(6,17-Dimethyl-8,15-diphenyldibenzo[b,i][1,4,8,11] -tetra-aza[14]annulenato)nickel(II) in solids: Two guest-free polymorphs and inclusion compounds with methylene chloride and fullerene (C60)-carbon disulfide

Article abstract of DOI:10.1021/ic0104555

Two guest-free polymorphs and two inclusion compounds of the macrocyclic title complex [NiL] have been isolated and characterized with single-crystal and/or powder XRD, solid-state ¹³C NMR, and other methods. The inclusion compound with methylene chloride, [NiL]*(CH₂Cl₂), is stable in air and thermally stable up to ～128 °C. Its crystal structure is consistent with van der Waals packing of the host [NiL] and guest CH₂Cl₂ molecules. The host complex has square-planar coordination of the nickel(II) center with four nitrogen atoms of the macrocycle with an average Ni-N distance of 1.86 A. The molecule has a saddle-shaped conformation with the guest molecule located between one phenylene and two phenyl rings of the host molecule. Isostructural compounds with chloroform and 2-chloropropane form only as mixtures along with a guest-free host polymorph. The inclusion compound with C₆₀ has a composition 3[NiL]*(C₆₀)*2(CS₂) and here also the crystal structure is consistent with a van der Waals type of packing. Three crystallographically inequivalent [NiL] molecules have geometries similar to that in the inclusion compound with methylene chloride. The concave surfaces of the complex molecules form a spherical cavity for the C₆₀ molecule. At-100 °C the C₆₀ molecule is disordered over two orientations centered at the same site. ¹³C NMR studies at room temperature show that the C₆₀ molecule is undergoing rapid pseudoisotropic rotation. The stability and other properties of the title and related complexes are discussed.

Full text of DOI:10.1021/ic0104555

5660
Inorg. Chem. 2001, 40, 5660-5667
(6,17-Dimethyl-8,15-diphenyldibenzo[b,i][1,4,8,11]-tetra-aza[14]annulenato)nickel(II) in
Solids: Two Guest-Free Polymorphs and Inclusion Compounds with Methylene Chloride
and Fullerene (C60)-Carbon Disulfide
D. V. Soldatov,#,‡ P. R. Diamente,† C. I. Ratcliffe,# and J. A. Ripmeester*,†,#
Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa,
Ontario K1A 0R6, Canada, and Department of Chemistry, Carleton University, Ottawa,
Ontario K1S 5B6, Canada
ReceiVed April 30, 2001
Two guest-free polymorphs and two inclusion compounds of the macrocyclic title complex [NiL] have been
isolated and characterized with single-crystal and/or powder XRD, solid-state 13C NMR, and other methods. The
inclusion compound with methylene chloride, [NiL]*(CH2Cl2), is stable in air and thermally stable up to ∼128
°C. Its crystal structure is consistent with van der Waals packing of the host [NiL] and guest CH2Cl2 molecules.
The host complex has square-planar coordination of the nickel(II) center with four nitrogen atoms of the macrocycle
with an average Ni-N distance of 1.86 Å. The molecule has a saddle-shaped conformation with the guest molecule
located between one phenylene and two phenyl rings of the host molecule. Isostructural compounds with chloroform
and 2-chloropropane form only as mixtures along with a guest-free host polymorph. The inclusion compound
with C60 has a composition 3[NiL]*(C60)*2(CS2) and here also the crystal structure is consistent with a van der
Waals type of packing. Three crystallographically inequivalent [NiL] molecules have geometries similar to that
in the inclusion compound with methylene chloride. The concave surfaces of the complex molecules form a
spherical cavity for the C60 molecule. At -100 °C the C60 molecule is disordered over two orientations centered
at the same site. 13C NMR studies at room temperature show that the C60 molecule is undergoing rapid pseudo-
isotropic rotation. The stability and other properties of the title and related complexes are discussed.
Introduction
Scheme 1
Macrocyclic metal dibenzotetraaza[14]annulenates have stimu-
lated continuing interest in a wide range of areas.1,2 These
complexes have a distinctive saddle-shaped geometry with
conformational rigidity and thus have the potential of forming
porous architectures. The complexes [M(TMTAA)] and [M(O-
MTAA)] (Scheme 1), studied recently, are versatile hosts
forming inclusion compounds with inorganic and organic
species, not only in the solid but also in solution.3-7 Because
of their concave surfaces, these host molecules may be selective
toward large globular molecules such as fullerenes; both
C603-5 and C706 have been confined as guests in solid inclusions.
A few other dibenzotetraaza[14]annulene complexes with the
same ligands have been reported to entrap solvent molecules
upon crystallization.8-10
The potential of tetraazaannulenates as host materials there-
fore needs to be more widely explored, the more so as two
extensive classes of structurally related host complexes have
been developed. Porphyrin-based complexes form inclusion
compounds numbering in the hundreds, with many variations
due to the wide range of metals, porphyrins and guests which
have been utilized.11-17 Metal bischelates with acetylacetonate-
type ligands make up another class of related complexes, which
may be considered as tetraaza[14]annulene precursors. We have
* To whom correspondence should be addressed.
# Steacie Institute for Molecular Sciences.
† Carleton University.
‡ On leave of absence from the Institute of Inorganic Chemistry,
Novosibirsk, Russia.
(1) Cotton, F. A.; Czuchajowska, J. Polyhedron 1990, 9, 2553-2566.
(2) Mountford, P. Chem. Soc. ReV. 1998, 27, 105-115.
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C. L. Chem. Eur. J. 1998, 4, 1384-1387.
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E. Inorg. Chem. 1992, 31, 3871-3872.
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Trans. 1999, 279-284.
(10) Kuchta, M. C.; Parkin, G. New J. Chem. 1998, 22, 523-530.
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Strouse, C. E. J. Am. Chem. Soc. 1990, 112, 1865-1874.
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P. A.; Tendick, S. K.; Strouse, C. E. J. Am. Chem. Soc. 1991, 113,
6549-6557.
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P. J.; Smith, N. O.; Skelton, B. W.; White, A. H.; Raston, C. L. J.
Chem. Soc., Dalton Trans. 1999, 2927-2932.
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Commun. 1999, 193-194.
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S. K.; Terzis, A.; Strouse, C. E. J. Am. Chem. Soc. 1993, 115, 9480-
9497.
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references therein.
10.1021/ic0104555 CCC: $20.00 © 2001 American Chemical Society
Published on Web 09/27/2001

Nickel(II) Tetraazaannulenate
Inorganic Chemistry, Vol. 40, No. 22, 2001 5661
Scheme 2
discovered recently that metal dibenzoylmethanates, when
modified with appropriate axial ligands, reveal remarkable
inclusion properties.18-32
The present study characterizes solid forms of [NiL] (Scheme
2) which is an extension of its maternal analogue by two
phenyls. The complex and its H2L macrocycle were first
Figure 1. Powder X-ray diffractograms of isolated solids: (1) [NiL],
low form; (2) [NiL], high form; (3) [NiL]*(CH2Cl2); (4) 3[NiL]*(C60)-
*2(CS2). The vertical bars show the positions of the most intense
reflections (>5% of the strongest peak) theoretically predicted from
the single-crystal data (using room-temperature unit cell dimensions).
Radiation: Co KR, λ ) 1.7902 Å.
33
reported in 1980 but it was studied only recently by single-
crystal XRD as a solvate with chloroform.34 Difficulties in
preparing suitable crystals, because of twinning and small size,
led to a limited structural solution for the host only, with some
centers representing disordered guest.35 The present study
elucidates the existence of two guest-free polymorphic forms
of the complex, and characterizes two inclusion compounds of
the complex, with methylene chloride and fullerene (C60)-
carbon disulfide.
(14) Byrn, M. P.; Curtis, C. J.; Hsiou, Y.; Khan, S. I.; Sawin, P. A.; Terzis,
A.; Strouse, C. E. In ComprehensiVe Supramolecular Chemistry,
MacNicol, D. D., Toda, F., Bishop, R., Eds.; Pergamon: Exeter, 1996;
Vol. 6, pp 715-732.
(15) Kumar, R. K.; Balasabramanian, S.; Goldberg, I. Inorg. Chem. 1998,
37, 541-552.
Experimental Section
(16) Kumar, R. K.; Diskin-Posner, Y.; Goldberg, I. J. Inclusion Phenom.
2000, 37, 219-230.
(6,17-Dimethyl-8,15-diphenyldibenzo[b,i][1,4,8,11]-tetra-aza[14]-
annulenato)nickel(II), [NiL]. The complex was prepared as described
earlier,33 by refluxing under nitrogen for 30 min a mixture of
o-phenylenediamine (10.8 g, 0.10 mol) and nickel acetate tetrahydrate
(12.4 g, 0.05 mol) in anhydrous butanol (200 mL), and then for a further
12 h after the addition of benzoylacetone (16.2 g, 0.10 mol). The green
crude product was filtered off, washed with butanol and methanol, dried
under nitrogen, and recrystallized from butanol. 1H NMR (CD2Cl2) (δ,
ppm): 2.24 (6H, -CH3), 5.06 (2H, >C-H), 5.61 and 5.96 (2H+2H,
aromatic a′ and b′), 6.70 and 6.89 (2H + 2H, aromatic a and b), 7.37
(10H, phenyls). Recrystallization of the product from a range of solvents
resulted in one of two solid forms, or their mixture. Both forms
(17) Goldberg, I. Chem. Eur. J. 2000, 6, 3863-3870 and references therein.
(18) Soldatov, D. V.; Enright, G. D.; Ripmeester, J. A. Supramol. Chem.
1999, 11, 35-47.
(19) Soldatov, D. V.; Ripmeester, J. A. Supramol. Chem. 2001, 12, 357-
368.
(20) Soldatov, D. V.; Ripmeester, J. A. Chem. Eur. J., 2001, 7, 2979-
2994.
(21) For other host materials based on metal bis-chelates see refs 22-32.
(22) Krueger, A. G.; Winter, G. Aust. J. Chem. 1971, 24, 1353-1359; 1972,
25, 2497-2501.
(23) Gable, R. W.; Hoskins, B. F.; Winter, G. Inorg. Chim. Acta 1985, 96,
151-159.
(24) Saalfrank, R. W.; Struck, O.; Nunn, K.; Lurz, C. J.; Harbig, R.; Peters,
K.; Schnering, H. G.; Bill, E.; Trautwein, A. X. Chem. Ber. 1992,
125, 2331-2335.
1
exhibited the same H NMR spectra after dissolving, which makes it
possible to assign them as two polymorphic modifications of the
complex.36 Powder X-ray diffractograms (PXRD) of the two pure
polymorphs are shown in Figure 1. Solid state 13C NMR spectra are
discussed in the next section.
(25) Squattrito, P. J.; Iwamoto, T.; Nishikiori, S. Chem. Commun. 1996,
2665-2666.
(26) Ivanov, A.; Kritikos, M.; Lund, A.; Antsutkin, O. N.; Rodina, T. A.
Russ. J. Inorg. Chem. 1998, 43, 1368-1376.
(27) Burdukov, A. B.; Ovcharenko, V. I.; Guschin, D. A.; Reznikov, V.
A.; Ikorskii, V. N.; Shvedenkov, Y. G.; Pervukhina, N. V. Mol. Cryst.
Liq. Cryst. 1999, 334, 395-404.
[NiL]*(CH2Cl2). This inclusion compound formed as a dark green
crystalline product in the course of fast evaporation (several hours) of
a solution of the complex in methylene chloride. By TGA the product
showed a mass loss of 13.9% in the 128-138 °C temperature range,
cf. calculated 13.9% for methylene chloride content in [NiL]*(CH2-
Cl2). The composition of the bulk product was also confirmed by solid
state 13C NMR and by comparing the experimental PXRD pattern with
that calculated from single-crystal X-ray analysis (Figure 1).
3[NiL]*(C60)*2(CS2). The fullerene C60 (144 mg, 0.20 mmol) was
dissolved with gentle heating in carbon disulfide (50 mL). [NiL] (315
mg, 0.60 mmol) was then added, and the resulting solution left to
evaporate to dryness. The 13C NMR spectra are discussed in the next
section, and experimental and calculated PXRD patterns can be
compared in Figure 1.
(28) Soldatov, D. V.; Ripmeester, J. A.; Shergina, S. I.; Sokolov, I. E.;
Zanina, A. S.; Gromilov, S. A.; Dyadin, Yu. A. J. Am. Chem. Soc.
1999, 121, 4179-4188.
(29) Soldatov, D. V.; Ripmeester, J. A. Chem. Mater. 2000, 12, 1827-
1839.
(30) Manakov, A. Yu.; Soldatov, D. V.; Ripmeester, J. A.; Lipkowski, J.
J. Phys. Chem. B 2000, 104, 12111-12118.
(31) Soldatov, D. V.; Ripmeester, J. A. J. Inclusion Phenomena 2001, 39,
81-84.
(32) Nossov, A. V.; Soldatov, D. V.; Ripmeester, J. A. J. Am. Chem. Soc.
2001, 123, 3563-3568.
(33) Eilmes, J.; Pelan, D.; Sledziewska, E. Bull. Acad. Pol. Sci. Ser. Chim.
1980, 28, 371-376.
(34) Eilmes, J.; Basato, M.; Valle, G. Inorg. Chim. Acta 1999, 290, 14-
20.
(35) Final parameters of that solution: R ) 0.087 for 1365 intense data
and 356 refined parameters; GOF ) 2.05 (intense data) and 1.60 (all
data); residual extrema: +0.63 and -0.82 e Å-3 (CCDC 114506,
Refcode HOKXOU, the data were kindly provided upon request from
the Editor).
(36) Following a widely accepted condition that two materials are poly-
morphs if they dissolve to give the same solution: McCrone, W. C.
In Physics and Chemistry of the Organic Solid State; Fox, D., Labes,
M. M., Weissberger, A., Eds.; Interscience: New York, 1965; Vol.
2, pp 725-767.

5662 Inorganic Chemistry, Vol. 40, No. 22, 2001
Soldatov et al.
Table 1. Summary of Low-Temperature Single-Crystal XRD
Powder XRD. Powder patterns were recorded on a Rigaku Geiger-
flex diffractometer (CoKR radiation, λ ) 1.7902 Å) over a 5-30° 2θ
range, 0.02° step scan with 1 or 2 s per step. Theoretical diffractograms
were calculated using atomic coordinates from the single-crystal XRD
analyses, but with unit cell dimensions determined at room tempera-
ture.37
Single-Crystal XRD. Single crystals of the two inclusion compounds
studied, in the form of dark-green plates, were picked out of the bulk
products. Unit cell dimensions were measured both at room tempera-
ture37 and at -100 °C, using the same crystals. Full XRD data sets
were collected at -100 °C.
A Siemens SMART CCD X-ray diffractometer with graphite-
monochromated Mo KR radiation (λ ) 0.7107 Å) was used to collect
the diffraction data. An empirical absorption correction utilized the
SADABS routine associated with the diffractometer. The final unit cell
parameters were obtained using the entire data set.
The structures were solved and refined using the SIR9238 and
SHELXTL39 packages, by direct methods followed by differential
Fourier syntheses. The structural refinement was performed on F 2 using
all data with positive intensities. Non-hydrogen atoms were refined
anisotropically. Isotropic approximations and geometric constraints were
applied for the minor orientation of the CH2Cl2 molecule. Minor
orientations of the disordered CS2 group were constrained to have the
same geometry as in the main orientation. Hydrogen atoms were refined
isotropically with thermal factors 1.2 or 1.5 times greater than those
for the adjacent carbon atoms. Site occupancy factors for guest
orientations were refined independently; in the last cycles their sums
were fixed to give the ideal stoichiometry as observed deviations were
not significant.40 The largest residual extrema on the final difference
map were located about guest Cl or S atoms.
Analysis of the packing was accomplished using the XP39 and
CLAT41 program packages. The following van der Waals radii were
applied:42,43 C, 1.71; H, 1.16; Cl, 1.90; N, 1.52; Ni, 1.63; S, 1.84 Å.
A summary of the crystal data and experimental parameters is given
in Table 1. Complete data can be found in the Supporting Information.
NMR Spectroscopy. 1H NMR Spectra were obtained for solutions
of the polymorphs in deuterated methylene chloride with a Bruker DRX-
400 instrument. Assignments were based on data reported earlier.33,44
Stoichiometry ratios derived by integration of bands with the XWIN
NMR 2.0 program package corresponded to the expected integral
numbers within the experimental error of 5%.
Solid state 13C cross-polarization/magic angle spinning (CP/MAS)
NMR spectra with 1H decoupling were obtained at 75.48 MHz at room
temperature on a Bruker AMX300 spectrometer equipped with a Doty
Scientific 5 mm CP/MAS probe. A standard CP pulse program was
used with fixed amplitude 1H decoupling during signal acquisition. 1H
90° pulse lengths were 2.7 µs, CP times were 3 ms, except for the C60
compound, and recycle times were 4-17s, depending on the sample.
Dipolar dephased spectra45 were obtained by interrupting the 1H
decoupling for 40 µs immediately after the CP sequence and before
starting the data acquisition. CP spectra for the C60 complex were
obtained with CP times 1, 5, 10 and 20 ms, and some spectra were
also obtained without CP but with 1H decoupling, using recycle times
Experiments
compound
[NiL]*(CH2Cl2)
3[NiL]*(C60)*2(CS2)
chemical formula C32H26N4Ni, CH2Cl2 3(C32H26N4Ni), C60, 2(CS2)
formula weight
space group
a, Å
b, Å
c, Å
610.2
2448.6
P1h (No. 2)
13.492(2)
15.701(2)
27.557(3)
74.16(1)
88.84(1)
76.09(1)
5445(1)
2
1.494
6.59
-100
0.7107
0.054
P1h (No. 2)
9.742(2)
11.615(2)
14.189(2)
66.84(1)
73.27(1)
75.06(1)
1394.5(4)
2
R, Å
â, Å
γ, Å
V, Å3
Z
D
calcd, g cm-3
1.453
µ(Mo KR), cm-1 9.18
T, °C
λ, Å
-100
0.7107
0.030
0.082
R1 (F)a
wR2 (Fo )b
0.111
2
a R1
)
∑||Fo|
-
|Fc||/∑|Fo|. b wR2
)
∑[w(Fo
-
Fc2)2]/
2
{∑[w(Fo )2]}1/2
.
2
up to 5 min. Chemical shifts were measured relative to external solid
hexamethylbenzene and then corrected to the TMS scale. Spinning
speeds were set in the range 6.06-6.5 kHz to avoid overlap of spinning
sidebands with isotropically shifted lines.
The initial spectra of the C60 compound were obtained using a 1 or
2 s recycle time, and it was found that these short intervals ultimately
resulted in gradual decomposition of the sample. This resulted in an
increasing noise level in each scan, presumably due to the formation
of charred, slightly conducting material. When the sample spinner was
opened following this episode there was also a strong smell of H2S,
indicating reduction of CS2. To circumvent this problem, recycle times
of 10s or longer were used subsequently.
Other Methods. TGA and DSC measurements were made using a
2050 Thermogravimetric Analyzer and a 2920 Modulated Differential
Scanning Calorimeter (TA Instruments), respectively. The heating rate
was 5° per minute in both methods. Isopiestic measurements were
performed with ∼100 mg samples of the high-temperature polymorph
(high form) of the complex; the samples were placed in the vapor of
the potential guest. More details on using the three techniques for similar
host-guest systems are given elsewhere.20,28,29,30,46
Results and Discussion
Solid Forms of [NiL]. Four solid phases containing the
complex [NiL] have been isolated and characterized in this
work: two guest-free polymorphs of the complex, an inclusion
compound with methylene chloride, [NiL]*(CH2Cl2), and a
double inclusion compound with C60 and CS2, 3[NiL]*(C60)-
*2(CS2). Powder diffractograms of all four phases are compared
in Figure 1, and are quite distinct.
The low-temperature polymorph (low form) was obtained
upon crystallization from warm chloroform or pyridine. DSC
analysis of this low form showed a weak (∼5 kJ/mol), diffuse,
endothermal effect in the 130-160 °C temperature range, likely
due to transformation into the high form.
The high form polymorph was reproducibly prepared by
placing the low form in an oven at 135 °C for 1 h. It also was
prepared directly in the course of crystallization from many
solvents, including benzene, n-butanol, chloroform, 2-chloro-
propane, pyridine, acetone and tetrahydrofuran. Fine-crystalline
or powder products were isolated from these solvents. If the
solutions were evaporated slowly, the final products were badly
contaminated with impurities, indicating decomposition of the
complex itself with time. The high form exhibited no guest
sorption or any other change in an atmosphere of n-heptane,
benzene or 2-chlorobutane (isopiestic experiments). The DSC
(37) At room temperature the unit cell dimensions were as follows. [NiL]*-
(CH2Cl2) (359 reflections): a ) 9.805(2), b ) 11.754(2), c ) 14.280-
(4) Å, R ) 67.22(2), â ) 72.99(2), γ ) 74.80(2)o, V ) 1430.1(6) Å3.
3[NiL]*(C60)*2(CS2) (310 reflections): a ) 13.565(3), b ) 15.836-
(4), c ) 27.743(7) Å, R ) 74.11(2), â ) 88.62(2), γ ) 75.88(2)o, V
) 5553(2) Å3.
(38) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Gualardi, A. J. Appl.
Crystallogr. 1993, 26, 343-350.
(39) Sheldrick, G. M. SHELXTL PC, Ver. 4.1, An Integrated System for
SolVing, Refining and Displaying Crystal Structure from Diffraction
Data; Siemens Analytical X-ray Instruments, Inc.: Madison, WI, 1990.
(40) Refined stoichiometries: x ) 0.989(6) for [NiL]*x(CH2Cl2) and x )
1.99(1) for 3[NiL]*(C60)*x(CS2).
(41) Grachev, E. V.; Dyadin, Yu. A.; Lipkowski, J. J. Struct. Chem. 1995,
36, 876-879.
(42) Zefirov, Yu. V.; Zorkii, P. M. Russ. Chem. ReV. 1995, 64, 415-428.
(43) Bondi, A. J. Phys. Chem. 1964, 68, 441-451.
(44) L’Eplattenier, F. A.; Pugin, A. HelV. Chim. Acta 1975, 58, 917-929.
(45) Opella, S. J.; Frey, M. H. J. Am. Chem. Soc. 1979, 101, 5854-5856.

Nickel(II) Tetraazaannulenate
Inorganic Chemistry, Vol. 40, No. 22, 2001 5663
Figure 3. Fragment of crystal packing in [NiL]*(CH2Cl2) comprising
two cavities with two guests in each and showing stacking of host
molecules.
very similar (1.330(2) to 1.340(2) Å), and likewise for the C-C
bonds (1.393(2) to 1.410(2) Å), indicating strong conjugation
within these fragments. The whole molecule has a typical saddle-
shaped conformation governed by strong repulsive intramo-
lecular interactions (Figure 2b). With the sum of the carbon
van der Waals radii of 1.71 × 2 ) 3.42 Å, the shortest contacts
(Figure 2b) between phenylenes and methyl carbons C32...C11
and C35...C21 are both 2.98 Å, and those between phenylenes
and phenyls C42...C16 and C45...C26 are 3.11 and 3.28 Å,
respectively.47 An overlap between ortho hydrogens of phenyl
and phenylene rings is avoided due to phenyls rotating out of
the plane of the six-membered rings by 46° (C15...C20) and
41° (C25...C30), the resulting H‚‚‚H contacts of 2.34 Å. The
degrees of curvature of the molecule may be judged from two
dihedral angles: the angle between the two NCCCN semi-rings
is 136° and the angle between the two phenylene rings is 116°.
For a planar unit both these angles would be 180°.
Figure 2. ORTEP drawings (50% probability level) of the host (a)
and guest (b) molecules in [NiL]*(CH2Cl2). The guest molecule is
shown as it is located with respect to the host. Minor orientation is
depicted by dashes. In this and subsequent Figures H atoms are omitted.
thermogram of the high form exhibited a series of exotherms
higher than 150 °C indicating irreversible degradation of the
complex.
The CH2Cl2 guest molecule has large thermal parameters and
is disordered over two orientations (Figure 2b) (the main
orientation is occupied by 90.4(4) %). It sits in a pocket formed
by two phenyls and one phenylene of the host molecule. The
short distance of 2.74 Å from one of the guest hydrogens to
the center of the C41-C46 aromatic ring may be indicative of
weak C-H...π interactions. Two adjacent pockets form a
centrosymmetric cavity with the center at (0,0.5,0.5). This cavity
is built up of exclusively hydrocarbon parts of the host, i.e.,
neither Ni nor N atoms are accessible from inside. The cavity
is closed so that the guest cannot move through the structure,
which is consistent with the stability of the compound in air.
Figure 3 shows a fragment of the crystal packing comprising
two cavities with centers at (0,0.5,0.5) and (1,0.5,0.5). Each host
molecule stacks up over a neighbor related by centrosymmetry,
with 5.18 Å between the Ni centers; four such pairs are shown
in Figure 3. Another neighbor host molecule is located on the
opposite side of the molecule, but with a longer Ni-Ni distance
of 7.27 Å.
The [NiL]*(CH2Cl2) inclusion compound formed as a bulk
monophase product upon fast evaporation of the solution of the
complex in methylene chloride. Other solvents, as mentioned
above, yielded guest-free forms. Crystallizations with addition
of [NiL]*(CH2Cl2) as nucleation agent yielded mixtures of the
high form of [NiL] and the inclusion form with chloroform or
2-chloropropane (as determined from PXRD and TGA results).
CH2Cl2 is therefore the only one of all the potential guests which
were tried which transforms the complex into the inclusion form
quantitatively. The TGA thermogram of [NiL]*(CH2Cl2) (see
Supporting Information) shows a surprisingly high thermal
stability, which implies that the guest molecules are tightly
confined inside the structure.
The 3[NiL]*(C60)*2(CS2) inclusion compound formed re-
producibly as a bulk product from carbon disulfide solution
containing stoichiometric quantities of the host complex and
fullerene. Because of the high solubility of the host, most
solvents washed out the host complex producing a solid residue
of C60.
Structure of 3[NiL]*(C60)*2(CS2). This inclusion compound
is triclinic, P1h. The asymmetric unit is formed by three
crystallographically different [NiL] molecules (A, B and C),
one C60 disordered over two positions, and two CS2 molecules,
one of which is also disordered. This results in 177 crystallo-
graphically independent non-hydrogen atoms and, due to guest
disorder, in as many as 2171 refined parameters. A symmetry
center produces the other half of the unit cell contents, thus
Structure of [NiL]*(CH2Cl2). This inclusion compound is
triclinic, P1h, with two formula units per unit cell. One entire
host molecule and one guest molecule form the asymmetric unit
of the structure. The CH2Cl2 molecule is disordered over two
orientations in a 9:1 occupancy ratio. Van der Waals contacts
dominate the packing in the structure everywhere.
The Ni atom of the host molecule (Figure 2a) has a square
planar coordination defined by the four N atoms of the
macrocycle, and the deviation of the Ni atom from this
equatorial plane is less than 0.02 Å. The Ni-N distances vary
between 1.862(1) and 1.868(1) Å. The N-Ni-N coordination
angles are ∼85° and ∼95° in the five- and six-membered rings,
respectively. All the N-C bonds of the six-membered rings are
(46) Soldatov, D. V.; Henegouwen, A. T.; Enright, G. D.; Ratcliffe, C. I.;
Ripmeester, J. A. Inorg. Chem. 2001, 40, 1626-1636.
(47) The derived values are given to the least significant figure here and
in the remainder of the text, unless standard deviations (in brackets)
are provided.

5664 Inorganic Chemistry, Vol. 40, No. 22, 2001
Soldatov et al.
Figure 4. Guest fullerene molecule in 3[NiL]*(C60)*2(CS2). Shown are F (63%) and G (37%) orientations (ORTEP, 50% probability level), and
their superposition. G and F are related by a rotation of ∼30° around the 6-fold axis of the molecule which is almost perpendicular to the plane of
the Figure.
resulting in six [NiL], two C60, and four CS2 molecules per unit
cell. The intermolecular contacts are consistent with van der
Waals packing.
The molecular structure is roughly the same for all three [NiL]
molecules, and similar to that for the CH2Cl2 inclusion
compound. The Ni-N distances vary between 1.847(1) and
1.883(2) Å, with an average of 1.862(3) Å for 12 bonds in three
molecules. The saddle-shaped conformation changes little from
molecule to molecule: The dihedral angles between the two
NCCCN semi-rings in each [NiL] are 135°, 136°, and 132°,
and those between the two phenylene rings are 128, 120 and
120° (A, B and C molecules, respectively). The phenyl
(C15...C20) is rotated from its adjacent six-membered ring by
52, 44 and 53°, and the phenyl (C25...C30) is rotated by 56°,
45°, and 52° (A, B and C molecules, respectively). The shortest
contacts are 2.99-3.02 Å (C32...C11), 3.00-3.02 Å (C35...C21),
3.16-3.31 Å (C42...C16), and 3.07-3.27 Å (C45...C26).
The C60 molecule occupies a general position in the structure.
High thermal atomic parameters in tangent directions (Figure
4) indicate the presence of rotation of the molecule, predomi-
nantly around one of its 6-fold axes, approximately parallel to
the c direction. The molecule is disordered over two orientations
(Figure 4), and the minor orientation G (37.1(1) %) is related
to the main orientation F through a rotation around the 6-fold
axis by ∼30°. The centroids of the two orientations are displaced
from each other by only 0.14 Å. It should be emphasized that
this crystal structure was studied at -100 °C and the minor
orientation was impartially observed from difference Fourier
synthesis. As evident from MAS 13C NMR spectra, the molecule
is rotating rapidly at room temperature (see below).
The C60 molecule is surrounded principally by five [NiL]
molecules (Figure 5). Three of them (A, B′, and C′ in Figure
5) contribute their large concavities (that is, concavities formed
by the six-membered rings) whereas the other two (“B and C”
in Figure 5) donate their minor concavities (concavities formed
by five-membered and phenylene rings). Many other inclusion
compounds with C60 as a guest are already known,3-5,7,48-57
but none display this kind of fit between the convex surface of
the C60 and the concave surfaces of several host molecules. The
surroundings are completed by other guest molecules, including
CS2 and another C60 molecule approaching the first at a C-C
distance of 3.90 Å. This shortest C60-C60 contact takes place
across the symmetry center at (0,0,0.5). The distance between
centroids of the adjoining fullerene molecules is 10.8 Å.
The interplay of host and guest molecules is shown in Figure
6. The molecules B of the complex (black) donate both of their
concavities to create sockets for C60 molecules, resulting in
alternating [NiL] and C60 molecules along the a direction. An
analogous motif was previously found for the related material
[Ni(OMTAA)]*(C60)*2(CS2).4 In the layer parallel to the (ab)
plane the sockets are completed with [NiL] (C) and CS2 (D)
Figure 5. One C60 molecule (large balls) surrounded by the host (black
sticks) and carbon disulfide (ball-and-stick) molecules in 3[NiL]*(C60)-
*2(CS2). The projection axis is the same as in Figure 4.
molecules. These layers alternate with inverted ones along the
c direction. In the layer parallel to the (ac) plane the A molecules
contribute their large concavities to the sockets and stack by
their minor concavities as in the CH2Cl2 compound (with 7.01
Å between Ni centers). As a whole, the architecture is
surprisingly complex and entirely different from what has been
observed before for analogous host complexes.3-10
13C NMR of Isolated Solids. 13C CP/MAS NMR spectra of
all four compounds are shown in Figure 7, and shifts and
assignments are given in Table 2. As a whole, the data indicate
that all of the solid phases contain [NiL] in a similar isomeric
state and have the same basic geometry. The absence or presence
of guests is also seen to be consistent with the claimed
stoichiometries.
The spectra of the low and high forms of the host [NiL]
complex, Figure 7a,b, have very similar maxima, but the low
form shows line broadening. Since the PXRD pattern of the
low form (Figure 1) shows it to be crystalline this broadening
is most likely due to trace paramagnetic impurities. Probably
both forms have the complex in a very similar conformation
and may have similar packing motifs, resulting, however, in
different crystal structures.
Examination of the spectra of the high form and [NiL]*(CH2-
Cl2), Figure 7b,c, d, reveal that these are similar to that for [NiL],
although small differences in the shifts and splitting patterns
are clear indicators of differences in the carbon environments.
Doublets for -CH3, bridging >C-H and the quaternary carbons
on the phenyl groups (carbons e) in both materials indicate that
there is more than half an L in the asymmetric unit. The
quaternary carbons of the phenylene groups and those attached
to N also show multiplicities that are incompatible with only
half a molecule in the asymmetric unit. The intensity of the

Nickel(II) Tetraazaannulenate
Inorganic Chemistry, Vol. 40, No. 22, 2001 5665
Figure 6. Views of the crystal packing in 3[NiL]*(C60)*2(CS2). (a) A
layer parallel to the (ab) plane (half thickness of the unit cell); host B
and C molecules are outlined in black and white sticks, respectively.
(b) A layer parallel to the (ac) plane (thickness of the unit cell); host
A molecules are outlined in white sticks.
Figure 7. 13C CP/MAS NMR spectra of solid [NiL] compounds: (a)
Low polymorph; (b) High polymorph; (c) [NiL]*(CH2Cl2); (d)
[NiL]*(CH2Cl2), dipolar dephased; (e) 3[NiL]*(C60)*2(CS2), the inset
shows the C60 line shape, static (top), MAS (below). The lines in the
region 30-80 ppm are spinning sidebands from the aromatic region,
with the exception of the CH2Cl2 resonance in (c) and (d).
guest CH2Cl2 carbon indicates a ∼1:1 host per guest ratio. This
implies that the asymmetric unit contains either an asymmetric
L molecule or 2 L molecules each with equivalent halves.
Figure 7d shows the dipolar dephased spectrum of [NiL]*-
(CH2Cl2), which is typical of the dephased spectra for all four
compounds studied. The dipolar dephased spectra show only
the quaternary carbons at full intensity, and any proton-bearing
carbons undergoing motion at reduced intensity. Thus the methyl
groups of the host and the CH2Cl2 guest show dynamics. Also,
there is a small amount of residual intensity in the aromatic
region due to a motion which is probably a partial reorientation
of the phenyl groups about their 2-fold axes. The phenylene
groups can be expected to be quite rigid, and any motion other
than those about the 2-fold axis would imply motion of the
whole complex.
asymmetric unit: CH3 (1:2:1:1:1), bridging CH (3:2:1), and
phenyl quaternaries (1:1:2:2). Experiments without CP but with
1H decoupling indicate that the C60 atoms have a much shorter
relaxation time than the other carbons, which probably reflects
its dynamics (see below), but using a 5-minute recycle time
the system appears to be fully relaxed, and the relative intensity
of the C60 versus the other carbons is consistent with the unit
cell content to within 15%. On the other hand, one can
discriminate against the C60 signal by using a short CP time;
there is a roughly 12-fold increase in intensity relative to the
most intense lines of the [NiL] between CP ) 1 ms and 20 ms.
Also note that with increasing CP time the quaternary carbons
of [NiL] gain intensity less rapidly than the proton-bearing
carbons. For the C60 and the quaternaries of [NiL] the lack of
attached 1H’s means that the CP is long range and 13C
The 13C CP/MAS spectrum of 3[NiL]*(C60)*2(CS2), Figure
7e, is more complex than those for the host polymorphs or the
CH2Cl2 compound. In particular, several resonances show
multiplets consistent with six-half [NiL] molecules in the

5666 Inorganic Chemistry, Vol. 40, No. 22, 2001
Soldatov et al.
Table 2. Assignments of 13C NMR Chemical Shifts (ppm) of [NiL]
Compounds (relative intensity in brackets)
of the chemical shift, however this was not detectable within
experimental limitations.
[NiL],
[NiL],
[NiL]*
3[NiL]*
[NiL] vs Other Dibenzotetraaza[14]annulenates. As shown
in this study, the [NiL] complex has certain attributes common
to molecular hosts: in particular, a conformationally stable
molecular structure, and variability of crystal packing.
No.a low form high form
(CH2Cl2)
(C60)*2(CS2)
CH3
2
2
21.7
25.8
21.7 (1)
25.9 (1)
23.1 (1)
24.9 (1)
21.7 (1)
22.7 (1)
23.2 (1)
25.2 (2)
27.4 (1)
112.5 (1)
114.3 sh (2)
115.4 (3)
120.1
The geometry of the [NiL] complex remains very similar for
all four independent molecules found in the two inclusion
complexes studied. This geometry is largely determined by the
strained coordination environment of the metal center. The short
Ni-N bonds are consistent with a low-spin state of the nickel
center arising from the tetragonal distortion characteristic of d8
and d9 cations. The complex therefore is diamagnetic, in both
the solid state and in solution. The restraints imposed by the
narrow coordination cavity of the macrocycle prevent transfor-
mation of the complex into a high-spin state through the
formation of two additional axial bonds. Even crystallizations
from neat pyridines do not change the square-planar coordination
environment of the nickel center. Another consequence of the
narrow coordination cavity is the rigid saddle-shaped conforma-
tion of the molecule, as this conformation makes it possible to
increase the dimensions of the cavity to some extent. The
resulting overall geometry is therefore very similar to that of
other, simpler complexes. For example, the average Ni-N
distance and dihedral angle between two phenylenes equal to
1.860(4) Å (16 bonds) and 121(3)° (4 molecules) for [NiL] in
the two structures of our work are quite similar to respective
values of 1.868(1) Å (42 bonds) and 125(1)° (14 molecules)
found in six inclusion compounds3,5 and two guest-free forms67,5
of the [Ni(TMTAA)] complex. Another comparison may be
made with the guest-free structure of [CuL], reported earlier.68
Longer coordination bonds with Cu-N (average distance of
1.923(3) Å for 8 bonds) result in greater distortion of the
coordination unit and thus the dihedral angles between the
phenylenes equal 136° and 133° for two [CuL] molecules.
Overall, however, the [CuL] species has the same type of
geometry as [NiL].
>C-H
∼115
∼117
115.2 (1)
117.7 (1)
111.7 (1)
118.1 (1)
aromatic 18 120.4 sh 120.2
120.4 sh
(a,b,a′,b′,
122.3
123.8 sh 123.7 sh
122.3
(8) 122.1
(8) 121.2
}
}
f′,g′,h′)b
122.8
126.1
122.0
(24)
122.4 sh
124.3
}
127.1 sh 127.9 sh
128.3
∼129
128.5
130.1
(10) 128.4
(10)
}
129.8 sh
131.1 sh
125.4 sh
126.0
127.2 sh
127.6
}
128.2
128.9
(30)
129.6
130.2 sh
132.6
133.6
}
quaternary 2
138.2
139.2 sh 139.4 (1)
138.1 (1)
135.8 (1)
140.1 (1)
138.9 (2)
139.6 (2)
140.3 (1)
141.1 (1)
147.8 (5)
148.2 sh (4)
149.2 sh (2)
149.9 sh (1)
154.5 sh (1)
e′
quaternary 4
146.4 sh 146.5 sh (1) 147.3 (2)
147.6
148.6 sh 148.6 sh (1)
c and c′
147.5 (2)
148.8 (2)
quaternary 4
155.7
158.1
155.7 (3)
158.2 (1)
154.6
d and d′
156.1 sh (4) 155.4 (2)
}
157.1 sh
156.7 (5)
157.4 sh (4)
CH2Cl2
C60
CS2
1
20
2/3
55.4 (1)c
143.8
192.6c
194.1
a Number of carbons per NiL unit. b See Scheme 2 for letter
designations. c Liquid CH2Cl2 at 54.4 ppm, liquid CS2 at 193.1 ppm.58
Crystal packing is a variable characteristic of the [NiL]
complex since two guest-free and two inclusion forms have been
magnetization takes longer to build up. There are two resonances
for CS2, again consistent with the asymmetric unit content. In
this instance, prohibitively long experimental times would be
required to obtain accurate relative intensities of the guest
molecules relative to those of the host.
The inset of Figure 7e shows the C60 resonance with
halfwidths of only 247 Hz (static) and ∼18 Hz (MAS).
Averaging of the chemical shift anisotropy (csa) to such a
narrow line unequivocally indicates rapid pseudo-isotropic
reorientation of the C60 molecule, as found in solid C60 itself at
room temperature (the csa for the C atoms of a static C60
molecule has a span )180 ppm ()13 587 Hz at a field of
7T)).59-66 This could be reorientation in such a manner that all
of the C atoms exchange sites or it could be rotational diffusion
over a sphere. The lattice site itself does not have high
symmetry, and so in theory there could be residual anisotropy
(53) Atwood, J. L.; Barbour, L. J.; Raston, C. L.; Sudria, I. B. N. Angew.
Chem., Int. Ed. Engl. 1998, 37, 981-983.
(54) Veen, E. M.; Postma, P. M.; Jonkman, H. T.; Spek, A. L.; Feringa,
B. L. Chem. Commun. 1999, 1709-1710.
(55) Tashiro, K.; Aida, T.; Zheng, J. Y.; Kinbara, K.; Saigo, K.; Sakamoto,
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1996, 24, 301-310.
(57) Hu, H. C.; Liu, Y.; Zhang, D. D.; Wang, L. F. J. Inclusion Phenom.
1999, 33, 295-305.
(58) Breitmaier, E.; Voelter, W. In Carbon-13 NMR Spectroscopy, 3rd ed.,
VCH: New York, 1987; p 233.
(59) For NMR of solid C60 see refs 60-64.
(60) Yannoni, C. S.; Johnson, R. D.; Meijer, G.; Bethune, D. S.; Salem, J.
R. J. Phys. Chem. 1991, 95, 9-10.
(61) Tycko, R.; Dabbagh, G.; Fleming, R. M.; Haddon, R. C.; Makhija,
A. V.; Zahurak, S. M. Phys. ReV. Lett. 1991, 67, 1886-1889.
(62) Tycko, R.; Haddon, R. C.; Dabbagh, G.; Glarum, S. H.; Douglass, D.
C.; Mujsce, A. M. J. Phys. Chem. 1991, 95, 518-520.
(63) Fowler, P. W.; Lazzeretti, P.; Malagoli, M.; Zanasi, R. J. Phys. Chem.
1991, 95, 6404-6405.
(48) For examples of other materials with C60 see refs 49-57.
(49) Pekker, S.; Faigel, G.; Fodor-Csorba, K.; Granasy, L.; Jakab, E.; Tegze,
M. Solid State Commun. 1992, 83, 423-426.
(50) Tegze, M.; Bortel, G.; Faigel, G.; Oszlanyi, G.; Pekker, S.; Stephens,
P. W. Nucl. Instrum. Methods Phys. Res., Sect. B 1995, 97, 585-
587.
(51) Matsubara, H.; Shimura, T.; Hasegawa, A.; Semba, M.; Asano, K.;
Yamamoto, K. Chem. Lett. 1998, 1099-1100.
(52) Takeshita, M.; Suzuki, T.; Shinkai, S. Chem. Commun. 1994, 2587-
2588.
(64) Yannoni, C. S.; Bernier, P. P.; Bethune, D. S.; Meijer, G.; Salem, J.
R. J. Am. Chem. Soc. 1991, 113, 3190-3192.
(65) NMR of C60 benzene solvate: He, H.; Barras, J.; Foulkes, J.;
Klinowski, J. J. Phys. Chem. B 1997, 101, 117-122.
(66) NMR of C60 pentane solvate: Aliev, A. E.; Harris, K. D. M.; Tegze,
M.; Pekker, S. J. Mater. Chem. 1993, 3, 1091-1094.
(67) Wang, Y.; Peng, S. M.; Lee, Y. L.; Chuang, M. C.; Tang, C. P.; Wang,
C. J. J. Chin. Chem. Soc. (Taipei) 1982, 29, 217-224.
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Chem. 1995, 34, 159-167.

Nickel(II) Tetraazaannulenate
Inorganic Chemistry, Vol. 40, No. 22, 2001 5667
isolated. The host thus exhibits a general tendency as for many
other systems conventional polymorphism36 and the ability to
include are found together.69 Small guest species such as CH2-
Cl2 or CHCl3 fill out the side pocket of the [NiL] molecule but
the large concave surfaces of the host are still used ineffectively.
Medium sized molecules of other solvents are not complemen-
tary to the host and thus remain indifferent to inclusion. Only
a large globular molecule such as C60 is able to provide
extended, and therefore effective, contact of two complementary
surfaces. The inclusion with C60 is much denser (Table 1) than
that with CH2Cl2, despite having lighter atoms. The [NiL]
therefore may be selective to very specific kinds of potential
guest candidates. This feature is inherent in simpler tetraazaan-
nulenates, [M(TMTAA)] and [M(OMTAA)] (Scheme 1),3-7
though it results in distinct supramolecular architectures.
The specific inclusion properties discussed above may be
significant when it comes to designing other tetraazaannulenates
bearing peripheral substituents. The overall stability of the final
complex may be of crucial significance in such design though.75
The [Ni(TMTAA)] complex is easily prepared by template
condensation (using nickel(II) acetate) of o-phenylenediamine
with acetylacetone, CH3COCH2COCH3, in boiling ethanol (bp
78 °C).44 The synthesis of [NiL] (with benzoylacetone, PhCOCH2-
COCH3) requires the higher temperature of boiling butanol (bp
118 °C) and the resulting complex shows a tendency to
decompose in most solvents. As evident from intramolecular
contacts in [NiL], the phenyl substituents do not create any
greater strain in the molecule than the methyl groups. The
destabilization may be due to the electronic properties of the
phenyl group, or there may be an entropy effect as the
macrocycle formation restricts transient rotation of the phenyls
in the initial reagent. Remarkably, our attempts to perform the
analogous synthesis with dibenzoylmethane (PhCOCH2COPh)
did not produce any condensation at all. Increasing the size of
the macrocycle itself could increase the stability of these and
new host tetraazaannulenates.
Acknowledgment. D.V.S. is grateful for support in the form
of a Visiting Fellowship.
Supporting Information Available: A figure showing the TGA
thermogram of [NiL]*(CH2Cl2). Full data for the structure determination
of [NiL]*(CH2Cl2) and 3[NiL]*(C60)*2(CS2) inclusion compounds at
-100 °C. This material is available free of charge via the Internet at
http://pubs.acs.org.
(69) Examples of versatile organic hosts displaying polymorphism: Gos-
sipol (7 guest-free polymorphs) (refs 70, 71); hydroquinone (3 guest-
free polymorphs) (ref 72); 4,5-Bis(4-methoxyphenyl)-2-(4-nitrophenyl)-
1H-imidazole (3 guest-free polymorphs) (ref 73); perhydrotriphenylene
(2 guest-free polymorphs) (ref 74).
IC0104555
(70) Ibragimov, B. T.; Talipov, S. A. J. Inclusion Phenom. 1994, 17, 325-
328.
(73) Sakaino, Y.; Fujii, R.; Fujiwara, T. J. Chem. Soc., Perkin Trans. 1
1990, 2852-2854.
(71) Gdanec, M.; Ibragimov, B. T.; Talipov, S. A. In ComprehensiVe
Supramolecular Chemistry; MacNicol, D. D., Toda, F., Bishop, R.,
Eds.; Pergamon: Oxford, 1996; Vol. 6, pp 117-145 and refs 48 and
68 therein.
(72) Mak, T. C. W., Bracke, B. R. F. In ComprehensiVe Supramolecular
Chemistry; MacNicol, D. D., Toda, F., Bishop, R. Eds.; Pergamon:
Oxford, 1996; Vol. 6, pp 23-60, and refs 6, 13, 14 therein.
(74) Allegra, G.; Farina, M.; Immirzi, A.; Colombo, A.; Rossi, U.; Broggi,
R.; Natta, G. J. Chem. Soc. B 1967, 1020-1028.
(75) It should be also noted that the template condensation yielding the
macrocyclic ligand is competed with simpler condensation between
o-phenylenediamine and â-diketone: Jaeger, E. G. Z. Anorg. Allg.
Chem. 1969, 364, 177-191.