Solid-State NMR Probe Molecules for Catalysts and Adsorbents: Concepts, Quantification, Accessibility, and Spatial Distribution

Cu(dppf) complexes can be synthesized from Cu-exchanged solids and enable a quantification of the Cu-accessibility by 31P MAS NMR spectroscopy

“…It is important to note that a complex formation is only possible if (1) the dppf has access to the copper and if (2) there is enough space available to form a complex. 32 A similar picture is observed if noble metals react with phosphines in inorganic complexes as triphenylphosphines and higher analogues. Also in this case a complex forms directly inside a mesopore that is large enough to host the resulting complex.…”

“…[47][48][49] These groups react with NH 3 to form NH 4 + which gives a quantifiable peak at 6.4 ppm. 32,50 The peak intensity indicates the accessibility of 0.17 mmol g −1 BAS. This is low compared to the ∼0.8 mmol g −1 BAS expected from the Si/Al ratio.…”

“…27,28 In this favourable cases, metalorganic complexes bear a phosphorus nucleus (I = 1 2 ) which can be investigated quantitatively using 31 P MAS NMR spectroscopy. [29][30][31][32][33][34] Finally it can be summarized that techniques to finely distribute such complexes in pores are of interest for the community. We herein thus also focus on how synthesized cationic complexes as counter ions in ion exchange position can be applied to characterize the support.…”