Solid-state 31P CP/MAS and static 65Cu NMR characterization of polycrystalline copper(I) dialkyldithiophosphate clusters

Solid‐State NMR and EXAFS Spectroscopic Characterization of Polycrystalline Copper(I) O,O′‐Dialkyldithiophosphate Cluster Compounds: Formation of Copper(I) O,O′‐Diisobutyldithiophosphate Compounds on the Surface of Synthetic Chalcocite

“…The 65 Cu NMR spectrum of 1, however, reveals two quadrupolar line shapes with relative intensities close to 1:1 (see Figure 7a and Table 3) suggesting the existence of two types of site with equal-sized populations. [16] These are substantially overlapped as the differences in isotropic chemical shift are much smaller than the quadrupolar line widths, as expected. The relative orientation dependence of the two interaction tensors (the chemical shift and quadrupolar interactions) for the narrower component of 1 (at 14.1 T) is reflected in the angle parameters (see Table 3).…”

“…The sites with larger quadrupolar constants (C Q = 46.0 MHz, d iso = 120 ppm) can be considered as a superposition of the copper sites in the core exhibiting electronic environments with lower symmetries. [16] As mentioned earlier, the structure of the Cu 8 S 12 (S) fragment is independent of the type of alkyl chain but the symmetry of the cluster compounds decreases with increasing length and branching of the alkyl chains. The larger the ligand, the lower is the symmetry group in which the cluster compounds crystallize.…”

“…This means that the six O,O'-diisobutyldithiophosphate ligands are chemically almost equivalent in pairs. [16] It was found that the 31 P CP/MAS NMR spectrum of 1 (Figure 2d) was drastically changed by recrystallization in CH 2 Cl 2 (Figure 2e). Instead of the three resonance lines, just one with an isotropic chemical shift at 101.6 ppm was observed, which suggests that the chemical environments for all of the phosphorus sites are very simi- In our previous study we reported that the [Cu 6 A C H T U N G T R E N N U N G {S 2 P-A C H T U N G T R E N N U N G (OEt) 2 } 6 ] cluster compound also displays a single resonance line in the 31 P CP/MAS NMR spectrum, with an isotropic shift at d iso = 101.0 ppm and the 31 P chemical-shift anisotropy (CSA) parameters d aniso = À74.6 ppm and h CS = 0.34 (for comparison to the data in Table 2).…”

“…[10,16,17] We have recorded copper K-edge extended X-ray absorption fine structure analysis (EXAFS) data for a series of octanuclear O,O'-di-A C H T U N G T R E N N U N G alkyldithiophosphate cluster compounds and discussed the stability of the Cu 8 S 12 (S) core. [10] This paper presents EXAFS analyses on polynuclear copper(i) O,O'-dialkyldithiophosphate clusters with different core compositions (Cu 4 , Cu 6 , and Cu 8 cores) and their structural relationships.…”

“…This study provides more accurate values for the NMR interaction tensors and their relative orientations than that reported earlier. [16] The presence of two quadrupolar line shapes with very different characteristics (see Table 3) is an indication of the presence of two copper centers with very different EFGs, despite the similarity in the local configuration. This indicates that the copper centers in the cube are coordinated in such a way that the local electronic charge distribution for one half of the sites is significantly different from the other half.…”