Self-assembly of rectangles and prisms via a molecular "clip"

Article abstract of DOI:10.1021/ic0508369

Aromatic molecular "clips" bearing two symmetrically bound platinum moieties have been prepared. The molecular "clip" 4 readily self-assembled with linear linkers such as 4,4′-bipyridyl, 1,4-bis[2-(4-isocyano-3,5-diisopropylphenyl)-ethynyl]benzene, and ni

Full text of DOI:10.1021/ic0508369

Inorg. Chem. 2005, 44, 7886−7894
Self-Assembly of Rectangles and Prisms via a Molecular “Clip”
Duckhyun Kim,† Jong Hyub Paek,† Moo-Jin Jun,‡ Jin Yong Lee,§ Sang Ook Kang,*,† and
Jaejung Ko*,†
Departments of Chemistry, Korea UniVersity, Jochiwon, Chungnam 339-700, Korea,
Yonsei UniVersity, Seoul, Korea, and Sungkyunkwan UniVersity, Suwon 440-746, Korea
Received May 24, 2005
Aromatic molecular “clips” bearing two symmetrically bound platinum moieties have been prepared. The molecular
“clip” 4 readily self-assembled with linear linkers such as 4,4 -bipyridyl, 1,4-bis[2-(4-isocyano-3,5-diisopropylphenyl)-
ethynyl]benzene, and nicotinic acid to form molecular rectangles. The overall dimensions of the rectangle 7 were
7.3 Å 15.3 Å. The molecular “clip” also self-assembled with tritopic pyridyl and isocyanide ligands to form trigonal
′
×
prismatic frameworks. The characterization of the supramolecules by multinuclear NMR, electrospray mass
spectrometry, and X-ray crystal structures is also reported.
Introduction
show enhanced guest selectivity, especially toward planar
aromatic guests,7 rectangles represent a crucial geometrical
model in the development of this area. Despite their relative
simplicity, molecular rectangles are much less common.8
Recently, the Hupp,9 Sullivan,10 and Su¨ss-Fink groups11 have
reported the preparation of a series of rhenium-, ruthenium-,
and manganese-based molecular rectangles. The most note-
worthy were built by Stang and co-workers12 from a ligand-
directed approach to molecular rectangles. They have
described the self-assembly reactions of a molecular “clip”-
The directed assembly of supramolecular entities from
discrete molecular building units has received considerable
attention.1 The continuing interest arises from the multitude
of assemblies, both two- and three- dimensional, that have
been reported in the recent literature. An attractive aspect
of this methodology is the rational design of structures of
diverse shapes, sizes, and symmetries. Such assemblies are
formed by the noncovalent or reversible dative interactions
between building units. By employment of a rational
transition-metal-mediated approach, many finite and nano-
scopic supramolecules have been prepared.2
Of the geometric shapes accessible through the directional-
bonding approach, tetranuclear squares have been the most
widely reported.3 Other high-symmetry structures, such as
triangles,4 hexagons,5 and dodecahedrons,6 have also been
documented. As lower symmetry hosts can be expected to
(4) (a) Kryschenko, Y. K.; Seidel, S. R.; Arif, A. M.; Stang, P. J. J. Am.
Chem. Soc. 2003, 125, 5193. (b) Schweiger, M.; Seidel, S. R.; Arif,
A. M.; Stang, P. T. Inorg. Chem. 2002, 41, 2556. (c) Piotrowski, H.;
Polborn, K.; Hilt, G.; Severin, K. J. Am. Chem. Soc. 2001, 123, 2699.
(d) Schweiger, M.; Seidel, S. R.; Arif, A. M.; Stang, P. J. Angew.
Chem., Int. Ed. 2001, 40, 3467. (e) Sautter, A.; Schmid, D. G.; Jung,
G.; Wu¨rthner, F. J. Am. Chem. Soc. 2001, 123, 5424.
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Chem. Soc. 2002, 124, 9990.
(6) (a) Olenyuk, B.; Levin, M. D.; Whiteford, J. A.; Shield, J. E.; Stang,
P. J. J. Am. Chem. Soc. 1999, 121, 10434. (b) Levin, M. D.; Stang, P.
J. J. Am. Chem. Soc. 2000, 122, 7428.
(7) Kuehl, C. J.; Kryschenko, Y. K.; Radhakrishnan, U.; Seidel, S. R.;
Huang, S. D.; Stang, P. J. Proc. Natl. Acad. Sci. U.S.A. 2002, 99,
4932.
* To whom correspondence should be addressed. E-mail:
jko@korea.ac.kr (J.K.).
† Korea University.
‡ Yonsei University.
§ Sungkyunkwan University.
(1) (a) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. ReV. 2000, 100,
853. (b) Holliday, B. J.; Mirkin, C. A. Angew. Chem., Int. Ed. 2001,
40, 2022. (c) Olenyuk, B.; Fechtenko¨tter, A.; Stang, P. J. J. Chem.
Soc., Dalton Trans. 1998, 1707. (d) Seidel, S. R.; Stang, P. J. Acc.
Chem. Res. 2002, 35, 972. (e) Fujita, M. Acc. Chem. Res. 1999, 32,
53.
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Ibukuro, F.; Kusukawa, T.; Fujita, M. J. Am. Chem. Soc. 1998, 120,
8561.
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X.; Stern, C. L.; Mirkin, C. A. Organometallics 2002, 21, 1017. (c)
Sun, S.-S.; Anspach, J. A.; Lees, A. J. Inorg. Chem. 2002, 41, 1862.
(d) Cotton, F. A.; Lin, C.; Murillo, C. A. J. Am. Chem. Soc. 2001,
123, 2670.
(8) (a) Kuehl, C. J.; Huang, S. D.; Stang, P. J. J. Am. Chem. Soc. 2001,
123, 9634. (b) Odell, B.; Reddington, M. V.; Slawin, A. M. Z.;
Spencer, N.; Stoddart, J. F.; Williams, D. J. Angew. Chem., Int. Ed.
Engl. 1988, 27, 1547. (c) Bu¨chner, M.; Geuder, W.; Gries, W.-K.;
Hu¨nig, S.; Koch, M.; Poll, T. Angew. Chem., Int. Ed. Engl. 1988, 27,
1553. (d) Resendiz, M. J. E.; Noveron, J. C.; Disteldorf, H.; Fischer,
S.; Stang, P. J. Org. Lett. 2004, 6, 651.
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1998, 120, 12982. (b) Benkstein, K. D.; Hupp, J. T.; Stern, C. L.
Angew. Chem., Int. Ed. 2000, 39, 2891.
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1998, 37, 5406.
(11) Yan, H.; Su¨ss-Fink, G.; Neels, A.; Stoeckli-Evans, H. J. Chem. Soc.,
Dalton Trans. 1997, 4345.
7886 Inorganic Chemistry, Vol. 44, No. 22, 2005
10.1021/ic0508369 CCC: $30.25
© 2005 American Chemical Society
Published on Web 10/01/2005

Self-Assembly of Rectangles and Prisms
Scheme 1
(A) as an efficient entry into the rectangular shape. 1,8-Bis-
[trans-Pt(PEt3)2(NO3)]anthracene possesses two labile co-
ordination sites directed in a nearly parallel fashion. To get
a variety of rectangles with different sizes and shapes, more
molecular “clips” with the above shape are required.
with a slightly excess of 3,5-di-tert-butylbenzaldehyde in the
presence of KOH to give 1. Reaction of tetralone with 1 in
boron trifluoride etherate gave 2 in 31% yield. The molecular
clip was easily synthesized by a double oxidative addition.
An oxidative addition reaction of 2.5 equiv of Pt(PEt3)4 with
2 gave the diplatinum species 3. Subsequent reaction with
silver nitrate resulted in formation of 4. Molecular clip 4 is
a crystalline solid that is stable in air and soluble in CH2Cl2,
toluene, diethyl ether, and THF. Spectroscopic data for 4
are completely consistent with its proposed structure. Five
distinct resonances at 8.40-6.75 ppm in the 1H NMR
spectrum and 13 peaks at 151.7-121.2 ppm for the aromatic
region in the 13C NMR spectrum are observed. The 31P NMR
spectrum of 4 shows a singlet at 12.2 ppm with concomitant
195Pt satellites (JPPt ) 2894 Hz). This value is comparable
to that observed for the 1,8-bis[trans-Pt(PEt3)2(NO3)]-
anthracene.12 The structure of 4 was established by single-
crystal X-ray analysis and is shown in Figure 1. Crystals of
4 were grown by the layering of hexane in a toluene solution
of the complex. Each unit contains one disordered toluene
molecule. The crystallographic data and processing param-
eters are given in Table 1. The compound crystallizes in the
triclinic system P1h with six molecules in a unit cell.
Therefore, there are three molecules in an asymmetric unit.
In Figure 1, only one molecule of them is shown. All of the
atoms in the spacer (except for the triethylphosphine ligands
and two oxygen atoms of nitrate anions) lie approximately
in the same plane. The coordination planes of both platinum
atoms are perpendicular to the plane of spacer. The dihedral
angle between the spacer and the 3,5-di-tert-butyl-phenyl
group is -14.3°, possibly because of steric hindrance with
neighboring ethylene units. Two platinum fragments are
nearly parallel with the distance of 7.34 Å.
Accordingly, we envisioned that if we could synthesize a
building unit with two parallel coordination sites facing in
the same direction such as 4, such a subunit would offer
another entry into new rectangles and trigonal prismatic
frameworks. Here we report the self-assembly reactions and
characterization of the members of a family of molecular
rectangles and supramolecular coordination cages with
trigonal prismatic frameworks via a new type of subunit (4).
Results and Discussion
Synthesis of a Molecular “Clip”. Our strategy for the
synthesis of self-assembled supramolecules of molecular
rectangles utilizes the molecular “clip” with two parallel
coordination sites facing in the same direction. The synthesis
of such molecular clip (4) followed many of the procedures
described previously for analogous compounds.13 The syn-
thetic procedures are outlined in Scheme 1.
The synthesis of 4 is conveniently prepared in four steps
from the 7-bromo-1-tetralone: 7-bromo-1-tetralone reacted
Synthesis of Bridging Ligands with Isocyanide Units,
5 and 6. The construction of many supramolecules has been
(12) (a) Kuehl, C. J.; Mayne, C. L.; Arif, A. M.; Stang, P. J. Org. Lett.
2000, 2, 3727. (b) Kuehl, C. J.; Huang, S. D.; Stang, P. J. J. Am.
Chem. Soc. 2001, 123, 9634. (c) Addicott, C.; Das, N.; Stang, P. J.
Inorg. Chem. 2004, 43, 5335. (d) Addicott, C.; Oesterling, I.;
Yamamoto, T.; Mu¨llen, K.; Stang, P. J. J. Org. Chem. 2005, 70, 797.
(e) Chi, K.-W.; Addicott, C.; Stang, P. J. J. Org. Chem. 2004, 69,
2910. (f) Gong, J.-R.; Wan, L.-J.; Yuan, Q.-H.; Bai, C.-L.; Jude, H.;
Stang, P. J. Proc. Natl, Acad. Sci. U.S.A. 2005, 102, 971.
(13) (a) Sommer, R. D.; Rheingold, A. L.; Goshe, A. J.; Bosnich, B. J.
Am. Chem. Soc. 2001, 123, 3940. (b) Crowley, J. D.; Steele, I. M.;
Bosnich, B. Inorg. Chem. 2005, 44, 2989. (c) Goshe, A. J.; Steele, I.
M.; Bosnich, B. J. Am. Chem. Soc. 2003, 125, 444.
Inorganic Chemistry, Vol. 44, No. 22, 2005 7887

Kim et al.
Figure 1. ORTEP drawing35 of molecular “clip” 4 with thermal ellipsoids drawn at the 30% probability level. Hydrogen atoms and toluene are omitted for
clarity. Selected bond distances (Å) and angles (deg): Pt(11)-C(46) 1.983(17), Pt(11)-O(11) 2.159(11), Pt(11)-P(11) 2.307(4), Pt(11)-P(12) 2.299(5);
C(46)-Pt(11)-O(11) 175.1(6), P(11)-Pt(11)-P(12) 178.86(17).
Table 1. Crystal and Structure Refinement Data for 4 and 7
nyl]benzene is achieved by Sonogashira cross-coupling
reaction in the presence of catalytic amounts of Pd(PPh3)4
param
4
7
and copper iodide. Formylation of such amino compounds
with formic acid and acetic anhydride affords the forma-
mides. Di- and triisocyanide ligands were prepared by the
dehydration reaction with triphosgene/triethylamine. A simi-
lar preparation of functionalized derivatives of 2,6-diisopro-
pylphenyl isocyanide has been reported by the Mayr group.15
Ligands 5 and 6 are crystalline white solids that are stable
in air and soluble in toluene, THF, and CH2Cl2. Spectroscopic
data for 5 and 6 are completely consistent with their proposed
structures. The 1H NMR spectrum of 5 contained a methine
resonance (3.38 ppm) and a methyl resonance (1.30 ppm).
Two singlets (7.54 and 7.33 ppm) in the 1H NMR spectrum
and six resonances (145.4-123.1 ppm) in the 13C NMR
empirical formula
fw
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
C
198H309N9O18P12Pt6
C
138H206N10O12P8Pt4‚12H2O
4645.72
triclinic
P1h
3429.34
triclinic
P1h
14.922(2)
27.176(4)
28.000(4)
85.828(3)
76.420(3)
76.017(3)
10 708(3)
2
1.441
4704
4.052
1.50-56.98
134 907
13.979(3)
17.444(3)
18.672(3)
73.179(3)
71.998(3)
80.578(3)
4131.0(13)
1
1.378
1740
3.514
2.38-57.12
51 729
20 466
0.0763
0.2014
0.956
Z value
D
calc (g/cm3)
F(000)
µ(Mo KR) (mm-1
2θ range (deg)
)
no. of reflcns measd
no. of observns (I > 2σ(I)) 53 205
R
0.0963
0.1987
0.904
spectrum could be assigned to the aromatic groups. The 13
C
Rw
NMR resonance of isocyanide group (170.3 ppm) is generally
of low intensity. The alkynyl group in 5 gives rise to
characteristic 13C NMR resonances at 91.0 and 90.2 ppm.
These values are comparable to these observed for the aryl
isocyanides.16
goodness of fit
based on the coordination bonding motif between M(II) (M
) Pd, Pt) acceptor units and nitrogen donor ligands or a
few examples of oxygen donor linkers.14 To synthesize
macrocycles via a new class of isocyanide-based carbon
donors, we decided to prepare the di- and triisocyanide
bridging ligands. Such ligands can be easily synthesized in
three steps, as shown in Schemes 2 and 3. In each step, the
reaction proceeds smoothly and the products can be obtained
in high yield. In the first step, substitution of the iodide in
4-iodo-2,6-diisopropylaniline by the ethynyl group to afford
1,4-bis- and 1,3,5-tris[(4-amino-3,5-diisopropylphenyl)ethy-
Self-Assembly of Molecular Rectangles. Molecular clip
4 was found to be a good scaffold to assemble a variety of
donor ligands. For example, the new molecular rectangle 7
was readily self-assembled in almost quantitative yield when
4 was combined with an equimolar amount of 4,4′-dipyridyl
in an acetone/H2O mixture (Scheme 4). 31P NMR of 7
indicated the formation of a singlet with 195Pt satellites,
shifted 5.1 ppm upfield (-∆δ) relative to 4 (∆JPt-P ) -300
(14) (a) Das, N.; Mukherjee, P. S.; Arif, A. M.; Stang, P. J. J. Am. Chem.
Soc. 2003, 125, 13950. (b) Mukherjee, P. S.; Das, N.; Kryschenko,
Y. K.; Arif, A. M.; Stang, P. J. J. Am. Chem. Soc. 2004, 126, 2464.
(c) Chi, K.-W.; Addicott, C.; Arif, A. M.; Stang, P. J. J. Am. Chem.
Soc. 2004, 126, 16569.
(15) (a) Lu, Z.-L.; Mayr, A.; Cheung, K.-K. Inorg. Chim. Acta 1999, 284,
205. (b) Lau, K. Y.; Mayr, A.; Cheung, K.-K. Inorg. Chim. Acta 1999,
285, 223. (c) Mayr, A.; Guo, J. Inorg. Chem. 1999, 38, 921.
(16) Yang, L.; Cheung, K.-K.; Mayr, A. J. Organomet. Chem. 1999, 585,
26.
7888 Inorganic Chemistry, Vol. 44, No. 22, 2005

Self-Assembly of Rectangles and Prisms
Scheme 2a
a Key: (i) Pd(PPh3)4, CuI, Et3N, THF; (ii) acetic anhydride, formic acid; (iii) triphosgene, Et3N, THF.
Scheme 3a
a Key: (i) acetic anhydride, formic acid; (ii) triphosgene, Et3N, THF.
Scheme 4a
a Key: (i) 4,4′-bipyridyl, acetone-H2O; (ii) 5, acetone-H2O; (iii) isonicotinic acid, acetone-H2O.
Hz). In a similar manner, reaction of 4 with bridging ligands
1,4-bis[2-(4-isocyano-3,5-diisopropylphenyl)ethynyl]ben-
zene (5) afforded the rectangle 8 with different size and
bipyridyl protons positioned toward the interior of the
rectangle experience an environment different from those of
periphery. A similar pattern was observed in the molecular
rectangle based on the 1,8-bis[trans-Pt(PEt3)2(NO3)]anthra-
cene.12a Additional evidence for the formation of the rectangle
7 was obtained from electrospray ionization mass spectros-
copy. Peaks attributable to the consecutive loss of nitrate
counterions, [M - 2NO3]2+ (m/z ) 1549.5), [M - 3NO3]3+
(m/z ) 1012.3), and [M - 4NO3]4+ (m/z ) 743.8), where
M represents the intact rectangle, were detected.
The structure of 7 was unambiguously established by
single-crystal X-ray analysis and is shown in Figure 2. The
crystallographic data and processing parameters are given
in Table 1. The crystal structure of 7 shows a rectangle with
an inversion center located at the midpoint of the two
bipyridine moiety. The entire aromatic framework appears
to be nearly coplanar with a slight dihedral angle (28°)
between the pyridyl planes of 4,4′-bipyridyl. As a conse-
1
bonding mode. The H NMR spectrum of 7 also indicated
the formation of highly symmetrical structure and displayed
spectroscopic differences from its monomeric subunit. The
protons in the positions R and â to the bridging pyridine
exhibit downfield shifts (∼0.45 ppm) due to the loss of
electron density upon coordination. As a result of increased
back-donation from the platinum to the phosphine moiety,
the protons of the methylene groups bonded to phosphorus
showed slightly upfield shift, 0.18 ppm. Of note is that four
sets of resonances from the pyridyl protons became in-
equivalent in the molecular rectangle. As revealed in the
crystal structure of 7, adjacent two bridging bipyridyl groups
are situated in the perpendicular to the coordination plane
to the platinum moiety. Clearly, rotation of bipyridyl rings
is restricted once the rectangle is formed. Therefore, the
Inorganic Chemistry, Vol. 44, No. 22, 2005 7889

Kim et al.
Figure 2. ORTEP drawing of rectangle 7 with thermal ellipsoids drawn at the 30% probability level. Hydrogen atoms, counterions, and H2O are omitted
for clarity. Selected bond distances (Å) and angles (deg): Pt(1)-C(18) 2.031(12), Pt(1)-N(1) 2.126(10), Pt(1)-P(1) 2.318(4), Pt(1)-P(2) 2.301(5); C(18)-
Pt(1)-N(1) 177.1(5), P(1)-Pt(1)-P(2) 173.51(13).
Scheme 5
quence, the fixed planar arrangement may be related to the
rotational barrier found less around platinum-nitrogen
bonds.17 The N(1)-Pt(1)-P(1) and P(1)-Pt(1)-P(2) angles
in 7 of 90.7(3) and 173.51(13)°, respectively, are consistent
with other slightly distorted square planar Pt(II) complexes.
The overall dimension of the rectangle, as defined by the
platinum corners, is 7.3 Å × 19.8 Å for 7. No solvent
molecules or counterions were not located in the cavity.
As the hydrogen-bond-mediated self-assembly of cyclic
arrays from bis(platinum) complexes containing nicotina-
mide, nicotinic acid, and isonicotinic acids were reported,18
we attempted a similar reaction to check whether such
methodology would be applied for the formation of a
rectangle using the molecular clip (4). The self-assembly
process was performed in the same general manner. Addition
of isonicotinic acid to 4 in an acetone/H2O mixture resulted
in the quantitative formation of a highly symmetrical
rectangle. The 31P NMR spectrum of this product exhibited
a singlet with concomitant 195Pt satellite indicating the
formation of a highly symmetrical species. Direct evidence
for the formation of rectangle 9 arises from the H NMR
1
spectrum, appearing as four sets of resonances from the
bridging pyridyl protons and a characteristic resonance at δ
12.70, assigned to a hydrogen-bonded carboxylic acid. The
appearance of four sets of resonances demonstrates that the
pyridyl protons positioned toward the interior of the rectangle
experience an environment different from those of the
1
periphery. H NMR titration studies demonstrates its self-
association to afford a hydrogen-bonded dimer in CDCl3
solution at 298 K. At low concentrations (< 0.05 mol dm-3),
molecular clip coordinated to isonicotinic acid self-associates
to form 9 with K2 ) 118.4 ( 1.6 mol-1 dm3 according to
the method of Saunders and Hyne.19 The value of the
dimerization constant is comparable to that of trans-(4,4′-
benzophenone)bis[(nicotinic acid)bis(triphenylphosphine)]-
diplatinum(II) bis(triflate) (K2 ) 98.2 ( 1.1 mol-1 dm3 at
298 K).18 Additional proof of 9 is obtained using mass
spectrometry. In the mass spectrum of 9, peaks attributable
to the consecutive loss of nitrate ions, [M - NO3]+ (m/z )
1640.7) and [M -2NO3]2+ (m/z ) 789.3), were observed.
(17) (a) Davies, M. S.; Diakos, C. I.; Messerle, B. A.; Hambley, T. W.
Inorg. Chem. 2001, 40, 3048. (b) Brown, J. M.; Pe´rez-Torrente, J. J.;
Alcock, N. W. Organometallics 1995, 14, 1195.
(18) Gianneschi, N. C.; Tiekink, E. R. T.; Rendina, L. M. J. Am. Chem.
Soc. 2000, 122, 8474.
(19) (a) Marcus, S. H.; Miller, S. I. J. Am. Chem. Soc. 1966, 88, 3719. (b)
Saunders, M.; Hyne, J. B. J. Chem. Phys. 1958, 29, 1319.
7890 Inorganic Chemistry, Vol. 44, No. 22, 2005

Self-Assembly of Rectangles and Prisms
Figure 3. Experimental (top) and calculated (bottom) isotopic distribution pattern of M - 4NO3 for 11.
The isotopic distributions matched well with the theoretical
isotopic ones. This mass data furnishes another evidence for
9.
1221.6), and [M - 5NO3]5+ (m/z ) 965.1), where M
represents the intact prismatic cage, were detected.
To demonstrate the versability of 4 as a useful ditopic clip,
a large trigonal prism 11 was synthesized, using the bridging
ligand 1,3,5-tris[2-(4-isocyano-3,5-diisopropylphenyl)ethy-
nyl]benzene. We chose the isocyanide ligand as a bridging
ligand because (i) the facile formation of adducts from Pt
complexes by isocyanide22 and (ii) the facile synthesis of a
variety of predesigned isocyanides. We also envisioned that
this ligand containing an alkynyl unit would have the
advantage of free rotating central rings. The self-assembly
of 11 proceeds quantitatively as shown in Scheme 5. The
3:2 stoichiometric addition of 4 with tritopic isocyanide
ligand 6 readily afforded the supramolecule 11. The 31P signal
with 195Pt satellites is shifted upfield by 3.2 ppm relative to
4 (∆JPtP ) -463 Hz). Of special note is that in the 1H NMR
spectrum seven resonances in the aromatic region appear.
This indicates that all the tritopic units are equivalent, due
to rapid rotation. This result is completely different from
the supramolecule 10. The mass spectrum of 11 gave [M
-3NO3]3+ (m/z ) 1865.1), [M - 4NO3]4+ (m/z ) 1382.8),
[M - 5NO3]5+ (m/z ) 1094.0), and [M - 6NO3]6+ (m/z )
901.3), confirming the proposed structure. The isotopic
distribution patterns matched well with the calculated ones.
The calculated and experimental isotope distribution patterns
of the M - 4NO3 peak of 11 are depicted in Figure 3. This
mass data, together with NMR data, provide strong evidence
for the proposed structure.
Self-Assembly of Trigonal Prisms. Although M3L2
prismatic frameworks remain relatively uncommon due to
the scarcity of a predesigned unit,20 Stang and co-workers21
recently reported the self-assembly of molecular prisms from
planar tritopic ligands, directed by a molecular clip. Molec-
ular clip 4 was also shown to be a good unit to assemble the
trigonal prisms. A trigonal prism 10 can be prepared by the
self-assembly from 2 equiv of tritopic 120° angular 1,3,5-
tris(4-ethynylpyridyl)benzene and 3 equiv of ditopic 0°
angular 4. In the 31P NMR spectrum of 10, a sharp singlet
at 7.1 ppm indicates the formation of a highly symmetric
assembly. The upfield shift of this resonance (-∆δ ) 5.1
ppm), together with the change in JPtP for the flanking 195Pt
satellites (∆JPPt ) -197 Hz), is indicative of coordination
1
of platinum to pyridine unit. The H NMR data for 10 are
consistent with the proposed trigonal prism. Of note is that
four sets of resonances for the bridging pyridyl protons
appear due to the restricted rotation of the bridging pyridine
unit.
Further proof for the trigonal prism is obtained using mass
spectroscopy. The ESI-mass spectrum of 10 showed promi-
nent peaks attributable to the consecutive loss of nitrate ions.
[M - 3NO3]3+ (m/z ) 1649.2), [M - 4NO3]4+ (m/z )
(20) (a) Hiraoka, S.; Fujita, M. J. Am. Chem. Soc. 1999, 121, 10239. (b)
Hiraoka, S.; Kubota, Y.; Fujita, M. Chem. Commun. 2000, 1509. (c)
Ikeda, A.; Yoshimura, M.; Udzu, H.; Fukuhara, C.; Shinkai, S. J. Am.
Chem. Soc. 1999, 121, 4296. (d) Kryschenko, Y. K.; Seidel, S. R.;
Muddiman, D. C.; Nepomuceno, A. I.; Stang, P. J. J. Am. Chem. Soc.
2003, 125, 9647. (e) Chi, K.-W.; Addicott, C.; Kryschenko, Y. K.;
Stang, P. J. J. Org. Chem. 2004, 69, 964.
As suitable quality crystals for X-ray crystallographic data
could not be obtained, a calculation is required to visualize
(22) (a) Lai, S.-W.; Chan, M. C.-W.; Cheung, K.-K.; Che, C.-M. Orga-
nometallics 1999, 18, 3327. (b) Lai, S.-W.; Lam, H.-W.; Lu, W.;
Cheung, K.-K.; Che, C.-M. Organometallics 2002, 21, 226.
(21) Kuehl, C. J.; Yamamoto, T.; Seidel, S. R.; Stang, P. J. Org. Lett. 2002,
4, 913.
Inorganic Chemistry, Vol. 44, No. 22, 2005 7891

Kim et al.
ously established the proposed structure. The molecular clip
4 also self-assembles with tritopic 120° angular bridging
ligands to afford trigonal prisms (10, 11). In particular, the
use of isocyanide-containing linkers toward a Pt acceptor
has potential to expand the range of the directional bonding
modes in self-assembly. Work will involve the synthesis of
various predesigned ligands and their self-assembly.
Experimental Section
All experiments were performed under a nitrogen atmosphere
in a Vacuum Atmospheres drybox or by standard Schlenk tech-
niques. THF, toluene, ether, and hexane were distilled from sodium
benzophenone. Methylene chloride, CHCl3, MeOH, and EtOH were
1
distilled under nitrogen from P2O5. The H, 13C, and 31P NMR
spectra were recorded on a Varian Mercury 300 spectrometer
operating at 300.00, 75.44, and 121.44 MHz, respectively. IR
spectra were recorded on a Biorad FTS-165 spectrometer. ESI-
MS spectra were recorded on a Micromass QTOF2 mass spec-
trometer. Elemental analyses were performed with a Carlo Elba
Instruments CHNS-O EA 1108 analyzer. Boron trifluoride ethyl
etherate, formic acid, triphosgene, 4,4′-dipyridyl, and isonicotinic
acid were purchased from Aldrich Chemical Co. 2,6-Diisopropyl-
4-iodoaniline,15a 7-bromo-1-tetralone,26 3,5-di-tert-butylbenzalde-
hyde,27 1,4-diethynylbenzene,28 1,3,5-triethynylbenzene,29 1,3,5-
31
tris(4-ethynylpyridyl)benzene,30 and Pt(PEt3)4 were prepared
according to literature methods.
7-Bromo-2-(3,5-di-tert-butylbenzylidene)-7-bromo-3,4-dihy-
dro-2H-naphthalen-1-one (1). A 250 mL Schlenk flask was
charged with 7-bromo-1-tetralone (4.00 g, 17.8 mmol) and 3,5-di-
tert-butylbenzaldehyde (5.16 g, 23.6 mmol). This was dissolved in
warm tetrahydrofuran (10 mL), and to this yellow solution was
slowly added a 4 wt % solution of KOH in methanol (80 mL). The
reaction was stirred for 36 h at room temperature. The solvent was
then removed under reduced pressure, and it was poured into 100
mL of water and extracted with methylene chloride. The organic
extract was dried over magnesium sulfate and filtered, and the
solvent was removed at reduced pressure. The residue was
chromatographed (1:2 benzene-hexane) to afford 5.53 g (73%) as
Figure 4. Ab initio calculation of optimized trigonal prism 11: (a) overall
figure; (b) side view for 11. The molecule seems to have a C3 symmetry or
a modified C3h symmetry. H atoms are omitted for clarity.
the size and shape of the molecule. A force field calculation
such as MM2 is often used for this purpose;23 however, it is
inconvenient to handle the molecular charges in such
calculations. In other words, it is almost impossible to
differentiate the molecular structures with different charges
in force field calculations. As the molecule 11 has a
molecular charge of +6, we carried out ab initio calculations
to obtain reliable structural information. The geometry of
11 was optimized by the calculations at the Hartree-Fock
(HF) theory using a suite of Gaussian 98 program.24 A shape
consistent effective core potential (ECP) of CRENBS25 was
used as a basis set for platinum (Pt), and minimal STO-3G
basis sets were used for all the other atoms. The optimized
structure shows that the molecule 11 has a center cavity with
a diameter of about 9.2 Å and has three arms with arm-to-
arm distance of about 4.5 nm as shown in Figure 4.
1
yellow oil. H NMR (CDCl3): δ 8.25 (s, 1H), 7.93 (s, 1H), 7.57
(d, 1H, J ) 8.1 Hz), 7.45 (s, 1H), 7.30 (s, 2H), 7.14 (d, 1H, J )
8.1 Hz), 3.15 (t, 2H, J ) 6.0 Hz), 2.91 (t, 2H, J ) 6.0 Hz), 1.36
(s, 18H). 13C{1H} NMR(CDCl3): δ 186.8, 151.0, 141.9, 139.1,
136.1, 135.8, 135.2, 134.9, 134.0, 131.1, 124.8, 124.1, 123.4, 123.0,
121.1, 35.0, 31.5, 28.5, 27.1. Anal. Calcd for C25H29BrO: C, 70.58;
H, 6.87. Found: C, 70.32; H, 6.64.
2,12-Dibromo-[7-(3,5-tert-butylphenyl)-5,6,8,9-tetrahydro-
dibenzo[c,h]acridine] (2,12-dibromo-DTDA) (2). A 500 mL flask
was flame dried under a continuous stream of argon. The flask
was charged with 1 (3.24 g, 7.62 mmol) and 7-bromo-1-tetralone
(1.71 g, 7.62 mmol). These solids were mixed before BF3‚Et2O
(17.0 mL, 135 mmol) was added to form a brown-colored mixture.
The reaction was then slowly heated to 115 °C and was maintained
at this temperature for 8 h. This solution was cooled to 0 °C. To
this was carefully added an ammonium acetate-ethanol solution
(130 mL, 3.00 M) for 45 min. The mixture was refluxed for 24 h.
Conclusion
A novel molecular “clip” 4 was prepared. The molecular
clip was found to be an effective one to assemble various
bridging ligands. Supramolecular rectangles (7-9) was
readily prepared via self-assembly through the use of 4. X-ray
crystallography, NMR, and mass spectral data unambigu-
(26) Newman, M. S.; Seshadri, S. J. Org. Chem. 1962, 27, 76.
(27) Newman, M. S.; Lee, L. F. J. Org. Chem. 1972, 37, 4468.
(28) Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara, N. Synthesis
1980, 627.
(29) Leininger, S.; Stang, P. J.; Huang, S. Organometallics 1998, 17, 3981.
(30) Amoroso, A. J.; Thompson, C. A. M. W.; Maher, J. P.; McCleverty,
J. A.; Ward, M. D. Inorg. Chem. 1995, 34, 4828.
(23) (a) Olenyuk, B.; Whiteford, J. A.; Fechtenko¨tter, A.; Stang, P. J. Nature
1999, 398, 796. (b) Schweiger, M.; Seidel, S. R.; Schmitz, M.; Stang,
P. J. Org. Lett. 2000, 2, 1255.
(24) Frish, M. J.; et al. Gaussian 98, revision A6; Gaussian Inc.: Pittsburgh,
PA, 1999.
(25) Ross, R. B.; Powers, J. M.; Atashroo, T.; Ermler, W. C.; LaJohn, L.
A.; Christiansen, P. A. J. Chem. Phys. 1990, 93, 6654.
(31) Yoshida, T.; Matsuda, T.; Otsuka, S. Inorg. Synth. 1990, 28, 122.
7892 Inorganic Chemistry, Vol. 44, No. 22, 2005

Self-Assembly of Rectangles and Prisms
During this time, the color changed from red to a pale yellow. After
cooling of the mixture to room temperature, the solvent was
removed under reduced pressure, 100 mL water was added, and
the sample was extracted into methylene chloride. The organic
extract was dried over magnesium sulfate and filtered, and the
solvent was removed at reduced pressure. The residue was
chromatographed (1:10 CH2Cl2-hexane) to afford 1.52 g (31.2%)
as a white crystal. Mp: 220 °C. 1H NMR (CDCl3): δ 8.65 (s, 2H),
7.47 (s, 1H), 7.42 (d, 2H, J ) 7.8 Hz), 7.08 (d, 2H, J ) 7.8 Hz),
7.02 (s, 2H), 2.78 (m, 4H), 2.70 (m, 4H), 1.36 (s, 18H). 13C{1H}
NMR (CDCl3): δ 151.1, 149.1, 137.3, 136.7, 136.4, 131.8, 131.3,
129.8, 128.4, 128.1, 123.6, 122.4, 121.1, 35.1, 31.6, 27.7, 25.8.
Anal. Calcd for C35H35Br2N: C, 66.78; H, 5.60. Found: C, 66.36;
H, 5.42.
1,4-Bis[2-(4-formamido-3,5-diisopropylphenyl)ethynyl]ben-
zene. A mixture of acetic anhydride (3.0 mL) and formic acid (3.0
mL) was heated for 2 h at 50-60 °C with stirring. The solution
was cooled to room temperature. 1,4-Bis[2-(4-amino-3,5-diisopro-
pylphenyl)ethynyl]benzene (0.46 g, 0.66 mmol) dissolved in ether
(20 mL) was slowly added to this solution. The resulting solution
was stirred at room temperature for 24 h and neutralized to pH 7
with 10% aqueous sodium carbonate. The organic phase was dried
over magnesium sulfate. After filtration and evaporation of the
solvent, the product was obtained as a white solid which can be
1
recrystallized from diethyl ether. Yield: 70%. Mp: 213 °C. H
NMR (CDCl3): δ 8.49 (s, 2H), 8.03 (d, 2H, J ) 11.7 Hz), 7.54 (s,
2H), 7.37 (s, 2H), 7.26 (s, 2H), 6.88 (d, 2H, J ) 11.7 Hz), 3.20
(heptet, 4H, J ) 6.9 Hz), 1.23 (d, 24H, J ) 6.9 Hz). 13C{1H} NMR
(CDCl3): δ 176.7, 146.6, 131.8, 130.3, 127.8, 127.2, 123.5, 91.1,
89.3, 27.8, 23.6. Anal. Calcd for C36H40N2O2: C, 81.17; H, 7.57.
Found: C, 80.88; H, 7.36.
2,12-Bis[trans-Pt(PEt3)2Br]DTDA (3). A 100 mL Schlenk flask
was charged under nitrogen with 2,12-dibromo-DTDA (0.41 g, 0.65
mmol) and Pt(PEt3)4 (1.09 g, 1.63 mmol). Freshly distilled toluene
(30 mL) was added to the flask under nitrogen by syringe, and the
resulting bright red solution was stirred for 60 h at 60 °C. The
solvent was then removed in vacuo. The white microcrystalline
residue was washed with methanol (3 × 50 mL) and dried in vacuo.
Yield: 89%. Mp: 270 °C. 1H NMR (CDCl3): δ 8.47 (s, 2H, JH-Pt
) 65.4 Hz), 7.43 (s, 1H), 7.26 (d, 2H, JH-Pt ) 68.4 Hz, J ) 7.8
Hz), 7.06 (s, 2H), 6.76 (d, 2H, J ) 7.8 Hz), 2.72-2.66 (m, 8H),
1.71 (m, 24H), 1.35 (s, 18H), 1.11 (t, 36H, J ) 6.9 Hz). 13C{1H}
NMR (CDCl3): δ 151.2, 150.8, 148.2, 147.5, 137.6, 137.3, 136.8,
134.8, 131.8, 128.5, 126.8, 125.4, 124.0, 35.0, 31.6, 28.1, 26.7,
14.4, 8.2. 31P{1H} NMR (CDCl3): δ 6.04 (JPt-P ) 2782 Hz). Anal.
Calcd for C59H95Br2NP4Pt2: C, 47.49; H, 6.42. Found: C, 47.32;
H, 6.34.
1,4-Bis[2-(4-isocyano-3,5-diisopropylphenyl)ethynyl]ben-
zene (5). To a stirred mixture of 1,4-bis[2-(4-formamido-3,5-
diisopropylphenyl)ethynyl]benzene (0.53 g, 1.00 mmol) and Et3N
(5.0 mL) in THF (15 mL) was added a solution of triphosgene
(0.35 g, 1.20 mmol) in THF (15 mL) at -78 °C. The mixture was
allowed to warm slowly to room temperature and stirred for 12 h.
The mixture was evaporated under reduced pressure to remove THF
and Et3N. The reaction mixture was extracted with CHCl3. The
compound 5 was purified by chromatography on silica gel using
n-hexane-methylene chloride (1:1, v/v) as the eluent to afford a
white crystalline solid. Yield: 78%. Mp: 229 °C. 1H NMR
(CDCl3): δ 7.54 (s, 4H), 7.33 (s, 4H), 3.38 (heptet, 4H, J ) 6.9
Hz), 1.30 (d, 24H, J ) 6.9 Hz). 13C{1H} NMR (CDCl3): δ 170.3,
145.4, 132.0, 127.2, 126.5, 124.1, 123.1, 91.0, 90.2, 29.4, 22.5. IR
(KBr pellet, cm-1): 2110 (ν(CtN)). Anal. Calcd for C36H36N2:
C, 87.05; H, 7.31. Found: C, 86.86; H, 7.18.
1,3,5-Tris[(4-amino-3,5-diisopropylphenyl)ethynyl]benzene.
This compound was prepared using the same procedure as that
described for 1,4-bis[2-(4-amino-3,5-diisopropylphenyl)ethynyl]-
benzene. Yield: 72%. Mp: 165 °C. 1H NMR (CDCl3): δ 7.58 (s,
3H), 7.22 (s, 6H), 3.92 (br, 6H, NH2), 2.88 (h, 6H, J ) 6.6 Hz,
CH), 1.29 (d, 36H, J ) 6.6 Hz, CH3). 13C{1H} NMR (CDCl3): δ
141.8, 132.3, 130.6, 124.6, 117.4, 112.2, 93.8, 86.0, 28.3, 22.5.
Anal. Calcd for C48H57N3: C, 85.28; H, 8.50. Found: C, 85.15; H,
8.37.
2,12-Bis[trans-Pt(PEt3)2NO3]DTDA (4). 2,12-Bis[trans-Pt-
(PEt3)2Br]DTDA (0.139 g, 0.0093 mmol) and AgNO3 (0.16 g, 0.93
mmol) in methylene chloride (30 mL) were placed in a Schlenk
flask. The reaction was stirred in the dark at room temperature for
24 h. A clear solution with a heavy creamy precipitate was formed;
the precipitate was filtered off, and the solvent was removed under
a flow of nitrogen. The residue was redissolved in a minimal amount
of methylene chloride, and then pentane was carefully added to
precipitate the residual AgNO3. The cloudy solution was filtered,
and the product was precipitated by the addition of pentane. The
crystals were obtained by layering hexane on the product dissolved
1
in toluene. Yield: 98%. Mp: 286 °C. H NMR (CDCl3): δ 8.40
1,3,5-Tris[(4-formamido-3,5-diisopropylphenyl)ethynyl]ben-
zene. This compound was prepared using the same procedure as
that described for 1,4-bis[2-(4-formamido-3,5-diisopropylphenyl)-
ethynyl]benzene. Yield: 85%. Mp: 208 °C. 1H NMR (CDCl3): δ
8.49 (s, 3H, CHO), 7.71 (s, 3H), 7.31 (s, 6H), 6.74 (s, 3H, NH),
3.21 (h, 6H, J ) 6.6 Hz, CH), 1.24 (d, 36H, J ) 6.6 Hz, CH3).
13C{1H} NMR (CDCl3): δ 163.8, 147.1, 130.5, 129.2, 127.8, 124.2,
123.4, 90.4, 88.3, 28.6, 23.4. IR (KBr pellet: cm-1): 1684 (ν-
(CO)). Anal. Calcd for C51H57N3O3: C, 80.60; H, 7.56. Found: C,
80.38; H, 7.45.
1,3,5-Tris[(4-isocyano-3,5-diisopropylphenyl)ethynyl]ben-
zene (6). Compound 6 was prepared using the same procedure as
that described for 5. Yield: 72%. Mp: 236 °C. 1H NMR (CDCl3):
δ 7.71 (s, 3H), 7.32 (s, 6H), 3.36 (h, 6H, J ) 6.9 Hz, CH), 1.31 (d,
36H, J ) 6.9 Hz, CH3).13C{1H} NMR (CDCl3): δ 170.3, 145.5,
130.8, 123.9, 123.0, 118.3, 116.8, 90.3, 89.2, 28.2, 22.5. IR (KBr
pellet: cm-1): 2109 (ν(CtN)). FAB-MS: m/z 705 [M+]. Anal.
Calcd for C51H51N3: C, 86.77; H, 7.28. Found: C, 86.33; H, 7.14.
General Procedure for the Preparation of Supramolecules
7-11. A 50 mL flask was charged with 2,12-bis[trans-Pt(PEt3)2-
NO3]DTDA (0.10 mg, 0.068 mmol) and 4,4′-dipyridyl (0.01 mg,
(s, 2H, JH-Pt ) 67.2 Hz), 7.43 (s, 1H), 7.23 (d, 2H, J ) 7.8 Hz),
7.04 (s, 2H), 6.75 (d, 2H, J ) 7.8 Hz), 2.66 (br, 8H), 1.58 (m,
24H), 1.34 (s, 18H), 1.15 (t, 36H, J ) 7.8 Hz). 13C{1H} NMR
(CDCl3): δ 151.7, 150.8, 148.3, 137.2, 134.8, 132.3, 128.7, 127.5,
125.9, 123.9, 123.4, 122.6, 121.2, 35.0, 31.6, 27.3, 26.7, 13.3, 7.8.
31P{1H} NMR (CDCl3): δ 12.2 (JPt-P ) 2894 Hz). Anal. Calcd
for C59H95N3O6P4Pt2: C, 48.65; H, 6.57. Found: C, 48.87; H, 6.72.
1,4-Bis[2-(4-amino-3,5-diisopropylphenyl)ethynyl]benzene. To
a mixture of 1,4-diethynylbenzene (0.50 g, 4.03 mmol) and 4-iodo-
2,6-diisopropylaniline (3.06 g, 10.09 mmol) in Et3N (20 mL) and
THF (20 mL) were added Pd(PPh3)4 (0.28 g, 0.24 mmol) and CuI
(0.05 g, 0.24 mmol). The reaction mixture was stirred at 60 °C for
20 h under nitrogen. Then the solvent was removed under reduced
pressure. The residue was extracted with diethyl ether and purified
by chromatography on silica gel using CH2Cl2-hexane (1:1, v/v)
as the eluent to afford orange powder. Yield: 86%. Mp: 257 °C.
1H NMR (CDCl3): δ 7.56 (s, 4H), 7.31 (s, 4H), 3.96 (br, 4H),
2.91 (heptet, 4H, J ) 6.60 Hz), 1.33 (d, 24H, J ) 6.60 Hz). 13C-
{1H} NMR (CDCl3): δ 141.2, 132.1, 131.2, 126.6, 123.1, 111.9,
93.0, 86.9, 27.8, 22.2. Anal. Calcd for C34H40N2: C, 85.67; H, 8.46.
Found: C, 85.32; H, 8.28.
Inorganic Chemistry, Vol. 44, No. 22, 2005 7893

Kim et al.
0.068 mmol) (1:1 molar ratio). A 12 mL volume of an acetone-
H2O mixture (2:1) was added to the flask, and the solution was
then heated overnight at 50-55 °C with stirring. The pure product
7 was obtained by recrystallization with CH2Cl2-hexane as a
colorless crystalline solid in 98% yield.
54H), 1.21 (m, 108H). 13C{1H} NMR (CDCl3): δ 150.9, 150.7,
150.0, 148.6, 137.1, 136.6, 135.5, 134.4, 133.8, 132.1, 131.4, 130.6,
129.3, 128.3, 126.3, 125.1, 123.4, 122.9, 95.9, 87.2, 35.0, 31.6,
29.1, 12.9, 8.2, 7.8. 31P{1H} NMR (CDCl3): δ 7.1 (JPt-P ) 2697
Hz). ESI-MS (m/z): 1649.2, [M - 3NO3]3+; 1184.4, [M -
4NO3]4+; 964.2, [M - 5NO3]5+. Anal. Calcd for C231H315N15O18P12-
Pt6: C, 54.06; H, 6.19. Found: C, 53.78; H, 6.04.
cyclo-Bis[(2,12-bis(trans-Pt(PEt3)2DTDA))(4,4′-dipyridyl)]-
1
(NO3)4 (7). Mp: 301 °C. H NMR (CDCl3): δ 9.14 (d, 4H, J )
5.7 Hz), 8.82 (d, 4H, J ) 5.4 Hz), 8.74 (d, 4H, J ) 5.4 Hz), 8.57
(d, 4H, J ) 5.7 Hz), 8.51 (s, 4H), 7.44 (s, 2H), 7.29 (d, 4H, J )
7.2 Hz), 7.04 (s, 4H), 6.91 (d, 4H, J ) 7.2 Hz), 2.69 (br, 16H),
1.40 (m, 48H), 1.34 (s, 36H), 1.18 (t, 72H, J ) 7.5 Hz). 13C{1H}
NMR (CDCl3): δ 154.0, 152.1, 151.0, 150.7, 148.8, 145.9, 137.3,
136.7, 135.8, 133.8, 131.9, 129.4, 128.8, 127.1, 125.9, 121.6, 35.0,
Bicyclo{tris[2,12-bis(trans-Pt(PEt3)2)DTDA]bis[1,3,5-tris[2-(4-
isocyano-3,5-diisopropylphenyl)ethynyl]benzene}(NO3)6 (11).
Mp: 199 °C. 1H NMR (CDCl3): δ 8.27 (s, 6H), 7.79 (s, 3H), 7.74
(s, 6H), 7.43 (d, 6H, J ) 7.8 Hz), 7.39 (s, 6H), 7.07 (s, 12H), 7.05
(d, 6H, J ) 7.8 Hz), 3.19 (septet, 12H, J ) 6.6 Hz), 2.71 (m, 24H),
1.83 (br, 72H), 1.35(s, 54H), 1.30 (d, 72H, J ) 6.6 Hz), 1.19 (m,
108H). 13C{1H} NMR (CDCl3): δ 165.8, 156.4, 150.9, 150.4,
148.9, 147.5, 145.3, 142.6, 136.9, 136.4, 135.0, 132.4, 131.6, 129.7,
128.1, 127.6, 126.2, 123.5, 122.7, 121.8, 91.0, 89.6, 35.1, 31.6,
30.9, 29.8, 29.5, 23.3, 15.7, 8.4. 31P{1H} NMR (CDCl3): δ 9.03
(JPt-P ) 2431 Hz). IR (KBr Pellet; cm-1): 2146 (ν(CtN)). ESI-
MS (m/z): 1865.1, [M - 3NO3]3+; 1382.8, [M - 4NO3]4+; 1094.0,
[M - 5NO3]5+; 901.3, [M -6NO3]6+. Anal. Calcd for C279H387N15-
O18P12Pt6: C, 57.96; H, 6.75. Found: C, 57.64; H, 6.62.
X-ray Crystallography. Suitable crystals of 4 and 7 were grown
by toluene- hexane and CH2Cl2-hexane, respectively. All X-ray
intensity data for compounds 4 and 7 were collected on a Bruker
SMART 1000 CCD diffractometer32 with graphite-monochromated
Mo KR radiation (λ ) 0.7107 Å). The collected data were processed
for integration; an empirical absorption correction was made on
the basis of the symmetry-equivalent reflection intensities (SAD-
ABS).33 Structures were solved by direct methods and refined by
full-matrix least-squares procedures against F2 using SHELXL97.34
All non-hydrogen atoms in compounds 4 and 7 were refined
anisotropically. All hydrogen atoms were included in the calculated
positions.
31.8, 28.1, 26.5, 12.9, 8.0. 31P{1H} NMR (CDCl3): δ 7.1 (JPt-P
)
2594 Hz). ESI-MS (m/z): 1549.5, [M - 2NO3]2+; 1012.3, [M -
3NO3]3+; 743.7, [M - 4NO3]4+. Anal. Calcd for C138H206N10O12P8-
Pt4: C, 51.39; H, 6.44. Found: C, 51.02; H, 6.28.
cyclo-Bis{(2,12-bis(trans-Pt(PEt3)2)DTDA)[1,4-bis[2-(4-isocy-
ano-3,5-diisopropylphenyl)ethynyl]benzene]}(NO3)4 (8). Mp: 191
1
°C. H NMR (CDCl3): δ 8.25 (s, 4H), 7.58 (s, 2H), 7.50 (d, 4H,
J ) 7.2 Hz), 7.44 (d, 4H, J ) 7.6 Hz), 7.38 (s, 8H), 7.22 (s, 4H),
7.06 (d, 4H, J ) 7.2 Hz), 7.02 (d, 4H, J ) 7.6 Hz), 3.22 (septet,
8H, J ) 6.9 Hz), 2.70 (br, 16H), 1.87 (br, 48H), 1.34 (s, 36H),
1.30 (d, 48H, J ) 6.9 Hz), 1.19 (t, 72H, J ) 7.5 Hz). 13C{1H}
NMR (CDCl3): δ 166.3, 150.9, 150.5, 148.8, 147.5, 146.7, 145.3,
137.0, 136.4, 134.9, 132.2, 132.0, 131.8, 129.6, 128.0, 127.5, 126.4,
122.9, 122.7, 92.6, 92.5, 90.3, 31.5, 30.7, 29.7, 23.3, 15.7, 15.5,
8.6, 8.2. 31P{1H} NMR (CDCl3): δ 9.1 (JPt-P ) 2439 Hz). IR (KBr
pellet, cm-1): 2148 (ν(CtN)). ESI-MS (m/z): 1892.1, [M -
2NO3]2+; 1240.4, [M - 3NO3]3+; 914.4, [M - 4NO3]4+. Anal.
Calcd for C190H262N10O12P8Pt4: C, 58.42; H, 6.76. Found: C, 58.04;
H, 6.58.
cyclo-Bis[(2,12-bis(trans-Pt(PEt3)2)DTDA)(isonicotinic acid)2]-
1
(NO3)4 (9). Mp: 311 °C. H NMR (CDCl3): δ 12.70 (br, 4H,
Acknowledgment. We are grateful to the Korea Research
Foundation (Grant KRF-2002-070-C000056).
COOH), 9.24 (d, 4H, J ) 5.1 Hz), 8.80 (d, 4H, J ) 5.4 Hz), 8.51
(s, 4H), 8.49 (d, 4H, J ) 5.1 Hz), 8.22 (d, 4H, J ) 5.4 Hz), 7.45
(s, 2H), 7.32 (d, 4H, J ) 7.5 Hz), 7.06 (s, 4H), 6.91 (d, 4H, J )
7.5 Hz), 2.70 (br, 16H), 1.65 (br, 48H), 1.36 (s, 36H), 1.22 (t, 72H,
J ) 7.5 Hz). 13C{1H} NMR (CDCl3): δ 169.2, 164.9, 152.8, 151.0,
150.7, 147.7, 142.6, 137.3, 136.6, 135.4, 133.7, 132.2, 129.4, 128.7,
126.6, 124.8, 122.2, 35.0, 31.6, 30.3, 12.9, 9.3, 8.3. 31P{1H} NMR
(CDCl3): δ 6.8 (JPt-P ) 2710 Hz). ESI-MS (m/z): 1640.7, [M
-NO3]+; 789.3, [M - 2NO3]2+. Anal. Calcd for C71H105N5O10P4-
Pt2: C, 50.08; H, 6.22. Found: C, 49.74; H, 6.08.
Supporting Information Available: Tables listing crystal-
lographic information, atomic coordinates and U(eq) values, bond
distances and angles, anisotropic displacement parameters, and
torsion angles and crystallographic data in CIF format for 4 and 7
(CCDC reference nos. 278206 and 278207). This material is
available free of charge via the Internet at http://pubs.acs.org.
IC0508369
Bicyclo{tris[2,12-bis(trans-Pt(PEt3)2DTDA)]bis[1,3,5-tris(4-
ethynylpyridyl)benzene]}(NO3)6 (10). Mp: 207 °C. 1H NMR
(CDCl3): δ 9.04 (d, 6H, J ) 5.4 Hz), 8.67 (d, 6H, J ) 5.7 Hz),
8.44 (s, 6H), 8.04 (d, 6H, J ) 5.4 Hz), 7.75 (s, 6H), 7.72 (d, 6H,
J ) 5.7 Hz), 7.44 (s, 3H), 7.25 (d, 6H, J ) 7.8 Hz), 7.05 (s, 6H),
6.90 (d, 6H, J ) 7.8 Hz), 2.69 (m, 24H), 1.47 (m, 72H), 1.35 (s,
(32) Bruker SMART (Version 5.0) and SAINT-plus (Version 6.0); Bruker
AXS Inc.: Madison WI, 1999.
(33) Sheldrick, G. M. SADAB; University of Goettingen: Goettingen,
Germany, 1996.
(34) Sheldrick, G. M. SHELXS97 and SHELXL97; University of Goettin-
gen: Goettingen, Germany, 1997.
(35) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565.
7894 Inorganic Chemistry, Vol. 44, No. 22, 2005