NMR investigation of chlorophosphorylation products of N‐vinylazoles

Abstract

The structure of novel phosphorus-containing N-vinylazoles prepared by action of phosphorus pentachloride has been studied by multinuclear (1)H, (13)C, (15)N, (31)P and two-dimensional (2D) NMR spectroscopy. N-vinyl-substituted 1,2-diazoles and 1,2,3-triazoles have undergone phosphorylation, exclusively, on double bond. N-vinylazoles-based hexa-coordinated phosphorus compounds have been synthesized for the first time. (31)P NMR spectroscopy provides the most convenient and unambiguous method for the investigation of E-Z-isomeric structures of phosphorylated enamines.

Quantum-chemical calculations of NMR chemical shifts of organic molecules: IV. Effect of intermolecular coordination on 31P NMR shielding constants and chemical shifts of molecular complexes of phosphorus pentachloride with azoles

“…While developing our studies on theoretical calculations of 31 P chemical shifts [1][2][3], in the present work we examined molecular complexes of phosphorus pentachloride with some azoles, N-vinylimidazole (I) and 1-allyl-3,5-dimethylpyrazole (II). In keeping with the results of our experimental [4] and theoretical studies [1], the phosphorus atom in chlorophosphonium group is capable of forming a dative bond with pyridine-type nitrogen atom (i.e., sp 2 -nitrogen atom possessing an unshared electron pair). As a result, the coordination number of phosphorus increases to 5 or 6, and its resonance signal in the 31 P NMR spectrum is displaced upfield; therefore, 31 P NMR spectroscopy can be used to analyze structure of such intramolecular complexes.…”

Quantum-chemical calculations of chemical shifts in NMR spectra of organic molecules: V. Stereochemical structure of unsaturated phosphonic acids dichlorides from 31P NMR spectral data

“…As seen from the analysis of the NMR spectra, compound I existed in the form of two isomers whose assignment was underlain by the measured spin-spin coupling constants 3 J РН that were sharply different for the confi gurational isomers with respect to the double bond [3]. In addition to these data it was interesting to test the possibility to use 31 Р NMR chemical shifts for assignment of the confi guration of compounds containing a double bond С=С linked to a phosphorus atom.…”

“…In this research we applied this approach to the study of the spatial arrangement of unsaturated phosphonic acids dichlorides containing in their structure the POCl 2 group linked to double bonds C=C and C=N, namely, of 2-(pyrazolyl) ethenylphosphonic acid dichloride (I) obtained by the oxidation of 2-(pyrazolyl)ethenyltrichlorophosphonium hexachlorophosphorate [3], N-dichlorophosphonylimin obenzoic acid chloride (II) prepared by procedure [5], N'-dichlorophosphoryl-N,N-dimethylchloroformamidine (III) obtained by the phosphorylation of N,N-dimethylurea with phosphorus pentachloride [4], , and also of 1-trichlorophosphazo-1-chloro-2-dichlorophosphoryl-2-azaethene (IV), the product of the reaction of urea with phosphorus pentachloride [6]. Compounds I-IV were identifi ed by the comparison of their 1 Н, 13 С, and 31 Р spectra with the published data [3][4][5][6].…”

Quantum-chemical calculation of NMR chemical shifts of organic molecules: III. Intramolecular coordination effects on the 31P NMR chemical shifts of phosphorylated N-vinylazoles

“…N-vinylpyrazole with phosphorus pentachloride according to the procedure described in [4]. The 31 P NMR spectra were recorded on Bruker DPX-400 and AV-400 spectrometers (161.98 MHz) at 298 K; samples were placed into 5-mm ampules, and 85% H 3 PO 4 was used as external reference.…”

“…The effect of coordination may attain a considerable value comparable with the overall range of variation of phosphorus chemical shifts. For example, phosphorus pentachloride, which is a known electrophilic phosphorylating agent, both in crystal and in polar solvents undergoes dissociation into ions, whereas in nonpolar solvents it exists as five-coordinate phosphorus species, and the δ P value changes from -300 to 80 ppm, depending on the degree of coordination [4] (Scheme 1).…”