Bhutra, M P

Sankhla, B S

Vaishnava, P P

English

IACS Institutional Repository

Indian J. rhys. 52B, 128-133 (1977)Infrared absorption spectra of samarium mono-, di-,and tri-glycolatesP. P. V a is iin a v a , M. P. B h u t r a  and B. S. S a n k i i l aDepartment o f i*hysics and Chemistry, University o f Jodhpur, JodhpurInfrared absorption spectra of mono-, di-, and iri-^lycolates of tripositive samarium have been studied in the region 4(XX)-250 in K Br pellets with a Perkin-Hlmcr 521 spectrophotometer, for the first time. About twelve bands in each glycolale have been observed and assigned to different modes of vibrations. Com­parison of data reveals that vibrational frequencies are independent of the co-ordination number of the metal in the region 4000- 700 cm ^ The number of metal-oxygen vibrational modes in the region 700-250 cm^  ^ suggests C^v » Vi, , and D;i symmetries for samarium mono-, di-, and tri-glycolates, respectively.J .  I n t r o d u c t i o nRecently, the analysis of the vibrational spectra of glycol derivatives of uranium (Rosado et al 1969), lead (Nakayama et al 1968), and other metals (Larson 1965, Miyake 1959) has appeared in the literature. A survey of the literature reveals that no work on infrared absorption spectra of glycol derivatives of samarium has been carried out so far. The infrared study of rare earth in different environments would give an idea about the structure, amount of metal-oxygen bonding and the vibronic contribution to the electronic spectra. The present communication reports the infrared absorption spectra ofSamarium mono-glycolatc (SM G )Samarium di-glycolatc : (SD G )Samarium tri-glycolate: (ST G )Sm(OPr^);i -f propane 1, 3 diol (OPrO Sm(CijHoOo) in molar ratio 1:1.Sm(OPr^);{ -1 2, 3 dimethyl butane 2, 3 diol(CftHiaOiO Sm(CGHi2 0 j )  in molar ratio 1 :2  andSm (O P r0a  +  propane 1, 3 diol (CoHmO^) Sm(C;iHoOi>)in molar ratio 1:3, for the first time. The results have been discussed in the light of theoretically calculated different modes of vibrations. An attempt has been made to investigate the metal-oxygen bonding in these complexes.Absorption sj/ectra of samarium glycolates2. fcXPIiRIMI'NIAI.129Sm (O Pr‘):t was prepared from siimarium eliloride by sodium alkoxidc method (Sankhla et al 1965). The reactions of Sm (OPr‘).t with propane ], 3 diol and 2, 3 dimethyl butane 2, 3 diol in different molar ratios have been described elsewhere (Sankhla & Kapoor. 1965).Spectra from 4000-250 e n r ' ol the powdered samples, less than 5(.i in particle size, in K B r pellets were recorded by using a Perkin-BImer model 521 spectrophotometer purged with dry air. 400 mg of KBr and an equivalent molar concentration of 1.8 mg of glycolates were pressed in an evacuated die under a total force of 10 tons for 2 nunules. No annealing was done as at 100-110°C a reaction with K Br may occur. The spectra were recorded al 25°C. The 25°C  temperature was not controlled but it remained nearly constant in the infrared beam of the spectrophotometer in ambient surroundings.3. R|-,SUI.TS and DlSt'USSIONThe observed vibrational frequencies have been tabulated in table 1. The intensities of the bands have been classified as weak(w), mcdium(m), strong(s), weak broad(wb), strong broad (sb) and have been indicated in the table 1.Table 1. Observed infrared frequencies, relative intensities and |assignments of samarium glycolatesSMG SDG STG Assignments_ ^  34(X)(sb) .^34CH>(sb) bonded OiH stretch2953 (w) 2%0(w) _ _ asym. Cll.  ^ stretch— 2930(w) C‘Hw stretch— 2872(w) — s>m. CH.  ^ stretch— — 2846 (w) CH^ stretch— ^ I490 (sb ) ^  1480(sb) i p OH dclorrnation1460(w) — asym. CH.  ^ dclomialion1381(w) — sym. C'H;. deformationI373(w) — — —do —— ^  1360(sb) ^  1350(sb) i.p OH deformation1150(w) ll50(w ) — CH^ rock1050(s) — 10S5(s) C -6  stretch of tert. alcoholic group912(w) 910(w) — C*0 stretch of pri. alcoholic group854 (m) 860 (w) CH-i rcKk_ ^ 650(w b) ^  650(wb) skeletal vibration560(w) 570(w) 582(w) ao.p. OH deformation__ 375 (m) 384(w) Sm-O stretch300(w) — 320(w) Sm-O stretch130  P. P . V aish n av a , M . P . B h u tra  an d  B . S. S an k h laThe struclural formulae of ihe samarium glycolalcs under study may be wriUen as()/ N(O Pr*)Sm (^O(SM G )o  oK /s /O(SI)G’\  Z ' \ /  oSmO/ \R<^ ^\ /  / 'VO /  \H //O/ \^  \ r\ /o\ .HO(^\\  /  \  /  \ /H(S T G )\/^ C Hwhere R — glyeol residue and Fr‘ — isopropyl group.The various modes of vibrations of the various groups in the complexes have been discussed below :OH stretching vibrationsIn the present study of glycol derivatives ot samarium, a broad band appearing at ^  3400 cni’  ^ in di- and ti i-glycolatcs has been assigned loassociated (Kuhn, 1952) OH stretching vibrations. The broad shape isusually attributed to the fact that the glycolates associate (Sankhla 6c Kapoor 1965) in to various polymeric forms in which the molecules involved inhydrogen bonding to different extent, so that the broad band observed iscomposite of number of sharper bands.OH dejorrmtion vibrationsUsually two broad btinds are observed (Nakaiiishi 1^62) in alcohols between 1500-13(X) cni”  ^ which may be assigned lo the in-piane deformation of the bonded OH. Also, broad and diffuse hmds in liquid stales in the region 750-6CK) cm  ^ arise (Bellamy 1966) from the oul-plane bonded OH defor­mation. In di-, and tri-glycolate of samarium, broad bands occurring at ^  1480,Absorption spectra of samarium ^lycolates 131/-1360, and ^ 650 cm~\ therefore, have been assigned (o in-nlane and ouNof- planc OH deformation, respectively.C -0 stretching vihratiansThe C-O sTetchin.fi vibrations due to primary, secondary and tertiary alcoholic groups have been found to appear (Bellamy 1^66) in the region 1075-lfXX), 1125-1090 and 1210-1100 cm  ^ respectively. SlVKi and SlTiVpossessing -CH.-O- group, and SDCi possessing’ C-O- group have been foundto absorb at 1060 and 1127 cm  ^ rcspcclivclv and therefore, have been assigned to C-O stretching vibrations of the tos?>cctive .nroup.C n ; and C JJ > ^ronp vihratii^nsTn organic materials the asymmetrical and symmetrical C-H stretching modes of CH >. group ‘u've rise (Bellamy 1966) to two bands at 2962 and 2S72 cm \ respectively. In samarium mono-, and di-glvcolalcs, a weak band at 2943 and 2960 cm  ^ respictivelv, thus has been assigned to asymmetrical CHm sTctchimi, while a band at 2872 can  ^ in samarium di-edvcolate has been assigned to symmctricid CH.; stretching.Tn aliphatic compounds the asymmetric (11; deformation absorbs near 1465 enr  ^ and the symmetric vibration near 1375 cm  ^ (McMurry Thronton, 1952). When (here are two methyls on one aliphatic carb(m atom, two bands with nearly equal intensity appear near 138S and H70 cm  ^ due to in-phas * and out-of-phase inlcracticm of the two symmetrical CH;. deformations (McMurry &. Tlironton 1952). In SMG a weak band at 1460 enr^ and two bands at 1381 and 1373 cm \ therefore, have been assigned to asymmetric and symmetric CH.. deformation respectivelyDue to the interacti(^n with skeletal sTealching modes mehyl rocking frequencies are most sensitive and variable in position. In aliphatic compounds, CH:» rock absorbs (Jones 1957) weakly at 1150-1120 env  ^ and 920-890 cm  ^Two weak bands appearing at 1150 and 910 cm^ in samarium mono-, and di-glycolatcs, thcrcfc^re, have K'cn assigned to CH ; r(Kkin<! vibrationsTwo charactcrisOc bands due to the in-phase aiKl out-of-phase vibrations of the hydroeen atom of CH_» group have been observed (Bellamy 1966) at 2926 and 2853 cm"’ respectively. Such bands in STG have been oKserved at 2930 and 2846 cm*** and have been assigned to (TTi* nroim vibrations.Skeletal vibrationsTt has been pointed out by Simnson and Sutherland (Simpstm & Sutherland 1949) that for isopropyl comr^ninds a skeletal vibration could be predictednear 850 c'm~^ A band at 854 cm-^ in SM G and a band at 860 cm  ^ in SEXj . therefore, have been assigned to skeletal vibration.Sm-O vibrationThe absorption bands below 700 cm -’ are generally ascribed to metal- oxygen stretching modes. A theoretical study (Nakamoto et al 1961) of different types of mental complexes (table 2) reveals that the number of infrared active vibrations are different for different types of metal complexes. The total number of such bands can give the geometry of the complex. In SM G, STG  and SE)G, two, three and two bands respectively have been observed inthe region 600-2.50 cm~’ , indicating C mv , D;, and Vh symmetries for the respective glyarlales.Table 2. Symmetry of metal complexes and the number of ir-active (M -O )stretching vibrations132 P . P . V a ish n a v a , M . P . B h u tra  a n d  B . S . S an k h laTypes of Distribution ofNo. of ir activemetal complexes Symmetry stretching vibs vibs.1:1 <72 V1 :2  (square planar) +  h | + 6 2 ,, +  b , 21 :2  (tetrahedral) 2a , -jr b j -f- bo 41:3 (octahedral) t >.2 a^  -f- a>i “b 2c 3A close study of Table T reveals that the spectra of the glycol dervatives of samarium are almost idnependent of the co-ordination number of the metal in the region 4(X)0-700 cm *’ , whereas in the region below 700 cm "* they depend on it. A slight shift in the metal-oxygen stretching vibations towards the higher wave numbers with the increase in co-ordination number from three to four and six, indicates the small interaction between the ligand and the metal-oxygen vibrations.A C K N O W M iD OEM ENTAuthors thank Prof. A. N. Nigain, Head, Department of Physics, University pf Jodhpur, Jodhpur for helpful discussions. Thanks are also due to Dr. S. P. Tandon for valuable suggestions.Absorption s[>ectra of samarium ^lycoiatesR eph r e n c es133Bellamy, L. J., 1%6, The in frared  Spectra o f  Complex Molecules, John Wiley & Sonts. Inc., New York.Jones, R. N., 1957, Spectrochim. Acta, 9, 235.Kuhn, L. P., I91S2, J. Amer. Chem. Soc., 74, 2493.Larson, R., 1965, Acta. C'hem. Scand., 19, 7^3 McMurry', H. L. & Thronton, V., Anal. Chein., 24, 3|8.Miyake, A., 1959, Bull rheni. Soc. (Japan), 32, 1.^ 81Nakanishi, K., 19S2, In frared A bsorption Sffectroscopy, Nankodo Company Ltd., Tokyo.Nakayama, wS., Watan*. F. & Aida, K., 196R, Asahi Garasii Kogyo Gijitsisu Shorci-Kai Kentyu Hokuku, 14, 81.Nakamoto, K , McCarthy, P J. & Martell, A. E ., 1961, J. Amer Chem. Soc., 83, 1273. Rosado, J. A., Polonio. J. B-. Maria, A. O , Rojas, 1.. Rojas. M., 1%9, \n Quim.., 65, 419. 'vSankhIa, B. S. & Kapoor, R. N., 19<»5, J. Less Common Metal, 10, 116. vSankhIa, B. S., Misra, S. N. & Kapoor, R. N., 1965 Chem. Ind. 382.Simpstm, D. N. & Sutherland, G. B. B. M., 1949, Proc. Roy Soc, A199, 169,

Infrared Absorption Spectra of Samarium Mono-, Di-, and Tri-Glycolates

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Infrared Absorption Spectra of Samarium Mono-, Di-, and Tri-Glycolates

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