Solvent effects on 15N NMR coordination shifts
Artikel i vetenskaplig tidskrift, 2013

(15)N NMR chemical shift became a broadly utilized tool for characterization of complex structures and comparison of their properties. Despite the lack of systematic studies, the influence of solvent on the nitrogen coordination shift, Δ(15)N(coord), was hitherto claimed to be negligible. Herein, we report the dramatic impact of the local environment and in particular that of the interplay between solvent and substituents on Δ(15)N(coord). The comparative study of CDCl(3) and CD(3)CN solutions of silver(I)-bis(pyridine) and silver(I)-bis(pyridylethynyl)benzene complexes revealed the strong solvent dependence of their (15)N NMR chemical shift, with a solvent dependent variation of up to 40 ppm for one and the same complex. The primary influence of the effect of substituent and counter ion on the (15)N NMR chemical shifts is rationalized by corroborating Density-Functional Theory (nor discrete Fourier transform) calculations on the B3LYP/6-311 + G(2d,p)//B3LYP/6-31G(d) level. Cooperative effects have to be taken into account for a comprehensive description of the coordination shift and thus the structure of silver complexes in solution. Our results demonstrate that interpretation of Δ(15)N(coord) in terms of coordination strength must always consider the solvent and counter ion. The comparable magnitude of Δ(15)N(coord) for reported transition metal complexes makes the principal findings most likely general for a broad scale of complexes of nitrogen donor ligands, which are in frequent use in modern organometallic chemistry.

Solvents

Nitrogen Isotopes

Fourier Analysis

Magnetic Resonance Spectroscopy

chemistry

methods

Författare

Roland Kleinmaier

Göteborgs universitet

Sven Arenz

Göteborgs universitet

Alavi Karim

Göteborgs universitet

Anna-Carin Carlsson

Göteborgs universitet

Mate Erdelyi

Göteborgs universitet

Magnetic Resonance in Chemistry

0749-1581 (ISSN) 1097-458X (eISSN)

Vol. 51 1 46-53

Ämneskategorier

Biokemi och molekylärbiologi

Kemi

DOI

10.1002/mrc.3907

PubMed

23208996