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Fluorinated tellurium(IV) azides and their precursors
Journal of Fluorine Chemistry 125 (2004) 997–1005
Fluorinated tellurium(IV) azides and their precursors Thomas M. Klapo¨tkea,*, Burkhard Krumma, Peter Mayera, Dieter Naumannb, Ingo Schwaba a
Department of Chemistry, University of Munich (LMU), Butenandtstr. 5–13(D), D-81377 Munich, Germany b Institute of Inorganic Chemistry, University of Cologne, Greinstr. 6, D-50939 Cologne, Germany Received 30 May 2003; received in revised form 8 September 2003; accepted 3 January 2004 Available online 25 March 2004
Abstract The perfluoroaryl tellurolates C6F5TeLi (1) and 4-CF3C6F4TeLi (2) were prepared. These intermediates were identified by NMR spectroscopy and may form, depending on the reaction conditions, either the corresponding ditellanes C6F5TeTeC6F5 (3) and CF3C6F4TeTeC6F4CF3 (4) by subsequent oxidation, or in the case of 1, a telluranthrene (C6F4Te)2 (5) by reaction with itself. The halogenation products of 5, ( C6F4Te)2F4 (6), (C6F4Te)2Cl4 (7), (C6F4Te)2Br4 (8), as well as the azidation product (C6F4Te)2(N3)4 (9) were synthesized. Furthermore, in pursuit of our recent work on tellurium azides, the syntheses and properties of R2Te(N3)2 (R ¼ CF3 (10), C6F2H3 (11)) and RTe(N3)3 (R ¼ CF3 (12) and C6F5 (13)) are reported. The crystal structures of CF3C6F4TeTeC6F4CF3 (4), (C6F4Te)2Br4 (8), and (C6F2H3)2Te(N3)2 (11) were determined. # 2004 Elsevier B.V. All rights reserved. Keywords: Ditellanes; Tellurium azides; Tellurolates; X-ray crystallography
1. Introduction Although tellurium species containing perfluorinated aryl or alkyl substituents have been known for many years and the preparation of ditellanes can be achieved by several routes [1,2], the synthesis of C6F5TeTeC6F5 is rather complicated [3,4]. The latter was first reported in 1968 [5], but this report was considered doubtful [3]. However, a rational synthesis was presented, by which C6F5TeTeC6F5 is accessible through irradiation. Unfortunately, this proved to be not reproducible, thus obtaining C6F5TeTeC6F5 only in low yields if the standard reaction procedure for aryl ditellanes is used [4]. Nevertheless, C6F5TeTeC6F5 has been fully characterized. In this work, further attempts were made in order to achieve a reproducible route to perfluoroaryl ditellanes with acceptable yields. The ditellane serves as the only precursor for the corresponding tellurium(IV) trifluoride C6F5TeF3 [6]. We were interested in C6F5TeF3 as a possible candidate for the synthesis of a perfluoroaryl substituted tellurium(IV) triazide, following the same strategy as outlined for (C6F5)2Te(N3)2 and other alkyl/aryltellurium(IV) diazides and triazides [7,8]. *
Corresponding author. Tel.: þ49-89-2180-77491; fax: þ49-89-2180-77492. E-mail address: [email protected] (T.M. Klapo¨tke). 0022-1139/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jfluchem.2004.01.017
A further subject of this study is the preparation and properties of the first perfluoroalkyl, namely, trifluoromethyl, substituted tellurium(IV) di- and triazides. Further reported perfluoroalkyl tellurium(IV) di- and trifluorides are (C2F5)2TeF2 and C2F5TeF3 [9]. During several attempts to prepare C6F5TeTeC6F5, a sideproduct containing tellurium was always present in significant amounts, which is attributed to the high reactivity of the initially formed tellurolate C6F5TeLi. In this report, identification, characterization, and some subsequent chemistry of this material will be accomplished.
2. Results and discussion 2.1. Ditellanes/telluranthrenes Similar to the standard procedures for the preparation of PhTeTePh for a synthesis of perfluoroaryl derivatives, the generation of the perfluoroaryllithium species RFLi (RF ¼ C6 F5 and 4-CF3C6F4) is the first step. The insertion of Te from finely ground tellurium powder into RFLi takes place only to a small extent as proved with C6F5Li, 4-CF3C6F4Li or other perfluoroaryl lithiums [4,10]. Recently, the successful use of phosphane tellurides as soluble tellurium sources in insertion reactions was reported.
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998
RFH
n-BuLi/ -70˚C
Te, -20˚C
RFLi
THF
RFTeLi
I2, reflux
RFTeTeRF
10 mol% n-Bu3P
Scheme 1. Synthesis of perfluorinated ditellanes.
Apart from Ph3P [11], mainly t-Bu3P and n-Bu3P [12] were used, the latter also in catalytic amounts. The synthesis of bis[2,4,6-tris(trifluoromethyl)phenyl]ditellane using n-Bu3PTe was claimed, but unfortunately no experimental details and spectroscopic data were disclosed [13,14]. Thus, we probed suitable conditions for an activation of tellurium powder by n-Bu3P in the reaction with RFLi to form RFTeLi (RF ¼ C6 F5 (1) and 4-CF3C6F4 (2)). Catalytic amounts of n-Bu3P and reaction times of more than 12 h turned out to be a suitable synthetic approach to perfluorinated tellurolates. A significant difference in the stability of 1 and 2 was observed when diethyl ether or THF were used as solvents. Red solutions of 1 and 2 in THF are stable even under reflux, but very sensitive towards hydrolysis. They exhibit broadened 19 F NMR resonances and 125 Te NMR resonances at d ¼ 323 (1) and 222 ppm (2), respectively, which is upfield relative to that of PhTeLi (d ¼ 122 ppm), in disagreement with the trends in ref. [15]. Oxidation of 1 and 2 with molecular oxygen did not result (or only in very small amounts) in the formation of the ditellanes. However, with iodine, the ditellanes RFTeTeRF (RF ¼ C6 F5 (3) and 4-CF3C6F4 (4)) were formed via the moderately stable RFTeI intermediates (Scheme 1), which can be detected in the NMR spectra (d125 Te [CDCl3] ¼ 768 (C6F5), 781 (4-CF3C6F4)). Attempts to isolate RFTeI have been unsuccessful so far. The ditellanes 3 and 4 are isolated in only moderate yields, due to the use of flash chromatography and subsequent fractional crystallization, and because of undesirable side reactions (Scheme 2). However, during the use of diethyl ether as solvent at 20 8C, and below in the case of 1, another fluorinated tellurium compound was always detected in significant amounts. This material was identified as octafluorotelluranthrene
(C6F4Te)2 (5). An intra- or intermolecular LiF elimination, where two molecules of tellurolate were involved, must have occurred. The formation of 5 could proceed either via a SNAr mechanism involving addition and elimination steps, or by initial cleavage of an ortho C–F bond of 1 followed by nucleophilic attack of another molecule of 1. The latter process can be understood as a special case of a SN1 type reaction, the intermediate zwitterionic species possibly being stabilized by the tellurolate acting as neighboringgroup forming a three-membered tellurirene, as suggested in ref. [10] and references therein. The octafluorotelluranthrene (5) can be formed by both types of reaction, leaving the pathway uncertain. In the case of 4-CF3C6F4TeLi (2), under the same reaction conditions, complex product mixtures inhibited the identification and isolation of corresponding telluranthrene derivatives, similarly to the telluranthrene isomers identified in ref. [10]. Under reflux conditions in Et2O with 1, the telluranthrene 5 can be isolated as the main product and purified by flash chromatography. Originally, 5 was obtained by the reaction of 1,2-diiodo-tetrafluorobenzene with tellurium at elevated temperatures above 300 8C, and additional purification was only achieved by means of reduction of the tetrabrominated derivative (C6F4Te)2Br4 [16]. The latter route, compared with ours, is rather expensive, and the overall yield is below 5%. Our new, more convenient method (Scheme 3) produces pure 5 in approximately 30% yield in a one-pot synthesis. The molecular structure of 4 in the crystalline state is shown in Fig. 1. The structural features are quite similar to those of C6F5TeTeC6F5 [4]. The dihedral angle CTeTeC is larger (100.7(3)8) than found in C6F5TeTeC6F5 (91.8(1)8), probably due to the increased sterical demand of the CF3C6F4-substituent. 2.2. 5l4, 10l4-Perfluorotelluranthrene derivatives
n-BuLi C6F5Li
C6F5H exc.
[n-Bu3PI]I
Te n-Bu3P n-BuTeLi C6F5TeLi (1)
I2
-LiI
(C6F5)2Te
n-BuTeI -LiI (n-BuTe)2
n-BuTeTeC6F5
(C6F5Te)2 (3)
I2
C6F5TeI -I2
Scheme 2. Possible reactions during the synthesis of 3.
Since the telluranthrene 5 can now be prepared in moderate yield, it was of interest to study the reactivity of this cyclic bifunctional tellane towards halogenation. As outlined previously for other fluoroaryl tellanes [17], the reactions with XeF2, SO2Cl2 and Br2 give the corresponding tetrahalogeno tellurium(IV) derivatives (C6F4Te)2F4 (6), (C6F4Te)2Cl4 (7), and (C6F4Te)2Br4 (8). All of them show a decreased solubility relative to that of 5 (with 6 as the least soluble), and the only suitable solvent for NMR measurements is DMSO-D6. Whereas 7 and 8 are quite stable, 6 is highly reactive towards glass in solution and needs to be stored at low temperatures, or in TeflonTM equipment. With Me3SiN3, all tellurium bound fluorine atoms react readily to the moisture-sensitive tetraazido derivative (C6F4Te)2(N3)4 (9). All halogeno derivatives (6–8) are of enormous
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999
F C6F5H
n-BuLi/ -70˚C Et2O
C6F5Li
Te, -20˚C 10 mol% n-Bu3P
reflux
C6F5TeLi
F
F
Te
F
F
Te
F
½
-LiF
(5) F
F
Scheme 3. Synthesis of octafluorotelluranthrene.
C8 C1 Te2 Te1
˚ ) and angles (8): Te1Te2 2.6948(9), Te1C1 2.110(8), Te2C8 Fig. 1. Molecular structure of CF3C6F4TeTeC6F4CF3 (4). Selected bond lengths (A 2.124(8), C1Te1Te2C8 100.7(3).
thermal stability, decomposing above 330 8C, while the tetraazide 9 can be heated slowly to its decomposition point at 180 8C. Although 9 does not seem to be friction sensitive, deflagration occurs when in contact with a Bunsen flame (Scheme 4). In relation to 5 (d125 Te ¼ 762 ppm), the 125 Te NMR shifts of the oxidized species 6–9 are observed as expected for Te(IV) compounds, found at ca. 300 ppm lower field. Somewhat irregular to the trends observed so far (usually the difluorides R2TeF2 are the least shielded), the tetrabromide 8 exhibits the lowest 125 Te NMR shift (d ¼ 1172 ppm in DMSO-D6). In the 19 F NMR spectra, two sets of fluorine
F F
resonances are observed, in addition for 6 a broadened resonance at d ¼ 63 ppm for the TeF2 moiety occurs. Slow evaporation of a saturated solution of 8 in benzene forms suitable single crystals. The molecular structure of 8 is depicted in Fig. 2. In a similar fashion as in acyclic dibromotelluranes R2TeBr2 [17], the bromine atoms occupy axial positions, while two equatorial positions at each tellurium center are connected to the planar ring systems. The inner C4Te2 ring itself is planar, unlike as in the structures of 5 or other Te(II) telluranthrenes [10,16]. In contrast to other compounds of the type R2TeX2 [17,18], for 8, no short secondary Te Br interactions are found. The Te–Br
F
F Te
F
F X Te
F
X
F
XeF2, SO2Cl2 or Br2 F
F
Te F
CFCl3, 0 ˚C
X = F (6), Cl (7), Br (8) F
F
X
Te
F
X
F
F
(5)
6: + 4 Me3SiN3 - 4 Me3SiF F
F N3
F
Te
N3
F (9)
F
N3 F
4
4
Te
F
N3 F
Scheme 4. Synthesis of 5l , 10l -telluranthrene derivatives of 5.
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1000
Br2
C6
Te
C1 Te
Br1
˚) Fig. 2. Molecular structure of (C6F4Te)2Br4 (8). Selected bond lengths (A and angles (8): TeBr1 2.6201(11), TeBr2 2.6615(10), TeC1 2.120(8), Br1TeBr2 174.60(4).
distances are almost identical to those of acyclic fluorophenyltelluranes R2TeBr2 [17]. 2.3. Trifluoromethyl tellurium(IV) and fluorophenyl diazides and triazides The bis-trifluoromethyl and the partially fluorinated bis2,6-difluorophenyl substituted tellurium(IV) diazides 10 and 11, as well as the trifluoromethyl and pentafluorophenyl tellurium(IV) triazides 12 and 13 are prepared similarly to the syntheses of the non-fluorinated analogues [8] (Scheme 5). Compound 11 was prepared in an effort to obtain structural data in addition to the crystal structures of Ph2Te(N3)2 and (C6F5)2Te(N3)2 (see structure discussion). All four compounds are yellowish moisture-sensitive solids, 10 being the most sensitive tellurium diazide regarding its propensity to explode and hydrolyze. This is probably due to the strong polarization effect of the CF3 group destabilizing the Na–Nb bond, leading to an increased tendency to eliminate molecular nitrogen. The triazide CF3Te(N3)3 (12) is even more sensitive and could not be obtained in pure form. The pentafluorophenyl derivative C6F5Te(N3)3 (13) was obtained in a mixture with (C6F5)2Te(N3)2 and Te(N3)4. The intermediate C6F5TeF3, formed by fluorination of 3, is known to dismutate even at low temperatures into (C6F5)2TeF2 and TeF4 [6]. Upon treatment with Me3SiN3, the corresponding azides were formed. Both species in this mixture have been unambiguously identified by their 125 Te NMR shifts by comparison with authentic samples in DMSO-D6. The diazide (C6F5)2Te(N3)2 (916 ppm, DMSOD6) was prepared according to [7], and the tetraazide
(RF)2TeF2
RFTeTeRF
Me3SiN3 CFCl3, 0 ˚C 1. XeF2 / 2. Me3SiN3 CFCl3, 0 ˚C
Te(N3)4 (1382 ppm, DMSO-D6) by reaction of TeF4 with Me3SiN3 [19,20]. The tellurium azides 9–13 show asymmetric stretching vibrations (nasN3) of the azido groups, as well as intense TeN stretching vibrations in their Raman spectra. For the tetraazide 9, between 2100 and 2000 cm1, more than five different peaks for nasN3 are found. Compared with Me2Te(N3)2 [8], in (CF3)2Te(N3)2 (10) both the nasN3 and the nTeN are shifted slightly to higher wavenumbers. The nTeC stretching vibration, for Me2Te(N3)2 at 550 cm1, is not detected. Three different nasN3 (axial out of phase, axial in phase, equatorial), are found between 2115 and 2048 cm1 for the triazides 12 and 13. In the case of (C6F2H3)2Te(N3)2 (11), two discrete peaks for nasN3 are visible in the Raman spectrum at 2072/2050 cm1, which is slightly higher than found for Ph2Te(N3)2 and (C6F5)2Te(N3)2 [7]. The 125 Te NMR shifts of the diazides are typically found at slightly higher field than those of the corresponding difluorides, for example d125 Te ¼ 1116 (10) versus 1200 ppm ((CF3)2TeF2, CDCl3). The resonances of the triazides 12 and 13 are found at lower field compared with those of the corresponding diazides. A cold solution in CH2Cl2/hexane led to nearly colorless crystals of 11 suitable for X-ray crystal structure analysis. The difference in the sterical arrangements of Ph2Te(N3)2 and (C6F5)2Te(N3)2, the orientation of the azide groups, was discussed in terms of steric reasons and electrostatic repulsions between free electron pairs of fluorine and nitrogen [7]. In the case of 11, the same orientation of the substituents as in Ph2Te(N3)2 is found (see Fig. 3a), although it does not crystallize isotypically (11: P1, Ph2Te(N3)2: Pbca). In both 11 and Ph2Te(N3)2 the azide groups, located in the axial positions, are oriented towards the aryl groups. The opposite was found for the structure of (C6F5)2Te(N3)2. That means, an increased electronegativity of C6F2H3 compared with C6H5 because of the introduction of two fluorine atoms in the ortho position, does not lead to a significant change in the orientation of the azide groups. The tellurium nitrogen ˚ , which distances are Te–N1 2.228(2) and Te–N4 2.202(2) A are also very similar to those found in Ph2Te(N3)2. The intermolecular Te N interactions (Te N4 2.970(2), ˚ ) found in the three-dimensional strucTe N1 3.287(2) A ture of 11 (Fig. 3b), are shorter than in the case of ˚ ), and cause in principle Ph2Te(N3)2 (Te N 3.141/3.497 A the same connectivity pattern (Te Na Te, but in (C6F5)2Te(N3)2: Te Ng Te, no Te Na ).
(RF)2Te(N3)2
RFTe(N3)3
RF = CF3 (10), C6F2H3 (11)
RF = CF3 (12), C6F5 (13)
Scheme 5. Synthesis of fluorinated tellurium(IV) diazides and triazides.
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1001
F1 N1 N2 N3 Te
F2
N6
N4
N5
F3
F4
(a)
N1(i) N4(i)
Te(ii)
Te(i)
N1(ii)
N4(ii)
Te
N4
N1
(b) ˚ ) and angles (8): Te–N1 2.228(2), Te–N4 2.202(2), Te–C1 2.113(2), Te–C7 Fig. 3. (a) Molecular structure of (C6F2H3)2Te(N3)2 (11). Selected bond lengths (A 2.106(3), C–F 1.350(3)–1.362(3), N1–N2 1.213(3), N2–N3 1.142(3), N4–N5 1.229(3), N5–N6 1.136(3), N1–Te–N4 167.71(8), C1–Te–C7 106.56(10), N1– ˚ ): Te N1 (i) N2–N3 177.5(3), N4–N5–N6 177.1(3). (b) Te N interactions in the structure of (C6F2H3)2Te(N3)2 (11). Selected contact distances (A 3.287(2), Te N4 (ii) 2.970(2); with i ¼ 1 x, 1 y, 1 z; ii ¼ x, 1 y, 1 z.
It can be concluded, that the arrangement of the azide groups is not due to electronic or steric reasons, because both effects are present, to substantial extents, in the two orthodifluorophenyl substituents as well. Therefore, the change in orientation as found in (C6F5)2Te(N3)2 can probably be explained by packing effects.
3. Experimental 3.1. General procedures All manipulations of air and moisture-sensitive materials were performed under an inert atmosphere of dry nitrogen or argon using flame-dried glass vessels and Schlenk techniques. Xenon difluoride (FluoroChem) and trimethylsilyl azide (Aldrich) were used as received. The compounds (CF3)2TeF2 and CF3TeTeCF3 were prepared according to the
literature [21,22]. Solvents were dried by standard methods [23], distilled and stored over molecular sieves. Raman spectra were recorded on a Perkin-Elmer 2000 NIR FT-Raman spectrometer fitted with a Nd-YAG laser (1064 nm), infrared spectra on a Perkin-Elmer 983G IR spectrometer between KBr plates. Mass spectroscopic data were obtained from a JEOL Mstation JMS 700 Spektrometer with fragments referring to the nuclei with the highest abundance (for example 130 Te). The elemental analyses were performed with a C, H, N-Analysator Elementar Vario EL. NMR spectra were recorded on a JEOL Eclipse 400 instrument, and chemical shifts are with respect to (CH3)4Si (1 H, 13 C), CH3NO2 (14 N), CFCl3 (19 F), and Me2Te (125 Te). Melting points were determined in capillaries using a Bu¨ chi B540 instrument. CAUTION: Covalent tellurium azides are potentially explosive; appropriate safety precautions such as Kevlar gloves, face shield, leather jacket must be taken, and the amounts of substance handled in pure form by trained
1002
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personnel should not exceed 100 mg. During the preparation of (CF3)2Te(N3)2 (10) once a vigorous explosion occurred, destroying the glass vessel completely. The yields and elemental analyses of the azides 9 and 10 were not determined due to safety reasons. 3.2. Preparation of RFTeTeRF (RF ¼ C6F5 (3), CF3C6F4 (4)) A solution of 25 mmol pentafluorobenzene or 4-trifluoromethyltetrafluorobenzene in ca. 30 ml THF was cooled to 78 8C, and 27.5 mmol of n-BuLi (2.5 M in hexanes) were slowly added with slight darkening of the reaction solution. After 1.5 h, 25 mmol of finely ground tellurium powder and 2.5 mmol n-Bu3P were added. The mixture was slowly warmed to 20 8C and held for 15 h at this temperature. Iodine (25 mmol) was added and the mixture warmed to ambient temperature, then refluxed for 2 h. After cooling to 20 8C again, small amounts of sulfur (0.25 mmol) were added and the mixture was then refluxed again for 30 min. Unreacted tellurium was separated by filtration at ambient temperature, and the resulting solution was poured into a solution of 25 mmol NaHSO3 in 150 ml H2O, and 150 ml of diethyl ether were added. Drying of the organic phase over CaCl2 and evaporation of the solvent in vacuo yielded dark brown oils which were subjected to flash chromatography with petrol ether/methylene chloride (10:1). The dark red solution was concentrated in vacuo and dark red rhombic crystals (3), or dark red needles (4), were finally separated from the pale yellow crystals of the corresponding monotellanes by fractional crystallization. C6F5TeTeC6F5 (3): yield (33%), spectroscopic data see [3,4]. CF3C6F4TeTeC6F4CF3 (4): yield (46%), mp 92–93 8C. Raman: n ¼ 1643 (25), 1377 (15), 917 (5), 782 (10), 718 (15), 502 (55), 444 (20), 403 (25), 310 (15), 197 (100, nTeTe), 175 (70) cm1. IR: n ¼ 1642 m, 1597 w, 1481 vs, 1468 vs, 1414 w, 1378 w, 1351 w, 1322 vs, 1294 w, 1259 w, 1213 m, 1181 s, 1156 s, 973 s, 920 s, 782 w, 715 s, 646 w, 546 w, 502 w, 422 w, 307 w cm1. 19 F NMR [CDCl3]: d ¼ 56:9 (t, 4 JFF ¼ 21:7 Hz, 3F, CF3), 113.0 (m, 2F, 2-F), 138.7 (m, 2F, 3-F) ppm. 13 C NMR [CDCl3]: d ¼ 149:0 (dm, 1 JCF ¼ 250:6 Hz, 2 JCTe ¼ 18:9 Hz, C-2), 142.4 (dm, 1 JCF ¼ 265:2 Hz, 3 JCTe ¼ 16:6 Hz, C-3), 120.6 (q, 1 JCF ¼ 274:8 Hz, CF3), 111.8 (m, C-4), 91.0 (tm, 2 JCF ¼ 31:1 Hz, 1 JCTe ¼ 420:1 Hz, 2 JCTe ¼ 8:5 Hz, C-1) ppm. 125 Te NMR [CDCl3]: d ¼ 338 (tm, 3 JTeF ¼ 65:2 Hz) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 689 [Mþ] (15), 670 [Mþ–F] (2), 563 [Mþ–Te] (50), 347 [CF3C6F4Teþ] (100). Calc. for C14F14Te2: C, 24.4. Found: C, 24.6. 3.3. Preparation of octafluorotelluranthrene (5), halogenation, and azidation products A solution of 20 mmol pentafluorobenzene in ca. 30 ml diethyl ether was cooled to 78 8C, and 22 mmol of n-BuLi
were added slowly. After 1.5 h, 25 mmol of finely ground tellurium powder and 2.5 mmol n-Bu3P were added. The dark suspension was slowly warmed to 20 8C and held for approximately 15 h at this temperature. After additional refluxing for 2.5 h, a yellow solution was separated from unreacted tellurium and concentrated in vacuo. Purification by column chromatography with petrol ether/methylene chloride (4:1) yielded an orange solution, which was concentrated until crystallization occurred to give orange crystals of 5. Yield: 33%, mp 122–124 8C. Raman: n ¼ 1610 (20), 1591 (20), 1483 (10), 1421 (10), 1294 (20), 1266 (40), 771 (45), 637 (15), 474 (100), 395 (20), 357 (45), 234 (70), 212 (95), 191 (35), 133 (15) cm1. 19 F NMR [CDCl3]: d ¼ 108:0 (m, 2F, 2-F); 151.6 (m, 2F, 3-F) ppm. 13 C NMR [CDCl3]: d ¼ 148:0 (d, 1 JCF ¼ 239:9 Hz, 2 JCTe ¼ 38:8 Hz, 3 JCTe ¼ 11:9 Hz, C-2), 140.1 (d, 3 JCF ¼ 253:6 Hz, 3 JCTe ¼ 12:7 Hz, C-3), 111.6 (m, 1 JCTe ¼ 332:1 Hz, 2 JCTe ¼ 71:9 Hz, C-1) ppm. 125 Te NMR [CDCl3]: d ¼ 762 (t, 3 JTeF ¼ 15:9 Hz) ppm. Mass spectra, elemental analysis and IR see also ref. [16]. 3.3.1. 1,2,3,4,5,5,6,7,8,9,10,10-Dodecafluoro-5l4, 10l4-telluranthrene (6) A solution of 2 mmol 5 in 15 ml of CFCl3 was cooled to 0 8C, and into the stirred solution, 4.2 mmol of XeF2 were added. The yellow color disappeared immediately and a colorless suspension was formed. After stirring for 1.5 h at ambient temperature, a colorless residue was separated from the supernatant. Yield: 88%, mp 333 8C (dec.). Raman: strong fluorescence. IR: n ¼ 1612 m, 1603 m, 1576 m, 1523 m, 1489 vs, 1459 vs, 1370 w, 1328 w, 1316 w, 1299 w, 1272 m, 1107 s, 1027 s, 813 w, 772 w, 634 w, 619 m, 595 w, 519 m, 485 m, 472 m, 424 m, 382 m, 361 m, 315 m, 296 m cm1. 19 F NMR [DMSO-D6]: d ¼ 63 (br, 2F, TeF), 122.0 (m, 2F, 2-F), 150.3 (m, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSO-D6]: d ¼ 147:3 (2 JTeC ¼ 43:8 Hz, C-2), 140.7 (C-3), 130.0 (1 JTeC ¼ 331:4 Hz, C-1) ppm. 125 Te{19 F} NMR [DMSOD6]: d ¼ 1112 (br) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 627 [Mþ] (43), 607 [Mþ–F] (24), 589 [Mþ–2F] (20), 442 [Mþ–F–TeF2] (78), 315 [Mþ–TeF–TeF2] (20), 296 [C12F8þ] (100). EA Calc. for C12F12Te2: C, 23.0. Found: C, 23.5. 3.3.2. 5,5,10,10-Tetrachloro-1,2,3,4,6,7,8,9-octafluoro5l4,10l4-telluranthrene (7) A solution of 0.7 mmol 5 in 15 ml of CFCl3 was cooled to 0 8C, and into the stirred solution, 5 ml (excess) of SO2Cl2 were added. The yellow color vanished rapidly and a colorless suspension was formed. After stirring for 4 h at ambient temperature, the resulting mixture was evaporated in vacuo yielding a colorless powder. Yield: 99%, mp > 345 8C (dec.). Raman: n ¼ 1615 (10), 1279 (10), 771 (15), 472 (25), 396 (20), 373 (25), 357 (25), 291 (100, nTeCl), 251 (35), 210 (43), 160 (20) cm1. IR:
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n ¼ 1621 m, 1600 s, 1549 w, 1501 vs, 1443 vs, 1354 w, 1318 m, 1304 m, 1271 m, 1118 s, 1104 s, 1017 s, 827 m, 805 w, 762 m, 722 w, 636 m, 605 w, 568 w, 519 w, 470 w, 370 m, 351 w, 297 m cm1. 19 F NMR [DMSO-D6]: d ¼ 114:6 (m, 2F, 2-F), 150.9 (m, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSOD6]: d ¼ 145:4 (2 JCTe ¼ 40:7 Hz, C-2), 138.9 (C-3), 130.4 (1 JCTe ¼ 369:0 Hz, C-1) ppm. 125 Te{19 F} NMR [DMSOD6]: d ¼ 1076 (br) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 658 [Mþ–Cl] (100), 623 [Mþ–2Cl] (29), 588 [Mþ–3Cl] (55), 551 [Mþ–4Cl] (45), 426 [Mþ–Te–4Cl] (80), 404 [Mþ–Te–F–4Cl] (25). EA Calc. for C12F8Te2Cl4: C, 20.7, Cl 20.8. Found: C, 20.7, Cl 22.0. 3.3.3. 5,5,10,10-Tetrabromo-1,2,3,4,6,7,8,9-octafluoro-5l4, 10l4-telluranthrene (8) A solution of 0.7 mmol 5 in 15 ml of CFCl3 was cooled to 0 8C. Into the stirred solution, 150 ml (excess) of bromine were added. The product precipitated immediately. After stirring for 1 h at room temperature, the resulting mixture was evaporated in vacuo, yielding a slightly yellowish powder. Yield: 96%, mp > 345 8C (dec.). Raman: strong fluorescence. 19 F NMR [DMSO-D6]: d ¼ 114:0 (m, 2F, 2-F), 150.2 (m, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSO-D6]: d ¼ 147:4 (2 JCTe ¼ 38:4 Hz, C-2), 140.8 (C-3), 131.9 (1 JCTe ¼ 386:7 Hz, C-1) ppm. 125 Te{19 F} NMR [DMSOD6]: d ¼ 1172 (br) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 792 [Mþ–Br] (30), 711 [Mþ–2Br] (7), 632 [Mþ–3Br] (95), 426 [Mþ–Te–4Br] (100). Mass spectra, elemental analysis and IR see ref. [16]. 3.3.4. 5,5,10,10-Tetraazido-1,2,3,4,6,7,8,9-octafluoro-5l4, 10l4-telluranthrene (9) Into a solution of 0.5 mmol of 5 in 30 ml CH3CN were added 1.2 mmol XeF2 in one portion at 0 8C. The colorless solution was stirred for 4 h, then 4.4 mmol of Me3SiN3 were added, changing the color to orange during addition. After 2 h at ambient temperature, a slightly yellowish residue had separated from the yellow solution. The mixture was evaporated in vacuo, yielding a yellow powder. Mp > 180 8C (dec.). Raman: n ¼ 2103 (20)/2086 (15)/ 2063 (20)/2033 (20)/2003 (15, nasN3), 1607 (5), 1345 (20), 1325 (15), 1278 (15), 1024 (5), 816 (10), 771 (10), 644 (20), 600 (10), 572 (20), 547 (20), 488 (60), 472 (45), 407 (30), 373 (70), 356 (70), 331 (100, nTeN), 308 (50), 266 (50), 228 (80), 206 (55), 157 (55) cm1. IR: 2050/2037 vs (nasN3), 1621 m, 1544 w, 1489 vs, 1456 vs, 1663 w, 1327 m, 1313 m, 1271 s, 1106 s, 1042 m, 1025 s, 809 w, 769 m, 732 w, 717 w, 566 m, 542 m, 470 w, 378 m, 352 w, 313 m cm1. 19 F NMR [DMSO-D6]: d ¼ 120:5 (m, 2F, 2-F), 149.5 (m, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSO-D6]: d ¼ 148:0 (C-2), 141.3 (C-3), 128.0 (C-1) ppm. 14 N NMR [DMSO-D6, Du1/2 (Hz)]: d ¼ 134 (Nb, 80), 165 (Ng, 300), 244 (Na, > 2000) ppm. 125 Te{19 F} NMR [DMSO-D6]: d ¼ 1074 (br) ppm. DCIMS 70 eV, m/z (rel. int.) ¼ 658 [Mþ–N3] (1), 595 [Mþ–3N3] (1), 553 [Mþ–4N3] (100).
1003
3.4. Preparation of trifluoromethyl and fluorophenyl tellurium di- and triazides 3.4.1. Bis(trifluoromethyl)diazido-l4-tellane (CF3)2Te(N3)2 (10) Into a stirred solution of 120 mg (0.4 mmol) (CF3)2TeF2 in 5 ml of CH2Cl2 were added 110 mg (0.9 mmol) Me3SiN3 at 0 8C. After 2 h of stirring, the yellow suspension was dried for several hours at ambient temperature in vacuo (103 mbar) to yield a slightly yellowish, friction sensitive powder. Mp 35 8C. Raman: n ¼ 2070 (20)/ 2025 (5, nasN3), 1328 (5), 1093 (5), 1039 (5), 743 (10), 642 (10), 355 (100, nTeN), 290 (10), 266 (10), 239 (10), 205 (10) cm1. IR: n ¼ 2144 m/2052 vs (nasN3), 1681 m, 1313 w, 1261m, 1170, 1102 m, 1054 s, 622 s, 527 m cm1. 19 F NMR: d ¼ 41:7 (2 JFTe ¼ 133:9 Hz) [CDCl3]; 49.6 [DMSO-D6] ppm. 13 C NMR: d ¼ 122:5 (1 JCTe ¼ 215:6 Hz) [{19 F}, CDCl3]; 127.0 (1 JCF ¼ 368:3 Hz) [DMSO-D6] ppm. 14 N NMR, Du1/2 (Hz): d ¼ 142 (Nb, 40), 237 (Ng, 1100), 275 (Na, 1700) [CDCl3]; 139 (Nb, 120), 199 (Ng, 580), 290 (Na, >2000) [DMSO-D6] ppm. 125 Te NMR: d ¼ 1116 (sept) [CDCl3]; 1152 (m) [DMSO-D6] ppm. EIMS 70 eV, m/z (rel. int.) ¼ 495 [CF3CF2TeTeCF2CF3þ] (8), 426 [CF3CF2TeTeCF2þ] (4), 337 [Te(CF3)3þ] (2), 324 [Mþ–N2] (1), 287 [(CF3)2TeFþ] (10), 283 [Mþ–CF3] (5), 282 [(CF3)2TeNþ] (5), 268 [(CF3)2Teþ] (10), 199 [CF3Teþ] (40), 69 [CF3þ] (100). 3.4.2. Bis(2,6-difluorophenyl)diazido-l4-tellane (C6F2H3)2Te(N3)2 (11) Into a solution of 0.7 mmol of (C6F2H3)2TeF2 in 5 ml of CH2Cl2 were added 2.0 mmol of Me3SiN3 at 0 8C. After 2 h of stirring, volatile materials were removed in vacuo, the yellowish residue was washed with 2 ml of CH2Cl2 and evaporated again to dryness. Yield 78%, mp 176 8C. Raman: n ¼ 3091 (30), 2072 (25)/ 2050 (20, nasN3) 1605 (10). 1464 (5), 1440 (5), 1317 (10), 1271 (15), 1154 (10), 1082 (5), 1037 (10), 753 (5), 696 (5), 646 (15), 555 (25), 378 (20), 344 (100, nTeN), 330 (50), 308 (65), 258 (15), 195 (25), 149 (25) cm1. IR: n ¼ 3084 m, 2066 s/ 2049 vs (nasN3), 2038 vs, 1604 s, 1592 s, 1580 s, 1538 w, 1468 vs, 1457 vs, 1317 m, 1261 m, 1233 s, 1151 m, 1082 m, 1034 w, 985 s, 785 s, 785 s, 753 m, 698 m, 640 br, 555 m, 535 m, 504 m cm1. 19 F NMR [CDCl3]: d ¼ 96:2/ 97.3 (m, 2F, 2-F) ppm. 13 C{19 F} NMR [CDCl3]: d ¼ 162:5 (br, C2), 136.5 (C4), 134.8 (C3), 105.3 (C1) ppm. 14 N NMR [CDCl3, Du1/2 (Hz)]: d ¼ 139 (Nb, 80), 191 (Ng, 300), 290 (Na, 1400) ppm. 125 Te{1 H} NMR [CDCl3]: d ¼ 773 (m) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 356 [Mþ–2N3] (100), 242 [C6F2H3Teþ] (55), 226 [C12H6F4þ] (80). Calc. for C12H6N6F4Te: C, 32.9; H, 1,4; N, 19.2. Found: C, 33.0; H, 1.3; N, 18.5. 3.4.3. Trifluoromethyltriazido-l4-tellane CF3Te(N3)3 (12) Into a stirred solution of 110 mg (0.3 mmol) CF3TeTeCF3 in 5 ml of CFCl3 were added 170 mg (1 mmol) XeF2 at 0 8C.
T.M. Klapo¨ tke et al. / Journal of Fluorine Chemistry 125 (2004) 997–1005
1004 Table 1 Crystal data and structure refinements
Empirical formula Formula mass Temperature (K) Crystal size (mm) Crystal system Space group ˚) a (A ˚) b (A ˚) c (A b (8) ˚ 3) V (A Z rcalc (g cm3) m (mm1) F(0 0 0) y range (8) Index ranges
Reflections collected Reflections unique R1, wR2 (2s data) R1, wR2 (all data) Max./min. transm. Data/restr./param. GOOF on F2 ˚ 3) Larg. Diff. peak/hole (e/A a
(CF3C6F4Te)2 (4)
(C6F4Te)2Br4C6H6 (8)
(C6F2H3)2Te(N3)2 (11)
C14F14Te2 689.33 200 0.03 0.09 0.37 Monoclinic C2/c 29.519(6) 6.1941(8) 18.932(3) 99.93(2) 3410(1) 8 2.686 3.567 2512 2.2–23.8 33 h 33 6 k 6 19 l 21 9082 2559 (Rint ¼ 0.101) 0.0512, 0.1255 0.0592, 0.1306 0.8938, 0.5806 2559/0/271 0.979 1.376/2.201
C18H6Br4F8Te2 949.04 200 0.02 0.10 0.10 Monoclinic P21/c 11.1563(6) 7.2559(4) 15.3136(9) 111.312(2) 1154.9(1) 2 2.729 9.515 860 2.9–19.8 10 h 10 6 k 6 14 l 14 6043 1040 (Rint ¼ 0.056) 0.0256, 0.0563 0.0342, 0.0607 0.6411, 0.3476 1040/0/145 1.190 0.400/0.381
C12H6F4N6Te 437.81 200 0.07 0.20 0.26 Triclinic P1 7.5448(2) 9.8636(2) 11.3422(3) 91.4537(8)a 730.08(3) 2 1.992 2.089 416 3.2–27.5 9 h 9 12 k 12 14 l 14 11028 3305 (Rint ¼ 0.046) 0.0245, 0.0569 0.0274, 0.0583 0.8923, 0.7278 3305/0/208 1.052 0.495/1.151
a ¼ 114.1008(8), g ¼ 106.2896(8)8.
After 40 min, into the turbid solution 260 mg (2.2 mmol) Me3SiN3 at 20 8C were added and stirred for additional 15 min until the effervescence had stopped. The yellow suspension was evaporated and dried in vacuo. Raman: n ¼ 2115 (35)/2091 (15)/2070 (15, nasN3), 737 (15), 662 (20), 422 (100), 402 (90), 365 (65, nTeN), 278 (50), 198 (50) cm1. 19 F NMR [DMSO-D6]: d ¼ 56:0 (s) ppm. 13 C NMR [DMSO-D6]: d ¼ 128:5 (1 JCF ¼ 363:8 Hz) ppm. 14 N NMR [DMSO-D6, Du1/2 (Hz)]: d ¼ 140 (Nb, 120), 230 (Ng, >2000), 260 (Na, >2000) ppm. 125 Te NMR [DMSO-D6]: d ¼ 1406 (m) ppm. 3.4.4. Pentafluorophenyltriazido-l4-tellane C6F5Te(N3)3 (13) Into a stirred solution of 110 mg (0.2 mmol) C6F5TeTeC6F5 in 10 ml of CFCl3 were added 120 mg (0.7 mmol) XeF2 at 0 8C. After 25 min, into the turbid solution 180 mg (1.6 mmol) Me3SiN3 at 0 8C were added and stirred for additional 10 min until the effervescence had stopped. The brownish suspension was evaporated and dried in vacuo. According to 19 F and 125 Te NMR spectra, the compounds (C6F5)2Te(N3)2 and Te(N3)4 were present each in ca. 30%. Raman: n ¼ 2110 (20)/2085 (30)/2048 (15, nasN3), 1639 (5), 1516 (5), 1319 (5), 1263 (5), 1088 (5), 803 (5), 648 (15), 587 (10), 536 (5), 493 (20), 418 (100), 381 (25), 341 (95, nTeN), 310 (30), 245 (20), 222 (20), 178 (30) cm1. 19 F NMR [DMSO-D6]: d ¼ 127:6 (br, 2F, 2-F), 147.9
(br, 1F, 4-F), 160.0 (br, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSO-D6]: d ¼ 146:4 (C-2), 142.8 (C-4), 137.5 (C-3), 117.4 (br, C-1) ppm. 14 N NMR [DMSO-D6, Du1/2 (Hz)]: d ¼ 140 (Nb, 120), 230 (Ng, >2000), 260 (Na, >2000) ppm. 125 Te NMR [DMSO-D6]: d ¼ 1277 (m) ppm. 3.5. X-ray crystallography Data for compound 4 were collected on a Stoe IPDS image plate area detector, data for compounds 8 and 11 were collected on a Nonius Kappa CCD. Thermal ellipsoids are shown with 50% probability. Structure solution and refinement were performed as outlined in ref [8]. Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication nos. CCDC 211267 (4), 211268 (8), and 211269 (11) (Table 1). Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, (fax: þ44-1223-336033 or e-mail: deposit@ ccdc.cam.ac.uk).
Acknowledgements Financial support of this work by the University of Munich and the Fonds der Chemischen Industrie is gratefully
T.M. Klapo¨ tke et al. / Journal of Fluorine Chemistry 125 (2004) 997–1005
acknowledged. We wish to thank the research students Mr. M.B. Rauscher and Mr. B.L.J. Kindler for their strong commitment during the preparation of some compounds. We are also indebted to and thank Prof. P. Klu¨ fers for generous allocation of X-ray diffractometer time.
References [1] M.T. Chen, J.W. George, J. Am. Chem. Soc. 90 (1968) 4580. [2] M. Akiba, M.V. Lakshmikantham, K.Y. Jen, M.P. Cava, J. Org. Chem. 49 (1984) 4819. [3] R. Kasemann, D. Naumann, J. Fluorine Chem. 48 (1990) 207. [4] T.M. Klapo¨ tke, B. Krumm, P. Mayer, K. Polborn, O.P. Ruscitti, J. Fluorine Chem. 112 (2001) 207. [5] E.S. Kostiner, M.L.N. Reddy, D.S. Urch, A.G. Massey, J. Organomet. Chem. 15 (1968) 383. [6] R. Kasemann, D. Naumann, J. Fluorine Chem. 41 (1988) 321. [7] T.M. Klapo¨ tke, B. Krumm, P. Mayer, O.P. Ruscitti, Inorg. Chem. 39 (2000) 5426. [8] T.M. Klapo¨ tke, B. Krumm, P. Mayer, H. Piotrowski, O.P. Ruscitti, A. Schiller, Inorg. Chem. 41 (2002) 1184. [9] C. Lau, J. Passmore, E.K. Richardson, T.K. Whidden, P.S. White, Can. J. Chem. 63 (1985) 2273.
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[10] T.M. Klapo¨ tke, B. Krumm, P. Mayer, H. Piotrowski, K. Polborn, J. Fluorine Chem. 123 (2003) 133. [11] G. Erker, R. Hock, Angew. Chem. 101 (1989) 181. Angew. Chem. Int. Engl. 28 (1989) 179. [12] L.-B. Han, F. Mirzaei, M. Tanaka, Organometallics 19 (2000) 722. [13] H. Voelker, D. Labahn, F.M. Bohnen, R. Herbst-Irmer, H.W. Roesky, D. Stalke, F.T. Edelmann, New J. Chem. 23 (1999) 905. [14] F.T. Edelmann, Comments Inorg. Chem. 12 (1992) 259. [15] B. Bildstein, K.J. Irgolic, D.H. O’Brien, Phosphorus Sulfur 38 (1988) 245. [16] D.P. Rainville, R.A. Zingaro, E.A. Meyers, J. Fluorine Chem. 16 (1980) 245. [17] T.M. Klapo¨ tke, B. Krumm, P. Mayer, K. Polborn, O.P. Ruscitti, Inorg. Chem. 40 (2001) 5169. [18] F.J. Berry, A.J. Edwards, J. Chem. Soc. Dalton Trans. (1980) 2306. [19] T.M. Klapo¨ tke, B. Krumm, K. Polborn, I. Schwab, in: 225th ACS National Meeting, New Orleans, 23–27 March 2003, Abstract INOR–456. [20] T.M. Klapo¨ tke, B. Krumm, P. Mayer, I. Schwab, Angew. Chem. Int. Ed. 42 (2003) 5843. [21] S. Herberg, D. Naumann, Z. Anorg. Allg. Chem. 492 (1982) 95. [22] J. Kischkewitz, D. Naumann, Z. Anorg. Allg. Chem. 547 (1987) 167. [23] D.F. Shriver, M.A. Drezdzon, The Manipulation of Air Sensitive Compounds, Wiley, New York, NY 1986.
Fluorinated tellurium(IV) azides and their precursors Thomas M. Klapo¨tkea,*, Burkhard Krumma, Peter Mayera, Dieter Naumannb, Ingo Schwaba a
Department of Chemistry, University of Munich (LMU), Butenandtstr. 5–13(D), D-81377 Munich, Germany b Institute of Inorganic Chemistry, University of Cologne, Greinstr. 6, D-50939 Cologne, Germany Received 30 May 2003; received in revised form 8 September 2003; accepted 3 January 2004 Available online 25 March 2004
Abstract The perfluoroaryl tellurolates C6F5TeLi (1) and 4-CF3C6F4TeLi (2) were prepared. These intermediates were identified by NMR spectroscopy and may form, depending on the reaction conditions, either the corresponding ditellanes C6F5TeTeC6F5 (3) and CF3C6F4TeTeC6F4CF3 (4) by subsequent oxidation, or in the case of 1, a telluranthrene (C6F4Te)2 (5) by reaction with itself. The halogenation products of 5, ( C6F4Te)2F4 (6), (C6F4Te)2Cl4 (7), (C6F4Te)2Br4 (8), as well as the azidation product (C6F4Te)2(N3)4 (9) were synthesized. Furthermore, in pursuit of our recent work on tellurium azides, the syntheses and properties of R2Te(N3)2 (R ¼ CF3 (10), C6F2H3 (11)) and RTe(N3)3 (R ¼ CF3 (12) and C6F5 (13)) are reported. The crystal structures of CF3C6F4TeTeC6F4CF3 (4), (C6F4Te)2Br4 (8), and (C6F2H3)2Te(N3)2 (11) were determined. # 2004 Elsevier B.V. All rights reserved. Keywords: Ditellanes; Tellurium azides; Tellurolates; X-ray crystallography
1. Introduction Although tellurium species containing perfluorinated aryl or alkyl substituents have been known for many years and the preparation of ditellanes can be achieved by several routes [1,2], the synthesis of C6F5TeTeC6F5 is rather complicated [3,4]. The latter was first reported in 1968 [5], but this report was considered doubtful [3]. However, a rational synthesis was presented, by which C6F5TeTeC6F5 is accessible through irradiation. Unfortunately, this proved to be not reproducible, thus obtaining C6F5TeTeC6F5 only in low yields if the standard reaction procedure for aryl ditellanes is used [4]. Nevertheless, C6F5TeTeC6F5 has been fully characterized. In this work, further attempts were made in order to achieve a reproducible route to perfluoroaryl ditellanes with acceptable yields. The ditellane serves as the only precursor for the corresponding tellurium(IV) trifluoride C6F5TeF3 [6]. We were interested in C6F5TeF3 as a possible candidate for the synthesis of a perfluoroaryl substituted tellurium(IV) triazide, following the same strategy as outlined for (C6F5)2Te(N3)2 and other alkyl/aryltellurium(IV) diazides and triazides [7,8]. *
Corresponding author. Tel.: þ49-89-2180-77491; fax: þ49-89-2180-77492. E-mail address: [email protected] (T.M. Klapo¨tke). 0022-1139/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jfluchem.2004.01.017
A further subject of this study is the preparation and properties of the first perfluoroalkyl, namely, trifluoromethyl, substituted tellurium(IV) di- and triazides. Further reported perfluoroalkyl tellurium(IV) di- and trifluorides are (C2F5)2TeF2 and C2F5TeF3 [9]. During several attempts to prepare C6F5TeTeC6F5, a sideproduct containing tellurium was always present in significant amounts, which is attributed to the high reactivity of the initially formed tellurolate C6F5TeLi. In this report, identification, characterization, and some subsequent chemistry of this material will be accomplished.
2. Results and discussion 2.1. Ditellanes/telluranthrenes Similar to the standard procedures for the preparation of PhTeTePh for a synthesis of perfluoroaryl derivatives, the generation of the perfluoroaryllithium species RFLi (RF ¼ C6 F5 and 4-CF3C6F4) is the first step. The insertion of Te from finely ground tellurium powder into RFLi takes place only to a small extent as proved with C6F5Li, 4-CF3C6F4Li or other perfluoroaryl lithiums [4,10]. Recently, the successful use of phosphane tellurides as soluble tellurium sources in insertion reactions was reported.
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998
RFH
n-BuLi/ -70˚C
Te, -20˚C
RFLi
THF
RFTeLi
I2, reflux
RFTeTeRF
10 mol% n-Bu3P
Scheme 1. Synthesis of perfluorinated ditellanes.
Apart from Ph3P [11], mainly t-Bu3P and n-Bu3P [12] were used, the latter also in catalytic amounts. The synthesis of bis[2,4,6-tris(trifluoromethyl)phenyl]ditellane using n-Bu3PTe was claimed, but unfortunately no experimental details and spectroscopic data were disclosed [13,14]. Thus, we probed suitable conditions for an activation of tellurium powder by n-Bu3P in the reaction with RFLi to form RFTeLi (RF ¼ C6 F5 (1) and 4-CF3C6F4 (2)). Catalytic amounts of n-Bu3P and reaction times of more than 12 h turned out to be a suitable synthetic approach to perfluorinated tellurolates. A significant difference in the stability of 1 and 2 was observed when diethyl ether or THF were used as solvents. Red solutions of 1 and 2 in THF are stable even under reflux, but very sensitive towards hydrolysis. They exhibit broadened 19 F NMR resonances and 125 Te NMR resonances at d ¼ 323 (1) and 222 ppm (2), respectively, which is upfield relative to that of PhTeLi (d ¼ 122 ppm), in disagreement with the trends in ref. [15]. Oxidation of 1 and 2 with molecular oxygen did not result (or only in very small amounts) in the formation of the ditellanes. However, with iodine, the ditellanes RFTeTeRF (RF ¼ C6 F5 (3) and 4-CF3C6F4 (4)) were formed via the moderately stable RFTeI intermediates (Scheme 1), which can be detected in the NMR spectra (d125 Te [CDCl3] ¼ 768 (C6F5), 781 (4-CF3C6F4)). Attempts to isolate RFTeI have been unsuccessful so far. The ditellanes 3 and 4 are isolated in only moderate yields, due to the use of flash chromatography and subsequent fractional crystallization, and because of undesirable side reactions (Scheme 2). However, during the use of diethyl ether as solvent at 20 8C, and below in the case of 1, another fluorinated tellurium compound was always detected in significant amounts. This material was identified as octafluorotelluranthrene
(C6F4Te)2 (5). An intra- or intermolecular LiF elimination, where two molecules of tellurolate were involved, must have occurred. The formation of 5 could proceed either via a SNAr mechanism involving addition and elimination steps, or by initial cleavage of an ortho C–F bond of 1 followed by nucleophilic attack of another molecule of 1. The latter process can be understood as a special case of a SN1 type reaction, the intermediate zwitterionic species possibly being stabilized by the tellurolate acting as neighboringgroup forming a three-membered tellurirene, as suggested in ref. [10] and references therein. The octafluorotelluranthrene (5) can be formed by both types of reaction, leaving the pathway uncertain. In the case of 4-CF3C6F4TeLi (2), under the same reaction conditions, complex product mixtures inhibited the identification and isolation of corresponding telluranthrene derivatives, similarly to the telluranthrene isomers identified in ref. [10]. Under reflux conditions in Et2O with 1, the telluranthrene 5 can be isolated as the main product and purified by flash chromatography. Originally, 5 was obtained by the reaction of 1,2-diiodo-tetrafluorobenzene with tellurium at elevated temperatures above 300 8C, and additional purification was only achieved by means of reduction of the tetrabrominated derivative (C6F4Te)2Br4 [16]. The latter route, compared with ours, is rather expensive, and the overall yield is below 5%. Our new, more convenient method (Scheme 3) produces pure 5 in approximately 30% yield in a one-pot synthesis. The molecular structure of 4 in the crystalline state is shown in Fig. 1. The structural features are quite similar to those of C6F5TeTeC6F5 [4]. The dihedral angle CTeTeC is larger (100.7(3)8) than found in C6F5TeTeC6F5 (91.8(1)8), probably due to the increased sterical demand of the CF3C6F4-substituent. 2.2. 5l4, 10l4-Perfluorotelluranthrene derivatives
n-BuLi C6F5Li
C6F5H exc.
[n-Bu3PI]I
Te n-Bu3P n-BuTeLi C6F5TeLi (1)
I2
-LiI
(C6F5)2Te
n-BuTeI -LiI (n-BuTe)2
n-BuTeTeC6F5
(C6F5Te)2 (3)
I2
C6F5TeI -I2
Scheme 2. Possible reactions during the synthesis of 3.
Since the telluranthrene 5 can now be prepared in moderate yield, it was of interest to study the reactivity of this cyclic bifunctional tellane towards halogenation. As outlined previously for other fluoroaryl tellanes [17], the reactions with XeF2, SO2Cl2 and Br2 give the corresponding tetrahalogeno tellurium(IV) derivatives (C6F4Te)2F4 (6), (C6F4Te)2Cl4 (7), and (C6F4Te)2Br4 (8). All of them show a decreased solubility relative to that of 5 (with 6 as the least soluble), and the only suitable solvent for NMR measurements is DMSO-D6. Whereas 7 and 8 are quite stable, 6 is highly reactive towards glass in solution and needs to be stored at low temperatures, or in TeflonTM equipment. With Me3SiN3, all tellurium bound fluorine atoms react readily to the moisture-sensitive tetraazido derivative (C6F4Te)2(N3)4 (9). All halogeno derivatives (6–8) are of enormous
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999
F C6F5H
n-BuLi/ -70˚C Et2O
C6F5Li
Te, -20˚C 10 mol% n-Bu3P
reflux
C6F5TeLi
F
F
Te
F
F
Te
F
½
-LiF
(5) F
F
Scheme 3. Synthesis of octafluorotelluranthrene.
C8 C1 Te2 Te1
˚ ) and angles (8): Te1Te2 2.6948(9), Te1C1 2.110(8), Te2C8 Fig. 1. Molecular structure of CF3C6F4TeTeC6F4CF3 (4). Selected bond lengths (A 2.124(8), C1Te1Te2C8 100.7(3).
thermal stability, decomposing above 330 8C, while the tetraazide 9 can be heated slowly to its decomposition point at 180 8C. Although 9 does not seem to be friction sensitive, deflagration occurs when in contact with a Bunsen flame (Scheme 4). In relation to 5 (d125 Te ¼ 762 ppm), the 125 Te NMR shifts of the oxidized species 6–9 are observed as expected for Te(IV) compounds, found at ca. 300 ppm lower field. Somewhat irregular to the trends observed so far (usually the difluorides R2TeF2 are the least shielded), the tetrabromide 8 exhibits the lowest 125 Te NMR shift (d ¼ 1172 ppm in DMSO-D6). In the 19 F NMR spectra, two sets of fluorine
F F
resonances are observed, in addition for 6 a broadened resonance at d ¼ 63 ppm for the TeF2 moiety occurs. Slow evaporation of a saturated solution of 8 in benzene forms suitable single crystals. The molecular structure of 8 is depicted in Fig. 2. In a similar fashion as in acyclic dibromotelluranes R2TeBr2 [17], the bromine atoms occupy axial positions, while two equatorial positions at each tellurium center are connected to the planar ring systems. The inner C4Te2 ring itself is planar, unlike as in the structures of 5 or other Te(II) telluranthrenes [10,16]. In contrast to other compounds of the type R2TeX2 [17,18], for 8, no short secondary Te Br interactions are found. The Te–Br
F
F Te
F
F X Te
F
X
F
XeF2, SO2Cl2 or Br2 F
F
Te F
CFCl3, 0 ˚C
X = F (6), Cl (7), Br (8) F
F
X
Te
F
X
F
F
(5)
6: + 4 Me3SiN3 - 4 Me3SiF F
F N3
F
Te
N3
F (9)
F
N3 F
4
4
Te
F
N3 F
Scheme 4. Synthesis of 5l , 10l -telluranthrene derivatives of 5.
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1000
Br2
C6
Te
C1 Te
Br1
˚) Fig. 2. Molecular structure of (C6F4Te)2Br4 (8). Selected bond lengths (A and angles (8): TeBr1 2.6201(11), TeBr2 2.6615(10), TeC1 2.120(8), Br1TeBr2 174.60(4).
distances are almost identical to those of acyclic fluorophenyltelluranes R2TeBr2 [17]. 2.3. Trifluoromethyl tellurium(IV) and fluorophenyl diazides and triazides The bis-trifluoromethyl and the partially fluorinated bis2,6-difluorophenyl substituted tellurium(IV) diazides 10 and 11, as well as the trifluoromethyl and pentafluorophenyl tellurium(IV) triazides 12 and 13 are prepared similarly to the syntheses of the non-fluorinated analogues [8] (Scheme 5). Compound 11 was prepared in an effort to obtain structural data in addition to the crystal structures of Ph2Te(N3)2 and (C6F5)2Te(N3)2 (see structure discussion). All four compounds are yellowish moisture-sensitive solids, 10 being the most sensitive tellurium diazide regarding its propensity to explode and hydrolyze. This is probably due to the strong polarization effect of the CF3 group destabilizing the Na–Nb bond, leading to an increased tendency to eliminate molecular nitrogen. The triazide CF3Te(N3)3 (12) is even more sensitive and could not be obtained in pure form. The pentafluorophenyl derivative C6F5Te(N3)3 (13) was obtained in a mixture with (C6F5)2Te(N3)2 and Te(N3)4. The intermediate C6F5TeF3, formed by fluorination of 3, is known to dismutate even at low temperatures into (C6F5)2TeF2 and TeF4 [6]. Upon treatment with Me3SiN3, the corresponding azides were formed. Both species in this mixture have been unambiguously identified by their 125 Te NMR shifts by comparison with authentic samples in DMSO-D6. The diazide (C6F5)2Te(N3)2 (916 ppm, DMSOD6) was prepared according to [7], and the tetraazide
(RF)2TeF2
RFTeTeRF
Me3SiN3 CFCl3, 0 ˚C 1. XeF2 / 2. Me3SiN3 CFCl3, 0 ˚C
Te(N3)4 (1382 ppm, DMSO-D6) by reaction of TeF4 with Me3SiN3 [19,20]. The tellurium azides 9–13 show asymmetric stretching vibrations (nasN3) of the azido groups, as well as intense TeN stretching vibrations in their Raman spectra. For the tetraazide 9, between 2100 and 2000 cm1, more than five different peaks for nasN3 are found. Compared with Me2Te(N3)2 [8], in (CF3)2Te(N3)2 (10) both the nasN3 and the nTeN are shifted slightly to higher wavenumbers. The nTeC stretching vibration, for Me2Te(N3)2 at 550 cm1, is not detected. Three different nasN3 (axial out of phase, axial in phase, equatorial), are found between 2115 and 2048 cm1 for the triazides 12 and 13. In the case of (C6F2H3)2Te(N3)2 (11), two discrete peaks for nasN3 are visible in the Raman spectrum at 2072/2050 cm1, which is slightly higher than found for Ph2Te(N3)2 and (C6F5)2Te(N3)2 [7]. The 125 Te NMR shifts of the diazides are typically found at slightly higher field than those of the corresponding difluorides, for example d125 Te ¼ 1116 (10) versus 1200 ppm ((CF3)2TeF2, CDCl3). The resonances of the triazides 12 and 13 are found at lower field compared with those of the corresponding diazides. A cold solution in CH2Cl2/hexane led to nearly colorless crystals of 11 suitable for X-ray crystal structure analysis. The difference in the sterical arrangements of Ph2Te(N3)2 and (C6F5)2Te(N3)2, the orientation of the azide groups, was discussed in terms of steric reasons and electrostatic repulsions between free electron pairs of fluorine and nitrogen [7]. In the case of 11, the same orientation of the substituents as in Ph2Te(N3)2 is found (see Fig. 3a), although it does not crystallize isotypically (11: P1, Ph2Te(N3)2: Pbca). In both 11 and Ph2Te(N3)2 the azide groups, located in the axial positions, are oriented towards the aryl groups. The opposite was found for the structure of (C6F5)2Te(N3)2. That means, an increased electronegativity of C6F2H3 compared with C6H5 because of the introduction of two fluorine atoms in the ortho position, does not lead to a significant change in the orientation of the azide groups. The tellurium nitrogen ˚ , which distances are Te–N1 2.228(2) and Te–N4 2.202(2) A are also very similar to those found in Ph2Te(N3)2. The intermolecular Te N interactions (Te N4 2.970(2), ˚ ) found in the three-dimensional strucTe N1 3.287(2) A ture of 11 (Fig. 3b), are shorter than in the case of ˚ ), and cause in principle Ph2Te(N3)2 (Te N 3.141/3.497 A the same connectivity pattern (Te Na Te, but in (C6F5)2Te(N3)2: Te Ng Te, no Te Na ).
(RF)2Te(N3)2
RFTe(N3)3
RF = CF3 (10), C6F2H3 (11)
RF = CF3 (12), C6F5 (13)
Scheme 5. Synthesis of fluorinated tellurium(IV) diazides and triazides.
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1001
F1 N1 N2 N3 Te
F2
N6
N4
N5
F3
F4
(a)
N1(i) N4(i)
Te(ii)
Te(i)
N1(ii)
N4(ii)
Te
N4
N1
(b) ˚ ) and angles (8): Te–N1 2.228(2), Te–N4 2.202(2), Te–C1 2.113(2), Te–C7 Fig. 3. (a) Molecular structure of (C6F2H3)2Te(N3)2 (11). Selected bond lengths (A 2.106(3), C–F 1.350(3)–1.362(3), N1–N2 1.213(3), N2–N3 1.142(3), N4–N5 1.229(3), N5–N6 1.136(3), N1–Te–N4 167.71(8), C1–Te–C7 106.56(10), N1– ˚ ): Te N1 (i) N2–N3 177.5(3), N4–N5–N6 177.1(3). (b) Te N interactions in the structure of (C6F2H3)2Te(N3)2 (11). Selected contact distances (A 3.287(2), Te N4 (ii) 2.970(2); with i ¼ 1 x, 1 y, 1 z; ii ¼ x, 1 y, 1 z.
It can be concluded, that the arrangement of the azide groups is not due to electronic or steric reasons, because both effects are present, to substantial extents, in the two orthodifluorophenyl substituents as well. Therefore, the change in orientation as found in (C6F5)2Te(N3)2 can probably be explained by packing effects.
3. Experimental 3.1. General procedures All manipulations of air and moisture-sensitive materials were performed under an inert atmosphere of dry nitrogen or argon using flame-dried glass vessels and Schlenk techniques. Xenon difluoride (FluoroChem) and trimethylsilyl azide (Aldrich) were used as received. The compounds (CF3)2TeF2 and CF3TeTeCF3 were prepared according to the
literature [21,22]. Solvents were dried by standard methods [23], distilled and stored over molecular sieves. Raman spectra were recorded on a Perkin-Elmer 2000 NIR FT-Raman spectrometer fitted with a Nd-YAG laser (1064 nm), infrared spectra on a Perkin-Elmer 983G IR spectrometer between KBr plates. Mass spectroscopic data were obtained from a JEOL Mstation JMS 700 Spektrometer with fragments referring to the nuclei with the highest abundance (for example 130 Te). The elemental analyses were performed with a C, H, N-Analysator Elementar Vario EL. NMR spectra were recorded on a JEOL Eclipse 400 instrument, and chemical shifts are with respect to (CH3)4Si (1 H, 13 C), CH3NO2 (14 N), CFCl3 (19 F), and Me2Te (125 Te). Melting points were determined in capillaries using a Bu¨ chi B540 instrument. CAUTION: Covalent tellurium azides are potentially explosive; appropriate safety precautions such as Kevlar gloves, face shield, leather jacket must be taken, and the amounts of substance handled in pure form by trained
1002
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personnel should not exceed 100 mg. During the preparation of (CF3)2Te(N3)2 (10) once a vigorous explosion occurred, destroying the glass vessel completely. The yields and elemental analyses of the azides 9 and 10 were not determined due to safety reasons. 3.2. Preparation of RFTeTeRF (RF ¼ C6F5 (3), CF3C6F4 (4)) A solution of 25 mmol pentafluorobenzene or 4-trifluoromethyltetrafluorobenzene in ca. 30 ml THF was cooled to 78 8C, and 27.5 mmol of n-BuLi (2.5 M in hexanes) were slowly added with slight darkening of the reaction solution. After 1.5 h, 25 mmol of finely ground tellurium powder and 2.5 mmol n-Bu3P were added. The mixture was slowly warmed to 20 8C and held for 15 h at this temperature. Iodine (25 mmol) was added and the mixture warmed to ambient temperature, then refluxed for 2 h. After cooling to 20 8C again, small amounts of sulfur (0.25 mmol) were added and the mixture was then refluxed again for 30 min. Unreacted tellurium was separated by filtration at ambient temperature, and the resulting solution was poured into a solution of 25 mmol NaHSO3 in 150 ml H2O, and 150 ml of diethyl ether were added. Drying of the organic phase over CaCl2 and evaporation of the solvent in vacuo yielded dark brown oils which were subjected to flash chromatography with petrol ether/methylene chloride (10:1). The dark red solution was concentrated in vacuo and dark red rhombic crystals (3), or dark red needles (4), were finally separated from the pale yellow crystals of the corresponding monotellanes by fractional crystallization. C6F5TeTeC6F5 (3): yield (33%), spectroscopic data see [3,4]. CF3C6F4TeTeC6F4CF3 (4): yield (46%), mp 92–93 8C. Raman: n ¼ 1643 (25), 1377 (15), 917 (5), 782 (10), 718 (15), 502 (55), 444 (20), 403 (25), 310 (15), 197 (100, nTeTe), 175 (70) cm1. IR: n ¼ 1642 m, 1597 w, 1481 vs, 1468 vs, 1414 w, 1378 w, 1351 w, 1322 vs, 1294 w, 1259 w, 1213 m, 1181 s, 1156 s, 973 s, 920 s, 782 w, 715 s, 646 w, 546 w, 502 w, 422 w, 307 w cm1. 19 F NMR [CDCl3]: d ¼ 56:9 (t, 4 JFF ¼ 21:7 Hz, 3F, CF3), 113.0 (m, 2F, 2-F), 138.7 (m, 2F, 3-F) ppm. 13 C NMR [CDCl3]: d ¼ 149:0 (dm, 1 JCF ¼ 250:6 Hz, 2 JCTe ¼ 18:9 Hz, C-2), 142.4 (dm, 1 JCF ¼ 265:2 Hz, 3 JCTe ¼ 16:6 Hz, C-3), 120.6 (q, 1 JCF ¼ 274:8 Hz, CF3), 111.8 (m, C-4), 91.0 (tm, 2 JCF ¼ 31:1 Hz, 1 JCTe ¼ 420:1 Hz, 2 JCTe ¼ 8:5 Hz, C-1) ppm. 125 Te NMR [CDCl3]: d ¼ 338 (tm, 3 JTeF ¼ 65:2 Hz) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 689 [Mþ] (15), 670 [Mþ–F] (2), 563 [Mþ–Te] (50), 347 [CF3C6F4Teþ] (100). Calc. for C14F14Te2: C, 24.4. Found: C, 24.6. 3.3. Preparation of octafluorotelluranthrene (5), halogenation, and azidation products A solution of 20 mmol pentafluorobenzene in ca. 30 ml diethyl ether was cooled to 78 8C, and 22 mmol of n-BuLi
were added slowly. After 1.5 h, 25 mmol of finely ground tellurium powder and 2.5 mmol n-Bu3P were added. The dark suspension was slowly warmed to 20 8C and held for approximately 15 h at this temperature. After additional refluxing for 2.5 h, a yellow solution was separated from unreacted tellurium and concentrated in vacuo. Purification by column chromatography with petrol ether/methylene chloride (4:1) yielded an orange solution, which was concentrated until crystallization occurred to give orange crystals of 5. Yield: 33%, mp 122–124 8C. Raman: n ¼ 1610 (20), 1591 (20), 1483 (10), 1421 (10), 1294 (20), 1266 (40), 771 (45), 637 (15), 474 (100), 395 (20), 357 (45), 234 (70), 212 (95), 191 (35), 133 (15) cm1. 19 F NMR [CDCl3]: d ¼ 108:0 (m, 2F, 2-F); 151.6 (m, 2F, 3-F) ppm. 13 C NMR [CDCl3]: d ¼ 148:0 (d, 1 JCF ¼ 239:9 Hz, 2 JCTe ¼ 38:8 Hz, 3 JCTe ¼ 11:9 Hz, C-2), 140.1 (d, 3 JCF ¼ 253:6 Hz, 3 JCTe ¼ 12:7 Hz, C-3), 111.6 (m, 1 JCTe ¼ 332:1 Hz, 2 JCTe ¼ 71:9 Hz, C-1) ppm. 125 Te NMR [CDCl3]: d ¼ 762 (t, 3 JTeF ¼ 15:9 Hz) ppm. Mass spectra, elemental analysis and IR see also ref. [16]. 3.3.1. 1,2,3,4,5,5,6,7,8,9,10,10-Dodecafluoro-5l4, 10l4-telluranthrene (6) A solution of 2 mmol 5 in 15 ml of CFCl3 was cooled to 0 8C, and into the stirred solution, 4.2 mmol of XeF2 were added. The yellow color disappeared immediately and a colorless suspension was formed. After stirring for 1.5 h at ambient temperature, a colorless residue was separated from the supernatant. Yield: 88%, mp 333 8C (dec.). Raman: strong fluorescence. IR: n ¼ 1612 m, 1603 m, 1576 m, 1523 m, 1489 vs, 1459 vs, 1370 w, 1328 w, 1316 w, 1299 w, 1272 m, 1107 s, 1027 s, 813 w, 772 w, 634 w, 619 m, 595 w, 519 m, 485 m, 472 m, 424 m, 382 m, 361 m, 315 m, 296 m cm1. 19 F NMR [DMSO-D6]: d ¼ 63 (br, 2F, TeF), 122.0 (m, 2F, 2-F), 150.3 (m, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSO-D6]: d ¼ 147:3 (2 JTeC ¼ 43:8 Hz, C-2), 140.7 (C-3), 130.0 (1 JTeC ¼ 331:4 Hz, C-1) ppm. 125 Te{19 F} NMR [DMSOD6]: d ¼ 1112 (br) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 627 [Mþ] (43), 607 [Mþ–F] (24), 589 [Mþ–2F] (20), 442 [Mþ–F–TeF2] (78), 315 [Mþ–TeF–TeF2] (20), 296 [C12F8þ] (100). EA Calc. for C12F12Te2: C, 23.0. Found: C, 23.5. 3.3.2. 5,5,10,10-Tetrachloro-1,2,3,4,6,7,8,9-octafluoro5l4,10l4-telluranthrene (7) A solution of 0.7 mmol 5 in 15 ml of CFCl3 was cooled to 0 8C, and into the stirred solution, 5 ml (excess) of SO2Cl2 were added. The yellow color vanished rapidly and a colorless suspension was formed. After stirring for 4 h at ambient temperature, the resulting mixture was evaporated in vacuo yielding a colorless powder. Yield: 99%, mp > 345 8C (dec.). Raman: n ¼ 1615 (10), 1279 (10), 771 (15), 472 (25), 396 (20), 373 (25), 357 (25), 291 (100, nTeCl), 251 (35), 210 (43), 160 (20) cm1. IR:
T.M. Klapo¨ tke et al. / Journal of Fluorine Chemistry 125 (2004) 997–1005
n ¼ 1621 m, 1600 s, 1549 w, 1501 vs, 1443 vs, 1354 w, 1318 m, 1304 m, 1271 m, 1118 s, 1104 s, 1017 s, 827 m, 805 w, 762 m, 722 w, 636 m, 605 w, 568 w, 519 w, 470 w, 370 m, 351 w, 297 m cm1. 19 F NMR [DMSO-D6]: d ¼ 114:6 (m, 2F, 2-F), 150.9 (m, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSOD6]: d ¼ 145:4 (2 JCTe ¼ 40:7 Hz, C-2), 138.9 (C-3), 130.4 (1 JCTe ¼ 369:0 Hz, C-1) ppm. 125 Te{19 F} NMR [DMSOD6]: d ¼ 1076 (br) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 658 [Mþ–Cl] (100), 623 [Mþ–2Cl] (29), 588 [Mþ–3Cl] (55), 551 [Mþ–4Cl] (45), 426 [Mþ–Te–4Cl] (80), 404 [Mþ–Te–F–4Cl] (25). EA Calc. for C12F8Te2Cl4: C, 20.7, Cl 20.8. Found: C, 20.7, Cl 22.0. 3.3.3. 5,5,10,10-Tetrabromo-1,2,3,4,6,7,8,9-octafluoro-5l4, 10l4-telluranthrene (8) A solution of 0.7 mmol 5 in 15 ml of CFCl3 was cooled to 0 8C. Into the stirred solution, 150 ml (excess) of bromine were added. The product precipitated immediately. After stirring for 1 h at room temperature, the resulting mixture was evaporated in vacuo, yielding a slightly yellowish powder. Yield: 96%, mp > 345 8C (dec.). Raman: strong fluorescence. 19 F NMR [DMSO-D6]: d ¼ 114:0 (m, 2F, 2-F), 150.2 (m, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSO-D6]: d ¼ 147:4 (2 JCTe ¼ 38:4 Hz, C-2), 140.8 (C-3), 131.9 (1 JCTe ¼ 386:7 Hz, C-1) ppm. 125 Te{19 F} NMR [DMSOD6]: d ¼ 1172 (br) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 792 [Mþ–Br] (30), 711 [Mþ–2Br] (7), 632 [Mþ–3Br] (95), 426 [Mþ–Te–4Br] (100). Mass spectra, elemental analysis and IR see ref. [16]. 3.3.4. 5,5,10,10-Tetraazido-1,2,3,4,6,7,8,9-octafluoro-5l4, 10l4-telluranthrene (9) Into a solution of 0.5 mmol of 5 in 30 ml CH3CN were added 1.2 mmol XeF2 in one portion at 0 8C. The colorless solution was stirred for 4 h, then 4.4 mmol of Me3SiN3 were added, changing the color to orange during addition. After 2 h at ambient temperature, a slightly yellowish residue had separated from the yellow solution. The mixture was evaporated in vacuo, yielding a yellow powder. Mp > 180 8C (dec.). Raman: n ¼ 2103 (20)/2086 (15)/ 2063 (20)/2033 (20)/2003 (15, nasN3), 1607 (5), 1345 (20), 1325 (15), 1278 (15), 1024 (5), 816 (10), 771 (10), 644 (20), 600 (10), 572 (20), 547 (20), 488 (60), 472 (45), 407 (30), 373 (70), 356 (70), 331 (100, nTeN), 308 (50), 266 (50), 228 (80), 206 (55), 157 (55) cm1. IR: 2050/2037 vs (nasN3), 1621 m, 1544 w, 1489 vs, 1456 vs, 1663 w, 1327 m, 1313 m, 1271 s, 1106 s, 1042 m, 1025 s, 809 w, 769 m, 732 w, 717 w, 566 m, 542 m, 470 w, 378 m, 352 w, 313 m cm1. 19 F NMR [DMSO-D6]: d ¼ 120:5 (m, 2F, 2-F), 149.5 (m, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSO-D6]: d ¼ 148:0 (C-2), 141.3 (C-3), 128.0 (C-1) ppm. 14 N NMR [DMSO-D6, Du1/2 (Hz)]: d ¼ 134 (Nb, 80), 165 (Ng, 300), 244 (Na, > 2000) ppm. 125 Te{19 F} NMR [DMSO-D6]: d ¼ 1074 (br) ppm. DCIMS 70 eV, m/z (rel. int.) ¼ 658 [Mþ–N3] (1), 595 [Mþ–3N3] (1), 553 [Mþ–4N3] (100).
1003
3.4. Preparation of trifluoromethyl and fluorophenyl tellurium di- and triazides 3.4.1. Bis(trifluoromethyl)diazido-l4-tellane (CF3)2Te(N3)2 (10) Into a stirred solution of 120 mg (0.4 mmol) (CF3)2TeF2 in 5 ml of CH2Cl2 were added 110 mg (0.9 mmol) Me3SiN3 at 0 8C. After 2 h of stirring, the yellow suspension was dried for several hours at ambient temperature in vacuo (103 mbar) to yield a slightly yellowish, friction sensitive powder. Mp 35 8C. Raman: n ¼ 2070 (20)/ 2025 (5, nasN3), 1328 (5), 1093 (5), 1039 (5), 743 (10), 642 (10), 355 (100, nTeN), 290 (10), 266 (10), 239 (10), 205 (10) cm1. IR: n ¼ 2144 m/2052 vs (nasN3), 1681 m, 1313 w, 1261m, 1170, 1102 m, 1054 s, 622 s, 527 m cm1. 19 F NMR: d ¼ 41:7 (2 JFTe ¼ 133:9 Hz) [CDCl3]; 49.6 [DMSO-D6] ppm. 13 C NMR: d ¼ 122:5 (1 JCTe ¼ 215:6 Hz) [{19 F}, CDCl3]; 127.0 (1 JCF ¼ 368:3 Hz) [DMSO-D6] ppm. 14 N NMR, Du1/2 (Hz): d ¼ 142 (Nb, 40), 237 (Ng, 1100), 275 (Na, 1700) [CDCl3]; 139 (Nb, 120), 199 (Ng, 580), 290 (Na, >2000) [DMSO-D6] ppm. 125 Te NMR: d ¼ 1116 (sept) [CDCl3]; 1152 (m) [DMSO-D6] ppm. EIMS 70 eV, m/z (rel. int.) ¼ 495 [CF3CF2TeTeCF2CF3þ] (8), 426 [CF3CF2TeTeCF2þ] (4), 337 [Te(CF3)3þ] (2), 324 [Mþ–N2] (1), 287 [(CF3)2TeFþ] (10), 283 [Mþ–CF3] (5), 282 [(CF3)2TeNþ] (5), 268 [(CF3)2Teþ] (10), 199 [CF3Teþ] (40), 69 [CF3þ] (100). 3.4.2. Bis(2,6-difluorophenyl)diazido-l4-tellane (C6F2H3)2Te(N3)2 (11) Into a solution of 0.7 mmol of (C6F2H3)2TeF2 in 5 ml of CH2Cl2 were added 2.0 mmol of Me3SiN3 at 0 8C. After 2 h of stirring, volatile materials were removed in vacuo, the yellowish residue was washed with 2 ml of CH2Cl2 and evaporated again to dryness. Yield 78%, mp 176 8C. Raman: n ¼ 3091 (30), 2072 (25)/ 2050 (20, nasN3) 1605 (10). 1464 (5), 1440 (5), 1317 (10), 1271 (15), 1154 (10), 1082 (5), 1037 (10), 753 (5), 696 (5), 646 (15), 555 (25), 378 (20), 344 (100, nTeN), 330 (50), 308 (65), 258 (15), 195 (25), 149 (25) cm1. IR: n ¼ 3084 m, 2066 s/ 2049 vs (nasN3), 2038 vs, 1604 s, 1592 s, 1580 s, 1538 w, 1468 vs, 1457 vs, 1317 m, 1261 m, 1233 s, 1151 m, 1082 m, 1034 w, 985 s, 785 s, 785 s, 753 m, 698 m, 640 br, 555 m, 535 m, 504 m cm1. 19 F NMR [CDCl3]: d ¼ 96:2/ 97.3 (m, 2F, 2-F) ppm. 13 C{19 F} NMR [CDCl3]: d ¼ 162:5 (br, C2), 136.5 (C4), 134.8 (C3), 105.3 (C1) ppm. 14 N NMR [CDCl3, Du1/2 (Hz)]: d ¼ 139 (Nb, 80), 191 (Ng, 300), 290 (Na, 1400) ppm. 125 Te{1 H} NMR [CDCl3]: d ¼ 773 (m) ppm. EIMS 70 eV, m/z (rel. int.) ¼ 356 [Mþ–2N3] (100), 242 [C6F2H3Teþ] (55), 226 [C12H6F4þ] (80). Calc. for C12H6N6F4Te: C, 32.9; H, 1,4; N, 19.2. Found: C, 33.0; H, 1.3; N, 18.5. 3.4.3. Trifluoromethyltriazido-l4-tellane CF3Te(N3)3 (12) Into a stirred solution of 110 mg (0.3 mmol) CF3TeTeCF3 in 5 ml of CFCl3 were added 170 mg (1 mmol) XeF2 at 0 8C.
T.M. Klapo¨ tke et al. / Journal of Fluorine Chemistry 125 (2004) 997–1005
1004 Table 1 Crystal data and structure refinements
Empirical formula Formula mass Temperature (K) Crystal size (mm) Crystal system Space group ˚) a (A ˚) b (A ˚) c (A b (8) ˚ 3) V (A Z rcalc (g cm3) m (mm1) F(0 0 0) y range (8) Index ranges
Reflections collected Reflections unique R1, wR2 (2s data) R1, wR2 (all data) Max./min. transm. Data/restr./param. GOOF on F2 ˚ 3) Larg. Diff. peak/hole (e/A a
(CF3C6F4Te)2 (4)
(C6F4Te)2Br4C6H6 (8)
(C6F2H3)2Te(N3)2 (11)
C14F14Te2 689.33 200 0.03 0.09 0.37 Monoclinic C2/c 29.519(6) 6.1941(8) 18.932(3) 99.93(2) 3410(1) 8 2.686 3.567 2512 2.2–23.8 33 h 33 6 k 6 19 l 21 9082 2559 (Rint ¼ 0.101) 0.0512, 0.1255 0.0592, 0.1306 0.8938, 0.5806 2559/0/271 0.979 1.376/2.201
C18H6Br4F8Te2 949.04 200 0.02 0.10 0.10 Monoclinic P21/c 11.1563(6) 7.2559(4) 15.3136(9) 111.312(2) 1154.9(1) 2 2.729 9.515 860 2.9–19.8 10 h 10 6 k 6 14 l 14 6043 1040 (Rint ¼ 0.056) 0.0256, 0.0563 0.0342, 0.0607 0.6411, 0.3476 1040/0/145 1.190 0.400/0.381
C12H6F4N6Te 437.81 200 0.07 0.20 0.26 Triclinic P1 7.5448(2) 9.8636(2) 11.3422(3) 91.4537(8)a 730.08(3) 2 1.992 2.089 416 3.2–27.5 9 h 9 12 k 12 14 l 14 11028 3305 (Rint ¼ 0.046) 0.0245, 0.0569 0.0274, 0.0583 0.8923, 0.7278 3305/0/208 1.052 0.495/1.151
a ¼ 114.1008(8), g ¼ 106.2896(8)8.
After 40 min, into the turbid solution 260 mg (2.2 mmol) Me3SiN3 at 20 8C were added and stirred for additional 15 min until the effervescence had stopped. The yellow suspension was evaporated and dried in vacuo. Raman: n ¼ 2115 (35)/2091 (15)/2070 (15, nasN3), 737 (15), 662 (20), 422 (100), 402 (90), 365 (65, nTeN), 278 (50), 198 (50) cm1. 19 F NMR [DMSO-D6]: d ¼ 56:0 (s) ppm. 13 C NMR [DMSO-D6]: d ¼ 128:5 (1 JCF ¼ 363:8 Hz) ppm. 14 N NMR [DMSO-D6, Du1/2 (Hz)]: d ¼ 140 (Nb, 120), 230 (Ng, >2000), 260 (Na, >2000) ppm. 125 Te NMR [DMSO-D6]: d ¼ 1406 (m) ppm. 3.4.4. Pentafluorophenyltriazido-l4-tellane C6F5Te(N3)3 (13) Into a stirred solution of 110 mg (0.2 mmol) C6F5TeTeC6F5 in 10 ml of CFCl3 were added 120 mg (0.7 mmol) XeF2 at 0 8C. After 25 min, into the turbid solution 180 mg (1.6 mmol) Me3SiN3 at 0 8C were added and stirred for additional 10 min until the effervescence had stopped. The brownish suspension was evaporated and dried in vacuo. According to 19 F and 125 Te NMR spectra, the compounds (C6F5)2Te(N3)2 and Te(N3)4 were present each in ca. 30%. Raman: n ¼ 2110 (20)/2085 (30)/2048 (15, nasN3), 1639 (5), 1516 (5), 1319 (5), 1263 (5), 1088 (5), 803 (5), 648 (15), 587 (10), 536 (5), 493 (20), 418 (100), 381 (25), 341 (95, nTeN), 310 (30), 245 (20), 222 (20), 178 (30) cm1. 19 F NMR [DMSO-D6]: d ¼ 127:6 (br, 2F, 2-F), 147.9
(br, 1F, 4-F), 160.0 (br, 2F, 3-F) ppm. 13 C{19 F} NMR [DMSO-D6]: d ¼ 146:4 (C-2), 142.8 (C-4), 137.5 (C-3), 117.4 (br, C-1) ppm. 14 N NMR [DMSO-D6, Du1/2 (Hz)]: d ¼ 140 (Nb, 120), 230 (Ng, >2000), 260 (Na, >2000) ppm. 125 Te NMR [DMSO-D6]: d ¼ 1277 (m) ppm. 3.5. X-ray crystallography Data for compound 4 were collected on a Stoe IPDS image plate area detector, data for compounds 8 and 11 were collected on a Nonius Kappa CCD. Thermal ellipsoids are shown with 50% probability. Structure solution and refinement were performed as outlined in ref [8]. Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication nos. CCDC 211267 (4), 211268 (8), and 211269 (11) (Table 1). Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, (fax: þ44-1223-336033 or e-mail: deposit@ ccdc.cam.ac.uk).
Acknowledgements Financial support of this work by the University of Munich and the Fonds der Chemischen Industrie is gratefully
T.M. Klapo¨ tke et al. / Journal of Fluorine Chemistry 125 (2004) 997–1005
acknowledged. We wish to thank the research students Mr. M.B. Rauscher and Mr. B.L.J. Kindler for their strong commitment during the preparation of some compounds. We are also indebted to and thank Prof. P. Klu¨ fers for generous allocation of X-ray diffractometer time.
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