1H{15N} GHMQC study of 5,7‐diphenyl‐1,2,4‐triazolo[1,5‐a]pyrimidine and 1H, 13C and 15N NMR coordination shifts in Au(III) chloride complexes of 1,2,4‐triazolo[1,5‐a]pyrimidines

Szłyk, Edward; Pazderski, Leszek; Łakomska, Iwona; Kozerski, Lech; Sitkowski, Jerzy

doi:10.1002/mrc.1051

Cited by 29 publications

(4 citation statements)

References 26 publications

(25 reference statements)

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“…When 3‐amino‐[1,2,4]‐triazole was used, the four aromatic 15 N resonances of 1b–e came in two narrow frequency regions, at δ = 225–230 ppm (N‐1 and N‐4) and at δ = 275–278 ppm (N‐3 and N‐8). The values of the encountered 15 N chemical shifts were very similar to those reported for 1a and for other [1,2,4]triazolo[1,5‐a]pyrimidine derivatives 8, 37. This 15 N chemical shift distribution pattern permitted us to conclude that 1b–e had the [1,2,4]triazolo[1,5‐a]pyrimidine parent structure.…”

Section: Resultssupporting

confidence: 79%

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by ¹H¹⁵N HMBC experiments

Salgado

Varela

Collazo

et al. 2010

Magnetic Reson in Chemistry

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The condensation of malonoaldehyde derivatives with either a 3-amino-[1,2,4]-triazole or a 3,5-diamino-[1,2,4]-triazole precursor was studied. In agreement with previous reports, two different bicycles, namely, bearing the regioisomeric [1,2,4]triazolo[1,5-a]pyrimidine (1) or [1,2,4]triazolo[4,3-a]pyrimidine (2) structural surrogates, could be obtained. We found that, depending on the triazole precursor, only one regioisomer resulted, either of the 1 or 2 series. We also observed that these two structural surrogates could be unambiguously differentiated by indirectly measuring their (15)N chemical shifts by (1)H-(15)N HMBC experiments. The occasional conversion of [1,2,4]triazolo[4,3-a]pyrimidines to the [1,2,4]triazolo[1,5-a]pyrimidine counterparts could be unequivocally determined by (15)N NMR data.

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Section: Resultssupporting

confidence: 79%

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by ¹H¹⁵N HMBC experiments

Salgado

Varela

Collazo

et al. 2010

Magnetic Reson in Chemistry

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“…The coordination shift Δ 15 N coord of the pyridinic nitrogen N1 is thus negative (higher shielding of 15 N). 15 N shieldings have been reported previously for N–metal coordination . The increase in nitrogen shielding on metal complexation matches earlier observations of similar trends in δ N of metal complexes and parallels the effects induced by alkylation or protonation of a nitrogen lone pair. , …”

Section: Resultssupporting

confidence: 88%

Dinuclear Coordination Compounds Based on a 5-Nitropicolinic Carboxylate Ligand with Single-Molecule Magnet Behavior

et al. 2017

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Isostructural dinuclear dysprosium and yttrium coordination compounds based on the 5-nitropicolinic carboxylate ligand were synthesized and characterized. The formation of these air-stable complexes is achieved via solvothermal routes employing water as the reaction solvent. The dysprosium-based complex exhibits single-molecule magnet behavior with frequency dependence of the out-of-phase susceptibility at zero direct-current field. High-resolution mass spectrometry (electrospray ionization) experiments and advanced NMR methods including diffusion NMR techniques were applied on the diamagnetic yttrium analogue and established that these species retained their solid-state structure in solution with hydrodynamic radii of 6.5 Å. Full H,C, N,Y, ΔH, ΔC, and ΔN NMR data are given, and through the analysis of the Ramsey equation, the first electronic insights of these derivatives are provided.

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“…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 …”

Section: Introductionmentioning

confidence: 99%

Solvent effects on ¹⁵N NMR coordination shifts

Kleinmaier

Arenz

Karim

et al. 2012

Magnetic Reson in Chemistry

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(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.

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¹H{¹⁵N} GHMQC study of 5,7‐diphenyl‐1,2,4‐triazolo[1,5‐a]pyrimidine and ¹H, ¹³C and ¹⁵N NMR coordination shifts in Au(III) chloride complexes of 1,2,4‐triazolo[1,5‐a]pyrimidines

Cited by 29 publications

References 26 publications

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by ¹H¹⁵N HMBC experiments

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by ¹H¹⁵N HMBC experiments

Dinuclear Coordination Compounds Based on a 5-Nitropicolinic Carboxylate Ligand with Single-Molecule Magnet Behavior

Solvent effects on ¹⁵N NMR coordination shifts

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1H{15N} GHMQC study of 5,7‐diphenyl‐1,2,4‐triazolo[1,5‐a]pyrimidine and 1H, 13C and 15N NMR coordination shifts in Au(III) chloride complexes of 1,2,4‐triazolo[1,5‐a]pyrimidines

Cited by 29 publications

References 26 publications

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by 1H15N HMBC experiments

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by 1H15N HMBC experiments

Dinuclear Coordination Compounds Based on a 5-Nitropicolinic Carboxylate Ligand with Single-Molecule Magnet Behavior

Solvent effects on 15N NMR coordination shifts

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¹H{¹⁵N} GHMQC study of 5,7‐diphenyl‐1,2,4‐triazolo[1,5‐a]pyrimidine and ¹H, ¹³C and ¹⁵N NMR coordination shifts in Au(III) chloride complexes of 1,2,4‐triazolo[1,5‐a]pyrimidines

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by ¹H¹⁵N HMBC experiments

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by ¹H¹⁵N HMBC experiments

Solvent effects on ¹⁵N NMR coordination shifts