The preparation and characterization of transition metal complexes supported on zirconium phosphate and their oxygen adducts
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Date
1981
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Abstract
The exchange of transition metal complexes {Co(NH(,3))(,6)}('3+), {Cu(NH(,3))(,4)}('2+) and {Cu(en)(,2)}('2+) between the layers of (alpha)-zirconium phosphate using butylamine intercalates has been investigated. The coordination of these transition metal complexes was proposed based on X-ray powder diffraction, UV-visible, IR and ESR spectra. The coexistence of two {Co(NH(,3))(,6)}('3+) phases was observed in the X-ray pattern. It is proposed that the complex occupies the center of the cavity in one phase and is located between two orthophosphate oxygens which define a face in the second. It is thought that the plane of the {Cu(NH(,3))(,4)}('2+) is oriented parallel to the zirconium layers. The exchange of {Cu(en)(,2)}('2+) proceeded through loss of an ethylenediamine ligand and incorporation of the complex as {Cu(en)(,1)}('2+). The ESR spectra of low surface exchanged copper(II) zirconium phosphates are presented, in which reversed ESR spectra (g(,(PERP)) > g(,(PARLL))) and signals attributed to nonlinear pairs of Cu(II) ions were observed. It is proposed that the reversed spectra are due to copper-aquo species with cis-distorted octahedral coordination (C(,2v)) or compressed tetragonal octahedral (D(,4h)). The ESR and visible spectra of these dehydrated samples have been interpreted as indicating that diffusion of the surface Cu(II) ions into the interior occurred on dehydration. In addition, the Cu(II) ions would then occupy sites which provide a distorted trigonal coordination. Copper(II)-ammonia and ethylenediamine complexes have been synthesized by exchange of the Cu(II) ion from aqueous solution followed by adsorption of the ligand from the gas phase. Addition of gaseous ammonia to the anhydrous (2.5:48) samples resulted in the formation of {Cu(NH(,3))(,4)}('2+). It has been suggested that the complex is coordinated between two orthophosphate oxygens from the top and bottom layers which occupy the axial positions. The Cu-N plane is thought to be at an angle to the layers. Evidence is presented which suggests that the adsorption of gaseous ammonia on the hydrated Cu(II) exchanged samples produces the {Cu(NH(,3))(,5)}('2+) surface species. Gas phase adsorption of ethylenediamine results in the formation of the bis-ethylenediamine-copper(II) complex. The reversible formation of 1:1 oxygen adducts of surface exchanged {Co(trien)(,1)}('2+) and {Co(phen)(,2)}('2+) complexes has been demonstrated by ESR. It is also suggested that the oxygen is bonded as a superoxo ion, O(,2)('-).
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Includes bibliographical references (leaves 138-143)
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Chemistry