This article was downloaded by: [Florida State University]On: 12 March 2013, At: 04:16Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number:1072954 Registered office: Mortimer House, 37-41 Mortimer Street,London W1T 3JH, UK

Phosphorus, Sulfur, andSilicon and the RelatedElementsPublication details, including instructions forauthors and subscription information:http://www.tandfonline.com/loi/gpss20

DIARYLTELLURIUM(IV)CARBOXYLATES: SYNTHESISVIA TELLUROXIDES ANDTHEIR CHARACTERIZATIONK. K. Verma a , Daya Soni a & Sunil Verma aa Department of Chemistry, M.D. University,Rohtak, 124001, INDIAVersion of record first published: 19 Dec 2006.

To cite this article: K. K. Verma , Daya Soni & Sunil Verma (2000):DIARYLTELLURIUM(IV) CARBOXYLATES: SYNTHESIS VIA TELLUROXIDES AND THEIRCHARACTERIZATION, Phosphorus, Sulfur, and Silicon and the Related Elements,166:1, 231-241

To link to this article: http://dx.doi.org/10.1080/10426500008076544

PLEASE SCROLL DOWN FOR ARTICLE

Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions

This article may be used for research, teaching, and private studypurposes. Any substantial or systematic reproduction, redistribution,reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden.

The publisher does not give any warranty express or implied or makeany representation that the contents will be complete or accurate orup to date. The accuracy of any instructions, formulae, and drug doses

should be independently verified with primary sources. The publishershall not be liable for any loss, actions, claims, proceedings, demand, orcosts or damages whatsoever or howsoever caused arising directly orindirectly in connection with or arising out of the use of this material.

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

Pliii.~phwi~r, Sitlftir and Silicon. ?OM). Vol. 166. pp. 23 1-24 I Rrprinrm available directly from the publisher Photocopying penirted by license only

8 2 0 0 OPA ~ O v e r s e ~ Publishers Association) Amsterdam N.V. Published under license by

the Gordon and Breach Science Publishers imprint. Printed in Malaysia

DIARY LTELLURIUM( IV) C ARBOXY LATES : SYNTHESIS VIA TELLUROXIDES AND

THEIR CHARACTERIZATION

K.K. VERMA', DAYA SON1 and SUNIL VERMA

Department of Chemistry, M.D. University Rohtak-124001, INDIA

(Received June I , 2000; Infinal form July 13. 2000)

The synthesis of some new diaryltellurium(1V) dicarboxylates (salicylate. benzoate. cinna- mate) and carboxylates (oxalate. o-phthalate. succinate) by the reactions of bis@-methoxy- pheny1)telluroxide and bis@-hydroxypheny1)telluroxide with the corresponding carboxylic acid is reported. The resulting carboxylates have been subjected to elemental analyses, con- ductance and cryoscopic measurements, infra-red and proton magnetic resonance spectral studies. Solution studies reflect the non-ionic nature of these compounds. Infra-red spectral studies predict the unidentate nature of salicylate, benzoate and cinnamate and bidentate nature of oxalate. o-phthalate and succinate groups. A PMR spectral study confirms their pro- posed stoichiometry. These compounds possess a trigonal bipyramidal structure with a tetra-coordinate central tellurium atom.

Keywords: Bis(p-methoxypheny1)-; bis(p-hydroxypheny1)telluroxides; diaryltellurium(1V) carboxylates

INTRODUCTION

Petragnani et al"] reported the preparation of diaryltelluriurn dicarboxy- lates by treatment of diaryltelluriurn dichlorides with silver carboxylates. Pant et a1[241 also reported the synthesis of diacetates, dibenzoates by reacting dichlorides with silver carboxylates. Srivastava et al[5961 synthe- sized some symmetrical as well as unsymmetrical diaryltellurium carbox- ylates by the metathetical reaction between freshly prepared silver carboxylates and organotellurium dichlorides. This method was very time- consuming and later on modified"] and the diaryltellurium carboxylates

* Corresponding Author.

23 I

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

232 K. K. VERMA et al.

were prepared by direct treatment of the dichloride with the carboxylic acid in the presence of silver oxide which involves the "in situ" formation of silver carboxylates.

A number of diaryltellurium dicarboxy lates were obtained by the treat- ment of the corresponding dichlorides with a basic anionic resin such as Amberlite IR 45)OH- in which OH-- was previously exchanged with car- boxylate anion17].

Tamagaki et all8] synthesized diphenyltellurium dicarboxylates in high yield employing diphenyltelluroxide and carboxylic acid anhydride, a method used previously by Sedekov and coworkers[9]. Reactions of diphe- nyltelluroxide with carboxylic acid also yield the carboxylates[81 and this appears to be the only report on synthesis of diaryltellurium carboxylates involving reactions between telluroxides and carboxylic acids. Diphe- nyltellurium dicarboxylates are also reported['*''] by the "carboxylate exchange" process from diphenyltellurium diacetates.

McWhinnie et al["] reported the synthesis of diaryltellurium carboxy- lates by the reactions of diaryltellurium dichlorides with sodium salts of o-phthalic acid and tetrabromo o-phthalic acid.

A few diaryltellurium carboxylates are known['"] to possess considera- ble biocidal activities. In view of this, it was thought desirable to synthe- size and characterize some new bis(p-rnethoxyphenyl)tellurium(IV) carboxylates and bis@-hydroxyphenyl)tellurium(IV) carboxylates by reactions of the corresponding diaryltelluroxides with carboxylic acids such as salicylic acid, benzoic acid, cinnamic acid, oxalic acid, o-phthalic acid and succinic acid.

RESULTS AND DISCUSSION

The formation of his@-anisyl)tellurium(IV) dichloride and bis(p-hydroxy- phenyl)tellurium(IV) dichloride by reactions of tellurium tetrachloride with anisole['2-'61 and phen01['~-'~] involves the electrophilic substitution of the aromatic ring by a chlorotellurium group at a position para to the methoxy or hydroxyl group.

2R-H + TeC14 --> RZTeC12 + 2HC1

The alkaline hydrolysis of these dichlorides yield the diaryltellurox- ides[W7-211

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

TELLUROXIDES 233

R2TeC12 + 2NaOH --> R2Te(OH)2 + 2NaCl A

R2Te(OH)2 --> R2TeO + H20

These diaryltelluroxides which are weakly basic in react with mono- and dicarboxylic acids to yield the diaryltellurium(1V)dicarbo- xylates and diaryltellurium(1V) carboxylates.

R2TeO + 2HL --> R2Te[L]2 + H2O

(HL = monocarboxylic acids - salicylic acid, benzoic acid and cinnamic acid)

R2TeO + H2[L2] --> R2Te[L2) + HzO

(Hz[Lt] = Dicarboxylic acids - oxalic acid, o-phthalic acid and succinic acid)

The reaction of bis@-hydroxypheny1)telluroxide with benzoic acid, cin- namic acid and succinic acid did not give any carboxylate, probably because of the less basic nature of this telluroxide as compared to bis(p-anisyl) telluroxide.

The bis(p-methoxyphenyl)tellurium(IV) carboxylates are white crystal- line solids whereas bis@-hydroxyphenyl)tellurium(IV) carboxylates are light orange in color. All these compounds are fairly stable in dry air. These are soluble in polar organic solvents except the oxalates and succi- nates which are insoluble. The his@-hydroxyphenyl)tellurium(IV) carbox- ylates are comparatively less soluble than the corresponding bis(p-anisyl)tellurium(IV) carboxylates.

Conductance and Cryoscopic Studies

The molar conductance data (Table I) in nitrobenzene, acetonitrile, acetone and dimethylsulphoxide reflect non-electrolyte type behaviour of these diaryltellurium(1V) carboxylates. The AM values at ca M for these compounds are much lower than those reported[231 for 1:l electrolytes, indicating their non-electrolytic nature in solutions. The cryoscopic data for carboxylates having sufficient solubility in nitrobenzene (Table I) well support the results of conductance measurements and reflect their mono- meric nature. The solution behaviour of these carboxylates is thus similar to those of other carboxylates reported in the literature[4951. It may be men- tioned here that the molecular weight determined by McWhinnie et al["l for o-phthalates in benzene reflects their dimeric nature.

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

I4

W

P

TABL

E I M

olar

cond

ucta

nce

and

mol

ecul

ar w

eigh

t dat

a of

dia

rylte

lluri

um(1

V) c

arbo

xyla

tes

R C

onrp

orrn

d ~

Mol

ur c

oird

ucra

iice A

, C

onc.

ran

ge

Forn

iula

A

vera

ge

ar c

a.

M o

1im

-l cn

r2 in

or’

iii m

mol

es/L

W

eigh

t h4

ol.w

t. for

itid

Nitr

ober

eire

A

cefo

rlitr

ile

Ace

tone

p-C

H@

C&

Rz

Te [

C~

H~

(OH

)C~

~]Z

0.

15

6.90

3.

90

3 57

-34.

90

616.

1 57

2. I

RzTe

[C

~H

~C

OO

]Z

0.15

3.

90

0.96

2.

03-3

3.09

58

4. I

560.

1

RzTe

[C6H

&H

CH

C00

]z

0.18

3.

00

0.72

3.

33-2

6.56

63

6.2

604.

5

RzTe

[(C

OO

)zI

429.

9 --

a il

a a

RzTe

[c

,jH

.~(c

~)z

l 0.

27

I 1.4

0 5.

05

2.91

-9.

I4

505.

9 50

8.3

a 1

a a

a a

a

RzTe

[CH

zCO

O)z

] 45

7.9

-_

p-H

OC

sH4

RzTe

[C,&

(OH

)CO

O]z

a(

22.0

8)b

588.

0 --

RzTe

[(C

OO

)zl

a(22

.26)

b 40

1.8

_-

RzTe

[C

~H

~(

C~

~)

ZI

‘(2

4.62

)b

477.

9 --

a a

a

a a

a

Valu

es o

f AM

rep

orte

d[”I

for

I: I

elec

trol

yte,

nitr

oben

zene

=20-

30,

acet

onitr

ile =

120

-1 60

, ace

tone

= 1

00-1

40 a

nd DMS

O =

35-

70.

a.

Insu

ffici

ent s

olub

ility

b.

Va

lues

in DMS

O

?F x <

n f

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

TELLUROXIDES 235

Infrared Spectra

The IR spectra of diaryltellurium(1V) carboxylates are quite complex and therefore, an attempt has been made to assign the group frequencies asso- ciated with the carboxylate group and thus to predict the linkage between tellurium and the carboxylate group.

The v,,COO in dicarboxylates (salicylate, benzoate and cinnamate) appear at around 1630 f. 15 cm-' whereas v,COO appear at about 1295 k

10 cm-'. This difference (AvCOO) indicates the unidentate nature of these c a r b o ~ y l a t e s [ ~ ~ * ~ ~ * ~ ~ ~ . Also a splitting of the C=O stretching frequency is observed in these dicarboxylates which may be attributed to a solid state effect, different environments of two carboxylate groups or coupling of vibrations of different carboxylate group^^^"^.

v,,(C=O) in monocarboxylates (oxalate, o-phthalate, succinate) appear between 1695-1615 cm-' and v,(CO) appear between 1300-1240 cm-'. The bands between 1400-1350 cm-' may be assigned to v,(CO) + v(CC)[~~] . The separation of v,,(CO) and v,(CO), which can be taken as a measure of ester like character of the carboxylate group, is very similar to that noted for derivatives of monocarboxylic This also reflects the bidentate chelate structure for these carboxylates[ul.

vTe=o at about 720 cm-' in the parent telluroxide disappears in these car- boxylates and new weak to medium intensity bands around 285 ? 5 cm-' appear which may be assigned to the tellurium-oxygen stretching fre- q u e n ~ y [ ~ ' ~ ] .

Proton Magnetic Resonance Spectra

'H NMR spectral data for bis@-methoxyphenyl)tellurium(IV) disalicylate, dibenzoate, o-phthalate and bis(p-hydroxyphenyl)tellurium(IV) o-phtha- late are presented in Table 11. The absence of COOH protons in the spectra of these carboxylates indicates the linkage of tellurium to the carboxylate group after deprotonation. The ratio of aromatic to methoxyhydroxyl pro- tons supports the proposed stoichiometry of these corn pound^[^^^^^^^. Also, the aryl protons of diaryltellur~xide['~~ appear to be deshielded in these carboxylates probably because of the greater electron withdrawing nature of the carboxylatotellurium group as compared to a telluroxide group.

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

TAB

LE 11

IR a

nd P

MR

spec

tral d

ata of d

iary

ltellu

rium

(1V

) car

boxy

late

s

P-C

H3w

6H4

R2Te

[C6H

.@H

)CO

OI2

16

3 I (

s)

1301

(s)

285

(m)

3.86

(s,

6H);

6.8

5 (m

. 4H

); 7

.05

(d. I

9Hz.

4H

); 7.

37 (

m,2

H);

7.72

(d. I

9H

z. 2H

); 7.

89 (

d,J

9Hz.

4H);

11

26(s

, 2H

)a

1294

(s)

285 (m)

3.79

(s.6

H);

7.01

(d,

J9H

z. 4

H);

7.35

-8.0

(m, 1

4H)'

1295

(s)

281

(w)

1302

(m) 2

86 (m

)

1300

(s)

286

(m)

1242

(s)

1295

(s)

284

(w)

3.77

(s.6

H);

7.02

(d. J

9H

2.4H

); 7

35 (m, 2H

); 7.

51 (m. 2H

); 7.

86 (d

. J

1254

(s)

9Hz,

4H

)'

1286

(s)

7;

7;

1247

(s)

s f 9 %

RzTe

[(C

H2C

O0)

21

1642

(s)

1294

(s)

286

(m)

p-H

OC

&

R2Te

[(c

o0)2

1 16

34 (s

) 12

41 (s

,b)

285

(m)

282

(m)

6.94

(d, J

9H

z. 4

H);

7.53

-7.5

6 (m

, 4H

); 7.

75 (d

, I 9

Hz,

4H

); 10

.10

1615

(m)

1255

(s)

R2Te

[C

gHq(

C00

)2]

1695

(s)

1641

(m)

(s,b

,2H

Ib

1281

(s)

a.

In C

DC1

3 b.

In D

MSO

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

TELLUROXIDES 231

On the basis of results presented in the paper, these compounds may have an ester type structure with probably w- trigonal bipyramidal arrangement of groups about the central four-coordinate tellurium atom with one site being occupied by a lone pair of electron^[^*^]. These carboxylates may even con- tain intermolecular Te-0 secondary bonds in the solid state[26271 which could not be ascertained due to non-availability of x-ray data.

EXPERIMENTAL

Reagents

Tellurium tetrachloride used was from E. Merck and was purified by a standard method[281 using a sublimation process. Phenol used was of BDH, Anal R quality and anisole was from SISCO Research Laboratories (India) and these were purified by standard methods[291 before use. Sali- cylic acid, benzoic acid, cinnamic acid, oxalic acid, o-phthalic acid and succinic acid were from LOBA CHEMIE, Extra Pure grade.

The solvents used were dried and purified by standard methods[29S01 before use.

Preparation of Diaryltelluroxides, R2Te0

(R = p-methoxyphenyl and p-hydroxyphenyl) Bis@-methoxypheny1)telluroxide was prepared by alkaline hydrolysis of bis@-methoxyphenyl)tellurium dichloride[20*211 which in turn was obtained by reaction of tellurium tetrachloride with ani~ole['~-'~].

Bis(phydroxypheny1)telluroxide was prepared by alkaline hydroly- is["^'^] of bis@-hydroxypheny1)tellurium dichloride. The dichloride was prepared by reactions of tellurium tetrachloride with phenol as reported in the litera~tre["~'~].

Synthesis of Bis(p-methoxyphenyl)tellurium(IV) carboxylates

R,Te [LI2 (R = p-methoxyphenyl, L = salicylate, Cdr,(OH)COO; benzoate, C6HsCOO-; cinnamate, C@sCHCHCOO-) A saturated solution of bis@-methoxypheny1)telluroxide (5 mmol) in dry methanol was added to a stirred solution of 10 mmol of carboxylic acid

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

238 K. K. VERMA et a/.

(salicylic acidhenzoic acidcinnamic acid) in the minimum amount of the same solvent. The contents upon stirring for about 2 hours yielded a white solid which was filtered, washed with methanol and dried in a vacuum desiccator over P4OI0.

R2Te[LJ (R = p-methoxyphenyl, [LJ = oxalate, (COO),2’; o-phthalate, C6H&200),2’; succinate, (CH2COO)2-)

A saturated solution of 5 mmol of dicarboxylic acid in dry methanol was added dropwise to a stirred methanolic solution of bis@-methoxyphe- ny1)telluroxide (5 mmol). The contents upon stirring for about 2-3 hours yielded a white colored solid which was filtered, washed with metha- nol/chloroform and dried in vacuo over P 4 0 j 0

Synthesis of bis(p-hydroxyphenyl)tellurium(IV) carboxylates

R2Te[LI2 (R = p-hydroxyphenyl and L = salicylate, C6H~OH)COO-)

A saturated solution of 2 mmol of salicylic acid in dry methanol was added to a suspension of bis@-hydroxypheny1)telluroxide ( I mmol). The clear red solution thus obtained was stirred for 3 4 hours. Turbidity if any, was filtered off and the clear solution was concentrated. This resulted in the separation of an orange colored solid, which was filtered, washed with chloroform and dried in a vacuum desiccator over P40,,,.

R2Te[LJ (R = p-hydroxyphenyl), [LJ = oxahte, (COO)?-; o-phthalate, c&dcoo),2-) To a stirred suspension of bis@-hydroxypheny1)telluroxide (2 mmol) in dry methanol a saturated solution of carboxylic acid (oxalic acid / o-phthalic acid) in methanol was added dropwise. This yielded a clear orange solution. The contents were stirred for about 2-3 hours, concen- trated to about one third of original volume and kept in a vacuum desicca- tor overnight. An orange colored solid separated out. This was filtered off, washed with chloroform and dried in vacuo.

The purity of these compounds was checked by T.L.C. using silica gel-G. The analytical data and physical properties of the complexes are presented in Table 111.

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

TAB

LE 11

1 Ph

ysic

al c

hara

cter

istic

s and

ele

nien

tal a

naly

ses o

f di

aryl

tellu

rium

(lV

) car

boxy

late

s

R lL

l/lL

2/

CO

”f/’

Oll

If‘l

C

olor

M

. p.

Krld

El

emen

tal A

naly

sis

(%)

(Eir

ipir

icd

Fo

riiw

lli)

“f

CJ

(70)

C

Fou

nd

H F

ound

Te

Fou

nd

(Cal

cd)

(Cal

cd)

(Cal

cd)

Whi

te

Whi

te

Whi

te

Whi

te

Whi

te

Whi

te

Ligh

t or

ange

Ligh

t or

ange

Ligh

t or

ange

195-

196

207-

208

155-

157

165-

166

167-

169

> 25

0

175-

1 78

‘

136-

138

’

145-

1 46

75

>80

80

80

>60

90

65

60

65

54.1

8 (5

4.59

)

56.9

8 (5

7.58

)

60.1

0 (6

0.41

)

44.3

4

(44.

70)

5 I .8

9 (5

2.22

)

46.9

2 (4

7.22

)

52.5

6 (5

3.11

)

42.0

2 (4

1.85

)

49.7

4 (5

0.27

)

3.48

(3

.93)

3.82

(4

.14)

4.02

(4

.44)

3.

00

(3.2

8)

3.14

(3

.59)

3.45

(3

.96)

3.06

(3

.43)

2.22

(2

.51)

2.49

(2

.95)

21 0

5 (2

0.71

)

21.1

3 (2

1.84

)

20.7

4 (2

0.06

)

29.3

0

(29.

68)

25.5

2 (2

5.22

)

28.1

1 (2

7.87

)

2 I .6

9 (2

I .70

)

3 I .2

6 (3

I .76

)

26.3

9 (2

6.70

)

P

c ;a

a.

Dec

ompo

se.

w

w

\o

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

240 K. K. VERMA et al.

Analytical Methods and Physical Measurements

Carbon and hydrogen analyses were obtained microanalytically from the Regional Sophisticated Instrumentation Centre, Panjab University, Chan- digarh. The tellurium content was estimated volumetrically[311. Conduc- tivity was measured at 35 2 1°C with a conductivity bridge type 305 Systronics model and the .molecular weights were determined by the cryo- scopic method in nitrobenzene. IR and far IR spectra were recorded at Regional Sophisticated Instrumentation Centre; Indian Institute of Tech- nology, Chennai on a BRUKER IFS 66v FT-IR spectrometer using KBr pellets/Polyethypellets techniques. 'H NMR spectra were recorded at Regional Sophisticated Instrumentations Centre, Indian Institute of Tech- nology, Bombay on a BRUKER DPX-300 spectrometer operating at 300 MHz in CDCl+MSO-d6 using tetramethylsilane as an internal refer- ence.

Acknowledgements The authors are thankful to Maharshi Dayanand University, Rohtak- 124001 (India) for providing necessary facilities.

References [ I ] M. Moura Campos. E.L. Suranyi, H. de Andrade Jr. and N. Petragnani. Tetrahedron,

20.2797 ( 1964). [2] B. C. Pant, Terrahedron Left.. 4779 (1972). [3] B. C. Pant, J. Organomeral. Chem.. 65.5 I (1974). [4] B. C. Pant, W. R. McWhinnie and N. S. Dance, J . Organomeral. Chem.. 63. 305

(1973). [ 5 ] T. N. Srivastava. P. C. Srivllstava and Rakesh Kurnar, Indian J . Chem., 21A. 309

(1982). [6] T. N. Srivastava and Jai Deo Singh, lndian J. Chem., 26A. 260 (1987). [7] N. Petragnani. J. V. Comasseto and N. H. Varella, J. Organomeral. Chem., 120, 375

(1976). [8] S. Tamagaki, 1. Hatanaka and S. Kuzuka, Bull. Chem. SOC. Jpn.. 50.2501 (1977). [9] I. D. Sadekov. A. A. Maksimenko, A. F. Vsachev and V.I. Minkin, Zh. Obshch. Khim..

45.2562 (1975). [ 101 K. J. Irgolic, J . Organomeral. Chem., 158,293 (1978). [ I I] N. Dance and W. R. McWhinnie. J . Organomeral. Chem., 104.317 (1976). [ 121 G. T. Morgan and R. E. Kellett, J . Chem. Soc., 1080 (1926). [I31 J. Bergman. Tefrahedron, 28, 3323 (1972). [I41 J. Bergman, 1. Org. Synrh., 57, 18 (1977). [I51 N. Petragnani. J.V. Comasseto. Synthesis, pp. 28,29 (1986). [I61 K. J. Irgolic, The Organic Chemistry of Tellurium, Gordon and Breach, New York

[I71 K. Kumar, Ph. D. thesis. IIT Delhi (1981). [I81 B. L. KhandelwaL K. Kumarand F. J. Berry, Inorg. Chim. A m , 47. 135 (1981).

( 1974) pp. I9,29-34.

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3

TELLUROXIDES 24 I

B. L. Khandelwal, A. K. Singh. R. Mehta and K. Kumar. Patent Govt. of India, IN 162096. 1988; CA 111. 114854~ (1989). S. V. Ley, C. A. Meerholz and D. H. R. Barton, Tetrahedron, Supplement No. I , 37.2 I3 (1981). N. Petragnani, Tellurium in Organic Synthesis, Academic Press, N.Y. (1994) p. 69. S. Patai and Zvi Rappopon, Eds., The Chemistry of Organic Selenium and Tellurium Compounds, Vol. I, John Wiley and Sons, New York (1986) p. 10. W. J. Geary, Coord. Chem. Rev., 7 .8 I ( I97 1 ). K. Nakarnoto, Infrared and Raman Spectra of Inorganic and Coordination Com- pounds, Part B. 5th Edn.. John Wiley and Sons, N.Y. (1997) pp. 60,74. T. N. Srivastava. V. K. Srivastava and S. Srivastava. Indian J. Chem., 26A. 265 (1987). I. 0. Bogason, D. Daktemieks, S. Huseby, K. Maanmannrnoe and H. Zhu, Phospho- rus, Sulfitr and Silicon, 71, 13 (1992). N. W. Alcock, W. D. Harrison and C. Howes, J. Chem. SOC. Dalton Trans., 1709 ( 1984). Georg Brauer. Handbook of Preparative Inorganic Chemistry. Vol. I . 2nd Edn.. Aca- demic Press (1967) N.Y.. p. 442. A. I. Vogel, A Textbook of Practical Organic Chemistry, 3rd Edn., Longman, London (1975). A. Weissberger. Ed.. Technique of Organic Chemistry, Vol. VII. 2nd Edn., Interscience Publishers, Inc. (1967). A. 1. Vogel, A Textbook of Quantitative Inorganic Analysis Including Elementary bisrritmental Analvsis, 3rd Edn. Longman. London, 324 (1975).

Dow

nloa

ded

by [

Flor

ida

Stat

e U

nive

rsity

] at

04:

16 1

2 M

arch

201

3