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Computational NMR Spectroscopy of Transition‐Metal/Nitroimidazole Complexes: Theoretical Investigation of Potential Radiosensitizers
Author(s) -
Ramalho Teodorico C.,
Bühl Michael,
FigueroaVillar José Daniel,
de Alencastro Ricardo Bicca
Publication year - 2005
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200590210
Subject(s) - chemistry , chemical shift , solvation , polarizable continuum model , imidazole , transition metal , computational chemistry , nuclear magnetic resonance spectroscopy , nitro , metal , crystallography , stereochemistry , molecule , organic chemistry , alkyl , catalysis
The computed chemical shifts of transition‐metal complexes with dimetridazole (= 1,2‐dimethyl‐5‐nitro‐1 H ‐imidazole; 1 ), a prototypical nitro‐imidazole‐based radiosensitizer, are reported at the GIAO‐BP86 and ‐B3LYP levels for BP86/ECP1‐optimized geometries. These complexes comprise [MCl 2 ( 1 ) 2 ] (M = Zn, Pd, Pt), [RuCl 2 (DMSO) 2 ( 1 ) 2 ], and [Rh 2 (O 2 CMe) 4 ( 1 ) 2 ]. Available δ ( 1 H) and δ ( 15 N) values, and Δ δ ( 1 H) and Δ δ ( 15 N) coordination shifts are well‐reproduced theoretically, provided solvation and relativistic effects are taken into account by means of a polarizable continuum model and suitable methods including spin–orbit (SO) coupling, respectively. These effects are particularly important for the metal‐coordinated N‐atom, where the contributions from solvation and relativity can affect δ ( 15 N) and Δ δ ( 15 N) values up to 10–20 ppm. The 195 Pt chemical shifts of cis ‐ and trans ‐[PtCl 2 ( 1 ) 2 ] are well‐reproduced using the zero‐order regular approximation including SO coupling (ZORA‐SO). Predictions are reported for 99 Ru and 103 Rh chemical shifts, which suggest that these metal centers could be used as additional, sensitive NMR probes in their complexes with nitro‐imidazoles.