H.-J. Frohn, V. V. Bardin
202 mmol) in water (40 ml) and 73 % HF (8 ml). After stirring
overnight the reaction mixture was saturated with KF and neutral-
ised with K2CO3 and finally extracted with MeCN (2 x 50 ml). The
brown extract was dried over MgSO4 and the solvent was removed
(evaporator). After washing of the sticky residue with toluene (2 x
40 ml) a white solid resulted which was dried in vacuum to give
1.8 g (47 % based on the reacted pentafluoropropene) of salt 1a.
Ϫ90 °C for 30 min and warmed to Ϫ10 °C within 2 h. The 19F
NMR spectrum showed the formation of Li [CF2ϭCClB(OMe)3]
2
[resonances atϭ Ϫ79.15 (d J(F2trans, F2cis) 52 Hz, 1F, F2trans) and
Ϫ93.20 (d, 1F, F2cis)]. The white suspension was poured into a
stirred solution of K [HF2] (21 g, 270 mmol) in water (50 ml) and
73 % HF (7 ml). After 3 h KF (excess) was added and the suspen-
sion was evaporated to dryness under reduced pressure. The solid
was extracted with MeCN (2 x 100 ml), the extract was dried over
MgSO4 and the solvent was removed (evaporator). The product
was washed with anhydrous ether (25 ml) and dried in a vacuum
desiccator over Sicapent to give 6.2 g (58 % yield based on CF2ϭ
CCl2) of salt 3c.
C3BF8K (237,93): calculated C 15.14, F 63.88; found C 15.7, F
63.2 %.
19F NMR (CH3CN): δ ϭ Ϫ54.16 (ddq 4J(CF3,F2trans) 22 Hz, 4J(CF3,F2cis
13 Hz, 4J(CF3,BF3) 5 Hz, CF3), Ϫ68.61 (qdq 4J(F2trans,CF3) 22 Hz,
)
2J(F2trans,F2cis
)
28 Hz, 3J(F2trans,B) 11 Hz, 1F, F2trans), Ϫ77.30 (qdq
4J(F2cis,CF3) 13 Hz, 2J(F2cis,F2trans) 28 Hz, 4J(F2cis,BF3) 13 Hz, 1F, F2cis),
Ϫ137.40 (qqd 1J(F,B) 42 Hz, 4J(BF3,CF3) 5 Hz, 4J(BF3,F2cis) 13 Hz, BF3).
11B NMR (CH3CN): δ ϭ 1.03 (dq 3J(B,F2cis) 11 Hz, 1J(B,F) 42 Hz).
C2BClF5K (204,38): calculated C 11.75, Cl 17.35, F 46.48; found
C 11.3, Cl 17.3, F 46.4 %.
IR ν (cmϪ1): 1726 (s), 1363 (s), 1267 (m), 1198 (m), 1141 (m), 1090 (s), 975
¯
19F NMR (CH3CN): δ ϭ Ϫ82.82 (d 2J(F2trans, F2cis) 53 Hz, 1F, F2trans),
Ϫ93.08 (d, 1F, F2cis), Ϫ141.80 (q 1J(F,B) 40 Hz, 3F, BF3). 11B NMR
(CH3CN): δ ϭ 0.78 (q 1J(B,F) 39 Hz).
(vs), 921 (s), 731 (w), 651 (w), 626 (w).
IR ν¯ (cmϪ1): 1723 (s), 1283 (s), 1194 (w), 1171 (m), 1070 (m), 1024 (m), 965
(s), 893 (m), 851 (vw), 808 (vw), 656 (w), 608 (w), 594 (w), 533 (vw).
Potassium 2,2-difluoroethenyltrifluoroborate K
[CF2ϭCHBF3] (2a)
A solution of CF2ϭCH2 (8.0 g, 125 mmol) in ether (40 ml) and
THF (160 ml) was cooled to Ϫ115 °C under an atmosphere of dry
argon and 1.5 M t-BuLi in pentane (55 ml, 82 mmol) was added
drop-wise within 20 min at Ϫ105 to Ϫ110 °C. The reaction mixture
was stirred at Ϫ100 °C for 40 min and a solution of B(OMe)3
(9.0 g, 86 mmol) in ether (4 ml) and THF (14 ml) was added drop-
wise at Ϫ95 to Ϫ100 °C within 30 min. The reaction mixture was
maintained at Ϫ95 to Ϫ100 °C for 1 h and then warmed to Ϫ10 °C
within 2 h. The 19F NMR spectrum contained resonances of Li
[CF2ϭCHB(OMe)3] at δ ϭ Ϫ75.73 (d 2J(F2trans,F2cis) 53 Hz, 1F,
1-Trifluoromethyl-2,2-difluoroethenyldifluoroborane
CF2ϭC(CF3)BF2 (1b) in PFP
Boron trifluoride (12 mmol) was bubbled into a stirred suspension
of 1a (257 mg, 1.07 mmol) in PFP (2 ml) at Ϫ50 °C for 30 min.
After centrifugation at Ϫ78 °C the mother liquor was separated
and collected in a cold (Ϫ45 °C) trap. The solution of 1b
(0.91 mmol, 85 %) in PFP was characterised by NMR.
19F NMR (PFP, Ϫ20 °C):
δ
ϭ
Ϫ42.24 (dq 2J(F2trans,F2cis
) 39 Hz,
4J(F2trans,CF3) 22.5 Hz, 1F, F2trans), Ϫ51.95 (qtd 4J(F2cis,CF3) 11 Hz,
4J(F2cis,BF2) 29 Hz, 2J(F2cis,F2trans
)
39 Hz, 1F, F2cis), Ϫ54.99 (tdd
3
F2trans) and Ϫ85.15 (dd J(F2cis,H) 44 Hz, 1F, F2cis) and the reson-
4J(CF3,BF2) 6.5 Hz, 4J(CF3,F2cis) 11 Hz, 4J(CF3,F2trans) 22.5 Hz, 3F, CF3),
Ϫ78.2 (br s, 2F, BF2) {lit. δ ϭ Ϫ47.6 (br, F2trans), Ϫ57.3 (dq, F2cis), Ϫ59.9
(dd, CF3), Ϫ82.2 (br s, BF2) ppm, 2J(F2cis,F2trans) 39.0, 4J(CF3, F2cis) 22.6,
4J(CF3, F2trans) 12.0 Hz [6]}. 11B NMR (PFP, Ϫ20 °C): δ ϭ 22.6 (br s).
ance of remaining CF2ϭCH2 (δ ϭ Ϫ82.27; AAЈBBЈ spin system).
The solution was poured into a solution of K [HF2] (30 g,
384 mmol) in water (50 ml) and 73 % HF (12 ml) and stirred over-
night. The reaction mixture was neutralised with KOH and K2CO3
and saturated with KF. The product was extracted with MeCN (3
x 60 ml), the solvent was evaporated and the residue was extracted
with acetone (2 x 75 ml). The extract was dried over MgSO4 before
the solvent was removed (evaporator). After drying in a vacuum
desiccator over Sicapent, salt 2a (6.6 g (47 %) was obtained.
2,2-Difluoroethenyldifluoroborane CF2ϭCHBF2 (2b)
in PFB
Boron trifluoride (10 mmol) was bubbled into a stirred suspension
of 2a (170 mg, 1.0 mmol) in PFB (1.5 ml) at Ϫ30 °C for 25 min.
The mother liquor was separated after centrifugation at Ϫ25 °C
and collected in a cold (Ϫ30 °C) trap. The solution of 2b
(0.55 mmol, 55 % ) in PFB was characterised by NMR.
C2HBF5K (169,93): calculated C 14.14, H 0.59, F 55.90; found C
14.6, H 0.71, F 55.2 %.
1H NMR (acetone-d6): δ ϭ 3.62 (qdd 3J(H,BF3) 4 Hz, 3J(H,F2trans) 10 Hz,
3J(H,F2cis) 41 Hz). 19F NMR (acetone-d6): δ ϭ Ϫ76.5 (br s, 1F, F2trans),
Ϫ83.85 (qdd 4J(F2cis 11
,
BF3) 7 Hz, 2J(F2cis,F2trans) 49 Hz, 3J(F2cis,H) 41 Hz,
1H NMR (PFB, Ϫ20 °C):ϭ 4.03 (tdd 3J(H,BF2) 6 Hz, 3J(H,F2trans) 6 Hz,
3J(H,F2cis) 33 Hz) {lit. δ ϭ 3.70 (td 3J(H,BF2) 6 Hz, d 3J(H,F2trans) 6 Hz,
3J(H,F2cis) 32.4 Hz) [7]}.
1F, F2cis) (This resonance contained additional lines caused by the 10B iso-
tope. The 19F chemical shift of the 10B isotopomer was located 0.0095 ppm
to higher frequency.), Ϫ135.59 (q 1J(F,B) 42 Hz, 3F, BF3). 11B NMR (ace-
tone-d6): δ ϭ 2.29 (dq 2J(B,H) 19 Hz, 1J(B,F) 47 Hz).
19F NMR (PFB, Ϫ20 °C):ϭ Ϫ52.1 (br s, 1F, F2trans), Ϫ58.27 (dtd
2J(F2cis,F2trans) 19 Hz, 4J(F2cis,BF2) 19 Hz, 3J(F2cis,H) 33 Hz, 1F, F2cis), Ϫ81.1
(br, 2F, BF2) {lit. δ ϭ Ϫ56.7 (1F, F2trans), Ϫ62.5 (1F, F2cis), Ϫ86.0 (br, 2F,
BF2); 2J(F2cis,F2trans) 19.6 Hz, 4J(F2cis,BF2) 19.6 Hz [7]}. 11B NMR (PFB,
Ϫ20 °C): δ ϭ 24.3 (br s).
IR ν¯ (cmϪ1): 3050 (CH) (vw), 1720 (s), 1370 (s), 1168 (m), 1088 (s), 969 (vs),
905 (vs), 815 (w), 759 (m), 627 (m), 569 (m).
Potassium 1-chlorodifluoroethenyltrifluoroborate K
[CF2ϭCClBF3] (3a)
1-Chlorodifluoroethenyldifluoroborane CF2ϭCClBF2
(3b) in PFP
1,1-Dichlorodifluoroethene (7.0 g, 52 mmol) was condensed into
ether (270 ml) at Ϫ90 °C under an atmosphere of dry argon and
cold 1.5 M t-BuLi in pentane (35 ml, 52 mmol) was added drop-
wise within 30 min at Ϫ100 to Ϫ95 °C. The reaction mixture had
been stirred at this temperature for 30 min before a solution of
B(OMe)3 (6.2 g, 59 mmol) in ether (10 ml) was added with a syringe
within 10 min. The reaction mixture was maintained at Ϫ85 to
Boron trifluoride (8 mmol) was bubbled into a stirred suspension
of 3a (220 mg, 1.07 mmol) in PFP (1.7 ml) at Ϫ45 °C for 20 min.
The suspension was warmed to 0 °C to remove the excess of BF3,
the mother liquor was separated by centrifugation at 0 °C and de-
canted into a cold (Ϫ30 °C) trap. The solution of 3b (0.76 mmol,
71 %) in PFP was characterised by NMR.
2468
2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
zaac.wiley-vch.de
Z. Anorg. Allg. Chem. 2003, 629, 2465Ϫ2469