CROATICA CHEMICA ACTA CCACAA 58 (3) 277-281 (1985)

CCA-1579YU lSSN 0011-1643

UDC 546.831Original Scientific Paper

Oxozirconium(IV) Complexes of NonamethylimidodiphosphoramideR. K. Agarwal* and S. C. Rastogi**

Department of Chemistry, Lajpat Rai Post-Graduate CoLLege, Sahibabad-201 005,Indi·a

Received November 26, 1984

A series of new complexes of the type ZrOX2(NlPA) (X = Cl,Br, I, N03, NCS, NCSe or BPh4) and ZrO(CI04h' 2(NlPA) havebeen synthesised and characterized through molar conductance, .molecular weight, magnetic measurement and in dependence onthe nature of anion.

INTRODUCTION

In recent years we have reported a number of oxozirconium(IV) complexesof oxygen donor molecules containing an X = O group (where X = C, N, Sor P)". Comparatively less is known about the compounds of oxozirconium(IV)with P = O containing ligands. Only triphenyl phosphine oxide", hexamethyl-phosphoramide" and octamethylpyrophosphoramide4 complexes of oxozirco-nium have been reported. In this series, we wish to report our results onoxozirconium(IV) complexes of nonamethylimidophosphoramide (NIPA) (I). It

is a very potential bidentate ligand. Lannert and Joestenš." and then Bolster?reported the preparation and identification of a large number of transition,non-transition and actinide metal complexes of NIPA.

* Author for correspondence.** Chemical Laboratories, P.O. Zawer Mines - 313901, Hindustan Zinc Ltd.

(Rajasthan) India.

278

Material

R. K. AGARW AL AND S. C. RASTOGl

EXPERIMENTAL

Zirconyl(IV) nitrate used was obtained from BDH, while perchlorate, thio-cyanate and selenocyanate were prepared from nitrate as reported earlier+? oxo-zirconium(IV) chloride was obtained from Reidal, while the bromide and iodidewere prepared from the chloride by displacement method. Oxozirconium(IV) tetra-phenylboronate was prepared in solution by mixing acetonic solutions of anhydrousZrOC12and NaBPh4 and filtering out the precipitated NaCPo. The ligand NIPAwas prepared by reported methods'"!',

Preparation of Complexes

All the complexes were prepared by a general method. li. solution of zir-conyl(IV) salt in methanol or acetone was treated with an excess of NIPli. in thesame solvent. The mixture was refluxed for 3 hr. and the excess solvent removedby distillation. The residual mass on treatment with diethyl ether yielded a crystal-line solid, which was filtered, washed with diethyl ether and dried in vacuumover P4010.

Analytical Procedures

The metal content of the complexes was determined as oxide'", The per-chlorate was determined by the method of Kurz and the halide contents byVolhard's method, while the thiocyanate was determined by titration of a slightlyacidic solution of the complex against standard AgN03.

The electrical conductances of the complexes were measured with a ToshniwalConductivity bridge at room temperature and their molecular weights were deter-mined cryoscopically in freezing PhN02. Magnetic susceptibility measurements onpowder form of the complexes were made at room temperature using Gouy'sbalance at ca. 11000 gauss.

RESULTS AND DISCUSSION

The analytical data correspond to the composition ZrOX~ . L (X = Cl, Br,I, N03, NCS, NCSe or BPh4) and ZrO(Cl04) • 2L (L = NIPA). The complexesare quite sensitive to atmospheric moisture. The molar conductances of thecomplexes in nitrobenzene indicate that chloro, bromo, iodo, thio & seneno-cyanato and tetraphenylboronato complexes are non-electrolytes, while theperchlorato complex behaves like uni-bivalent electrolyte. The molecularweight determined cryscopically in freezing PhNOz supports the similarelectrolytic behaviour of the complexes. The magnetic measurements at roomtemperature (20 0c) of the complexes show them to be diamagnetic.

Detailed IR studies of the free ligands have been reported by J oestenš-"and bolester". Pertinent IR data are summarized in Table II. We have comparedthe IR spectra of NIPA and its complexes with those of hexamethylenephosphor amide'' and octamethylpyrophosphoramide4 and their complexes withzirconyl(IV) ions. The PNP stretch has been assigned to the peak at 885 cm'",while the PNC stretching has been assigned to 978 crn" and 745 cm-I. Boththe PNP and PNC stretching frequencies for complexes of NIPA are shiftedto higher frequencies. The P = O stretch, a broad band in the IR spectrumof the ligand, appears at ca. 1203 cm" split mto a sharp strong at ca. 1200 crrr 'and a sharp medium intensity peak at ca. 1180 cm'" in the spectra of allcomplexes. According to Joesten et a1.5,6 this effect is attributed to the couplingbetween two PO vibrations via the metal atom to which they are both coor-dinated. It is further noted that in all NIPA complexes the PO bending

J

TA

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EI

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IPA

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ular

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IPA

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03h

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318

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521

530

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608

616

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~ -.J ~

280 R. K. AGARWAL AND S. C. RASTOGI

vibration is shifted to higher energy; the magnitude and direction of thisshift indicates that coordination occurs via the oxygen atoms of the ligand".

It would not be possible to assign a Zr=O (oxocation) stretching frequency,since this occurs in the same region as v (PNC) (1000-950 cm-I).

Some new medium or weak bands are observed in the range 400-350cm-I in these complexes where the ligand itself has no absorptions. Thesenew bands are tentatively assigned as v (M-O). These frequencies are in goodagreement with M-O stretching modes observed for several transition metalcomplexes1,12,13.

TABLE II

Pertient Infrared Data (cm-I) of Oxozirconium(IV) Complexes of NIPA

Compound v (P=O) v(P-N-P) v(PNC) v (PNC) v(M-O)

NIPA 1195s 885s 975m 745wZrO(NIPA)C12 1200s 900m 990m 750w 400m

1185s 980mZrO(NIP A)Br2 1202s 895m 988m 749w 395m

1185s 980shZrO(NIPA)h 1200s 890m 990m 750w 390m

1180m 985shZrO(NIPA)2(CI04h 1198s 890m 985m 755w 395m

1180mZrO(NIPA)(N03h 1200s 885m 990m 758w 390w, 385sh

1180m 980shZrO(NIPA)(NCSh 1200s 900m 985m 760w 395m

1185m 980shZrO(NIPA)(NCSe)2 1185s 885m 980m 752w 380m

1155shZrO(NIPA)(BPh4h 1185s 890m 990m 758w 385m

1160sh 985m

In [ZrO(NIPA)2](Cl04h both the 1'.3and 1'~IR bands of perchlorate appearas a strong absorption at 1082 and 620 cm-I respectively, showing the ioniccharacter of the perchlorate groups. The absence of the V3 bands of ionicnitrate (D3h)around 1360 cm-I and the occurence of two strong bands at 1520and 1300 cm-I in the spectrum of ZrO(NIPA)(N03)2 suggest the coordinationof nitrate in this complex'<P. The bidentate nature of nitrato groups isrevealed by the presence of bands at 1030 cm-I (1'.2),805 crn? (1'.6),and 720 crrr-'(1'.3/1'5)16. The combination bands (VI + 1'4)in 1800-1700 region appear at 1740and 1700 cm-I in this complex. By applying the Lever separation method!",the separation of these bands (40 cm-I) clearly indicates bidentate nit ratecoordination. Furthermore, the band associated with (Zr-O) (nitrato) istentatively assigned at ca. 215 cm-I as weak absorption. In thio and seleno-cyanato complexes the presence of bands in the region 2060 crrr" (vC=N), 860cm"! (1'.C-X) and 475 cm-I (o NCX) (X = S or Se) in normally associated withthe terminal N-bonding thio and selenocyanato group". This is quite possible

OXOZIRCONIUM(IV) COMPLEXES 281since zirconium is a typical hard metal. The N-bonding is further evidencedby a (Zr-N) absorption (tentatively assigned) at 270 crn"! for thiocyanateand 230 cm for selenocyanate", The investigation of ZrO(NIPA)(BPh4h showsthe four medium or strong bands at 1480, 1450, 1435 and 1390 cm'", whichmay indicate the covalent nature of BPh4 ions, bonded to the metal ionthrough the n-bond of a phenyl grouplO,2l,22.

In the chloro complex Zr-CI stretching vibrations occur at 290 cm " witha shoulder of 275 cm-lo The Zr-Br and Zr--I stretching vibrations could notbe observed in the spectral range studied.

REFERENCES

1. R. K. A g a r w aland S. C. R a s tog i, Thermoehim. Aeta 63 (1983) 113 andreferences therein.

2. R. K. Agarwa1, A. K. Srivastava, and T. N. Srivastava, IndianJ. Chem. 18 (1979) 459.

3. A. •K. S r iva s t a v a, R. K. Ag a r w a 1, and T. N. S r iva s t a v a, Croat.Chem. Acta 54 (1981) 329.

4. R. K. Ag a r w aland S. C. R a s tog i, Nat. Aead. Sei Letters (In Press)5. K. P. Lan ner t and M. D. Joe ste n, Inorg. Chem. 7 (1968) 2048.6. M. D. Joe ste n, R. C. Ko c h, T. W. Mar t i n, and J. H. Ven a b l e (Jr),

J. Amer. Chem. Soc. 93 (1971) 1138.7. M. W. G. de B o 1ste r, The Coordination Chemistry of Aminophosphine

Oxides and ReLated Compounds, Ph. D. thesis, Leiden, 1972.8. P. Ram a m u r t h y and C. C. Pat e 1, Naturwiseensehaften 22 (1961) 693.9. J. R. Chopra, A. N. Pandey, S. P. Sharma, and R. K. Agarwa1,

Croat. Chem. Aeta 55 (1982) 283.10. R. K. Ag a r w a 1, A. K. S r iva s t a v a, and T. N. S r iva s t a v a, Curr.

Sei. (India) 48 (1979) 1077.11. H. R u d y and A. De b o, Chem. Abstr. 55 (1961) 142a.12. S. K. Ma dan and A. M. D o n o h u e, J. Inorg. Nud. Chem. 28 (1966) 1303.13. V. V. Sava n t, P. Ram a m u r t h y, and C. C. Pat e 1, J. Less Common

MetaL 22 (1970) 479.14. C. C. Ad d i s o n and N. Log a n, Adv. Inorg. Chem. Radioehem. 6 (1964) 95.15. N. M. K ara y a n n i o, C. M. Mi k u 1s k i, L. L. P y tle w s k i, and M. M.

Lab e s, J. Inorg. Nucl, Chem. 34 (1972) 3139. .16. R. W. He ste r and W. L. Gro s srna n, Inorg. Chem. 5 (1966) 1308.17. A. B. P. Lever, E. Mantiovani, and B. S. Ramaswamy, Can. J.

Chem. 49 (1971) 1957.18. J. L. B u r mei ste r, Coord. Chem. Rev. 3 (1968) 225.19. R. G. P e ars o n, J. Chem. Edue. 45 (1968) 581, 643.20. N. M. Ka ray a n n i s, C. M. Mi k u 1s k i, L. L. P Ytle w s k i and M. M.

Lab e s, J. Inorg. Nuct. Chem. 34 (1972) 3139.21. R. R. Sc h r o c k and J. A. O s b o r n, Inorg. Chem. 9 (1970) 2339.22. R. J. Hai n e s and A. L. Du - Pre e z e, J. Am. Chem. Soc, 93 (1971) 2820.

SAŽETAK

Kompleksi o'ksocirkonija(IV) s nonametilimidodifosforamidom

R. K. AgarwaL i S. C. Rastogi

Sintetiziran je niz komp1eksnih spojeva tipa ZrOX2(NIPA) (gdje su: NIPA--nonametilimidodifostor-arnid, X = Cl, Br, I, N03, NCS, NCSe i BPh4) i ZrO(C10.1)2. 2(NIPA).

Karakterizacija komp1eksnih specija izvršena je određivanjem mol arne pro-vodnosti, molarne mase, magnetskih svojstava i IR-spektara.