Characterization of Hexahydroxycyclotriphosphazene Salicylate; Epr, Nmr, Xrd Spectra

Introduction

A few of the adducts of [NP(OH)₂]₃ with organic acids have been synthesized and reported.^1-6 U.V., E.P.R., ¹HNMR and XRD investigations of hexahydroxycyclotriphos-phazene salicylate are being reported here with.

Experimental

[NP(OH)₂]₃ was prepared by the reaction of NaOH on (NPCl₂)₃ synthesized,⁷ in non aqueous solvent. The white mass formed was refluxed with salicylic acid in presence of 1 ml conc. H₂SO₄ in alcohol used as solvent. Perken Elmer 15 PC (200 nm – 800 mn), Varian’s X-E-4 band (RT), Bruker DRX-300 spectrometer (RT) were used to record subsequently for U.V., E.P.R. and ¹HNMR spectra. For XRD PW – 1710, X-ray powder differectometer was used (l = 1.5418Å, CuK_a as source of radiation) in the 2q range 0^o – 80^o.

Results and Discussion

Hexahydroxycyclotriphosphazene salicylate has been formulated as P₃N₃[(CO)₃O₆(C₆H₄)₃], on the basis of its quantitative⁸ estimation, mass and I.R. spectrum as reported (loc. cite). The three bands at 210, 225, 305 nm have appeared in its U.V. spectrum. The band at 210 nm = 5.9 ev is due to the ionic environment or charge transfer transition, while the remaining bands are corresponding to π→π* transition⁹ due to the double bond in adduct. The low values of band gap energy, ΔEg = 0.1965, 0.723 ev and high value of number of conducting electrons, Nc = 2.1931 x 10⁵ and 4.3979 x 10⁵ indicate the good conductive nature of the adduct.

The hyper fine peaks in its E.P.R. spectrum¹⁰ suggests the paramagnetic character of the adducts. The two prominent peaks (fig. 1) of high intensity selected for calculations. The values of g_z > 2 indicate the presence of covalent bonding along with the ionic bonding as referred by the low values of g_x = g_y < 2 as suggested by its the U.V. spectrum.

Figure1: E.P.R. Spectrum of the adduct   Click here to View figure

 

The values of magnetic moment, m_eff 1.6944, 1.6587 B.M. and magnetic susceptibilities, x_A = 1.1966 and 1.1467 x 10^-3 e.s.u., also infer the paramagnetic character of the adduct, having one unpaired electron on its oxygen atom predicting that during the reaction H⁺ of [NP(OH)₂]₃ has reacted in presence of conc. H₂SO₄ and reacted with OH^– of salicyclic acid with the elimination of H₂O molecule and forming hexahydroxycyclotriphosphazene salicylate. The peaks have divided into three parts repeating successively, suggesting that three molecule of salicylic acid have reacted with one molecule of [NP(OH)₂]₃ as follows:

Scheme 1  Click here to View scheme

 

¹HNMR spectrum (fig. 2) of the adduct possess four sets of signals, out of which four signals, a set in the range of chemical shift, δ6.677 – δ8.103 ppm are due to two parallel P-N bands linked with other P-N band of the P₃N₃ ring showing the two signals at the chemical shift, δ8.636 and δ8.949 ppm. The

Figure2: 1HNMR Spectrum of the adduct   Click here to View figure

 

three signals in the range of chemical shift, δ2.184 – δ6.329 ppm are according to the H atoms of three C₆H₅ groups linked differently to P₃N₃ ring. Again a broad signal of low intensity at the chemical shift, δ10.856 to δ11.636 ppm is for the P-N ring. Thus from the ¹HNMR spectrum, it is clear that three salicylic molecules have linked to one P₃N₃ ring through oxygen atoms differently as shown by its structure (fig. 3).

Figure3: Structure of the adduct   Click here to View figure

 

The values of interplaner distance d, calculated¹¹ (table -1) from its XRD are very much close to theoretical values. The values of sin²Φ, and milar index, hkl alongwith the axial ratios and axial angles were calculated. The values of axial ratios, a₀ = 3.3128 Å, b₀ = 1.5615 Å, c₀ = 9.6938 Å and axial angles a = 108.44^o, β = 153.44^o and γ = 90.01^o inferred the triclinic geometrical packing of the molecule in the adduct.

Table1: XRD Patter of the adduct

S. No.	2q (degree)	Sin2q	q(h2 + k2 + l2)	hkl	d(Å)
					Obs.	Theo.
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.	7.67 15.33 21.67 23.00 25.83 30.33 32.00 36.83 42.50 47.83 50.67 64.00	0.00447 0.01779 0.03533 0.03974 0.04995 0.06843 0.07597 0.09979 0.13136 0.16220 0.18310 0.28081	0.00447 x (1) 0.00444 x (4) 0.00441 x (8) 0.00441 x (9) 0.00454 x (11) 0.00488 x (14) 0.00446 x (17) 0.00453 x (22) 0.00452 x (29) 0.00450 x (36) 0.00446 x (41) 0.00453 x (62)	100 200 220 221 311 321 322 332 432 442 443 732	11.5317 5.7811 4.1016 3.8671 3.4492 2.9474 2.7971 2.4407 2.1272 1.9032 1.8015 1.4548	11.516 5.7748 4.0974 3.8635 3.4462 2.9443 2.7944 2.4382 2.1252 1.9000 1.8000 1.4535

q_avg = 0.05415

a₀ = 3.3128 Å, b₀ = 1.5615 Å, c₀ = 9.6938 Å, a = 108.44^o, β = 153.44^o, g = 90.01^o

Acknowledgement

Authors are thankful to the Director C.D.R.I. Lucnow, Director SAIF, Punjab University, Chandigarh, Director SAIF, IIT Bombay, Director ACMS IIT Kanpur to provide instrumental facilities

References

1. Rani, I.; Jadon, S.P.S. Asian J. Chem., 2008, 20(7), 5711-5716.
2. Rani, I.; Jadon, S.P.S. Int. J. Chem. Sci., 2008, 6(2), 519-525.
3. Gupta, A.; Jadon, S.P.S. Int. J. Chem. Sci., 2009, 7(4), 2867-2871.
4. Gupta, A.; Jadon, S.P.S. Int. J. Chem. Sci., 2012, 10(1), 159-165.
5. Gupta, A.; Jadon, S.P.S. RJPBCS, 2012, 3(4), 11-19.
6. Gupta, A.; Jadon, S.P.S. Am. Int. J. Formal Appl. Sci., 2014, 7(1), 97-105.
7. Jadon, S.P.S. Asian J. Chem., 2003, 15, 151; 2005, 17, 1312.
8. Vogel, A.I. A Text Book of Quantitative Inorganic, Longman, London, 1961.
9. Figgis, B.N. Introduction to Ligand Fields, Wiley Eastern Limited, New Delhi, 1976.
10. Pake, G.E. The physical principles of electron paramagnetic resonances, W.A. Binjamin, Inc., 1973.
11. Woolfson, M.M. An Introduction to X-ray Crystallography, Vikas Publishing House Pvt. Ltd., Cambridge University Press, 1978.

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