Upon adsorption of aniline and acetonitrile, Cu(II) forms complexes containing two molecules of each in CuK-L gallosilicate based on resolved nitrogen superhyperfine. However, no resolved nitrogen superhyperfine between hydrazine and Cu(II) is seen. Adsorption of carbon monoxide, benzene, propanol and dimethyl sulfoxide causes changes in the ESR spectrum of Cu(II), indicating migration of Cu(II) into cation positions in the main channels where adsorbate coordination can occur. Cu(II) forms complexes with one moleeule of benzene and two molecules of propanol based on ESEM data in both K-L gallosilicate and K-L aluminosilicate. However, Cu(II) interacts directly with one dimethyl sulfoxide in K-L aluminosilicate but only indirectly at a longer distance with one dimethyl sulfoxide in K-L gallosilicate based on ESEM data.

Incorporation of Gallium into Zeolites: Syntheses, Properties and Catalytic Application

“…Owing to the required long-range ordering, these details are detectable by neutron diffraction to a limited extent only. Recently, Yu et al 317,318 studied the exchange of K + ions in K [Ga]-L (Si/Ga ) 2.6) by Cu 2+ ions through EPR and electron spin-echo modulation (ESEM) spectroscopy. Results were compared with those of Cu 2+ -exchanged K[Al]-L. The state and coordination of the Cu 2+ species were found to be quite similar with both types of zeolites.…”

CuIIlocation and adsorbate interaction in CuII-exchangedsynthetic Na-omega gallosilicate EPR and electron spin echo modulation studies

“…However, the possibility of CuII forming square-planar tetraamine complexes in the main channel cannot be ruled out by comparison with other channel-type molecular sieves. 15,18,44,56,57 Another N-containing adsorbate, pyridine, is too big to enter a gmelinite cage and thus no interaction between pyridine and CuII is observed.…”

Stereochemical behavior of 2 J(Se,H) and 3 J(Se,H) spin‐spin coupling constants across sp3 carbons: a theoretical scrutiny

“…Recently, a good number of geminal and vicinal 77 Se-1 H spinspin coupling constants, 2 J(Se,H) and 3 J(Se,H), were examined, both experimentally and theoretically, in the representative series of organoselenium compounds including open-chain olefinic selenides -a parent divinyl selenide [1] and related selanylalkenes, [2] as well as in five-membered and six-membered selenium-containing heterocyclesselenophenes, [3] diselenanes and diselenolanes, [4] together with the derivatives of thiaselenetane, selenasilole, thiaselenole, thiaselenolane and dihydrothiaselenine, [5] and also some much larger organoselenium molecules of biochemical origin, like those as alkyl-and arylselenoglycosides, [6] the later being of particular biological interest as stable glycosyl donors for oligosaccharide syntheses. [7] At the same time, open-chain olefinic selenides provide a wide spectra of their application in material science and organic synthesis as well as being the potential precursors of the selenium-based biologically active molecules, [8] whereas the title five-membered and six-membered selenium-containing heterocycles serve as precursors of conducting materials and prospective starting materials for the preparation of chiral organic selenides.…”