Cobalt-containing aluminophosphate five (CoAPO-5) was synthesized and shown to contain tetrahedral Co2+ residing within framework atomic positions and also as extraframework cations. The isolated framework Co2+ atoms can be oxidized by 02 at 500 °C to Co3+ which is stabilized in tetrahedral coordination by the oxide lattice. The framework Co3+ is easily reduced to Co2+ by a variety of reducing agents.

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Electron spin resonance studies on Ni+ in NiCa-X zeolite indicate the formation of two new Ni+ complexes, Ni+(H2) and Ni+(H2),, with n = 2 or 3 located in the a-cages in addition to a previously observed Ni+(H2) complex in the 8-cage. Both of the new cy-cage complexes are stable only in the presence of hydrogen and disappear after short outgassing at room temperature but are immediately restored after readsorption of hydrogen. Thus, the total number of Ni' spins is reversible with the desorption/readsorption of hydrogen. The formation of Ni+ ion pairs has been suggested to explain this behavior. After hydrogen desorption various molecules have been adsorbed on Ni+Ca-X zeolite. For Ni+ complexes with water and methanol a distorted octahedral symmetry is suggested which involves three lattice oxygens and three adsorbate molecules. The Ni+-ammonia complex has planar symmetry with two lattice oxygens and two adsorbate molecules. After adsorption of ethylene and propylene "reversed" g values in the ESR spectra (gl > g,,) are seen due most likely to compressed tetrahedral or compressed square-pyramidal geometry.

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Synthesis of MCM-22 zeolite has been achieved without agitation. MCM-22 samples prepared with and without agitation were characterized by various physical methods. With all synthesis parameters except agitation during crystallization remaining the same, MCM-22 zeolite prepared without agitation contains a lower Si/Al ratio and larger crystallite size than MCM-22 obtained with agitation. After exchange by Ni(II), Ni(I) is stabilized in Na-MCM-22 zeolite by thermal and hydrogen reduction and characterized by electron spin resonance spectroscopy. NiNa-MCM-22 heated under vacuum at temperatures above 673 K for prolonged periods produces a weak isolated Ni(I) species with g ⊥ ) 2.106. When dehydrated and oxidized NiNa-MCM-22 is reduced with hydrogen, two isolated Ni(I) species are observed, depending on the reduction temperature. The two Ni (I) species interconvert thermally. Adsorption of D 2 O on reduced NiNa-MCM-22 leads to the formation of a Ni(I)-(D 2 O) n complex. Adsorption of ammonia on reduced NiNa-MCM-22 leads to a Ni(I)-(ND 3 ) n complex with similar ESR characteristics. The similar ESR spectra suggest that both species are localized at the same site in the molecular sieve structure and have similar symmetry with two or three molecular ligands coordinated by the Ni(I) ion. Adsorption of ethylene on NiNa-MCM-22 produces two Ni(I)-(C 2 H 4 ) n complexes located at different sites. Similarly, methanol adsorption on NiNa-MCM-22 leads to the formation of two Ni(I)-(CH 3 -OD) n complexes with axially symmetric g values. The behavior of Ni(I) in MCM-22 zeolite to form more than one complex with relatively large molecules such as methanol and ethylene can be explained on the basis of the two independent pore structures in MCM-22.

The incorporation of nuclear quadrupole interaction into electron spin-echo modulation spectra by second-order perturbation methods has been developed for both two-pulse and three-pulse echo sequences. The results have been compared with exact numerical diagonalization of the Hamiltonian and with a first-order perturbation treatment. Model calculations have been carried out for deuterium (I=1) and aluminum (I=5/2) nuclei. It is shown that the second-order expressions can be used to obtain relatively accurate values for the number and distance of interacting nuclei at electron–nuclear distances greater than 0.26 nm. The procedure is more limited when the quadrupolar interaction exceeds the dipolar interaction when neither can be neglected.

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