H.-J. Frohn, T. Schroer / Journal of Fluorine Chemistry 112 22001) 259±264
263
0.029 mmol). The suspension was immediately warmed to
20 8C and stirred for 2 days. The main product was C6F5H.
Only traces of 3 were detected.
m, m-F),[FꢀHF) ]À ꢀÀ142.9,s) C F6 ꢀÀ162.9,s); molar
n
6
ratio: 34:100/n1:48. In addition,several unidenti®ed spe-
cies of minor concentration with 19F NMR shift values from
À99.2 to À167.1 ppm were observed.
3.6. Preparation of [C6F5Xe] [HF2] 23f)
The thermal stability of 3f in solution was tested at a
30 mg sample in 0.2 ml CD3CN at 20 8C. After 7 days one-
third of 3 was still present besides C6F6 and [FꢀHF)n]À and
after 14 days the decomposition was complete. The 19F
NMR resonance of [FꢀHF)n]À had shifted to À182.9 ppm.
The compound 2a ꢀ1090 mg,2.129 mmol) was added to a
solution of 1 ꢀ1189 mg,7.026 mmol) in 25 ml aHF at
À78 8C. The stirred suspension was warmed to 20 8C. After
4 h the amount of solid decreased signi®cantly and the
mother liquor became yellow. KF ꢀ124 mg,2.134 mmol)
was added and the amount of precipitation increased. The
suspension was stored at À78 8C for 16 h,the mother liquor
separated,the solid residue suspended in CCl 3F ꢀ4 ml,
À78 8C) and all the volatile components pumped off at
À40 8C/10À2 h Pa. The solid was dissolved in CD3CN
ꢀ0.2 ml, À40 8C) and a 1H and 19F NMR spectra were
3.8. Reaction of 2a with [FXe] [SbF6] in aH F
Two samples of 2a,each with 20 mg in 0.2 ml aHF at
À78 8C,were reacted with different quantities of a saturated
aHF solution of [FXe] [SbF6] and warmed to À40 8C.
Sample ``a'' a suspension with a minor quantity of [FXe]
[SbF6] was directly characterized by 19F NMR spectro-
recorded. 3 ꢀÀ125.6,m,
o-F,with
129Xe satellites:
scopy: [c-C6F7Xe] ꢀÀ90.7,F-2; À93.7,F-6,6; À108,8
3JF;Xe 68:1 Hz; À142.7,t,
p-F, 3JF;F 20:3 Hz;
F-3,3; À147.3 F-5; À151.4,F-4); [ c-C6F9Xe] ꢀÀ83.0,F-2;
À155.3,m, m-F), 4d ꢀÀ149.1,s,BF),
4b ꢀÀ136.4,m,
À99.1 F-6,6; À115.4,F-3,3; À127.7,F-5,5; À131.3,F-4,
4); and c-C6F9H ꢀÀ103.8,F-66, ; À119.4,F-33, ; ꢂÀ120,F-
2, À133.2,F-4,4 and F-5,5) were formed in the molar ratio
of 100:18:56. Sample ``b'' was treated with [FXe] [SbF6] as
long as a solution resulted. 19F NMR spectra showed [c-
3
o-F; À144.7,m,b,BF 2; À160.2,t, p-F, JF;F 19:8 Hz;
À165.1 m, m-F); molar ratio: 3:4d:4b 64:100:75. The
mother liquor was evaporated at ꢃÀ10 8C/10 h Pa,the
yellow viscous residue suspended in CCl3F ꢀÀ78 8C,
15 ml) and stirred for 16 h. The solid was separated and
pumped at À40 8C/10À2 h Pa for 2 h. Afterwards,the solid
was suspended in 10 ml SO2 at À70 8C. The mother liquor
was separated from the solid residue ꢀ306.9 mg,mainly
C6F9Xe] as the only product.
3.9. Reaction of 2a with 3 equivalents of 1 in a
1 M NaF/aHF solution
K[BF4]),SO was distilled off and the residue pumped at
2
À60 8C/10À2 h Pa. The viscous residue was stirred in 15 ml
CCl3F at À78 8C for 16 h,the solid was separated,washed
three times with 10 ml CCl3F ꢀÀ78 8C) and pumped at
À40 8C/10À2 h Pa for 6 h. 3f ꢀ1696 mg,5.028 mmol,
78.7% yield) was obtained as slightly yellow solid which
became waxy when warmed to 20 8C.
The compound 2a ꢀ500 mg,0.977 mmol) was added to a
solution of NaF ꢀ514 mg,12.24 mmol) in 12 ml aHF
ꢀÀ78 8C). The suspension was warmed to À50 8C, 1
ꢀ496 mg,2.930 mmol) was added and was stirred for 5 h
at À50 8C and 20 min at À30 8C until a yellow solution was
formed. 19F NMR spectra at À40 8C showed 3 ꢀÀ122.9,m,
o-F,with 129Xe-satellites; À137.2,t, p-F; À150.9,m, m-F),
4d ꢀÀ149.0,qꢀ1:1:1:1),BF), 4e ꢀÀ99.0,m,F-6,6; À111.9,
m,F-3,3; À130.8,m,F-2; À133.5,m,b,BF 3; À152.0,m,F-
5; À159.1,m,F-4) and C 6F6 ꢀÀ162.9,s) in a molar ratio of
100:17:17:4.
1H NMR ꢀCD3CN, À40 8C): 9.9 ꢀs,[HF ]À); 13C NMR
2
1
ꢀCD3CN, À40 8C): 83.0 ꢀt,with 129Xe-satellites, JC;Xe
2
135:5 Hz, JC;F 26:2 Hz,C-1),138.3 ꢀd,m,
1JC;F
255:4 Hz,C-35,),144.4 ꢀd,m,
1JC;F 253:0 Hz,C-26,),
144.9 ꢀd,t,t, 1JC;F 258:8 Hz, JC;F 13:5 Hz, JC;F
2
3
4:5 Hz,C-4); 19F NMR ꢀCD3CN, À40 8C): À127.1 ꢀm,with
129Xe-satellites, JF;Xe 72:6 Hz, o-F) À142.4 ꢀs, t1=2
3
200 Hz,[HF ]À), À144.6 ꢀt,t, JF;F 20:1 Hz, JF;F 4:6
3
4
4. Conclusion
2
Hz, p-F), À156.1 ꢀm, m-F); 129Xe NMR ꢀCD3CN, À40 8C):
3
Fluorine-aryl substitution on XeF2 can be achieved suc-
cessfully with ꢀC6F5)3B in aHF. The presence of a three-
coordinated boron species is required for the fast transfer of
an aryl group from the borane to 1. All the aryl groups
bonded to boron can be transferred. The reaction proceeds
even when the base FÀ is added in a large stoichiometric
excess. In the presence of the strong Lewis acid SbF5
oxidation of the C6F5 group occurred and cycloalkenylxe-
nonium cations were formed. It seems reasonable to suspect
that this new methodical approach of aryl transfer can also
be adopted to other strongly oxidizing element ¯uorides
with a hypervalent ¯uorine±element±¯uorine bond.
À3780 ꢀt,m, t1=2 49 Hz, JXe;F 71 Hz).
3.7. Thermolysis of 23f)
The compound 3f ꢀ25 mg) was heated ꢀ1±2 8C/min) in a
FEP-inliner. At 25 8C a high viscous melt resulted. Further
heating was accompanied by evolution of gas. The sample
was maintained at 100 8C for 15 min and then cooled to
À78 8C forming a glassy yellow material which was dis-
solved in CD3CN at À40 8C and characterized by 1H and 19
F
NMR spectroscopy: 3 ꢀÀ125.7,m, o-F,with 129Xe satellites,
3
3JF;Xe 69:1 Hz; À142.9,t, p-F, JF;F 19:7 Hz; À155.1,