tetraalkyl ammonium Fluoro Antimonate

International Journal of Pure & Applied Chemistry 4(4), (October-December 2009) pp. 253-256

Synthesis and Reactivity of Two Fluoroantimonate Complexes(III): tetraalkyl ammonium Fluoro Antimonate (R)4N[SbX3F], (R = C2H5, C4H9) Z. Javanshir1, S. Ghammamy*2, K. Mehrani1, A. Moghimi3 and R. Rahimi4 1

Departments of Chemistry, Faculty of Science, Islamic Azad University, Ardebil Branch, Ardabil, Iran

2

Department of Chemistry, Faculty of Science, Imam Khomeini International University, Qazvin, Iran 3 4

Department of Chemistry, Faculty of Science, Azad Islamic University, Varamin Iran

Department of Chemistry, Faculty of Science, elmo sanat International University, Tehran, Iran

ABSTRACT: Two new ionic complexes of main metals with tetrabutylammonium and tetraethylammonium cations were synthesized. One of them is tetraethylammonium tetrafluoroantimonate(III), (C 2H5)4N [SbF4] (TEATFA), that easily synthesized in a nearly quantitative yield using a direct reaction of SbF 3 and tetraethylammonium fluoride. Another is tetrabutylammonium fluoroantimonate(III), [(C 4H9)4N][SbF4], (TBATFA), that has been synthesized by reaction of tetrabutylammonium fluoride with SbF3 salt. These compounds were characterized by IR, UV/Visible, 19 F NMR, 13C NMR and 1H NMR techniques. Keywords: Tetraalkylammonium Fluoride; Antimony complexes; Fluoride addition; Fluorocomplexes; Synthesis; Characterization.

Introduction In recent years there has been a great deal of interest in the metal fluorocompounds. This is because of the important prerequisites for a fluorocompound to be useful that are its mildness, versatility, selectivity and operational simplicity. The unique properties of fluorine impart an unusual reactivity to the metal-fluorine bond which can be exploited in preparative inorganic chemistry or in catalysis [1, 2]. In addition, the development of main metal mediated M-F bond formation processes is still a virtually unexplored field [3]. The numbers of antimony (III) fluorocomplexes are still scarce, and very few studies on their reactivity have been reported. Particularly the fluorides have been subject of an intense scientific discussion since the first synthesis of such a compound [4, 5]. We had prepared and reported synthesis of a number of anions with tetralkylammonium counter ion previously [6]. We have managed to prepare two new To whom correspondence be made: [email protected] or [email protected]

fluorocompounds of antimony that are the analog of the above fluorocompounds. Fluorocompounds have been known for many years and many methods have been used to synthesize them, but the compounds, tetraethylammonium tetrafluoroantimonate and tetrabutylammonium tetrafluoroantimonate (III) have not been synthesized and reported so far. In this paper a direct, simple and one-step method has been used to synthesize these compounds. Tetraethylammonium fluoride and tetrabutylammonium fluoride are two ionic compound that theirs fluorinating power predicted for a long times and many efforts have been made for preparation of theirs anhydrous powder. For this purpose, many fluorocompounds of main group elements were produced such as:, PbCl 2F, PbI2F, [7] IF8-, [8] TeF5-, SeF5- , [9] PF4- [10] and in fewer amount some of transition metal fluoro complexes like that: MoF7-, WF7, ReOF6-, [11] CrO3F- ,[12] MoO3F-. [13] Synthesis of WF7- and MoF7- were a starting point of preparation of [MX6+x]-x and [MOmX6+x-2m]-x types compounds of 16 group. There were two primary incentives for selection of (CH3)4N+ as the counter ion. Firstly, quaternary ions such as tetramethylammonium are often used as phase

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Z. Javanshir, S. Ghammamy, K. Mehrani, A. Moghimi & R. Rahimi

transfer catalysts. Secondly, quaternary ions such as Tetrabutylammonium are used as crystal growing agents. The numbers of antimony(III) fluorocompounds are still scarce, and very few studies on their reactivity have been reported. The subject of such investigations have high importance, particularly in inorganic fluorides and complexes. In this paper, a direct, simple and one-step method has been used to synthesize a new antimony fluorocompound.

51.32, 51.35. Mp: 125°C. C8H20F4NSb: Cacld. %C, 29.29; %H, 6.10; %N, 4.27. Found: %C, 29.70; %H, 6.21; %N, 4.28. UV/Visible, IR, 1H-NMR and 13C-NMR were all consistent with the TEATFA structure. In 19F-NMR of this compound a broad peak was seen higher than 73ppm. Tetraethylammonium tetrafluoroantimonate is soluble in acetonitrile and dimethyl sulphoxide (DMSO) and not soluble in dichloromethane, ether and toluene, and diethylether.

Experimental

Synthesis of (TBATFA), (C4H9)4N[SbF4]

Material and Instruments

Tetrabutylammonium tetrafluoro antimonate (III), [(C4H9)4N][SbF4] was prepared by dissolving SbF3 (0.20 g, 1.12 mmol) in MeCN and addition of this solution to a solution of tetrabutylammoniumfluoride (0.29 g, 1.1 mmol) in MeCN under stirring was formed. After 1 h stirring, the mixture was filtered, washed with ether (2 × 15 ml), and dried at room temperature. There is an absorption in the compound electronic spectrum Table 2. IR spectrum at 533 (ms) cm -1 have been attributed to í Sb-F and absorptions at 1469(s), 3225(sh), 463(w) cm-1, have been attributed to ν15 N-C, νCH2 C-H and ν19 N-C of (C 4H 9) 4N + counter ion respectively. 1 H-NMR (500 MHz, CD3CN): δ = 1.22 (t, 3H, -CH3), δ = 1.6 (m, 4H, -CH2 -CH2-), δ = 2.7 (t, 2H, -CH2-), 13CNMR (124.44 MHZ, CD3CN): δ 13.74, 19.73, 24.21, 59.06. Mp: 115°C. C16H36F4NSb: Cacld. %C, 43.66; %H, 8.18; %N, 3.18. Found: %C, 44.65; %H, 8.22; %N, 3.19. UV/Visible, IR, 1 H-NMR and 13 C-NMR were all consistent with the TBATFA structure. Tetrabutylammonium tetrafluoroantimonate is soluble in diethylether, metanol (DMSO), acetone and not soluble in chloroform, water, heptan and toluene.

SbF3 (Merck, p.a.) was used without further purification. Solvents were purified by standard methods. Infrared spectra were recorded as KBr disks on a Shimadzu model 420 spectrophotometer. The UV/Visible measurements were made on an Uvicon model 922 spectrometer. 1HNMR and 13 C-NMR were recorded on a Bruker AVANCE DRX 500 spectrometer at 500 and 125 MHz, respectively. All the chemical shifts are quoted in ppm using the high-frequency positive convention; 1H-NMR and 13C-NMR spectra were referenced to external SiMe 4. Antimony was estimated iodometrically. The per cent composition of elements was obtained from the Microanalytical Laboratories, Department of Chemistry, OIRC, Tehran. Reagents grade SbF 3 was used and anhydrous tetraethylammonium fluoride (C 2 H 5 ) 4 NF, tetrabutylammonium fluoride (C4H9)4NF was prepared by the method reported by Christe. Synthesis of (TEATFA), (C2H5)4N[SbF4] To a solution of tetraethylammonium fluoride (0.26 g, 1.7 mmol) in MeCN was added a solution of trifluoro antimony SbF3 (0.27g, 1.5 mmol) in MeCN under stirring at room temperature until an orange precipitate was formed. After 1 h stirring, the mixture was filtered, washed with hexane (2 × 15 ml), and dried at room temperature. Table 1 shows the assignment of UV/visible spectrum that was consistent with the TEATFA structure. IR, 1H-NMR and 13C-NMR were all consistent with the TEATFA structure. The typical absorptions in its IR spectrum at 538 (s) cm-1 have been attributed to ν Sb-F and absorptions at 1450(s), 3110(s), 480(m) cm-1, have been attributed to ν15 N-C, νCH2 C-H and ν19 N-C of (C2H5)4N+ counter ion respectively. 1H-NMR (500 MHz, CD3CN): δ = 3.19 (t, 3H, -CH3), δ = 1.15 (m, 2H, - CH2-), 13C-NMR (124.44 MHZ, CD3CN): δ 6.92, 51.29,

Results and Discussion We had reported the synthesis of a number of fluorocompounds, with the belief that those reagents could be used for the in catalysis of organic substrates. We now report the synthesis of the TEATFA that is analog of the above antimony compounds. The reported methods for their preparation involved non-mild or hard conditions such as high temperetures or use of acids such as HF. The method used for the synthesis of TEATFA and TBATFA does not involve direct use of HF or reaction of MHF2 (M = NH4, K) with SbF3 and is based on the concept of high reactivity of tetraethylammonium fluoride, (C2H5)4NF and tetrabutylammonium fluoride, (C4H9)4NF and its power to Fluoride addition to other compounds.

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Synthesis and Reactivity of two Fluoroantimonate Complexes(III):

The advantages of the new method are: (a) there is no side product, (b) the reaction is quite fast, (c) mild conditions and (d) the accompanied color change that providing visual means for ascertaining the progress of the reaction. (C2H5)4N][SbF4] was prepared by the reaction of (C2H5)4NF and SbF3 in a 1:1 ratio in MeCN solvent as follows:

(C2H5)4NF + SbF3 → (C2H5)4N[SbF4] In the vibrational spectrum of this compound, the known bands of cation were seen that confirmed with literature data (Table 1). Electronic spectrum of TEATFA a transition in acetonitrile at 271nm (ε = 244mol.–1lit.cm–1) that belongs to B1 → A1 transition Table 3.

Table 1 The Frequencies (cm–1) and Assignment of Cation and Anion of (C2H5)4N[SbF4] (cm–1)

Assignment

Intensity

(cm–1)

Assignment

Intensity (s)

1450

ν15, CH2, asym.def

3430

νCH2 + ν19

(s)

1397

ν16, CH2, sym.str

(s)

3315

νCH2 + ν8

(sh)

1298

νrock, CH2, roking ν14

(m)

3110

νCH2, asym.str

(s)

998

ν18, NC4, asym.str

(s)

2980

ν13, νCH2, asym.str

(w, br)

479

ν19, NC4, def.

(m)

2955

ν14, asym.str

(w, br)

480

ν19, NC4, def.

(m)

2780


(w, br)

2655

ν7 + ν16

(w)

538

Sb-F (B1)

(w)

2458

ν3 + ν8 + ν16

(w)

459

Sb-F (A1)

(m, br)

1850

ν8 + ν15

(w, br)

429

Sb-F (A1)

(m)

(C2H5)4N+

–

[SbF4]

Table 2 The Frequencies (cm-1) and Assignment of Cation and Anion of (C4H9)4N[SbF4] (cm–1)

Assignment

Intensity

(C4H9)4N+

(cm–1)

Assignment

Intensity

1469

ν15, CH2, asym.def

(s)

3425

νCH2 + ν19

(w, br)

1379

ν16, CH2, sym.str

(m)

3315

νCH2 + ν8

(w)

1163

νrock, CH2, roking ν14

(m)

3225

νCH2, asym.str

(sh)

1024

ν18, NC4, asym.str

(w)

3010


(w)

463

ν19, NC4, def.

(w)

2955


(s)

453

ν19, NC4, def.

(ms)

2852


(s)

2765

ν7 + ν16

(w)

533

Sb-F (B1)

(ms)

2350

ν3 + ν8 + ν16

(w)

476

Sb-F (A1)

(w, br)

1950

ν8 + ν15

(w, br)

447

Sb-F (A1)

(w, br)

Table 3 Transitions of TEATFA λ(ε, M-1cm-1) 271 (244) B1 → A1

–

[SbF4]

(C4H9)4NF + SbF3 → (C4H9)4N[SbF4] Transitions of TBATFA were given in Table 4. Table 4 Transitions of TBATFA λ (ε, M-1cm-1)

Table 3 shows the assignment of UV/visible spectrum that was consistent with the TBATFA structure. The compound (C 4H9)4N[SbF3] was prepared by the reaction of (C4H9)4NF and SbF3 in a 1:1.1 ratio in MeCN solvent as follows:

257 (482) B1 → A1

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Z. Javanshir, S. Ghammamy, K. Mehrani, A. Moghimi & R. Rahimi

Conclusion Two tetraethylammonium fluoride, tetrabutylammonium fluoride salts of SbF 3 were synthesized simply. (C2H3)4N[SbF4] was prepared by the reaction of (C2H5)4NF and SbF 3 in a 1:1 ratio in MeCN solvent and (C4H9)4N[SbF4] was prepared by the reaction of (C4H9)4NF and SbF3 in a 1:1.1 ratio in MeCN solvent. Electronic and vibrational spectra of these two new fluorocomplexes studied. These compounds were characterized by IR, UV/ Visible, 13C-NMR, 1H-NMR and 19F-NMR techniques. These new fluorocompounds can be classified and use as high temperature ionic liquids. Like other ionic liquids, all the ionic liquids studied here were immiscible with non polar solvents such as toluene, benzene, Et2O and hexane, and were completely miscible with polar solvents such as acetonitrile, acetone, and chloroform due to their high polarity. Production of these compounds shows the ability of tetraethylammonium Fluoride and tetrabutylammonium Fluoride in fluoride addition to transition metal and main group elements compounds. Acknowledgement The authors thank the Research Office of Payame Noor University (PNU) for supporting this work. REFERENCES [1]

(a) J. E. Veltheer, P. Burger, R. G. Bergman, J. Am. Chem. Soc, 117, 12478, 1995.

(b) V. V. Grushin, Angew. Chem., Int. Ed. Engl, 37, 994, 1998. (c) S. J. Archibald, T. Braun, J. F. Gaunt, Hobson, J. E. Perutz, R. N. J. Chem. Soc. Dalton Trans, 2013, 2000. [2]

B. L. Pagenkopf, E. M. Carreira, Chem. Eur. J. 5, 3437, 1999.

[3]

P. Barthazy, R. M. Stoop, M. Wörle, A. Togni, A. Mezzetti, Organometallics, 19, 2844, 2000.

[4]

N. Bartlett, Proc. Chem. Soc, 218, 1962.

[5]

M. Lein, G. Frenking, Aust. J. Chem, 57, 1191, 2004.

[6]

E. L. Muetterties, J. Am. Chem. Soc, 81, 1084, 1959.

[7]

Z. Javanshir, K. Mehrani, S. Ghammamy, L. Saghatforoush, S. Seyedsadjadis, A. Hassanijoshaghani, Bull. Korean Chem. Soc, 29, 1464, 2008.

[8]

A. R. Mahjoub, K. Seppelt, Angew. Chem.Int. Ed. Engl, 30, 7, 876, 1991.

[9]

A. R. Mahjoub, D. Leopold, K. Seppelt, Z. anorg. Chem, 618, 83, 1992.

[10] K. O. Christe, D. A. Dixon, H. P. A. Mercier, J. C. P. Slnder, G. J. Schrobilgelq, W. W. Wilson, J. Am. Chem. Soc, 116, 2850, 1994. [11] S. Giese, K. Seppelt, Angew. Chem. Int. Ed. Engl. 33(4), 461, 1994. [12] A. R. Mahjoub, S. Ghammami, A. R. Abbasi, Hosseinian, A. J. Chem, 39A, 434, 2000. [13] A. R. Mahjoub, S. Ghammami, A. R. Abbasi, Hossainian, J. Chem. Research, 486, 2000.