High Field 27Al ENDOR Reveals the Coordination Mode of Cu2+ in Low Si/Al Zeolites

• Published in: Journal of the American Chemical Society Vol. 128; no. 22; pp. 7160 - 7161
• Main Authors: Carl, Patrick J, Vaughan, David E. W, Goldfarb, Daniella
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 07.06.2006
• Subjects: Chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron-nuclear double resonance (endor), electron double resonance (eldor); Exact sciences and technology; General and physical chemistry; Ion-exchange; Magnetic double resonances and cross effects; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Physics; Surface physical chemistry; Zeolites: preparations and properties; Hyperfine coupling constant; Active site; ENDOR spectrometry; Aluminosilicates; Experimental study; Aluminium 27; Molecular sieve; Hyperfine structure; Electronic structure; Transition metal Ions; Copper ion; Quadrupole coupling constant; Ion exchange; Modified material
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0617643

The siting of Cu2+ in zeolites with low exchange levels has been a subject for debate due to the lack of experimental evidence that provide directly the interaction between the Cu2+ ion and the zeolite framework. High field 27Al ENDOR provided highly resolved orientation selective ENDOR spectra from which both the 27Al hyperfine and quadrupole principal components and orientations relative to the g tensor principal axis system were determined for a dehydrated Cu2+ exchanged zeolite X with Si/Al = 1. The results show that all three Cu−Al distances in the six-member ring are equivalent, in contrast to DFT predictions using cluster models.