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Carbon Networks Based on Dehydrobenzoannulenes Synthesis of Graphdiyne Substructures.

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Substructures (boldface) of the graphdiyne network (see following pages).
Angew. Chem. Int. Ed. Engl.
1997,36,No. 8
8 VCH VerlagsgesellschofrmbH, 0-69451 Weinheim, 1997
0570-0833/97/3607-083S $17SO + SO/O
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Carbon Networks Based on Dehydrobenzoannulenes: Synthesis of Graphdiyne Substructures**
Michael M. Haley,* Stephen C. Brand,
and Joshua J. Pak
Exploration into the formation of novel carbon allotropes
continues to be an area of intense investigation."' To datc, most
synthetic rcsearch has focused on planar polymeric networks
comprising sp and .spz carbon
Diederich et al.
have prepared a variety of pcrethynylated monomers such
as tetraeth~nylethene,[~]
tetraethynylb~tatriene,~~~
and hexaethynyl[3]radialene.[51Copper-mediated oxidative oligomerization of cis doubly deprotected tetraethynylethene derivatives
produccd rcmarkable annulenic substructures,[('] which were
themselves potential precursors to additional networks. Whereas desilylation and subsequent oxidative dimerization of the
perethynylated molecules should lead to the desired diacetylenic
carbon allotropes, the deprotected polyynes are highly unstable
and decompose even in dilute solutions at subzcro temperatures; thus, oligomcrization or polymerization studies of these
systems have been restricted significantly.
Incorporation of a stabilizing aromatic ring into the network
backbone might makc preparation and isolation of larger substructures feasible. Replacement of the ethene units in a polymer
with benzene moieties thus leads to the all-carbon network 1.
With a heat of formation of 18.3 kcal pcr g-atom
graphdiyne['] (1) is thc most stable carbon allotrope containing
diacetylenic linkages. Graphdiync should exhibit fascinating
propertics such as high, third-order nonlinear optical susceptibility, conductivity or superconductivity when doped with alkali
metals, and cnhanced redox actpity. The latter is due to the fact
that the large holes (about 2.5 A) in the planar sheets can facilitate through-sheet transport of smaller ions and accommodate
a variety of larger mctal ions. I n addition, graphdiyne could
provide a method of dopant storage that is not available to
graphite, namely intrasheet intercalation. In pursuit of
graphdiyne, wc report here the preparation and charactcrization of annulenic substructurcs 2 and 3.
Macrocycle 2a, the smallest subunit of 1, has had a long
and varied history. Originally claimed in 1957 to be the product
of Eglinton-Glaser coupling of 1,2-diethynylbenzene (4,
Scheme l),['I it was shown by chemical meansr'"' and by X-ray
-
+
TMEDA
4
2a(0%)
5 (35%)
Scheme 1 Cyclooltgomeriz,ition of 1.2-dtrthynylbeti/ene
crystallography["1 that strained dimer 5, not trimer 2a, was the
sole product of the cyclization reaction. Recent work by Swager
and co-workers has shown that, even with a different catalytic
system, only 5 is produced from 4."" Howcvcr, it is interesting
to note that inclusion of two alkyl or alkoxy groups on 4 did lead
to a mixture of dimers, trimers, and tetramcrs that were difficult
to separate." Given these problems, any further attempts to
prepare exclusively 2a warranted a different synthetic roule.
An intramolecular oxidative dimerization reaction was envisaged for forming 2a (Scheme 2). The requisite hexayne 6a was
2 2a (31%)
2b (56%)
SiiPr,
7
1
6a, R=H (71%)
6b, R=nDec (75%)
in,
/ \
-
= =
2a, R=H
2b, R=nDec
[*I
[**I
Scheme 2 Synthesis of 2a.h. 21) 1,2-Dtiodohetizeiie (for 6a) 01-4.5-didecyI-1,2-diiodobenzene (for 6b), KOH, H,O. [Pd(PPh,),]. [Pd(PPh,),Ci,],c'ul. Et,N. THF;
b) Bu,NF. EtOH, THF: C) Cu(OAc),.H,O. p>ridine. McOH
/ \
-
3a, R=tBu
3b, R=nDec
Prof. M. M. Haiey, S. C. Bt-and, J. J. Pak
Department of Chemistry, University of Oregon
Eugene. OR 97403 (USA)
Fax: Int. code +(541)346-0487
e-mail haleyw oregon.uot-cgon.edu
Wc st-atefully acknowledge the donors of The Petroleuin Reseach Fund (administered by the ACS), the National Science Foundation (NSF), and the
University of Oregon for support of this research. We thank Brian Arbogast
and Robert Schneidmiller for obtaining MS and DSC data, respectively.
M. M H acknowledges the NSF for a CAREER Award (1995-1998).
easily constructed in 71 YOyield from triyne 7 ' I 3 I and 1,2-diiodobenzene by an in situ deprotection/alkynylation sequence." 31 Desilylation of 6a with Bu,NF followed by dimerization with Cu(OAc), in pyridine furnished 2a as the sole
product. The poor solubility of 2a crcatcd difficulties for
product manipulation and was no doubt responsible for the low
yield of isolated 2a (about 30- 35 %). The outcome improved on
repetition of the synthesis with 4,5-didecyl-l,2-diiodobenmacrocycle 2b was isolated in 56% yield, which is
attributable to the solubilizing effect of the twin decyl groups.
Assembly of bismacrocycle 3 was considerably more involved. From thc outset, we recognized the nccd for including
solubilizing substituents. Our initial attempt made use of four
teur-butyl groups at the corners of the molecule (Schcme 3).
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R
R
R
AH*
N3Et2
8a, R=tBu (87%)
8b. R=nDec (80%)
Table 1 . Selected physical data for Za, 3b, 6a, and 8b- lob.
9a, R = B u (49%)
9b, R=nDec (42%)
R
iPr3Si
SiiPr3
lOa, R=tBu (36%)
lob, R=nDec (33%)
Scheme 3. Synthesis of3a.b. a) (BnNEt,)1CI2. CH,CI,; b) 1. NaNO,, HCI, H,O,
CH,CN. THE'; 2 Et,NH. K,CO,. H,O; c) iPr,SiC=CH, [Pd(PPh,),CI,I, CuI,
Et,N; d) Mel. 120'C; e) Me,SiC-CC-CH,
[Pd(PPh,),CI,], CuI, Et,N,
f ) 1.2.4.5-tetraiodobenzene. KOH, H,O, [Pd(PPh,),], [Pd(PPh,),CI,], CuI, Et,N,
THF; g) Bu,NE EtOH, T H F , h) Cu(OAc),. pyridine, MeOH, Et,O.
Iodination of 4-tert-butylaniline with BnEt,N+ICl; [14] followed by conversion of the amino group into a diethyltriazine
r n ~ i e t y ~gave
' ~ I 8a in 87% yield. Sequential alkynylation of 8a
with triisopropylsilylacetylene,conversion of the triazene into
an iodide with iodomethane at 120 OC,[lS1and alkynylation with
afforded triyne 9a in
excess l-trimethylsilylbuta-1,3-diyne~'61
49 YO overall yield. In the presence of 1,2,4,5-tetraiodobenzene,[' 71 9a reacted by the in situ deprotection/alkynylation seq ~ e n c e [ ' to
~ ]give the tetracoupled product 10a in 36% yield.
Although modest, this yield implies an average conversion of
about 90% for each of the eight transformations necessary.
Subsequent removal of the four triisopropylsilyl groups was
accomplished with Bu,NF and could be readily followed by
TLC. Oxidative intramolecular coupling of the free acetylenes
with Cu(OAc), led to 3a in less than 10% yield, since isolation
of purified product proved impossible due to extremely limited
solubility.
In hope of improving the solubility of the final product, the
synthetic sequence was repeated with 4-decylaniline to provide
dodecayne lob (Scheme 3). Desilylation and oxidative cyclization with anhydrous CU(OAC),['~~
gave 3b. Elution of the crude
product adsorbed on silica gel with hexanes/CH,Cl, (3/1) removed undesired by-products without desorbing 3b. Treatment
with boiling CH,Cl, followed by carbon disulfide extracted the
bismacrocyde into solution. Recrystallization from CH,Cl, afforded an excellent yield of pure 3b as a bright yellow solid,
which was moderately soluble in carbon disulfide, hot
dichloromethane, and hot toluene. Only limited solubility was
observed in most solvents at room temperature.
All annulenic structures and intermediates were unequivocally identified and characterized spectroscopically (Table 1). Both
as pure solids and In solution, the macrocycles proved remarkably robust and remained spectroscopically unchanged over a
period of several weeks in air. Onset of decomposition occurred
around 200 'C. DSC analysis showed this to be an extremely
exothermic process that occurred over a relatively narrow 1015 ' C range. The possibility that this is a topochemical polymerization of the diacetylene moieties["] is an intriguing prospect
that we are pursuing.[201
Angrii Chrm Inr Ed Engl 1997, 36, No. 8
2a: M.p. = 210'C (decomp.); 'H NMR (300 MHz, CDCI,): 6 -7.68 ( A A ' , J =7.9
and 1.3 Hz, 6 H ) , 7.42 ( B H , J = 7 . 9 , 1.3 Hz, 6 H ) ; 13C NMR (75 MHz, CDCI,):
6 = 132.72, 128.81, 125.29, 80.73, 77.21; UV (CH,CI,): 1.,, ( E ) = 266 (134001, 280
(18900), 309 (42500), 330 (69400). 359 (19000), 369 (21 100) nm; IR (CH,CI,):
i =3054,2207cm-l;MS(El,7OeV):m/z(%)=372(Mi,100),371(8),370(26),
368 ( l l ) , 91 (24).
3b: M.p. = 200°C (decomp.); 'H NMR (300 MHz, CS,/CD,CI, 2/1): 6 =7.90 (s,
2H), 7.62 (d, J = 8.2 Hz. 4H), 7.50 (s, 4H), 7.29 (d, J = 8.2 Hz, 4H), 2.72 (t,
J = 7 . 5 H z , 8H), 1.76-1.62 (m. 8H), 1.46-1.25 (m, 56H), 0 9 4 (t. J = 6 . 3 H z ,
12H); I3C NMR (75 MHz, CS,/CD,CI, 2/1): 6 =145.35, 136.86, 133.48, 133.27,
129.97, 126.03, 125.82, 122.93,83.78, 82.14,81.79,80.21, 78.97. 78.40, 36.76, 32.88,
31.93, 30.61, 30.57, 30.46, 30.34, 30.22, 23.81, 15.04; UV (CH,CI,): i.,,,
( E ) = 307
(20700). 357 (35400), 375 (48600), 413 (22800), 430 (18000)nm; IR (KCI):
C = 2199, 1594cm-'; MS (FAB, positive ions, 121 mV): m;z =1226.8 ( M i , 100).
6a: Orangegum; 'HNMR(300 MHz, CDCI,):6 =7.57-7.47(m, 6H), 7.38-7.25
(m, 6H). 1.16 (s, 42H); 13C NMR (75 MHz, CDCI,): 6 =133.14, 132.98, 132.63,
128.91,128.53,125.69,125.34,124.82,82.02,81.47,81.15,80.63.78.11,77.72. 17.68,
12.25; UV(CH,CI,):1,,, ( E ) = 221 (30100),238(25800).267(15400), 316(9800),
337 (8600). 361 (6300) nm; MS(El,70 eV): m / z = 6 8 6 ( M + , 13),643 (11). 601 (20).
559 (18). 517 (12).
8b: Orangeoil;'HNMR(300MHz,CDCI3)-6
=7.67(d,J=1.7Hz, lH),7.26(d,
J = 8.1 Hz, 1 H), 7.08 (dd, J = 8.1 and 1.7 Hz, 1 H), 3.79 (4, J = 7.2 Hz, 4 H ) , 2.53
(t,J=7.8Hz,2H),1.65-1.52(m,2H),143-1.20(m,20H).0.89(t,J=6.6Hz,
3H); I3C NMR (75 MHz, CDCI,): 6 =148.27. 141.59, 139 15, 138.67, 128.88,
117.07, 34.91, 31.89, 31.43, 29.61, 29.58, 29.48, 29.42, 29.33. 29.18, 29.11. 22.69,
14.13; MS (EI, 70eV): m/z = 443 ( M + ,loo), 371 (30).
9b: Orange oil; ' H N M R (300 MHz, CDCI,): 6 =7.36 (d, J = 8.0 Hz, 1 H), 7.28
(d,J=1.8Hz,lH),7.06(dd,J=8.0and1.8Hz,lH),2.56(t,J=7.8Hz,2H),
1.62-1.54 (m, 2H), 1.26 (br. s, 14H), 1.17 (s, 21 H), 0.89 (t, J = 6.8 Hz, 3 H), 0.22
(s. 9H); I3C NMR (75 MHz, CDC1,): 6 =144.24, 132.56, 132 14, 128.32, 127.44,
121.73, 104.72, 95.40, 90.86, 88.24, 77.31, 75.54, 35.75, 31.89. 31.06, 29.60, 29.54,
29.44, 29.32, 29.25, 22 68, 18.70, 14.12, 11.33, -0.39; IR (KCI): i = 2207, 2159,
2098 c m - ' , MS (FAB, positive ions, 121 mV): mi- = 519 ( M i + H , 33). 475 (54).
lob: Yellow gum; ' H N M R (300MHz, CDCI,): 6 =7.59 (s, 2H). 7.45 (d.
J = 8.1 Hz, 4 H ) , 7.31 (d, J = 1.6 Hz, 4 H ) , 7.08 (dd. J = 8.1 and I.6 Hz, 4 H ) , 2.58
(t, J = 7 . 5 H z , SH), 1.65-1.55 (m, 8H). 1.26 (br. s, 56H). 1.16 (s, 84H). 0.88 (t.
J =7.2 Hz, 12H); 13C NMR (75 MHz, CDCI,): 6 = 144.52. 137.55. 132.84, 132 27,
128.34, 127.20. 125.47,121.77, 104.70,95.79.83 69.81.14,78.67,35.79,31.91,31.05,
29.60, 29.56, 29.45, 29.33, 29.25, 22.69, 18.71, 14.12. 11.34. IR (KCI): 3 = 3039,
2214,2145,1607cm-';MS(FAB,positiveions,
121 mV):m,; = 1 8 5 7 . 3 ( M t + 2 H .
100). 1856.3 (98), 1855.3 ( 5 8 ) , 1814.3 (34).
It is widely accepted that annelation of arenes provides rigidity and stability to the annulenic core, but weakens the diatropicity of the macrocycle significantly.[2'I Trisannelated systems,
such as 2, are believed to no longer reveal global delocalization
but only local aromaticity in the benzenoid rings.[2'] We believe
this generalization is not valid for 2 or 3, since the diatropic
character of the [I 8lannulene core can be readily discerned from
the 'H NMR and electronic absorption spectra. Although all
protons are at a remote distance from the central 71 system, the
benzene resonances of the macrocycles show small but distinct
downfield shifts (A6 = 0.2-0.25) relative to their acyclic precursors. For example, the two protons on the central benzene of
desilylated 10b appear as a singlet at 6 = 7.70, yet at 6 = 7.94 for
3b.[221 Diederich et al. observed a similar effect in cyclobutenodehydroannulenes 11 and l2.LZ3]
The electronic absorption spectrum of 2a (Figure 1) exhibits
the characteristic pattern for this dehydroannulene core. Comparison of the assigned four diagnostic peaks with spectra reported for related annulenes 11-16 is presented in Table 2. It is
interesting to note that the wavelengths of these peaks in tribenzo derivative 2a, although slightly blue-shifted, agree within
3-19 nm with the corresponding peaks in the parent system
13.[24]A bathochromic shift (about 40 nm) is observed for 3b,
which is likely due to cross-conjugation of the two 18 71 electron
circuits. In all cases, the trend in peak intensities (2 + l + 3,4)
is maintained. Based on this strong spectral correlation, we
conclude that, contrary to accepted convention, the dehy-
VCH Verlugsge.~ell.~chuf~
mbH, 0.69451 Weinhelm. 1997
OS70-0833/97/3608-0837$17501 SO10
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COMMUNICATIONS
dro[l8]annulene nuclei in our benzannelated systems must retain their diatropic character. Extension of this work to the
preparation of larger graphdiyne substructures and highly functionalized derivatives is currently under investigation.
Received: November 12, 1996 [Z9761 IE]
German version: Angew. Chem. 1997, 109, 863-866
-
-
Keywords: alkynes annulenes . aromaticity carbon allotropes
12
111 a) F. Diederich, Y Rubin, Angew. Chem. 1992,104,1123- 1146; Angew. Chem.
Int. Ed. Engl. 1992.31, 1101- 1123; b) E Diederich, Nature (London) 1994,
369, 199-207; c) F. Diederich in Modern Acetylene Chemistry (Eds.: P. J.
Stang. F. Diederich), VCH. Weinheim, 1995; d) U. H. F. Bunz, Angew. Chem.
1994, 106, 1127-1132; Angew. Chem. Int. Ed. Engl. 1994, 33, 1073-1076,
e) U. H. F. Bunz, J. E. C Wiegelmann-Kreiter, Chem. Ber. 1996, 129, 785797.
[2] R. H. Baughman, H. Eckhardt, M. Kertesz, J Chem. Phys. 1987, 87, 66876699.
[3] Y. Rubin, C. B. Knobler, F. Diederich, Angew. Chem. 1991, 103, 708-710;
Angew. Chem. Int. Ed. Engl. 1991,30, 698-700.
13
[4] J.-D. van Loon, P. Seiler, F. Diederich, Angew. Chem. 1993, 105, 1235-1237;
Angew. Chem. Int. Ed. Engl. 1993,32, 1187-1189.
[5] T. Lange, V. Gramlich, W. Amrein, F. Diederich, M. Gross, C. Boudon, J.-P.
Gisselbrecht, Angew. Chem. 1995,107, 898-901 ; Angew. Chem. Inr. Ed. Engl.
1995,34,805-809.
[6] J. Anthony, C. B. Knobler, F. Diederich, Angew. Chem. 1993, f05,437-440;
Angew. Chem. Int. Ed. Engl. 1993,32, 406-409.
[7] R. Baughman, private communication. This value can also be calculated from
the numbers in Table 5 of ref. (21.
[8] The term graphdiyne comes from the name graphyne (21, which in turn is
derived from graphite. Graphyne, the monoacetylenic analogue of 1, can be
viewed as resulting from replacement of one-third of the carbon-carbon bonds
in graphite by -C=C- linkages. It follows that the diacetylenic version be called
15
graphdiyne.
[91 G. Eglinton, A. R. Galbraith, Proc. Chem. SOC.1957, 350-351.
[lo] a) 0. M. Behr, G . Eglinton, R. A. Raphael, Chem. Ind. 1959,
699-700; b) 0. M. Behr, G. Eglinton, A. R. Galbraith, R. A.
Raphael, J Chem. SOC.1960,3614-3625.
I l l ] W K. Grant, J. C. Speakman, Proc. Chem. SOC.1959, 231.
[12] Q . Zhou, P. J. Carroll, T. M. Swager, J. Org. Chem. 1994, 59,
1294- 1301.
[13] M. M. Haley, M. L. Bell, J. J. English, C. A. Johnson, T. J. R.
Weakley, J Am. Chem. Soc. 1997,119, 2956-2957.
(141 S. Kajigaeshi, T. Kakinami, H. Yamasaki, S . Fujisaki, T. Okamoto, Bull. Chem. SOC.Jpn. 1988,61,600-603.
[IS] J. S . Moore, E. J. Weinstein, Z. Wu, Tetrahedron Lett. 1991, 32,
2465-2466.
[16] L. Brandsma, Preparative Acefylenic Chemistry. Elsevier, Amsterdam, 1988, p. 118.
[17] D. L. Mattern, J Org. Chem. 1991,56, 5903-5907.
[lS] T. M. Cresp, J. Ojima, F. Sondheimer, J Org. Chem. 1977, 42,
2130-2134.
I191 a) Polydiacetylenes (Eds.: D. Bloor, R. R. Chance), Martinus
0.em
Nijhoff, Boston, 1985, and references therein; b) G . Wegner,
250.0
300 .B
350 .0
400.0
Pure Appl. Chem. 197?,49,443-454.
hlnm
[20] R. Baughman, M. M. Haley, unpublished results.
in debydrobenzoannulenes, see
I2l] For a discussion Of ring
Figure 1. Electronic absorption spectra of 2a in CH,CI, ( T = 295 K, d = 1 cm, = 3.76 x
A. T. Balaban. M. Banciu. V. Ciorba. Annulenes. Benzo-. Hetero-.
10- M) .
Homo-Derivatives. and their Valence Isomers, Vol. 2, CRC Press,
Boca Raton, 1987, p. 146.
[22] The numbers are for spectra obtained in 99.6 % CD,CI,.
Table 2. Selected peaks from the electronic absorption spectra of Za, 3b, and 11[23] Y Li, Y. Rubin, F. Diederich, K. N. Houk, L A m . Chem. SOC.1990, 112,
16 [a].
1618-1622.
1241 W. H. Okamura, F. Sondheimer, L Am. Chem. Soc. 1967, 92, 5991 -5992.
Compd
Peak 1
Peak 2
Peak 3
Peak 4
~251Y. Tobe, T. Fujii, H. Matsumoto, K. Naemura, Y Achiba, T. Wakabayashi, J
Am. Chem. SOC.1996, 118,2758-2759.
2a [b]
309 (42500)
330 (69400)
359 (19000)
369 (21 100)
(261 F. Diederich, Y. Rubin, C. B. Knobler, R. L. Whetten, K. E. Schriver, K.
Houk, Y. Li, Science 1989, 245, 1088-1090.
3b [b]
357 (35400)
376 (48600)
413 (22800)
430 (18000)
322 (36700)
340 (74600)
387 (9200)
395 (13800)
11 [b,el
12[c,e]
330 (35800)
346 (65100)
396 (12400)
407 (13400)
388 (17600)
13[c,fl
317(41500)
333 (75800)
378 (15500)
384 (99000)
404 (216000)
438 (61000)
452 (64000)
14 [d,g]
15[b,h]
340 (48000)
356 (60200)
403 (16100)
415 (23500)
16[b,i]
359 (45000)
375 (87600)
420 (17700)
432 (21000)
-
~
~~~
[a] Peak assignments are as shown in Figure 1. [b] In CH,CI,. [cl In cyclohexane. [dl In pentane. [el Ref. [23]. If] Ref. [24]. [gl Ref. [6]. [h] Ref. 1251
[i] Ref. [26].
838
0 VCH
Verlagsgesellschafr mbH. 0-69451 Weinheim, 1997
0570-0833l97l3608-083S$17.50+ SOj0
Angew. Chem. Int. Ed. Engl. 1991,36, No. 8
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