and titanium(IV) - Springer Link

Transition Met. Chem. 9, 35-38 (1984)

Furylacrylates of A1m and TiTM

600 -

35

tant. The very rapid rates of the oxidation of [IrCl6] 3-(2~ and [Fe(CN)6] 4-(21) were attributed to axial bridging via the chloroand cyano-ligands. It is very likely that iodide could be oxidized by copper(III) imine-oxime complexes by an innersphere pathway with the iodide weakly coordinated in an axial position. This, at least, could be true for the pathway firstorder in [I-] since a rapid association between iodide and the copper(III) complexes is necessary to account for the thirdorder kinetics.

48O "T

360 IK

2 2z~o 120

Acknowledgement 115

310

~5

6'.0

'This work was supported by the Research Council of the University of Kuwait under grant No. SCOO9.

7'.5

IOS[H*I,H

Figure 5. Dependence of k3 on [H§ for the [Cum(Pre)]+/I- iodide reaction. copper(III)-peptides (u). This mechanism is given by Equations

(7)-(12). CumL + I- _fast

[CHIIIL(I_)] kl

(7)

[CuIIIL(I)] ~ CllUL q- I" k8, k-a

(8)

[CuUIL([)] + I - ~ CuIIL + 12 k9, k-9

(9)

I ' + [-

fast I;

culnL + I2

fast >Cull L + I2

I2 + I- ~ I ;

(10) (11) (12)

It is to be noted that CumL stands for [Cum(Enio)] +, [Cum(Pre)] + and [CuIII(PreH)]2+. For this mechanism it can be shown that k2 = K~ks and k3 = Klk9. From the observation that second-order dependence on [I-] is maintained even at 0.40M it was concluded that Ks is very small. This is also consistent with low-spin d s square-planar structure proposed for copper(III) complexes. These complexes do not readily add ligands axially. Both outer-sphere and inner-sphere pathways have been proposed in oxidations by copper(III)-peptide. The type of mechanism that operates depends on the nature of the reduc-

References (1) W. Margerum and G. D. Owens, in H. Sigel (Ed.), Metal Ions in Biological Systems, Vol. 12, Marcel Dekker, New York, 1981, p. 75. (2) G. O. Morpurgo and A. A. G. Tomlinson, J. Chem. Soc. Dalton Trans., 74.4 (1977). - (3) y. Sulfab and D. W. Margerum, unpublished results. - (4) y. Sulfab, M. A. Hussein and N. I. A1-Shatti, Inorg. Chim. Acta, 67, L33 (1982). - (5) K. Nag and A. Chakravorty, Coor. Chem. Rev., 33, 87 (1980). - (6) M. M. Aly and F. A. El-Said, J. Inorg. Nucl. Chem., 43, 287 (1981). - (7)A. Vaciago and L. Zambonelli, J. Chem. Soc. A, 218 (1970). - (s) A. W. Addison, M. Carpenter, L. K.-M. Lau, and M. Wicholas, Inorg. Chem., 17, 1545 (1978). - (9) j. Faure and J. Joussot-Dubian, Bull. Soc. Chim. Ft., 3064 (1967). (10)W. H. Woodruff, D. C. Weatherburn and D, W. Margerum, Inorg. Chem., 10, 2102 (1971). 01) j. M. T. Raycheba and D. W. Margerum, Inorg. Chem., 20, 45 (1981). - (12)F. Secco, S. Celsi and C. Grati, J. Chem. Soc. Dalton Trans., 1675 (1972). - (13)G. J. Vandegrift and J. Rocek, J. Am, Chem. Soc., 99, 137 (1977). - (14)G. S. Laurence and K. J. Ellis, J. Chem. Soc. Dalton Trans, 2229 (1972). - (15)A. V. Hershey and W. C. Bray, J. Am. Chem. Soc., 58, 1760 (1936). - (16)B. R. James and R. J. P. Williams, J. Chem. Soc., 2007 (1961). - (27)C. J. Hawkins and D. D. Pervin, J. Chem. Soc., 1351 (1962). - (i8) .E.R. Dockal, T. E. Jones, W. F. Sokol, R. J. Engerev, D. B. Rorabacher and L. A. Ochrrymowycz, J. Am. Chem. Soc., 98, 4322 (1976). - (19)G. S. Patterson and R. H. Holm, Bioinorg. Chem., 4, 257 (1975). - (20)G. D. Owens and D. W. Margerum, Inorg. Chem., 20, 1446 (1981). (~1)j. M. Anast and D. W. Margerum, [norg. Chem., 21, 3494 (1982).

(Received August 1st, 1983)

TMC1020

Synthesis and some Properties of Furylacrylates of Aluminium(III) and Titanium(IV) Rajananda Saraswati and Pramesh N. Kapoor* Department of Chemistry, University of Delhi, Delhi-110007, India

Summary Compounds of the type [M(OPri)m_.(FA),] (where m = 3 andn=lto3whenM=A1;andm=4andn---lto4when * Author to whom all correspondence should be directed. 9 Verlag Chemie GmbH, D-6940 Weinheim, 1984

M = Ti) have been synthesised by the reactions of aluminium and titanium isopropoxides with furylacrylic acid (HFA) in benzene. The corresponding tertiary butoxide derivatives, [M(OBut)m_n(FA)n], were also obtained by the alcohol-interchange technique. These compounds have been characterised by elemental analysis, and i.r. and p.m.r, spectra. 0340-4285/84/0101--0035502.50/0

36

R. Saraswati and P. N. Kapoor


Introduction

Metal carboxylates have attracted a great deal of attention and have been the subject of various reviews 0, 2). Apart from their application as water-proofing materials, lubricants, paints and varnishes, etc. they also provide interesting information regarding the nature of bonding (monodentate, bidentare or bridging) in these carboxylates. Although a number of carboxylates of aluminium and titanium have been reported (3-6) in non-aqueous media, it appears that no efforts have been made to synthesis metal carboxylates with olefinic acids. Results and Discussion

Reactions of aluminium(III) and titanium(IV) i-propoxides were carried out with furylacrylic acid (HFA) in different stoichiometric proportions in anhydrous refluxing benzene and the products of the type [Al(OPri)3_n(FA)n] and [Ti(Opri)4_n(FA)n] were isolated.

Al(OPri)3 + nHFA

C6H6;. [Al(OPri)3_n(FA)n] + nPriOH

Ti(OPri)4 + nHFA

C6H6) [Ti(OPri)4_n(FA).] + nPriOH

(where n = 1-3 for aluminium and n = 1-4 for titanium) The i-propanol produced during the reaction was fractionated out as a binary azeotrope (benzene: i-propanol) and was estimated by an oxidimetric method (7). This provides a convenient method for the checking of the completion of the reaction. In order to synthesise the corresponding t-butoxide derivatives, reactions of mixed i-propoxy furylacrylate derivatives were carried out with t-butanol (excess) in refluxing benzene [Al(OPri)3_n(FA)n] +

ButO H C6H6 [AI(OBut)3_n(FA)n] (excess) + nPriOH

Table 1. Synthesis of furylacrylates of aluminium(III) and titanium(IV). Reagent

Molar ratio

Reflux time (h)

Product

Colour and Yield (%)

Found (Calcd.)% PriOH Metal

(1)

(2)

(3)

(4)

(5)

(6)

(7)

1: 1

8

AI(OPri)2(FA)

pale yellow solid 90

1.27 g (1.26 g)

9.3 (9.6)

1 :2

10

AI(OPri)(FA)2


1.20 g (1.26 g)

7.7 (7.5)

1 :3

13

AI(FA)3


2.28 g (2.30 g)

6.5 (6.2)

Al(OPri)3 HFA Benzene Al(OPri)3 HFA Benzene Al(OPri)3 HFA Benzene AI(OPri)(FA)2 ButOH Benzene AI(OPri)(FA)z ButOH Benzene Ti(OPri)4 HFA Benzene Ti(OPri)4 HFA, Benzene Ti(OPr~)4 HFA Benzene Ti(OPri)4 HFA Benzene Ti(OP~)3(FA) BffOH Benzene Ti(OPrl)2(FA)2 ButOH Benzene Ti(OPri)(FA)3 Bu'OH Benzene

(3.49 g) (2.36 g) (50 cm3) (2.18 g) (2.96 g) (60 cm3) (2.71 g) (2.96 g) (50 cm3) (0.70 g) (5 cm3) (50 cm3) (0.70 g) (5 cm3) 60 cm3) (3.98 g) (1.94 g) (60 cm3) (2.28 g) (2.21 g) (60 cm~) (2.08 g) (3.04 g) (70 cm3) (1.21 g) (2.35 g) (70 cm3) (0.38 g) ( 5 cm3) (70 cm3) (0.92 g) (5 cm3) (65 cm3) (0.27 g) ( 5 cm3) (60 cm3)

1: excess

5

AI(OBut)z(FA)

light yellow solid 90

0.23 g (0.22 g)

8.5 (8.6)

1: excess

6

AI(OBut)(FA)2

light yellow solid 90

0.11 g (0.10 g)

7.0 (7.1)

1:1

9

Ti(OPri)3(FA)

dark brown semi-liquid 90

0.82 g (0.83 g)

13.1 (13.2)

1 :2

10

Ti(OPri)z(FA)2

brown paste 85

0.87 g (0.94 g)

10.8 (10.9)

1:3

12

Ti(OPr')(FA)3

brown solid 85

1.30 g (1.30 g)

9.1 (9.2)

1:4

15

Ti(FA)4

brown solid 85

1.02 g (1.04 g)

8.1 (9.3)

1: excess

15

Ti(OBut)3(FA)

yellowish brown solid 90

0.18 g (0.18 g)

11,8 (11.8)

1: excess

15

Ti(OBut)2(FA)2

dark brown paste 85

0.23 g (0.24 g)

10.2 (10.2)

1: excesa

15

Ti(OBut)(FA)3

dark brown paste 85

0.023 g (0.024 g)

9.0 (9.0)

Furylacrylates of A I m and TiIv


[Ti(OPri)4_n(FA)] +

ButOH C6H6>[Ti(OBut)4_~(FA)~] (excess)

+ nPriOH

(where n = 1 or 2 for aluminium and n = 1, 2 or 3 for titanium) The i-propanol liberated during the reaction was estimated by the oxidation method (7). The furylacrylate derivatives of aluminium are pale yellow solids which are insoluble in common organic solvents. All these compounds tend to decompose when attempts are made to distil them under reduced pressure. Furylacrylate derivatives of titanium are pasty brown to orange solids, soluble in benzene, chloroform and acetone. Moreover, these compounds become insoluble on keeping them for a few weeks. All these compounds also decompose on heating under reduced pressure. In addition to the bands shown in Table 2, the i.r. spectrum of furylacrylic acid shows a band at ca. 1610 cm -1 due to v(C= C), ( C - O - H ) in-plane bending vibrations at ca. 1545 and ca. 1480 cm -1, a characteristic band at ca. 1075 cm -1 due t o a ring breathing vibration. In the complexes, furylacrylic acid can be monodentate (1), bidentate (2), or bridging (3).

CH=CHC\o M

\O/]VI

(1)

(2) ~ _

O---~M CH=CH-Cx// O--M

(3) The non-appearance of bands in the 3600-3200 cm -1 region in the i.r. spectra of the complexes is consistent with the absence of carboxylate O H (Table 2). The shift of v ( C = O ) to lower frequencies and of v ( C - O ) to higher frequencies rules out the possibility of the ligand acting in a monodentate fashion. The bands assigned to ring-breathing and ( C - O - C ) vibrations, show no appreciable shift indicating that the oxygen atom of the furan ring does not take part in coordination. The olefinic coordination of the ligand to the metal is also ruled out since there is no significant shift in v(C=C). A broad and strong new band observed in the region 650-500 cm -~ in the spectra of all the complexes may be assigned to v ( A l - O ) or v(Ti-O). Table 2. Characteristic infrared frequencies (cm -l) for furylacrylates of aluminum(III) and titanium(IV). Compound

v(OH) v(C=C) v(C-O-C) v(C=C) v(C-O) A*

HFA AI(OPr~)2(FA) AI(OPri)(FA)2 AI(FA)3 AI(OBut)2(FA) AI(OBut)(FA)2 Ti(OPr~)3(FA) Yi(OPr~)z(FA)2 Ti(OPr')(FA)3 Ti(FA)4 Ti(OBut)a(FA) Ti(OBut)2(FA)2 Ti(OBut)(FA)3

3380 -

1625 1610 1640 1635 1635 1635 1630 1630 1630 1625 1635 1635 1630

1015 1020 1015 1015 1015 1015 1020 1010 1015 1015 1020 1015 1020

1680 t555 1565 1460 1560 1565 1540 1550 1550 1545 1550 1555 1550

1260 1350 1355 1370 1360 1355 1320 1365 1330 1350 1320 1330 1335

420 205 210 190 240 210 220 185 220 195 230 225 215

Table 3. Important 1H n.m.r, chemical shifts (1:) of furylacrylates of titanium(IV). Compound

Carboxyl CO2H

Ring CH

HFA -1.6 Ti(OPri)3(FA) Ti(OPr~)2(FA)2 Ti(OPrt)(FA)3 Ti(FA)4 Ti(OBut)3(FA) Ti(OBut)2(FA)2 Ti(OBut)(FA)3

2.9 3.4 3.0 3.2 3.2 3.3 3.3 3.4

3.6 3.6 3.6 3.6 3.6 3.7 3.7 3.7

a

= ,,(c=o)

- A(C-O).

2.4 2.5 2.6 2.6 2.7 2.8 2.8 2.8

Olefinic CH

Methyl of Pr i or But groups

2.7 2.7 2.8 2.9 2.9 2.5 2.5 2.4

8.6(m) 8.8(d) 8.8(d) 9.1(d) 9.0(m) 8.9(m)

3.8 3.5 3.4 3.8 3.6 3.4 3.4 3.4

All the furylacrylates of aluminium are insoluble in common organic solvents so p.m.r, spectra could not be obtained. The p.m.r, spectra of the furylacrylates of titanium(IV) show all the signals due to the ligand except the signal at -1.6 ~, which confirms the absence of the proton of the CO2H group. Two sets of doublets (methyl proton peaks) were observed in the p.m.r, spectrum of [Ti(OPr)3(FA)] in CDC13 at room temperature. The area of the upfield doublet is approximately double the area of low field doublet. The upfield doublet may be due to methyl protons of the terminal isopropoxy groups and low field doublet may be due to bridged isopropoxy groups. The spectrum of the compound showed methyl and methine due to i-propoxy groups in the ratio of 6 : 1, Similarly two singlets (methyl proton peaks) were observed in the p.m.r, spectrum of [Ti(OBut)3(FA)]. The area of the upfield singlet is approximately double the area of the low field singlet. The following plausible structure, (4), is, therefore, proposed on the basis of i.r. and p.m.r, spectral studies.

U

n

OR R

OR O

"~

OR~

OR U

(R = P r

o r Bu )

(4) The p.m.r, spectrum of the [Ti(OPri)2(FA)2] also indicates that two types of isopropoxy groups are present. The area of the upfield doublet appears to be equal to the area of the low field doublet. However, slight broadening in the methyl proton resonances was observed. This may be due to exchange of bridging and terminal isopropoxy groups at room temperature. The following plausible, (5), structure is proposed. R 1

Opri Pr 0 9

o

] O,x O

Pr"

"~C/ I R

O Pr

e = l~nfl- CH=CH *

37

(5)

38

R. Saraswati and P. N. Kapoor


Table 4. 1H n.m.r, chemical shifts (T) of methyl of protons of i-propyl or t-butyl group in Ti(OR)n(FA)4_n. Compound

Terminal

Ti(OPY)3(FA) Ti(OBut)3(FA) Ti(OPr)2(FAh

8.64 8.52

Bridging 8.74 -

8.83 9.06 8.58

8.90 9.14 8.67

The spectrum of [Ti(FA)4] shows no signal at ca. 9 9 indicating the complete absence of an isopropoxy group. The methyl proton peaks for some of the compounds, [Ti(OR)n(FA)4-n] are given in Table 4.

Experimental Strict precautions were taken to exclude moisture. Benzene ( A R BDH) and ButOH were dried and purified by standard methods. Furylacrylic acid was prepared by the method reported earlier (8). Aluminium (9) and titanium (1~ i-propoxides were prepared by reported methods. The i.r. spectra were recorded on a Perkin Elmer-621 spectrophotometer using Nujol mulls or KBr pellets. The n.m.r. spectra were recorded on a Perkin-Elmer R-32 spectrometer in CDC13. Titanium was estimated (11) as TiO2. Aluminium was estimated (v) as the oxinate. The i-propanol content of the azeotropes was estimated by an oxidimetric method (7).

Reaction of titanium i-propoxide with furylacrylic acid ~molar ratio 1 : 1) A mixture of Ti(OPri)4 (3.98 g) and furylacrylic acid (1.94 g) in benzene (60 cm 3) was heated under reflux for nine hours, i-Propanol liberated was collected azeotropically at 70-80~ The temperature of the reaction mixture rose to 80 ~ an indication of completion of reaction. The excess of

solvent was removed at 40~ mm Hg. The final product was a dark brown semi-liquid. Yield 90%. The compounds [Ti(OPri)2(FA)2], [Ti(OPri)(FA)3], [Ti(FA)4], [AI(OPrl)2(FA)], [AI(OPri)(FA)2] and [AI(FA)3] were prepared similarly (Table 1).

Preparation of Ti(OBu92(FA) A mixture of Ti(OPri)3(FA) (0.38 g) and ButOH (5 cm 3) (excess) with benzene (50 cm 3) was heated under reflux for 15 h. The i-propanol liberated was collected azeotropically at 70-80~ The excess of solvent was removed at 40~ mm Hg. The final product was a yellowish-brown solid. Yield 90%. The compounds [Ti(OBut)2(FA)2], [Ti(OBut)(FA)3], [AI(OBut)2(FA)], and [AI(OBut)(FA)2] were prepared similarly, (Table 1).

Acknowledgements One of the authors (R.S.) thanks the Council of Scientific and Industrial Research, New Delhi for the financial aid.

References (~) C. Oldham, Progress in Inorganic Chemistry, Interscience New York, Vol. 10, 1968, p. 223. - (2) R. C. Mehrotra and R. Bohra, Metal Carboxylates, Academic Press, 1983. - (3) R. C. Mehrotra, Nature, 172, 74 (1953). - (4) K. C. Pandey and R. C. Mehrotra, Z. Anorg. Allg. Chem., 290, 87 (1957). - (5) K. C. Pandey and R. C. Mehrotra, Z. Anorg. Altg. Chem., 290, 95 (1957). - (6) K. C. Pandey and R. C. Mehrotra, Z. Anorg. Allg. Chem., 291, 97 (1957). - (7) D. C. Bradley, R. C. Mehrotra and W. Wardlaw, J. Chem. Soc., 2027 (1952). - (8) A. I. Vogel, Practical Organic Chemistry, ELBS III Edit., 1973, p. 834. (9) D. C. Bradley, F. M. A. Halim and W. Wardlaw, J. Chem. Soc., 3450 (1950). - (10)W. G. Young, W. H. Hartung and F. S. Grosslay, J. Am. Chem. Soc., 58, 100 (1936). (21)A. I. Vogel, Quantitative Inorganic Analysis, Longmans Green and Co., London, 4th Edit., 1978. (Received August 9th, 1983)

TMC 1024