Syntheses and reactions of some new C-pentafluorophenyl and tetrafluorophenylene carborane systems

Article abstract of DOI:10.1016/S0022-328X(99)00672-5

The reaction of para-PhCB₁₀H₁₀CLi with excess C₆F₆ produced para-PhCB₁₀H₁₀CC₆F₅ (52%) and the tetrafluorophenylene bridged system 1,4-(para-PhCB₁₀H₁₀C)₂C₆F ₄ (31%). The C-pentafluorophenyl compound para-PhCB₁₀H₁₀CC₆F₅ afforded good yields of 1,4-tetrafluorophenylene bridged carboranes with suitable nucleophilic reagents: 1-(para-PhCB₁₀H₁₀C)-4-(ortho-HCB₁₀H ₁₀C)C₆F₄ from ortho-HCB₁₀H₁₀CLi, 1-(para-PhCB₁₀H₁₀C)-4-HOC₆F₄ from KOH and 1-(para-PhCB₁₀H₁₀C)-4-EtOC₆F₄ from KOEt. Addition of the monolithiated carborane, meta-PhCB₁₀H₁₀CLi, to excess C₆F₆ produced meta-PhCB₁₀H₁₀CC₆F₅ (19%) and the two-cage carborane 1,4-(meta-PhCB₁₀H₁₀C)₂C₆F ₄ (70%). Reactions of the novel C-pentafluorophenyl meta carborane, meta-PhCB₁₀H₁₀CC₆F₅, with nucleophiles, ortho-HCB₁₀H₁₀CLi and ⁿBuLi, gave 1-(meta-PhCB₁₀H₁₀C)-4-(ortho-HCB₁₀H ₁₀C)C₆F₄ and 1-(meta-PhCB₁₀H₁₀C)-4-ⁿBuC₆F ₄, respectively. The structure of 1-(para-PhCB₁₀H₁₀C)-4-EtOC₆F₄ was determined by a single crystal X-ray diffraction study.

Full text of DOI:10.1016/S0022-328X(99)00672-5

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 597 (2000) 157–163
Syntheses and reactions of some new C-pentafluorophenyl and
tetrafluorophenylene carborane systems
Andrei S. Batsanov, Mark A. Fox *, Judith A.K. Howard, Kenneth Wade 1
Department of Chemistry, Durham Uni6ersity Science Laboratories, South Road, Durham DH1 3LE, UK
Received 2 August 1999; received in revised form 15 October 1999
Dedicated with great affection and respect on the occasion of his 70th birthday to Professor Stanis*law Pasynkiewicz, a prolific and original
author on organometallic subjects who has kept the organometallic flag flying over Warsaw for four decades, notably by organising excellent
regular organometallic conferences that ensured that the community remained in contact during difficult times.
Abstract
The reaction of para-PhCB10H10CLi with excess C6F6 produced para-PhCB10H10CC6F5 (52%) and the tetrafluorophenylene
bridged system 1,4-(para-PhCB10H10C)2C6F4 (31%). The C-pentafluorophenyl compound para-PhCB10H10CC6F5 afforded good
yields of 1,4-tetrafluorophenylene bridged carboranes with suitable nucleophilic reagents: 1-(para-PhCB10H10C)-4-(ortho-
HCB10H10C)C6F4 from ortho-HCB10H10CLi, 1-(para-PhCB10H10C)-4-HOC6F4 from KOH and 1-(para-PhCB10H10C)-4-EtOC6F4
from KOEt. Addition of the monolithiated carborane, meta-PhCB10H10CLi, to excess C6F6 produced meta-PhCB10H10CC6F5
(19%) and the two-cage carborane 1,4-(meta-PhCB10H10C)2C6F4 (70%). Reactions of the novel C-pentafluorophenyl meta
carborane, meta-PhCB10H10CC6F5, with nucleophiles, ortho-HCB10H10CLi and nBuLi, gave 1-(meta-PhCB10H10C)-4-(ortho-
HCB10H10C)C6F4 and 1-(meta-PhCB10H10C)-4-nBuC6F4, respectively. The structure of 1-(para-PhCB10H10C)-4-EtOC6F4 was
determined by a single crystal X-ray diffraction study. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Hexafluorobenzene; ortho Carborane; meta Carborane; para Carborane; Crystal structure; Multinuclear NMR
substituents capable of dative p bonding [4]. Studies of
systems containing perfluoroaryl residues attached to
the carbon atoms of icosahedral carboranes appeared
likely to be rewarding because of the competitive elec-
tron-withdrawing features such systems would present.
We therefore embarked on such a study, only to find
that though derivatives of the ortho, meta and para
carboranes, 1,2-, 1,7- and 1,12-C2B10H12, respectively,
are abundant in the open literature [5], derivatives
containing C-attached pentafluorophenyl residues have
proved elusive. They are presumably involved as inter-
mediates in reactions between C-lithiocarboranes and
C6F6 from which, however, only tetrafluorophenylene
(C6F4)-bridged bis(carborane) systems were isolated.
For example, only the tetrafluorophenylene-bridged
two-cage systems 1,4-(ortho-PhCB10H10C)2C6F4 (1), 1,4-
(ortho-MeCB10H10C)2C6F4 (2) and 1,4-(meta-MeCB10-
H10C)2C6F4 (3) were isolated from reactions between an
excess of hexafluorobenzene, C6F6, and the lithiocarbo-
ranes, ortho-PhCB10H10CLi, ortho-MeCB10H10CLi and
meta-MeCB10H10CLi [6] (Scheme 1).
1. Introduction
There is much contemporary interest in compounds
containing perfluorinated aryl groups bound to a variety
of centres, notably in connection with their strongly
electron-withdrawing properties. For example, Lewis
acids like B(C6F5)3 are vital components of polymerisa-
tion catalysts derived from early transition metal metal-
locenes [1]. Perfluorinated aromatics are also known to
form stacked arrays with their hydrocarbon analogues
in which the CꢀF and CꢀH rings alternate in the stacks
[2]. Interestingly, stacked arrays of aromatic ring sys-
tems bearing icosahedral carborane residues have been
reported by Mingos and co-workers [3] and ourselves,
and we have studied the electron-withdrawing proper-
ties of icosahedral carborane residues when attached to
* Corresponding author. Fax: +44-191-3861127.
E-mail addresses: m.a.fox@durham.ac.uk (M.A. Fox), ken-
neth.wade@durham.ac.uk (K. Wade)
1 Also corresponding author.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00672-5

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A.S. Batsano6 et al. / Journal of Organometallic Chemistry 597 (2000) 157–163
It was suggested that the replacement of a fluorine
2. Experimental
atom by a carboranyl group leads to such strong acti-
vation of the fluorine atom in the para position of the
ring as to cause the intermediates RCB10H10CC6F5 (i.e.
4–6) to react with the carboranyllithium RCB10H10CLi
much more rapidly than the starting hexafluorobenzene
[6]. The intermediates 4–6 presumably involved were
not isolated in the reported reactions even with a large
excess of C6F6.
Generally the reaction rate of pentafluorobenzenes,
C6F5R, with nucleophiles increases when the electron-
withdrawing strength of R increases [7]. It is well
known that the electron-withdrawing strength of the
carboranyl group at the cage carbon decreases in the
order ortho, meta and para. The isolation of a pen-
tafluorophenyl carborane, RCB10H10CC6F5, was there-
fore considered more likely in the case of para
carboranes.
Indeed, in this study we have isolated the first C-pen-
tafluorophenyl para carborane 1,12-PhCB10H10CC6F5
(7) in good yield by the reaction of the para-carbo-
ranyllithium, 1,12-PhCB10H10CLi, with an excess of
C6F6. The fluorine atom at the para position in
PhCB10H10CC6F5 (7) is readily substituted by nucleo-
philes to give the new tetrafluorophenyl derivatives
8–11. Here we also describe the isolation of meta
analogue 1,7-PhCB10H10CC6F5 (12) from the reaction
of the meta-carboranyllithium, 1,7-PhCB10H10CLi, with
excess C6F6 and the reactions of the pentafluorophenyl
carborane 12 with nucleophiles to yield new te-
trafluorophenylene systems 13–16.
NMR spectra were recorded on a Bruker AC250
1
(250.1 MHz H, 235.3 MHz 19F, 80.3 MHz 11B and
62.9 MHz 13C) instrument. CDCl3 was used as solvent
in all NMR spectra recorded here and chemical shifts
1
were referenced to SiMe4=0.00 ppm for H and 13C,
externally to BF3·Et2O=0.0 ppm for 11B and externally
to CFCl3=0.0 ppm for 19F. Infrared spectra were
recorded as potassium bromide discs using a Perkin–
Elmer 1720× FTIR spectrometer. Mass spectra were
recorded on a VG Micromass 7070E instrument operat-
ing in the EI mode at 70 eV. Calculated values of Mr
show the full isotope range 10Bn to 11Bn including a 13C
contribution where this is likely to have observable
intensity; the less-probable combinations are seldom
observed in practice.
Hexafluorobenzene, potassium hydroxide and n-
butyllithium in hexanes were all obtained commercially
(Aldrich) and used as received. Ortho-carborane, 1,2-
C2B10H12, was purified by sublimation under high vac-
uum. 1-Phenyl-meta-carborane and 1-phenyl-para-
carborane were made by our copper coupling method
with iodobenzene and the related parent carborane
[8,9]. Stirring refers to the use of a magnetic stirrer,
washed to washing the organic layer with 3×20 ml
distilled water, dried to drying the organic layer with
anhydrous magnesium sulphate and filtering off the
solid and solvent-removed to removing solvent by ro-
tary evaporator followed by pumping to dryness in
vacuo at 0.1 mmHg.
Scheme 1.

A.S. Batsano6 et al. / Journal of Organometallic Chemistry 597 (2000) 157–163
159
2.1. Synthesis of para-PhCB10H10CC6F5 (7) and
1,4-(para-PhCB10H10C)2C6F4 (8)
methanol–acetonitrile to yield 2.08 g (68%) of the
mixed cage compound 9. Found: C, 37.38; H, 5.33; Mr,
500–514; Anal. Calc. for C16H26B20F4: C, 37.65; H,
5.10; Mr, 502–516. l(11B), −1.6, −7.8, −11.7;
l(19F), −131.5 (2F, ortho F), −137.7 (2F, meta F);
l(1H), 7.21 (m, 5H, phenyl CH), 4.80 (s, 1H, cage CH),
4.0–1.0 (m, 20H, BH); l(13C), 145.7 (d, JCFꢀ260,
ortho CF), 145.5 (d, JCFꢀ260, meta CF), 135.8 (ipso
phenyl C), 128.7 (ortho CH), 128.2 (meta CH), 126.8
(para CH), 116.8 (CCF), 113.5 (CCF), 88.7 (cage CPh),
70.8 (cage CC6F4), 66.4 (cage CC6F4), 60.5 (t, JCF=13;
cage CH). 6max cm−1 3128m (carboranyl CH stretch);
3066w (phenyl CH stretch); 2613s (BH stretch); 1497w,
1480w, 1458s (fluoroaryl skeletal ring stretch); 1409w,
1383w, 1304w, 1261w, 1211w, 1160w, 1098m, 1041w,
1019w, 997s, 975w, 882w, 785w, 747w, 716m, 691m,
491w, 409w.
A total of 2.2 g (10 mmol) of 1-phenyl-para-carbo-
rane in 40 ml dry diethyl ether was added slowly with
10 mmol of n-butyllithium (4.8 ml of 2.1 M in hexanes)
at 0°C under nitrogen. After warming to room temper-
ature (r.t.) with stirring, the solution was then added
dropwise to 3.5 g (20 mmol) of hexafluorobenzene in 20
ml of Et2O at 0°C. After stirring for 24 h at r.t., the
resulting mixture was washed with 50 ml of dilute acid
and the insoluble solid was filtered off. The ether layer
was washed, dried and solvent-removed to give a white
solid. This was combined with the insoluble solid and
subjected to soxhlet extraction with hot acetonitrile.
The extracted solvent on cooling gave 2.0 g (52%) of
the pentafluorophenyl carborane (7). Found: C, 43.40;
H, 3.90; Mr, 379–389; Anal. Calc. for C14H15B10F5: C,
43.52; H, 3.89; Mr, 380–391. l(11B), −12.1; l(19F),
−133.3 (2F, ortho F), −152.6 (t, JFF=21.4, 1F, para
F), −161.5 (t, JFFꢀ19.5, 2F, meta F); l(1H), 7.23 (m,
5H, phenyl CH), 4.0–1.0 (10H, BH); l(13C), 145.7 (d,
2.3. Synthesis of 1-(para-PhCB10H10C)-4-HOC6F4 (10)
A total of 0.77 g (2 mmol) of the pentafluorocarbo-
rane (7) was mixed with 1.4 g (25 mmol) of KOH in
refluxing THF for 30 min. THF was vacuum-removed
and the resulting solid was added with Et2O and dilute
acid. The ether layer was separated, washed, dried and
solvent-removed to leave the hydroxy compound 10
(0.55 g, 72%). Found: Mr, 376–387; Anal Calc. for
C14H16B10F4O; Mr, 378–389. l(11B), −11.9; l(19F),
−135.0 (2F, ortho F), −162.4 (d, 12.5, 2F, meta F);
l(1H), 7.23 (m, 5H, phenyl CH), 5.69 (br, 1H, OH),
4.0–1.5 (m, 10H, BH); l(13C), 145.6 (d, JCF=240,
ortho CF), 137.6 (d, JCF=232, meta CF), 136.1 (ipso
phenyl C), 135.3 (aromatic CO), 128.5 (ortho CH),
128.1 (meta CH), 126.9 (para CH), 106.1 (CCF), 87.3
(cage CPh), 72.3 (cage CC6F4). 6max cm−1 3554m,
3440brm (OH stretch); 3066w (phenyl CH); 2680w,
2611s (BH stretch); 1655m, 1595w; 1527s, 1485s, 1446m
(fluoroaryl skeletal ring stretch); 1332w, 1309w, 1260w,
1234m, 1173w, 1093s, 1030m, 984m, 970m, 880w, 801w,
783w, 744w, 729w, 707w, 689m, 646w, 596w, 491w.
JCF=261, ortho CF), 140.7 (d, JCF=258, para CF),
137.8 (d, JCF=256, meta CF), 135.9 (ipso phenyl C),
128.6 (ortho CH), 128.1 (meta CH), 126.8 (para CH),
110.9 (CCF), 88.1 (cage CPh), 71.4 (cage CC6F5). 6max
cm−1 3058w (phenyl CH stretch); 2683w, 2673w, 2626s,
2613s, 2603s (BH stretch); 1653m; 1531s, 1489s, 1481s
(fluoroaryl skeletal ring stretch); 1446w, 1310w, 1090s,
1061w, 1041w, 1019w, 999s, 975w, 881w, 785w, 747w,
732w, 721w, 707w, 693m, 641w, 493w.
The insoluble solid in the thimble was identified as
the tetrafluorophenylene-bridged two-cage compound 8
(0.9 g, 31%). Found: C, 45.01; H, 5.27; Mr, 578–589;
Anal. Calc. for C22H30B20F4: C, 45.05; H, 5.12; Mr,
578–593. l(11B), −11.3; l(19F), −133.6; l(1H), 7.21
(m, 10H, phenyl CH), 4.0–1.0 (20H, BH); l(13C), 145.5
(d, JCF=267, CF), 136.0 (ipso phenyl C), 128.6 (ortho
CH), 128.1 (meta CH), 126.8 (para CH), 118.7 (CCF),
88.1 (cage CPh), 71.3 (cage CC6F4). 6max cm−1 3061w
(phenyl CH stretch); 2669w, 2611s (BH stretch); 1496m,
1477w, 1455s (fluoroaryl skeletal ring stretch); 1301w,
1117m, 1066w, 1045w, 998m, 975w, 878w, 782w, 749w,
719w, 687m, 644w, 491w, 415w.
2.4. Synthesis of 1-(para-PhCB10H10C)-4-EtOC6F4
(11)
A total of 0.77 g (2 mmol) of para-PhCB10H10CC6F5
(7) was dissolved in 10 ml of 1:1 diethyl ether–ethanol
and added with 1.4 g (25 mmol) of KOH in ethanol (10
ml). After heating the mixture with stirring at 50°C, the
mixture was solvent-removed. The residue was dis-
solved in ether (10 ml), washed, dried and then solvent-
removed to give a white solid. Recrystallisation of the
solid with chloroform gave crystals of the ethoxy
derivative 11. (0.65 g, 79%) Found: Mr, 406–415; Anal.
Calc. for C16H20B10F4O; Mr, 406–417. l(11B), −12.0;
l(19F), −135.0 (2F, ortho F), −156.7 (d, JFF=16.0,
2F, meta F); l(1H), 7.22 (m, 5H, phenyl CH), 4.31 (q,
2.2. Synthesis of 1-(para-PhCB10H10C)-4-(ortho-
HCB10H10C)C6F4 (9)
A total of 0.86 g (6 mmol) of ortho carborane in 15
ml of Et2O was treated with 6 mmol of butyllithium (3
ml of 2.1 M in hexanes) under nitrogen with stirring.
After 30 min, 2.32 g (6 mmol) of the pentafluoro
carborane (7) was added slowly to the stirred mixture
and then refluxed for 1 h. The cooled mixture was
washed, dried and solvent-removed to give a white
solid. The white solid was recrystallised from

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A.S. Batsano6 et al. / Journal of Organometallic Chemistry 597 (2000) 157–163
2H, JHH=7 Hz, CH2), 4.0–1.0 (10H, BH), 1.37 (t, 3H,
HH=7 Hz, CH3); l(13C), 145.9 (d, JCF=259, ortho
Mr, 381–388; Anal Calc. for C14H15B10F5: C, 43.52; H,
3.89; Mr, 380–391. l(11B), −3.1 (1B), −5.9 (1B),
−10.5 (6B), −13.5 (2B); l(19F), −132.9 (2F, ortho F),
J
CF), 140.9 (d, JCF=250, meta CF), 136.7 (aromatic
CO), 136.1 (ipso phenyl C), 128.5 (ortho CH), 128.1
(meta CH), 126.9 (para CH), 108.3 (CCF), 87.5 (cage
CPh), 72.2 (cage CC6F4), 70.7 (CH2), 15.4 (CH3). 6max
cm−1 3071w (phenyl CH stretch); 2978w, 2930w (alkyl
CH stretch); 2680w, 2611s (BH stretch); 1646m, 1595w;
1511s, 1498m, 1470s, 1447m (fluorophenyl skeletal ring
stretch); 1417w, 1391m, 1367w, 1261w, 1178w, 1099s,
1067w, 1041w, 1031w, 1015m, 992s, 927w, 884w, 800w,
783w, 745w, 709w, 691s, 625w, 601w, 493w, 461w.
−151.8 (t, JFF=21.2, 1F, para F), −161.0 (t, JFF
ꢀ
18.8, 2F, meta F); l(1H), 7.47 (2H, d, ortho phenyl
CH), 7.31 (m, 3H, meta, para phenyl CH), 4.0–1.0
(10H, BH); l(13C), 146.2 (d, JCF=258, ortho CF),
141.1 (d, JCF=258, para CF), 138.0 (d, JCF=262, meta
CF), 134.7 (ipso phenyl C), 128.9 (ortho CH), 128.4
(meta CH), 127.7 (para CH), 110.0 (CCF), 78.2 (cage
CPh), 66.2 (cage CC6F5). 6max cm−1 3058w (phenyl CH
stretch); 2693w, 2659m, 2615s, 2595s (BH stretch);
1650m, 1634w, 1601w; 1531s, 1481s (fluoroaryl skeletal
ring stretch); 1447m, 1420w, 1373w, 1314w, 1261w,
1175w, 1139w, 1085s, 1056w, 1033m, 1013s, 1001s,
966w, 935w, 917w, 868w, 801w, 747m, 726m, 703w,
693m, 663w, 627w, 605w, 577w, 490w.
2.5. Crystal structure study of
1-(para-PhCB10H10C)-4-EtOC6F4 (11)
The diffraction experiment was carried out at T=
150 K, using a SMART 3-circle diffractometer with a
1K CCD area detector and a Cryostream open-flow N2
cryostat with graphite-monochromated Mo–Ka radia-
The unsublimed residue was recrystallised from hot
acetonitrile to give the two-cage derivative 13 (2.05 g,
70%) Found: C, 44.69; H, 5.03; Mr, 581–589; Anal.
Calc. for C22H30B20F4: C, 45.05; H, 5.12; Mr, 582−590.
l(11B), −4.7 (4B), −9.9 (16B); l(19F), −132.7; l(1H),
7.47 (4H, d, ortho phenyl CH), 7.31 (6H, m, meta, para
phenyl CH), 4.0–1.0 (20H, BH); l(13C), 146.0 (d,
,
tion (u=0.71073 A) and a full hemisphere of reciprocal
space scanned by ꢀ in 0.3° frames.
2.5.1. Crystal data for 11
C16H20B10F4O, M=412.42, monoclinic, space group
JCF=260, CF), 134.7 (ipso phenyl C), 128.9 (ortho
P21/n (no. 14), a=10.594(1), b=19.072(1), c=
CH), 128.4 (meta CH), 127.7 (para CH), 115.1 (CCF),
78.2 (cage CPh), 66.1 (cage CC6F4). 6max cm−1 3092w,
3066w (phenyl CH stretch); 2702w, 2652m, 2619s,
2609s, 2582s, 2571s (BH stretch); 1596w; 1495m, 1453s
(fluoroaryl skeletal ring stretch); 1393w, 1306m, 1261w,
1241w, 1191w, 1120m, 1105w, 1076w, 1037w, 1016w,
1002s, 977w, 943w, 916w, 895w, 867w, 851w, 813w,
795w, 765w, 743m, 721s, 685s.
3
,
,
19.879(1) A, V=3989.3(5) A (from 512 reflections
with 12BqB23°), Z=8,
Dcalc. =1.37
g
cm−3
,
F(000)=1680, v=1.0 cm−1, colourless crystal of
0.4×0.35×0.35 mm, 2q548°, 20847 total data, 6010
unique (Rint=0.051), 4557 observed with I]2|(I).
The structure was solved by direct methods and refined
by full-matrix least-squares against F2 of all data (non-
H atoms anisotropic, methyl group as rigid body, other
H atoms riding, total of 597 variables) to wR (F2, all
data)=0.169, goodness-of-fit 1.15, R (F, observed
data)=0.059, max/min residual electron density 0.20,
2.7. Synthesis of
1-(meta-PhCB10H10C)-4-(ortho-HCB10H10C)C6F4 (14)
−0.22 e A−3, using SHELXTL (Version 5) software
A total of 0.43 g (3 mmol) of ortho carborane in 15
ml of Et2O was treated with 3 mmol of butyllithium
(1.5 ml of 2.1 M in hexanes) under nitrogen with
stirring. After 30 min, 1.16 g (3 mmol) of meta-
PhCB10H10CC6F5 (12) was added slowly to the stirred
mixture and then refluxed for 1 h. The cooled mixture
was washed, dried and solvent-removed to give a white
solid. The solid was recrystallised from methanol to
give 0.86 g (56%) of the mixed-cage derivative 14.
Found: C, 38.10; H, 5.19; Mr, 500–515; Anal. Calc. for
C16H26B20F4: C, 37.65; H, 5.10; Mr, 502–516. l(11B),
−1.5, −8.3, −9.6, −11.7; l(19F), −131.2 (2F, ortho
F), −137.3 (2F, meta F); l(1H), 7.45 (2H, d, ortho
phenyl CH), 7.34 (1H, t, para phenyl CH), 7.32 (2H, t,
meta phenyl CH), 4.83 (s, 1H, cage CH), 4.0–1.0 (m,
20H, BH); l(13C), 146.3 (d, JCF=263, ortho CF), 145.3
(d, JCF=256, meta CF), 134.5 (ipso phenyl C), 129.0
(ortho CH), 128.5 (meta CH), 127.7 (para CH), 116.0
(CCF), 114.0 (CCF), 78.3 (cage CPh), 66.4 (cage
,
(G.M. Sheldrick, Bruker Analytical X-ray Instruments,
Madison, WI, USA, 1995).
2.6. Synthesis of meta-PhCB10H10CC6F5 (12) and
1,4-(meta-PhCB10H10C)2C6F4 (13)
A total of 2.2 g (10 mmol) of 1-phenyl-meta-carbo-
rane in 40 ml dry diethyl ether was added slowly with
10 mmol of n-butyllithium (4.8 ml of 2.1 M in hexanes)
at 0°C under nitrogen. After warming to r.t. with
stirring, the solution was then added dropwise to 3.5 g
(20 mmol) of hexafluorobenzene in 20 ml of Et2O at
0°C. After stirring for 24 h at r.t., the mixture was
washed, the ether layer separated, dried and the sol-
vent-removed to leave a white solid. The solid was
subjected to vacuum sublimation and 0.73 g (19%) of
crystalline solid obtained was identified as the pen-
tafluorophenyl compound 12. Found: C, 43.86; H, 4.01;

A.S. Batsano6 et al. / Journal of Organometallic Chemistry 597 (2000) 157–163
161
Scheme 2.
CC6F4), 65.7 (cage CC6F4), 60.0 (t, JCF=13; cage CH).
3. Results and discussion
6max cm−1 3139m (carboranyl CH stretch); 3065w
(phenyl CH stretch); 2592s (BH stretch); 1495m,
1489m, 1458s (fluoroaryl skeletal ring stretch); 1306m,
1245w, 1210w, 1161w, 1121w, 1098m, 1035w, 998s,
969w, 938w, 871w, 853w, 809w, 737m, 715s, 691m,
663w, 641w, 628w, 603w.
Scheme 2 summarises the reactions of fluoroaryl para
carboranes carried out here. The reaction of 1-phenyl-
12-lithio-para-carborane and an excess of C6F6 af-
forded para-PhCB10H10CC6F5 (7) and para-1,4-
(PhCB10H10C)2C6F4 (8) in 52 and 31% yields, respec-
tively. Isolation of the two-cage compound 1,4-
(PhCB10H10C)2C6F4 (8) suggests the fluorine atom at
the para position of the pentafluorophenyl carborane
PhCB10H10CC6F5 (7) is activated by the carboranyl
group. Reactions of 7 with nucleophiles gave te-
trafluorophenylene derivatives bearing new substituents
at the para position of the fluorophenyl ring. With 7,
the reagents ortho-HCB10H10CLi, KOH and KOEt
gave 1-(para-PhCB10H10C)-4-(ortho-HCB10H10C)C6F4
(9), 1-(para-PhCB10H10C)-4-HOC6F4 (10) and 1-(para-
PhCB10H10C)-4-EtOC6F4 (11), respectively in good
yields.
A crystal of the ethoxy tetrafluorophenyl carborane
(11) was subjected to an X-ray structural determina-
tion. The asymmetric unit of 11 comprises two
molecules, A and B (see Fig. 1) in each of which the
aromatic rings are nearly coplanar (dihedral angles of
2.5° in A and 8.4° in B). The (OC2) plane of the ethoxy
group is inclined to the perfluorophenyl plane by 55.0°
(A) and 59.2° (B). All aryl rings in the structure are
parallel within 10° and pack in layers parallel to the
2.8. Synthesis of 1-(meta-PhCB10H10C)-4-nBuC6F4 (15)
A total of 0.77 g (2 mmol) of the pentafluoro carbo-
rane (12) in dry ether was added with 2.1 mmol of
n-butyllithium (1.0 ml of 2.1 M in hexanes) and
refluxed for 20 min. The mixture was treated with water
and the ether layer was separated, washed, dried and
solvent removed to leave a clear oil identified as the
butyl compound 15. (0.72 g, 85%) Found: Mr, 419–427;
Anal. Calc. for C18H24B10F4; Mr, 418–429. l(11B),
−3.2 (1B), −5.3 (1B), −10.1 (6B), −12.0 (2B);
l(19F), −135.4 (2F, ortho F), −144.1 (2F, meta F);
l(1H), 7.51 (2H, d, ortho phenyl CH), 7.32 (3H, m,
meta, para phenyl CH), 4.0–1.0 (10H, BH), 2.85 (t,
J
HH=7.5, 2H, C6F4CH2), 1.72 (quintet, JHHꢀ7.5, 2H,
CH2CH2CH3), 1.52 (quintet, JHH$7.5, 2H, CH2CH3),
1.08 (t,
HH=7.5, 3H, CH3); l(13C), 145.4 (d,
J
JCF$258, ortho and meta CF), 134.9 (ipso phenyl C),
128.7 (ortho CH), 128.4 (meta CH), 127.8 (para CH),
122.3 (CBu), 111.6 (CCF), 78.0 (cage CPh), 67.1 (cage
CC6F4), 31.0 (CCH2), 22.5 (CH2CH2CH3), 13.6 (CH3).
6max cm−1 3062w (phenyl CH stretch); 2960m, 2929m,
2872m (alkyl CH stretch); 2605s (BH stretch); 1596m;
1496m, 1470s (fluoroaryl skeletal ring stretch); 1381w,
1289m, 1261w, 1210w, 1192w, 1159w, 1123m, 1108m,
1078m, 1056m, 1003w, 988m, 921w, 872w, 854w, 801w,
777w, 745m, 731m, 691s, 667w, 627w, 617w, 603w.
crystallographic (1
0 2) plane. The independent
molecules are related via an approximate (non-crystal-
lographic) inversion centre at (1/2, 1/8, 1/4), but for
slightly
different
conformations
around
the
C(cage)ꢀC(aryl) bonds [different relative orientation of
aryl rings and the cage].

162
A.S. Batsano6 et al. / Journal of Organometallic Chemistry 597 (2000) 157–163
,
Fig. 1. Two independent molecules in the structure of 1-(para-PhCB10H10C)-4-EtOC6F4 (11). Selected bond lengths in A: C(1A)ꢀC(13A) 1.527(4),
C(12A)ꢀC(21A) 1.514(4), C(16A)ꢀO(1A) 1.365(3), C(1B)ꢀC(13B) 1.520(4), C(12B)ꢀC(21B) 1.521(4), C(16B)ꢀO(1B) 1.360(3).
Scheme 3.
Scheme 3 shows visually the reactions of the new
fluorophenyl meta carboranes that have taken place
here. The reaction of the lithio-carborane meta-
PhCB10H10CLi and excess C6F6 gave a mixture of
meta-PhCB10H10CC6F5 (12) and 1,4-(meta-PhCB10-
H10C)2C6F4 (13) in 19 and 70% yields, respectively. The
lower yield of 12 compared with the para analogue 7 is
expected from the stronger electron-withdrawing char-
acter of the meta carboranyl carbon. The electron-with-
drawing character of the phenyl-meta-carboranyl group
at the cage carbon is comparable to a phenylethynyl
group as the reactions of PhCꢁCLi and C6F6 produced
PhCꢁCC6F5 and 1,4-(PhCꢁC)2C6F4 in 10–15% and
50% yields, respectively [10].
Since the tetrafluorophenylene-bridged two-cage
compound 1,4-(meta-PhCB10H10C)2C6F4 (13) is formed
in this reaction, the pentafluorophenyl compound 12
is clearly susceptible to nucleophiles at the para posi-
tion of the C6F5 ring. This is confirmed by the reac-
tions of ortho-HCB10H10CLi and of nBuLi with
meta-PhCB10H10CC6F5 (12), which give 1-meta-
PhCB10H10C-4-(ortho-HCB10H10C)C6F4 (14) and 1-
(meta-PhCB10-H10C)-4-nBuC6F4 (15) in good yields,
respectively.
All of the new carborane derivatives discussed in this
study were characterised by 19F-, 1H-, 13C- and 11B-
NMR, mass and FT-IR spectroscopy. Points of inter-
estin the NMR data for carboranes 7–15 are

A.S. Batsano6 et al. / Journal of Organometallic Chemistry 597 (2000) 157–163
163
1. the substituent effects of a carboranyl group on the
fluorine NMR chemical shifts of perfluorobenzenes
are shown to be comparable to an ethynyl group
(−134.2 ppm (ortho), −149.9 (para), −159.6 (meta)
for HCꢁCC6F5) [11],
sity Christopherson Fellowship (J.A.K.H.) for financial
support.
References
2. the 19F peaks assigned to fluorines nearest to the
carborane moiety are found to be broad which may
be due to long-range boron–fluorine (4JBF) couplings
and
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served for peaks assigned to the unsubstituted ortho
carboranyl carbons in the 13C-NMR spectra of 9 and
14.
4. Conclusions
Two C-pentafluorophenyl carboranes and some new
C6F4-bridged species were made for the first time in this
study. Both carboranes, para- and meta-PhCB10H10CC6-
F5, were isolated from reactions between para- and
meta-PhCB10H10CLi, respectively with excess hexafluo-
robenzene. Reactions of the C-pentafluorophenyl carbo-
ranes with nucleophiles gave tetrafluorophenylene species
in which the fluorine atom at the para position of the fluo-
roaryl group had been easily replaced by the nucleophile.
5. Supplementary material
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Crystallographic data for the structure analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 132905 for compound 11. Copies
of the information can be obtained free of charge from
the Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (Fax +44-1223-336033 or e-mail:
deposit@ccdc.ac.uk or http://www.ccdc.cam.ac.uk).
Acknowledgements
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[11] W. Bru¨gel, Handbook of NMR Spectral Parameters, vol. 3,
Heyden, London, 1979, p. 788.
We thank EPSRC (M.A.F.) and the Durham Univer-
.