113Cd NMR spectra

An easily accessible hexadentate derivative of tacn, namely 1,4, 7-tris(u-aminobenzyl)- 1,4,7-triazacyclononane (tabtacn), forms a 1 1 complex [Cd(tabtacn)](C104)2 0.5 H20 Pc2 njPna2, Z = 4) with a distorted trigonal prismatic CdN6 core. The Cd—N bonds to the N donors in both the tacn moiety and in the aniline pendant arms are very similar in a rather narrow range (rav(Cd—N) 237 pm).178 Both solution and solid-state H, 13C, and 113Cd NMR spectra have been measured and analyzed with respect to details of the stereochemistry and to dynamics in solution. 

The shifts in the 113Cd spectra due to the electron hyperfine interaction from an Mn++ ion two bonds distant could then be used to obtain a transferred hyperfine interaction constant A that could be compared to the value obtained from ESR measurements. For 125Te, the nearest neighbor Mn++ apparently broadened the NMR signal beyond detectability the transferred hyperfine interaction constant A for Mn++ ions in the second shell was calculated from the 125Te shifts. 

Information about the surface and interface structures in hexadecylamine-capped CdSe NC of 2 nm size has been obtained by a variety of 1H, 13C, 113Cd, and 77Se NMR techniques [342]. The 77Se CP-MAS-NMR spectrum showed five partially resolved peaks from surface or near-surface Se environments. It was possible to obtain 2D heteronuclear correlation (HETCOR) spectra between 1H and the other three nuclei despite the inherent sensitivity limitations (the 77Se- 3I-I HETCOR experiment required 504 h ). The latter experiment indicated that the methylene protons of the hexadecylamine chain interact with the surface Se atoms via a tilt of the chain toward the surface. The surface Se atoms were not seen to interact with thiophenol present, and it was suggested that thiophenol binds to a selenium vacancy at the surface. 

---