Experimental and quantum‐chemical studies of ¹H, ¹³C and ¹⁵N NMR coordination shifts in Au(III), Pd(II) and Pt(II) chloride complexes with picolines

Abstract

(1)H, (13)C and (15)N NMR studies of gold(III), palladium(II) and platinum(II) chloride complexes with picolines, [Au(PIC)Cl(3)], trans-[Pd(PIC)(2)Cl(2)], trans/cis-[Pt(PIC)(2)Cl(2)] and [Pt(PIC)(4)]Cl(2), were performed. After complexation, the (1)H and (13)C signals were shifted to higher frequency, whereas the (15)N ones to lower (by ca 80-110 ppm), with respect to the free ligands. The (15)N shielding phenomenon was enhanced in the series [Au(PIC)Cl(3)] < trans-[Pd(PIC)(2)Cl(2)] < cis-[Pt(PIC)(2)Cl(2)] < trans-[Pt(PIC)(2)Cl(2)]; it increased following the Pd(II) --> Pt(II) replacement, but decreased upon the trans --> cis-transition. Experimental (1)H, (13)C and (15)N NMR chemical shifts were compared to those quantum-chemically calculated by B3LYP/LanL2DZ + 6-31G**//B3LYP/LanL2DZ + 6-31G*.

Structural correlations for 1H, 13C and 15N NMR coordination shifts in Au(III), Pd(II) and Pt(II) chloride complexes with lutidines and collidine

“…In the present work, we report the 1 H, 13 C and 15 N NMR studies of [AuLCl 3 ], trans ‐[PdL 2 Cl 2 ] and trans ‐/ cis ‐[PtL 2 Cl 2 ] complexes with lutidines or collidine, discussing their chemical (δ 1H , δ 13C , δ 15N ) and coordination shifts (Δ 1H coord , Δ 13C coord , Δ 15N coord ; Δ coord = δ complex − δ ligand ) in relation to the type of the central atom [Au(III), Pd(II), Pt(II)], geometry ( trans ‐ or cis ‐), metal‐nitrogen bond lengths and the position of both methyl groups in the pyridine ring system. This study follows our recent researches on analogous coordination and organometallic compounds with pyridine,10–12 picolines,13 phenylpyridines,14, 15 2,2′‐bipyridine, 1,10‐phenanthroline and their methyl or phenyl derivatives,10, 11, 16 as well as quinolines 17…”

“…ca 0.05–0.1 M ), by a Varian INOVA 500‐MHz NMR spectrometer, equipped with an inverse 1 H{ 31 P/ 15 N} 5‐mm Z‐SPEC Nalorac probe with an actively shielded z ‐gradient coil. The pulse sequences were principally the same as those applied upon our previous NMR studies on analogous Au(III), Pd(II) and Pt(II) chloride complexes with pyridine, picolines and phenylpyridines 10–15. TMS ( 1 H, 13 C) and external CH 3 NO 2 ( 15 N) were used as references.…”

Fragmentation pathways analysis for the gas phase dissociation of protonated carnosine-oxaliplatin complexes

“…[48] The use of the B3LYP/LANL2DZ computational protocol in investigating transition metal containing compounds is well established. [49][50][51][52][53][54][55][56][57][58][59][60][61] In fact, it was recently used to successfully investigate the structures of the anti-arthritic drug auranofin and its complexes with cysteine; [45] to model CO adsorption on Pt nanoclusters; [62] to obtain structural information and binding energies for the complexation of cis-and trans-Pt(NH 3 ) 2 Cl + to guanine; [57] to investigate monomeric complexes between cisplatin and glutathione; [63] to obtain excellent agreement with X-ray data for cisplatin analogues [64] and oxaliplatin analogues [65] ; as well as to examine the mechanism of Pt and Pd catalysed coupling and cyclopropanation reactions between olefins. [66] Most recently, this level of theory was used to study the interactions of the anticancer Pt containing drug oxaliplatin with each of the cytoplasmic thiol containing tripeptide ligands γ-L-glutamyl-L-cysteinyl-glycine (GSH) [67] as well as the biologically active βalanine-L-histidine dipeptide carnosine.…”

Solvent effects on 15N NMR coordination shifts

“…Furthermore, they were used in the determination of the metal coordination sites in ambiguous heterocyclic complexes . Azine complexes with Ag I , Pd II /Pt II and Au III , and also Os II , Ru II , Rh III , and first‐row transition metals such as Fe II and Co III have been examined by 15 N NMR spectroscopy. With the increasing ease of access to 15 N NMR, the investigation of 15 N chemical shifts ( δ 15 N) is being extended to ever more complex areas …”