Paul, R. C.

Sharma, A. K.

Sharma, N. C.

Verma, R. D.

English

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dependence on [Ce&+] and [Ag+] and a fractionalorder on [R2CHOH].Taking the reciprocals of Eq. (1), we get Eq. (3).1 1 {1 1 } 1kObs= [R2CHOH] k+kK[Ag+] +k[Ag+] ... (3)From Eq. (3) it is evident that the plot of l/kobsversus 1/[R2CHOH] at constant [Ag"] should belinear with an intercept. This was found to bethe case in the present study (Fig. 1, curve C).From the intercept and slope values of the abovelinear plot, the Ioirnation constant (K) of the ~g+-isopropanol adduct was evaluated to be 0·781 Iitremole'< which is in agreement with the value (0'728litre mole'<) obtained in the Ag" -catalysed Ce(IV)oxidation of isopropanol. The value of k for s~ep(iii) in Scheme 1 was found to be 2·08 X 1()-2 litremole+ seel at 45°C which is higher than the value(1·45 X 10-2 litre mole'< sec-I) of k obt~in~d uS.ingAg" alone as the catalyst under otherwise Idenh~alconditions, indicating that in the rate determiningstep Ag" -substrate adduct is oxidized by Mn3+and not by Ce4+. This is understandable as Mn3+is a better oxidant than Ce4+ in H2S04 medium.In the Ag+-catalysed reaction-, the formationof Ag+-substrate adduct accounted for the enhancedreaction rate while in Mn2+-catalysed reactions,the change in the reactive species from Ce4+ toMn3+ was assumed to increase the reaction rate.In the mixed catalyst (Ag++Mn2+) system theobserved catalytic effect was found to be greaterthan the sum of the effect s due to the two catalyststaken separately owing to the participation. in t~erate limiting step two different reactive species, VIZ.Ag+-isopropancl adduct and Mn3+.References1. SAIPRAKASH,P. K. & SETHURAM,B., Indian J. Chem., 11(1973), 246.2. SAIPRAKASH,P. K. & SETHURAM,B., J. Indian chem, Soc.,50 (1973), 211.3. MCCURDY(Jr), W. H. & GUILBAULT,G. G., Analyt, cis«,32 (1960), 647; 33 (1961), 580.4. MUHAMMAD,S. S. & SETHURAM,B., Acta chim, hung.,46 (1965), 115, 125.5. SAIPRAKASH,P. K., Ph.D. thesis, Osmania University,1974, 154.Adducts of Oxovanadium(IV} Chloroacetateswith Pyridine & QuinolineR. C. PAUL, N. C. SHARMA,R. D. VERMA &A. K. SHARMADepartment of Chemistry, Panjab UniversityChandigarh 160014Received 31 October 1975; accepted 16 January 1976Pyridine and quinoline adducta of oxovanadium-(IV) chloroacetates have been prepared. The adductsare motsture-s enstttve and insoluble in COITlITlonrga-nic solvents. The adducts have been characterizedon the basis of analytical, infrared and electronicspectral data.INcontinuation of our earlier work on oxovanadium-(IV) carboxylates-, in this note we now reportthe preparation and characterization of the adductsNOTESof oxovanadiumff'V) acetate and chloroacetateswith pyridine and quinoline.All manipulations were carried out in a dry boxas far as possible.Oxovanadium(IV) dichloride was prepared bythe method already reported-. Acetic acid andacetic anhydride were purified by the procedureoutlined in the Iiteraturev", Monochloroacetic acid(BDH, LR) and trichloroacetic acid (E. Merck) werefirst crystallized from benzene and ether respectivelyand then distilled collecting the fractions distillingat 189°/750 mm and 194°/750 mm respectively.Dichloroacetic acid was distilled under reducedpressure, b.p. 105-7°/26 mm. Carbon tetrachloridewas distilled over P205• Pyridine (BDH, b.p. 114°/750 mm) and quinoline (BDH, b.p. 235°/750 mm)were purified by distillation after keeping themovernight over potassium hydroxide beads.Preparation of carboxylates - Bis(acetato)oxova-nadium(IV) was prepared by refluxing oxovana-dium(IV) dichloride with excess 01 acetic acid. Whenno more HCl gas was evolved the reaction was takenas complete. The light grey solid formed was filteredunder reduced pressure, washed with dry CC14 anddried in vacuo. Oxovanadium(IV)chloroacetates weprepared by acid interchange method developedin our Iaboratory+" i.e. refluxing bis(acetato) oxova-nadium(IV) with excess of respective chloroaceticacid. The compounds thus obtained were filtered,washed with dry CC14 and dried in vacuo.Preparation of adducts - A known weight of therespective bis(chloroacetato)oxovanclium(IV) was re-fluxed with excess of pyridine or quinoline in dryCC14· The adducts thus formed were filtered, washedwith dry CC14 and dried in vacuo. The 1:1 adductsof bis(acetato)oxovanadium(IV) with pyridine andbis(monochloroacetato)oxovandium(IV) with pyridineand quinoline were prepared by refluxing the twocomponents in dry CC14 in stoichiometric ratios.Analytical data of these adducts are given inTable 1.The infrared spectra of the compounds were takenin nujol using sodium chloride/silver chloride plateson a Perkin Elmer 337 spectrophotometer. Far IRTABLE 1 - ANALYTICALDATA OF OXOVANADlUM(IV)CHLOROACETATEADDUCTSWITH PYRIDINE AND QUINOLINEFormula Colour Found (%) (calc.)*V CI NVO (CH2CICOO)2.py Brown 15·65 20·66 4·13(15·31) (21·32) (4·20)VO(CH2C!COO)2.2Py Light 12·25 16·94 6·13green (12·37) (17·23) (6·79)VO(CH2CICOO)2·Q do 13·50 18·15 (3-46)VO(CHCI2COO) a- 2Py(13·31) (18·53) (3065)Black 11-11 28·99 6·00VO(CHCI2COO)..2Q(10·60) (29·52) (5·82)Greenish 9·23 25·14 5·03black (8·78) (24·44) (4'81)VO (CClaCOO)2. 2Py Light 9·03 37·69 4·87blue (9·27) (37·72) (5·09)VO(CClaCOO)2·2Q Dark 8·12 33·49 4·93green (7·84) (32·76) (4·30)*Vanadium was estimated gravimetrically; chlorine byVolhard's method; and nitrogen by Duma's method.703INDIAN J. CHEM., VOL. 14A, SEPTEMBER 1976TABLE 2 - REFLECTANCESPECTRA (kK) OF THE ADDUCTSOF OXOVANADIUM(IV)CHLOROACETATEWITHPYRIDINE AND QUINOLINECompound Bands (kK)I II III Charge transferVO(CH3COO)..Py 10'75 18·46 22·37 31·98, 40·12VO(CH1CICOO)2'py 10·99 19·42 23·26 33'33, 40·98VO(CH1CICOOhQ 9·52 17·15 24'39 31'75, 41'75, 43-29VO(CHCl.COO)2·2Py 11·76 17-24 21·74 32·47, 39·53VO(CHC12COO)2·2Q 11·49 17·09 21'51 31'65, 39'06, 44·44VO(CC12COO)2·2Py 11·87 18·13 32'06, 43·27VO(CCI3COOJ.,2Q 10·00 18·52 31'85, 35·09, 43·02, 49'02spectra of the compounds were recorded on aGrubb-Parson DM4 Mark II spectrophotometer.Diffuse reflectance spectra of the compounds wererecorded on a Unicam SP-735 spectrophotometer.The solution of oxovanadium(IV) dichloride inacetic acid and acetic anhydride is quite stable atroom temperature. However the reaction sets inon refluxing the solution to give precipitates of thesame solvolysed product bis (acetato) oxovanadium-(IV). Autoionization of acetic anhydride repre-sented by the equilibrium>, (CH3CO)20~CH3CO+ +CH3COo- is well established. Thus, the solvolysisof oxovanadium(IV) dichloride may be representedby the following reaction scheme:VOCl2(s) +2CHaCOOH(l) ~ VO(CH3COO)2(S) +2HCl(g)VOC12(s) +2(CHaCO)20(1) .....,..VO(CHaCOO)2(S)+2CH3COCl(l)The acid interchange reaction proceeds quicklyand the exchanged acid is easily removed unclersuction. The reaction, in general, may be repre-sented as follows:VO(CH3COO)2(S) +2RCOOH(l)~ VO(.RCOO)2(S)+2CH3COOH(l)(R = CH2Cl, CHCl2 and CCI3)The solid adducts Cor oxovanadium(IV) chloro-acetates with pyridine and quinoline are mosituresensitive and are insoluble in usual organic solvents.The v(V =0) in bisjacetato/chloroacetatojoxova-nadium(IV) appearing around 900 crrr! in theirIR spectra shifts to lower region in the adducts(Table 1) and appear at 882, 795, 812, 820, 816,845 and 830 crrr- respectively, due to lowering ofV =0 bond order.Amongst the characteristic non-ligand vibrationsin the spectral region 1400-1700 crrr? are theasvmmetric and symmetric carboxylate stretchingvibrations of the 'oxovanadium(IV) chloroacet ateswhich have been found to shift to higher and lowerfrequency regions respectively in the adducts. Sincethe carboxylate stretching frequency is known tobe sensitive to the electronic environment of thecarboxylate group, the observed shifts indicate theelectron donation by the nitrogen of the ligand tovanadium in these complexes. This is in agreementwith earlier observations on the infrared spectraof the adducts of metal carboxylates with someoxygen donor Iigands''-". .The v(V-N) in the adducts of oxovana~lUm(IV)dichloride, and bis(halosulphato)oxovanadlUm(IV),VO(SOaXlz. where X = F or Cl, with some nitrogen704donorss-? have been observed in the range 410-486crrr" depending upon the environment of vanadium-nitrogen bonds. In the present results a mediumintensity band between 410 and 430 crrr+ has beenassigned to this mode of vibration.The in-plane ring deformation and out-of-planering deformation bands of coordinated pyridineare found to occur in VO(CH2ClCOOh.Py at 1608,620 and 425 crrr+: in VO(CHCl2COO)2.2Py at1602, 637 and 440 cm-l and in VO(CClaCOO)2.2Pyat 1600, 633 and 432 ern? respectively, showing thecoordination-" of pyridine to oxovanadium(IV)species. Quinoline which is akin to pyridine instructure shows similar changes on coordination.A band at 1449 ern? associated with the heterocyclicring of quinoline exhibits a shift to a higher frequencyon complex formation. In the complexes VO(CH2CICOO)2.2Q, VO(CHCl2COO)2·2Q and VO(CCl3COO)2'20 this band occurs at 1498, 1504 and 1500 ern+respectively. showing an upward shift of ",50 crrr+.The other two significant bands associated with theheterocyclic ring of quinoline are VSb at 1613 andV19a at 1512 crrr". These occur in the complexesVO(CH2CICOO)2.2Q at 1633 and 1544 cm+; In VO(CHCI2COO)2.2Q at 1648 and 1578 cm+: and inVO(CCI3COOh2Q at 1649 and 1538 crrr+: respec-tively. The bands associated with the carbocylicring do not show any significant changes.Three bands (I, II, III) are usually expected foroxovanadiumtfV) ion (C4V symmetry) and theseare often called as d-d or ligand field bands. Inthese adducts bands around 17-19 kK mav beattributed to d"Y~dx'_Y' transitions, while around21-24 kK to dxy~dz' (Table 2). The low energy bandobserved around 10-12kK maybe assigned to d "Y~dxz,dyz transitions. The other bands above 30 kK maybe of charge transfer origin. These results are inaccordance with the predictions based on theBallhausen-Gray scheme-", and are in agreement withthe results in other oxovanadium(IV) complexes".References1. PAUL, R. C., SHARMA,N. C., SINGH, S. & SHARMA,A. K.,Proc, Indian natn. Sci. Acad., 40 (1974), 64.2. PAUL, R. c.. VASISHT,S. K., MALHOTRA,K. C. & PAHIL.S. S., Analyt. Chem., 34 (1962), 820.3. PAUL, R. C., MALHOTRA,K. C. & VAIDYA, O. C., IndianJ. Chem., 3 (1965), 1.4. PAUL, R. C., GHOTRA, J. S. & BAINS, M. S., j. inorg,nucl. Chem., 27 (1965), 265.S. SCHMIDT,V. H., WITTKOPF, I. & JANDER, G., Z. anorg:Chem., 256 (1948), 113.6. KITCHENS, J. & BEAR, J. L., j. inorg, nucl, Chem., 31(1969), 2415.7. PAUL, R. C., SINGH, P., MAKHNI,H. S. & CHADHA,S. L.,J. inorg. nucl. Chem., 32 (1970), 3694.8. SHARMA,N. C., Preparative chemistry of oxovanadium 6-related compounds, Ph.D. thesis, Panjab University,1975.9. PAUL, R. C., SHARMA,N. C., VERMA, R. D. & SHARMA,A. K., Indian J. Chem., (communicated).10. GILL, N. S., NUTTAL, R. H., SCAIFE, D. E. & SHARP,D. W. A., J. inorg. nucl. cs-«, 18 (1961), 79.11. BALLHAUSEN,C. J. & GRAY, H. B., I norg, Chem., 1(1962), 111.Addition Compounds of Bis(halosulphato}oxo-vanadium(IV) with Pyridine & QuinolineR. C. PAUL, N. C. SHARMA,R. D. VERMA& A. K. SHARMADepartment of Chemistry, Panjab UniversityChandigarh 160014Received 20 October 1975; accepted 16 January 1976Pyridine and quinoline adducts of oxovanadium(IV)halosulphates have been prepared and characterized onthe basis of analytical, magnetic moment, infrared andelectronic spectral data. The magnetic moment values,which are lower than the spin-only value, indicatepolymeric nature of the adducts.THE addition compounds of oxovanadium(IV) di-chloride (VOC12)and chloroacetates [V~(1<'CC?0)2'where R=CH2Cl-, CHCl; or CCla] with nitro-gen donors have been reported by us. ~arlierl,2.However, little is known about the addit ion com-plexes of donors like pyridine or quinol.ine with .thehalosulphates of transition metals or then oxycanonsexcept those of cobalt, nickel or copper chlorosul-phates or fluorosulphates=". vVe now report thepreparation of bis(pyridine) and bis(quinoline) com-plexes of oxovanadium(IV) halosulphates, Thecomplexes have been. characterized on the b~sis oftheir IR and electronic spectra and magnetic sus-ceptibility studies.All the manipulations were carried out in a drybox as far as possi.ble.Fluorosulphuric acid was prepared by the knownmethod 7 and purified by double distillation bef<;>reuse. Chlorosulphuric acid (BDH) of known puritywas used as such. Oxovanadium(V) trichloride,and oxovanadium(IV) dichloride, were preparedas described earliers-". Pyridine (BDH, b.p. 114°1750 mm) and quinoline (BD~, b.p. 23~0/750 mm)were kept overnight over solid pot~sslUm hydro-xide and distilled before use. Dichloromethanewas distilled over phosphorus pentoxide,Bis(halosulphato)oxovanadium(IV), . VO(S03X)2(X is F or Cl), were prepared by r~fluxI~g YOCls ~rVOC12 with excess of halosulphunc acid III an 011bath at __ 120°. Initially there was only ~. chan~ein the colour of solution, but after some time solidcompounds separated out. These were filtered invacuo washed with dichloromethane and finallydried'in vacuo. Both the reactions give identicalproducts. . . "The adducts (Table 1) with pyndl,?e or qum?l~newere prepared by refluxing a solution containingexcess of the base in dichloromethane and a knownweight of bis(halosulphato)oxovanadium(IV).NOTESThe infrared spectra of the compounds were takenin nujol in silver chloride plates on a Perkin Elmer337 spectrophotometer. The far IR spectra wererecorded on a Grubb-Parson DM4 mark-II spectro-photometer, while the diffuse reflectance spectra ofthe compounds were recorded on a Unicam SP-735spectrophotometer. Magnetic susceptibilities of thecompounds were determined using Gouy balance.The lowering of V =0 bond order is reflected inlowering of 'IV=0 frequency in the IR spectra ofthe complexes. The 'IV=0 band in VO(SOSF)2and VO(SOsCI)2 occurs at 980 and 958 crrr+ respec-tively. In the complexes VO(SOSF)2·2Py, VO(SOSF)2'2Q, VO(SOaCl)2.2Py and VO(SOaCl)2.2Q, this bandoccurs at 948, 918, 927 and 910 crrr? respectively.A medium intensity band in the above complexesat --416-431 em+ is attributed to '1V-N. The lower-ing of 'IV =0 band and the presence of the bandaround 416-431 crrr+ indicate coordination ofpyridine or quinoline to oxovanadium(IV) species.The symmetry of the halosulphate group in thesecomplexes is lower than Cay, because the IR spectraof the complexes show splitting of the doublydegenerate '14 and 'Is modes. The vS-F alsoregisters an increase when the symmetry is lowerthan C3v. However, the vS-F values revert to theionic values in the complexes+". ThevS-F in VO(SOSF)2.2Py and VO(SOSF)2.2Q at 757 and 754 em=respectively confirm these views.The bands of pyridine, i.e. at 403 (out-of-planering deformation) and at 601 and 1578 crrr- (in-planering deformation) shift to higher frequencyregion when pyridine i~ coordinated to metalslO,ll.The 1578 crrr+ band shifts to 1600 and 1611 crrr+respectively in VO(SOSF)2.2Py and VO(SOsCl)2.2Py,while 601, 403 crrr" bands shift to 638, 644,435 and425 crrr+ in these complexes respectively. Thesechanges indicate the coordination of pyridine tooxovanadium(IV) species. Quinolir;e is akin topyridine in structure, therefore, the major changesiD' the absorption frequencies are confined only toheterocyclic ring. The modes ('1sa,Vsb, v19a and V19b)occur at 1578, 1613, 1512 and 1449 crrr! respectivelyin pure quinoline and have been attributed to theheterocyclic ring frequencies involving C-C andC-N stretching frequenciest". These bands shiftTABLE 1 - ANALYTICALDATA OFBIS(HALOSULPHATO)OXOVANADIUM(IV)ADDUCTSWITHNITROGEN DONORSFormula Colour Found (%) (calc.)*V SVO(S03F)2·2Py Light 11·89 14·39blue (12·05) (15'13)VO(S03F)2·2Q Dark 9·54 11·95green (9'75) (12'23)VO(S03Clh·2Py Brown 10·80 14·01(11'18) (14'03)VO(S03Clh·2Q do 8·73 11·06(9'17) (11'51)Cl N5·92(6'61)5·42(5'35)14·68 5·92(15'57) (6'14)12·28 4·83(12'77) (5-03)*Vanadium determined gravimetrically as vanadium(V)oxide; sulphur determined as sulphate; chlorine by Volhard'smethod; and nitrogen by Duma's method.705

Adducts of Oxovanadium(IV) Chloroacetates with Pyridine & Quinoline

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Adducts of Oxovanadium(IV) Chloroacetates with Pyridine & Quinoline

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