A series of Pd and Pt chloride complexes with pyridine (py), 2,2'-bipyridine (bpy) 1,10-phenanthroline (phen), general formulae trans-/cis-[M(py)2Cl2], [M(py)4]Cl2, trans-/cis-[M(py)2Cl4], [M(bpy)Cl2], [M(bpy)Cl4], [M(phen)Cl2], [M(phen)Cl4], where M = Pd, Pt, was studied by 1H, 195Pt, 15N NMR. The 90-140 ppm low-frequency coordination shifts are discussed in terms such structural features the as type platinide metal, oxidation state, sphere geometry ligand. results quantum-chemical NMR...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of conformational barriers in 1,5-cyclooctadiene by proton and carbon-13 nuclear magnetic resonanceF. A. L. Anet Lech. KozerskiCite this: J. Am. Chem. Soc. 1973, 95, 10, 3407–3408Publication Date (Print):May 1, 1973Publication History Published online1 May 2002Published inissue 1 1973https://pubs.acs.org/doi/10.1021/ja00791a068https://doi.org/10.1021/ja00791a068research-articleACS PublicationsRequest reuse permissionsArticle...

(1)H, (13)C and (15)N NMR studies of gold(III), palladium(II) platinum(II) chloride complexes with dimethylpyridines (lutidines: 2,3-lutidine, 2,3lut; 2,4-lutidine, 2,4lut; 3,5-lutidine, 3,5lut; 2,6-lutidine, 2,6lut) 2,4,6-trimethylpyridine (2,4,6-collidine, 2,4,6col) having general formulae [AuLCl(3)], trans-[PdL(2)Cl(2)] trans-/cis-[PtL(2)Cl(2)] were performed the respective chemical shifts (delta(1H), delta(13C), delta(15N)) reported. The deshielding protons carbons, as well shielding...

Abstract Rotational barriers of the dimethylamino group in different enamino aldehydes and ketones have been applied for evaluation their conformation. It has maintained that repulsion between bulky substituents causes twisting molecule rather than planar deformations. Arguments against these alternative concepts based on analysis J HH ( 13 CH) coupling constants fragments discussed.

(1)H, (13)C, (15)N and (195)Pt NMR studies of gold(III) platinum(II) chloride organometallics with N(1),C(2')-chelated, deprotonated 2-phenylpyridine (2ppy*) the formulae [Au(2ppy*)Cl(2)], trans(N,N)-[Pt(2ppy*)(2ppy)Cl] trans(S,N)-[Pt(2ppy*)(DMSO-d(6))Cl] (formed in situ upon dissolving [Pt(2ppy*)(micro-Cl)](2) DMSO-d(6)) were performed. All signals unambiguously assigned by HMBC/HSQC methods respective (13)C coordination shifts (i.e. differences between chemical same atom complex ligand...

Abstract Au(III), Co(III) and Rh(III) chloride complexes with pyridine (py), 2,2′‐bipyridine (bpy) 1,10‐phenanthroline (phen) of the general formulae [M 1 LCl 3 ], trans ‐[M 2 L 4 Cl ] + , mer (LL)Cl cis (LL) where M = Au; Co, Rh; py; LL bpy, phen, were studied by H 13 C HMBC 15 N HMQC/HSQC. The H, coordination shifts (the latter from ca − 78 to 107 ppm) are discussed in relation type metal, electron configuration, sphere geometry ligand. chemical also calculated quantum‐chemical NMR...

Abstract 1 H, 13 C and 15 N NMR studies of iron(II), ruthenium(II) osmium(II) tris‐chelated cationic complexes with 2,2′‐bipyridine 1,10‐phenanthroline the general formula [M(LL) 3 ] 2+ (M = Fe, Ru, Os; LL bpy, phen) were performed. Inconsistent literature H signal assignments corrected. Significant shielding nitrogen‐adjacent protons [H(6) in H(2) phen] metal‐bonded nitrogens was observed, being enhanced series Ru(II) → Os(II) Fe(II) for bpy phen both nuclei. The carbons are deshielded,...

Abstract A 13 C magnetic resonance investigation of 22 compounds the general formula OC 1 (R )C 2 )C 3 ) NR 4 R 4′ has been carried out in order to confirm conformational assignments estimated previously by PMR and IR spectroscopy. The effects nonplanarity hindered rotation have discussed based on chemical shifts shapes , signals.

Heparins can be contaminated with oversulfated chondroitin sulfate, OSCS, the impurity being linked to adverse clinical events that certain lots of heparins have had on humans. Here, we propose labeling N-acetyl peaks in (1)H NMR spectra parameter D(t), describing translational diffusion coefficient available from DOSY NMR. We show how applied as a routine method for screening obtaining profile when using

Abstract Carbon‐13 magnetic resonance spectra of the s‐ cis and trans rotamers enamino ketones thiones general formula \documentclass{article}\pagestyle{empty}\begin{document}${\rm X =}\mathop {\rm C}\limits^{\rm 1} (}\mathop R}\limits^{\rm {\rm)}\mathop 2} H 3} HN}\mathop {{\rm R}_{\rm 2}}\limits^{\rm 4}$\end{document} (where × = O or S R‐1, R‐4 alkyl) have been obtained. With dimethylaminoacrolein its thione analogue, restricted rotation could only be observed in latter. The chemical shift...

The inclusion complexes of β-cyclodextrin (β-CD) with prednisolone 1, ethinyloestradiol 2 and estriol 3 in aqueous solution were investigated using 1H NMR molecular modelling. spectra the steroids studied presence β-CD are fully assigned interpreted by means 2D GCOSY NOESY spectra. parallel interpretation chemical shift changes dipolar contacts allows mode binding to be established. On basis ROESY data, “low resolution” have been determined multistep restrained dynamics calculations....

Abstract The pulse sequence INEPT was used to obtain proton‐coupled 15 N‐NMR spectra in natural isotope abundance for enamines substituted 2‐position with electron‐with‐drawing groups. chemical shifts and coupling constants are discussed terms of their relationship structural features such as multiple N ‐alkyl substitution, double‐bond configuration, H‐bonding, N‐lone‐pair delocalization within the conjugated system, steric effects. It is concluded that a sensitive probe local modifications...

Abstract 1 H, 13 C and 15 N NMR studies of platinide(II) (M = Pd, Pt) chloride complexes with methyl phenyl derivatives 2,2′‐bipyridine 1,10‐phenanthroline [LL 4,4′‐dimethyl‐2,2′‐bipyridine (dmbpy); 4,4′‐diphenyl‐2,2′‐bipyridine (dpbpy); 4,7‐dimethyl‐1,10‐phenanthroline (dmphen); 4,7‐diphenyl‐1,10‐phenanthroline (dpphen)] having a general [M(LL)Cl 2 ] formula were performed the respective chemical shifts (δ 1H , δ 13C 15N ) reported. H high‐frequency coordination (Δ coord complex − ligand...

Abstract 13 C magnetic resonance spectra of several enamino ketones with secondary and tertiary amino groups were obtained for trifluoroacetic acid solutions. In both series O ‐protonation is predominant the chemical shifts are related to electron density changes respect parent base. The compounds interpreted in terms slow rotation around C–1C–2 C–3N bonds discernible at room temperature. ‐protonated forms undergo further reaction on C–2 yielding pyridinium salts. mechanism formation...

Abstract D.n.m.r. studies have been performed involving the measurement of rates trans ‐ cis isomerization aliphatic enamino ketones type RCOCHCHNHR 1 , by means equilibration experiments and method finding coalescence temperature. Simultaneous observation dynamic NH proton exchange processes latter has facilitated assignment rate‐determining reaction step in title compounds studied aprotic solvents. Thermodynamic parameters are discussed dipolar transition state to a nonpolar solvent...

Topotecan (TPT) is in clinical use as an antitumor agent. It acts by binding to the covalent complex formed between nicked DNA and topoisomerase I, inserts itself into single-strand nick, thereby inhibiting religation of nick acting a poison. A crystal structure analysis ternary has shown how drug binds (B. L. Staker, K. Hjerrild, M. D. Feese, C. A. Behnke, B. Burgin, Stewart, Proc. Natl. Acad. Sci. U.S.A., 2002, 99, 15 387-15 392), but left number unanswered questions. Herein, we NMR...

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

Tris(pentafluorophenyl)corrole and its (15)N-enriched isotopomer were studied in [D8]toluene solution by 1D 2D variable-temperature NMR techniques to establish the mechanisms of tautomerization NH protons inside interior corrole macrocycle. Three such rate processes could be identified which two modulate spectral line shapes at temperatures above 205 K third is NMR-inaccessible as it very fast. The latter involves proton engaged an unsymmetrical sponge unit formed pyrrole nitrogen atoms....