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Experimental and quantum‐chemical studies of 1 H, 13 C and 15 N NMR coordination shifts in Pd(II) and Pt(II) chloride complexes with quinoline, isoquinoline, and 2,2′‐biquinoline
Author(s) -
Pazderski Leszek,
Toušek Jaromír,
Sitkowski Jerzy,
Kozerski Lech,
Szłyk Edward
Publication year - 2007
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2105
Subject(s) - chemistry , ligand (biochemistry) , chemical shift , crystallography , coordination sphere , proton nmr , nmr spectra database , paramagnetism , stereochemistry , spectral line , crystal structure , biochemistry , receptor , physics , astronomy , quantum mechanics
1 H, 13 C, and 15 N NMR studies of platinide(II) (M = Pd, Pt) chloride complexes with quinolines (L = quinoline–quin, or isoquinoline–isoquin; LL = 2,2′‐biquinoline–bquin), having the general formulae trans‐/cis‐ [ML 2 Cl 2 ] and [M(LL)Cl 2 ], were performed and the respective chemical shifts (δ 1H , δ 13C , δ 15N ) reported. 1 H coordination shifts of various signs and magnitudes (Δ 1H coord = δ 1H complex − δ 1H ligand ) are discussed in relation to the changes of diamagnetic contribution to the relevant 1 H shielding constants. The comparison to the literature data for similar complexes containing auxiliary ligands other than chlorides exhibited a large dependence of δ 1H parameters on electron density variations and ring‐current effects (inductive and anisotropic phenomena). The influence of deviations from planarity, concerning either MN 2 Cl 2 chromophores or azine ring systems, revealed by the known X‐ray structures of [Pd(bquin)Cl 2 ] and [Pt(bquin)Cl 2 ], is discussed in respect to 1 H NMR spectra. 15 N coordination shifts (Δ 15N coord = δ 15N complex − δ 15N ligand ) of ca. 78–100 ppm (to lower frequency) are attributed mainly to the decrease of the absolute value of paramagnetic contribution in the relevant 15 N shielding constants, this phenomenon being noticeably dependent on the type of a platinide metal and coordination sphere geometry. The absolute magnitude of Δ 15N coord parameter increased by ca 15 ppm upon Pd(II) → Pt(II) replacement but decreased by ca . 15 ppm following trans → cis transition. Experimental 1 H, 13 C, 15 N NMR chemical shifts are compared to those quantum‐chemically calculated by B3LYP/LanL2DZ + 6–31G**//B3LYP/LanL2DZ + 6–31G*, both in vacuo and in CHCl 3 or DMF solution. Copyright © 2007 John Wiley & Sons, Ltd.