INDIAN J. CHEM., VOL. 21A, MARCH 1982

TAIlU! 2 - OIlSF.RVED AND CALCULATED FREQUENCIES ANDPED FOR trans-ACRYLYL CHLORIDE

Observed frequencies (cm") Calc. Description", PED (%)(cm"")

Katon and RedingtonFeairheller and Kennedy

3124304129891746

3123304329891785

3136 Va CHi (100)3038 v. CHI (97)2972 vCH (98)1760 vC=O(53)+3C-C=o (1O)+vC-C(19)1604 vC=C(49)+vC=O

(37)1429 3CH2 (85)1347 IlCH(29)+vC=C(14)

+IlCH2(12)+yCH,(20)

1314 vC-C(34)+vC-CI(16) HCH(19)

1126 yCH. (62)761 3C--C-0(~5)+vC-

CI(25) +vC-C(20)556 vC-CI(35) +IIC C

-0(24) HC--C =0(13)

513 1l0-C-Cl(51)+IlC-C-O(S':!)

238 /lC-C=C(20)HC-C-0(51)+/lO-

C-Cl (37)

1626 1619

13971347

13971285

1277 938

1142758

609

1149451

609

492 384

448 260

·v-stretehing, II-bending, y-roeking.

The vC-C mode has been assigned at 1277 em'?by Katon and Feairheller! and at 938 cm-1 byRedington and Kennedy", The calculated frequencyis 1314 cnr+ confirming the assignment of Katonand Feairheller-. The C=C-C bending mode hasbeen assigned at 448 cm-1 by Katon and Feair-heller- and at 260 cm-l by Redington and Kennedys,In acrylyl fluoride this mode is assigned at 277 ern"?by Redington", The calculated frequency is ",240cm-1 confirming the assignment by Redington andKennedy. Katon and Feairheller! have also ob-served a band at 266 em"? but they have assignedit to an out-of-plane skeletal mode. In view of thisthe assignment of C= C-C bending mode at 260cm-! seems to be reasonable. Similarly other mixedmodes, SC-C= 0, ~O-C-C1 and SC-C-CI havebeen described by Redington and Kennedy- asO-C-CI scissoring and O-C-CI rocking modes.They have assigned these modes at 451 and 384 em-I.While Katon and Feairheller! have described these asS-C-C-O and ~O-C-CI modes at 758 and 492 cm-1respectively. The band at 384 crrr-! has been assignedto SO-C-CI mode in the cis-isomer. Thecalculated values for these modes are 761 and513 cm-l which are closer to those assigned byKaton and Feairheller- and thus their assignmentsseem to be correct.

References1. KATON,J. E. & FEAIRHELLEROR), W. R., J. chem, Phys.,

47 (1967), 1248.

284

2. REDINGTON,R. L. & KENNEDY,J. R., Spectrochim. Act a.30A (1974), 2197.

3. KEWLEY, R., HEMPIflLL, D. C., & CURL, (JR), R. F., J.molec. Spectrosc .• 44 (1972), 443.

4. UKAJI, T., Bull chem. Soc. Japan, 30 (1957), 737.S. CARLSON,G. L., FATELEY,W. G. & WITKOWSKI, R. E.,

J. Am. chem. Soc., 89 (1967), 6437.6. REDINGTON, R. L., J. chem. Phys., 62 (1975), 4927.7. KEIRNS, J. J. & CURL (JR), R. F., J. chem. Phys .• 48

(1968), 3773.8. LIN, F. F. S. & SERVIS, K. L., J. Am. chem. Soc., 94-

(1972), 5794.9. WILSON (JR), E. B., J. chem. Phys., 7 (1939), 1047; 9

(1941), 76.10. SCHACHTSCHNEIDER,J. H., Vibrational analysis of poly-

atomic molecules (Shell Development Co., California),1964.

11. RAMAN RAO, G., BALASUBRAMANIAN.V. & VENKATA;RAMIAH, K., Indian J. pure & appl. Phys .• 13 (1975),546.

12. BALFOUR,W. J. & PHIBBS,M. K., Spectrochim. Acta. 3SA(1979), 385.

13. SOM, J., BHAUMIC, D., MUKHERJEE,D. K. & KASTHA,G. S., Indian J. pure & appl. Phys., 12 (1974). 149.

Cation Effect on Octahedral Hexaoxy Ions in OrderedPerovskites of the Type A2BllBVIOa

R. K. GOEL·t & M. L. AGARWALtDepartment of Physics, D. N. College, Meerut 250002

Received 2 JIIly 1980; revised and accepted 17 JIIly 1981

Effect of the cation A,BII on the relative bond strengths htthe anions BVIOg- in ordered perovskites AsBIIBVIO. (A=Ba.Sr, Pb, La; BII = Mg, Ni, Co, Zn, Cd, Ca, Li, Na; BVI = W,Mo, Te, U) has been examined employing model force fields,viz. general valence force field (GVFF), modified orbital valenceforce field (MOVFF) and modified Urey-Bradley force field(MUBFF). Coriolis coupling constants C. (f lu X flu) have alsobeen computed.

LIEGEOIS-Duyckaerts and Tartel recently studiedthe vibrational spectra of ordered, cubic pero-

vskites of the type A2BlIRvIOS (A = Ba, Sr, Pb, La;BlI = Mg, Ni, Co, Zn, Cd, Ca, Li, Na; BVI = W,Mo, Te, U) and analysed the spectra of BVIO~- ionsassuming octahedral symmetry. However, the V2

fundamental belonging to eg species was not observedby them in most of the cases. Because of the pre-sence of a variety of cations, the problem is muchcomplicated but interesting. Thus, it was thoughtworthwhile to compute the unobserved fundamentalv2(e.,) by applying modified orbital valence forcefield (MOVFF) model with (F' = -liIOF)2 and thenby employing general valence force field (GVFF)and modified Urey-Bradley force field (MUBFF)models to study (A2BIl)6t- cations more elaboratelythan done earlier" on the strength of the chemicalbonds in BV10g- ions. It was also aimed to computethe Corio lis coupling constants ~2(Jiu X Jiu) ofthese systems using a TDC-316 computer.

tPresent address : Department of Physics, College ofScience, University of Salah aden, Arbil, Iraq.

tPresent address : Department of Physics, D. S. College.Aligarh.

NOTES

The fundamental vibrational wave numbers usedin the present study are given in Table 1. The GVFF,MUBFF and MOVFF stretching force constants arecollected in Table 2. The values of other force con-stants and those of mean amplitudes of vibration atthree temperatures are available with the authors. Agood agreement has been observed between the obser-

ved and calculated frequencies in the force fieldmodels used in the present study. The values ofunobserved fundamental v2(el1) calculated by MOVFFmodel (Table 1) agree well with the previously repor-ted values'< in different cations except in the case ofTeO~- anion when the cation A2BII contains lead andlanthanum.

TABLE1 - FUNDAMENTALVIBRATIONALWAVBNUMBERS(in crrr") OFSOMEOCTAHEDRALBV10g- IONS

System VI(aU) v.(es)* V3UIU) V,UIU) V6U2i) v.c.f.u)t(BaSr)MgWO. 847 686.6 656 380 446 315.37Ba2NiWO. 816 672.5 610 382 434 306.88Ba2MgWO. 813 657.9 618 381 441 311.83Ba2ZnWO. 822 664.6 605 357 431 304.76Ba2CdWO. 845 708.3 620 340 405 286.38Ba2CaWO. 838 688.9 620 338 413 292.04(BaSr)CaWO. 828 669.5 614 343 423 299.11Ba2MgMoO. 779 592.8 605 387 438 309.71Ba.ZnMoO. 785 614.3 594 385 428 302.64Ba2CdMoO. 808 650.9 615 350 401 283.55Ba2CaMoO. 802 664.1 603 360 407 287.79Sr2MgTeO. 782 635.1 715 413 431 304.76PbSrMgTeO. 775 730.1 700 402 366 258.80(pbl·.SrO.6)MgTeO. 766 717.5 693 395 362 255.97Pb2MgTeO. 761 687.7 685 373 359 253.85(BaSr)MgTeO. 758 622.6 695 410 420 296.98(pb1•5Bao.6)MgTeO. 753 699.7 675 395 364 257.39(PbBa)MgTeOe 742 712.6 666 409 364 257.39(BaLa)LiTeOe 716 565.4 675 417 428 302.64Ba2MgTeO. 724 594.2 650 410 414 292.74Ba2CdTeO. 745 648.3 667 392 385 272.24(BaLa)NaTeO. 716 552.9 677 410 430 304.06Ba2CaTeO. 748 633.6 680 402 402 284.26Ba.NiUO. 743 647.7 595 315 350 247.49Ba2MgUO. 753 682.7 604 341 352 248.90Ba2ZnU06 762 667.2 600 310 348 246.07

*Computed from MOVFF, tComputed from Vi = .y2 V.

TABLE2 - STRETCHINGFORCE CoNSTANTS(in mdyn/A) AND CoRIOLlS COUPLING CONSTANTSOF SOME OCTAHEDRALBV10:- IONS

System K K fr ~2(!Iu x flu)~Mx(MUBFF) (MOVFF) (GVFF)* My

(BaSr)MgWO. 4.048 3.125 4.359 0.323 3.390Ba2NiWO. 3.669 2.907 3.984 0.308 3.390Ba2MgWO. 3.642 2.799 3.954 0.312 3.390Ba.ZnWO. 3.664 2.745 3.939 0.321 3.390Ba2CdW06 4.010 3.201 4.259 0.330 3.390Ba2CaW06 3.910 3.012 4.156 0.331 3.390(BaSr)CaWO. 3.764 2.813 4.017 0.328 3.390Ba2MgMo06 2.939 2.175 3.410 0.161 2.449Ba2ZnMo06 2.993 2.308 3.459 0.154 2.449Ba2CdMoO. 3.357 2.664 3.742 0.203 2.449Ba2CaMo06 3.325 2.567 3.732 0.189 2.449Sr2MgTeO. 3.740 3.211 4.200 0.260 2.824PbSrMgTe06 4.072 4.142 4.508 0.262 2.824(Pbl'5SrO'5)MgTeOe 3.970 4.011 4.391 0.263 2.824Pb2MgTeO. 3.826 3.686 4.201 0.271 2.824(BaSr)MgTeO. 3.533 3.096 3.986 0.256 2.824(Pbl'5Bao'5)MgTeOe 3.767 3.785 4.188 0.258 2.824(PbBa)MgTeO. 3.726 3.903 4.177 0.245 2.824(BaLa)LiTeOe 3.104 2.650 3.574 0.243 2.824Ba2MgTeO. 3.117 2.749 3.570 0.236 2.824Ba2CdTeO. 3.496 3.263 3.910 0.257 2.824(BaLa)NaTeO. 3.085 2.549 3.538 0.249 2.824Ba2CaTeOe 3.490 3.172 3.926 0.255 2.824Ba2NiUO. 3.488 3.013 3.667 0.367 3.857Ba2MgUO. 3.673 3.389 3.883 0.362 3.857Ba2ZnUO. 3.643 3.148 3.817 0.369 3.857

*MiiUer's methodWl2•

285

INDIAN J. CHEM., VOL. 21A, MARCH 1982

It is interesting to note that the value of stretchingforce constant K(Table 2) of UO:- ion in the presenceof various cations follows the order : K(Ba2Mg)6+ >K(Ba2Zn)8+ > K(Ba2Ni)6+, which is in agreementwith the order of increasing electronegativities ofmagnesium, zinc and nickel. But the trend is reversedfor MoOg- anion in the presence of these cations.This may be explained on the basis of change in theionic radius, which increases from magnesium tozinc. Greater the value of ionic radius of the cation,greater will be the bond strength. The order of bondstrengths for wog- in the presence of differentcations is: (Ba2Ni)6+>(Ba2Mg)6r>(Ba~Zn)H. Thisorder can be explained on the basis of cell constantswhich are! 8.06 A, 8.09 A and 8.11 A for Ba2NiW06.BazMgWOs and Ba2ZnWOS respectively; smallercell constant will shorten the W-O bond. A similareffect has been reported by Del-lair et al.6 for IO~- invarious perovskites. The maximum bond strengthof WO:- in the presence of (BaSr)Mg6+ cation canbe explained from its cell constant, which is smallest-(8.00A) in this case. The lower value of K or fr for(BaSr) Ca W06 than that for Ba2Ca W06 is in accor-dance with the total electronegutivities of cations. ForBaaCd6 ~ it is greater than that for BaaCa6f- or(BaSr)Ca6+, thus we should expect a still lowervalue of K for WO: - ion in the case of Ba2CdH cationcompared to Ba2Ca6+-, while reverse is the observedtrend. The cell constant values 8.40A and 8.34Afor Ba.Ca WOs and Ba~CdW06 respectively, supportthis trend. Similar trend has also been observed forBa~CdBvIOs and BaaCaBVlOs (BVI,= Mo, Te).However, it is noted from Table 2 that the values of Kot f; for BIvOg- (BIV = W, Mo, Te) in the presenceof Ba~Cd8+ and BazCa6+ cations are comparable,which may be due to the closer values of ionic radiiof calcium and cadmium.

Ahmad et al,' pained out in the case of IOg- thatsmaller the mass of the cation, stronger will be thebond. This explains the higher strength of Te-Obond in the presence of (BaSr)Mg6+ cation comparedto that in the presence of (Ba2Mg)6+ cation. Thecell constants also favour this trend. The order ofthe Tc-O bond strengths is : (BaLa)NaTe06 <(gaLa) LiTe 08 < Sr2MgTe06• This order is alsofavoured by their cell constants which are 8.27A,8.0fA and 7.90A respectively. When Te-O bondstrength (or K or fr) of the system A2BIlTeOe iscompared when the cations Sr2Mg6+ and (pbSr)Mg6+(or cations containing lead) are present, it is observedthat the bond in general is strengthened when one orboth the strontium atoms are replaced by lead. Thisis because of the greater ionic radius of lead thanthat of strontium, resulting in lesser perturbation ofthe Te-O bond when the cations contain lead. Theobserved trend of Te-O bond strength in the presenceof various cations containing lead is also favouredby their respective cell constants.

It is interesting to note that the strengths of thebonds (K) (Table 2) are in the order : (W-O) >(Mo-O) in the presence of cations Ba2Mg6t andBa.,Zn6+ and (W-O) > (Tc-O) in the presence ofcation (BaSr)Mg6+ also. This is in accordance with the

286

electronegativities of tungsten, molybdenum andtellurium. A similar trend is followed for UO:- asthat for MoO:- and TeO:-, in agreement with thetrend reported in literature=", The values of Corio-lis coupling constant ~{fiuX fiu) (Table 2) in-crease with the mass ratio VMs VI/Mo, which isfavoured by the trend given by Cyvin-v,

Authors are thankful to Dr S. P. Gupta, Principal,D. N. College, Meerut for providing necessary facili-ties and to Dr K. Kumar, Department of Chemistry,D. N. College, Meerut for discussion.

References

1. LlEGllOlS-DuYCKAERTS, M. & TARTE, P., Spectrochim, Acta,30A (19n), 17;1.

2. NAKAMOTO, K., Infrared spectra of inorganic ani coordi-nation compounds (John Wiley, New York), 197J, 315.

3. PANl):j'{, A. N., VERMA, U. P. & CHOPRA, J. R., IndianJ. pure appl, Phys .. 18 (1980), 510.

4. Cors-nr, A. F., HOSFD:lAAD, H. E. & BLASSE, G., J.inorg, nucl, Chem., 34 (1972), 3401.

5. LmGEOIS-DuYCKAERTS, M., Bull. Soc. chim. Bellf., 83(1974), 443.

6. De HAIR, J. TH. W.• CORS\1'IT, A. F. & BLASS!!, G., J.inorg, nucl. Chem., 36 (197~), 313.

7. AHMAD. P., DIXIT, L. & SANYAL, N. K., Indian J. pureappl. Phys., 12 (1974), 489.

8. GOEL, R. K., SHARMA, S. D. & PANDEY, A. N., Spectrosc,LeU., 10 (1977), 915.

9. GOEL. R. K. & SHARMA, S. D., Acta Phys . Polonica, 57(1980), 251.

10. CYVIN, S. J., Molecular vibrations and mean square ampli-tudes (Elsevier, Amsterdam), 1968.

11. MdLLER, A. & PEACOCK, C. J., Molec. Phys., 14 (1968),393.

12. PEACOCK, C. J. & MJLLER, A., J. molec, Spectrosc., 26(1968), 454.

X-ray Study of Ternary System Containing Oxides ofYttrium (III), Niobium (V) & Titanium (IV)

R. N. PHATAK, J. A. KULKARNI & V. S. DARSHANE·Inorganic Chemistry Division. Institute of Science,

Bombay 40) 032

Received & July 1981; accepted 21 August 1981

X-ray study of the ternary system Y.Os-Nb.O,-TiO. showsthat range of existence of euxenite phase Is limlted and on alternat-ing the ratios of cations to anion additional phases (pyrochloreor fergusonlte) are observed. The composition Yo.•NbTi06-fshows two crystallographic phases, euxenlte as major and Nb.TiO.as minor. The composltlon YNbTio .•O... consists of euxeniteand fergusonlte phases. The slight change in lattice constants ofeuxenlte and fergusonlte indicates deviations from stoichiometry,

N0 work seems to have been reported on theternary system Y 203- Nb20.- Ti02 which is

expected to show a relationship between euxeniteand fergusonite, the two distinct species of metamictminerals, found in nature along with other rareearth minerals', Such an investigation is expectedto give an approximate composition range of exis-tence of each phase and extent of any solid solubilitybetween them. In both these minerals cations toanion ratio is 1 :2.