Modular construction of a series of heteronuclear metallamacrocycles

Article abstract of DOI:10.1039/b809643k

High modularity in a series of heteronuclear d⁸-d¹⁰ metallamacrocycles built on differentiated ligands is demonstrated. The Royal Society of Chemistry.

Full text of DOI:10.1039/b809643k

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Modular construction of a series of heteronuclear metallamacrocyclesw
´
Stephane A. Baudron* and Mir Wais Hosseini*
Received (in Cambridge, UK) 9th June 2008, Accepted 5th August 2008
First published as an Advance Article on the web 29th August 2008
DOI: 10.1039/b809643k
High modularity in a series of heteronuclear d8–d10 metalla-
macrocycles built on differentiated ligands is demonstrated.
Metallo-organic cyclic architectures of the polygon type have
received much attention owing to their inherent shape as well as
potential applications in catalysis, optics or magnetism.1 These
discrete species are defined by the endocyclic role played by
metal centres i.e. the closed structure results from the connec-
tion of the organic ligands by metal centres or complexes.
Among the many structures reported, molecular rectangles
are the most simple and illustrative examples of this class of
molecules. It is interesting to note that the majority of cases
reported so far deal with homometallic species obtained by self-
assembly processes engaging one type of ligand and a unique
metal centre or metal complex. Using a variety of ligands and
metals, we have reported several metallamacrocycles of this
type.2 Heterometallic metallamacrocycles are of interest since
they are based on the precise positioning of at least two different
metal centres within a cyclic architecture. However, the pre-
paration of such assembly is more complex and requires a
stepwise construction approach. We have recently developed a
sequential construction strategy based on organic ligands 1 and
2 (Scheme 1) bearing two differentiated coordination poles, a
primary (enedithiolate) and a secondary one (4,5-diazafluorene).3
As a result of this differentiation, upon reaction with a first
metal complex (Ma) bearing an auxiliary ligand protecting
Scheme 1
Complexes 3 and 4 were prepared in 57 and 72% yield,
respectively by reaction of in situ generated tetraethylammo-
nium salt of 13b with one equivalent of dpppMCl2 (Scheme 1).z
Upon slow diffusion of a MeCN solution of CuBr(SMe2)
into a CH2Cl2 solution of 3, bright orange crystals appeared
after few days. X-Ray diffraction analysis on single crystal
(monoclinic, P21/c) revealed the presence of the centrosym-
metric metallamacrocycle 7 and two CH2Cl2 solvent mole-
cules.y The Cu(I) center is coordinated to the two nitrogen
atoms of the 4,5-diazafluorene moiety and one Brꢀ anion
(Fig. 2). The unsymmetrical nature of the coordination of
the two nitrogen atoms to the Cu(I) is analogous to what has
been reported for other complexes with 4,5-diazafluorene
derivatives.4 Interestingly the formation of Cu–S contact
some of the coordination sites, a discrete species is generated.
The latter, possessing a secondary coordination pole at its
periphery, leads to either homonuclear complexes in the
presence of the same metal Ma or to heterometallic discrete
or infinite network architectures in the presence of a different
protected metal complex (Mb) or metal center, respectively.
Searching for other heterometallic species, we have pursued
our approach using both ligands 1 and 2 and other metal
centres and capped complexes. Unexpectedly, we discovered
that this approach also leads to the formation of [2+2]
heteronuclear metallamacrocycles resulting from the double
interconnection of two heterobimetallic complexes in head-to
tail fashion through sulfur–metal interactions (Fig. 1).
In order to explore the generality of this observation, we
have varied each parameter (L, Ma and Mb and X) and wish to
report herein on a systematic study of the formation of such
species combining ligands 1 and 2 with two metal centres
(Ma = PdII or PtII and Mb = CuI or AgI).
Laboratoire de Chimie de Coordination Organique (UMR 7140),
´
Universite Louis Pasteur, Institut Le Bel, 4 rue Blaise Pascal, 67000
Strasbourg, France. E-mail: sbaudron@chimie.u-strasbg.fr,
E-mail: hosseini@chimie.u-strasbg.fr; Fax: +33 390241325;
Tel: +33 390241323
w CCDC 690632–690637. For crystallographic data in CIF or other
electronic format see DOI: 10.1039/b809643k
Fig. 1 Sequential construction of heteronuclear metallamacrocycles.
ꢁc
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To study the role played by the second metal center (Mb),
another d10 cation, silver(I), was used. A CH2Cl2 solution of 4
was reacted with a MeCN solution of AgSbF6 forming small
ꢀ
orange crystals (triclinic, P1).y The crystal contains 10 and one
CH2Cl2 solvent molecule. Once again, the metallamacrocycle 10,
resulting from the face-to-face disposition of two 4 complexes
interconnected by two Ag–S and one Ag–Pt contacts of 3.220(2),
3.242(2) and 2.9506(6) A is obtained (Fig. 4, top). The later
distance is shorter than the sum of the van der Waals radii
(3.47 A) for Pt and Ag.5 Although AgSbF6 was used, surpris-
ingly, a chloride anion is found in the structure. We have noticed
that when AgOTf was employed, the same chloride complex was
also obtained. To assess whether the halide anion resulted from
the solvent decomposition, the same reaction using CH2Br2 as
solvent instead of CH2Cl2 afforded the analogous metallamacro-
cycle 11 incorporating two Brꢀ anions as a CH2Br2 and water
solvate (Fig. 4, bottom). For the binding of Ag(I) by
4,5-diazafluorene, several coordination modes ranging from
monodentate to bis monodentate have been reported.8 Here,
the Ag(I) cation is coordinated by both nitrogen atoms albeit in
an unsymmetrical fashion, particularly in 10. As for 7, the
4,5-diazafluorene moieties overlap with a p–p stacking distance
of 3.36 and 3.344 A, in 10 and 11, respectively.
Fig. 2 View of the metallamacrocycle 7. The phenyl rings of the dppp
as well as the hydrogen atoms are omitted for clarity. Selected bond
lengths (A): Cu1–N1, 2.278(5); Cu1–N2, 2.150(5); Cu1–Br1, 2.3581(9);
Cu1–S2, 2.3425(14); Cu1–Pd1, 3.1211(8).
(2.3425(14) A) interconnects the two heterometallic moieties 3
and thus leads to the formation of the cyclic structure. In addition
to Cu–S contact, p–p stacking interactions (d = 3.33 A) between
the two 4,5-diazafluorene moieties are also present. Furthermore,
a short Cu–Pd distance is also observed (3.1211(8) A).
In order to investigate the role played by the ligand and the
first metal center (Ma), the palladium and platinum complexes
5 and 6, respectively were prepared in 87 and 52% yield,
respectively and characterized by solution NMR, UV-vis,
mass spectrometry and X-ray single crystal analysis (not
presented here).z Reaction of 5 in CHCl3 with one equivalent
of CuBr(SMe2) in MeCN led to dark red crystals (triclinic,
In order to investigate the role played by the ligand, the
complex 6 based on the ligand 2 was used, leading to the
crystallization of the metallamacrocycle 12 (monoclinic P21/c)
as a CH2Cl2 and CH3CN double solvate.y This macrocycle has
an arrangement analogous to the one observed for 9. A short
Pt–Ag distance is detected (Fig. 5).
ꢀ
P1).y The latter is composed of 8 and six CHCl3 solvent
molecules (Fig. 3, top). The geometry around the metal center
is rather similar to the one observed for 7 with a Cu–Pd
distance of 2.9314(14) A, shorter than the sum of the van der
Waals radii, 3.03 A,5 suggesting the presence of d8–d10 inter-
actions6 as previously observed for other dithiolate based
complexes.7 The main difference between the two metallama-
crocyles 7 and 8 lies in their size, a direct result of the structure
of the bridging ligands 1 and 2. When using the platinum
complex 6, isomorphous crystals containing 9 and six CHCl3
solvent molecules were obtained and analysed by XRD.y As
showed in Fig. 3 (bottom) the metallamacrocycle presents an
analogous structure with a Cu–Pt distance of 2.909(2) A
shorter than the sum of the van der Waals radii (3.15 A)5
implying again the same type of d8–d10 interactions.
The stability of the metallamacrocycles in solution was
probed by electrospray mass spectrometry for compounds 7,
8, 9 and 12. In all cases, the metallamacrocyles could be
identified. Unfortunately, owing to the very limited solubility
of these compounds in common organic solvents, no solution
NMR studies could be performed.
In conclusion, we have discovered a robust sequential
strategy for the synthesis of new heteronuclear [2+2]
Fig. 3 View of the metallamacrocycles 8 (top) and 9 (bottom). The
phenyl rings of the dppp as well as the hydrogen atoms are omitted for
clarity. Selected bond lengths (A): for 8, Cu1–N1, 2.149(8); Cu1–N2,
2.331(8); Cu1–Br1, 2.3590(17); Cu1–S1, 2.349(3); Cu1–Pd1 2.9314(14).
For 9: Cu1–N1, 2.132(13); Cu1–N2, 2.351(15); Cu1–Br1, 2.372(3);
Cu1–S1, 2.395(5); Cu1–Pt1, 2.909(2).
Fig. 4 View of the metallamacrocycles 10 (top) and 11 (bottom). The
phenyl rings of the dppp as well as the hydrogen atoms are omitted for
clarity. Selected bond lengths (A): for 10: Ag1–N1, 2.508(6); Ag1–N2,
2.357(6); Ag1–Cl1, 2.4495(15); Ag1–S1, 3.220(2); Ag1–S2, 3.242(2);
Ag1–Pt1, 2.9506(6). For 11: Ag1–N1, 2.423(9); Ag1–N2, 2.501 (9);
Ag1–Br1, 2.5634(12); Ag1–S1, 2.746(2); Ag1–Pd1, 3.0424(11).
ꢁc
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all data. Crystal data for [(6)CuBr]2(CHCl3)6, 9: C88H70Br2Cl18Cu2N4-
ꢀ
P4Pt2S8, M = 2879.02, triclinic, space group P1 (No. 2), a =
13.5454(13), b = 13.6020(13), c = 14.9359(15) A, a = 70.051(6),
b = 87.390(6), g = 82.447(6)1, V = 2564.3(4) A3, T = 173(2) K,
Z = 1, Dc = 1.864 g cmꢀ3, m = 4.648 mmꢀ1, 16 484 collected
reflections, 10 180 independent (Rint = 0.0834), GooF = 0.983, R1
=
0.0934, wR2 = 0.2233 for I 4 2s(I) and R1 = 0.1807, wR2 = 0.2944 for
all data. Crystal data for Crystal data for [(4)AgCl]2(CH2Cl2), 10:
ꢀ
C79H66Ag2Cl4N4P4Pt2S4, M = 2071.20, triclinic, space group P1
(No. 2), a = 9.9781(2), b = 12.6890(3), c = 17.2016(4) A, a =
101.3700(10), b = 96.1060(10), g = 109.7470(10)1, V = 1974.00(8)
A3, T = 173(2) K, Z = 1, Dc = 1.742 g cmꢀ3, m = 4.388 mmꢀ1, 28772
collected reflections, 8915 independent (Rint = 0.0449), GooF = 1.070,
Fig. 5 View of the metallamacrocycle 12. The phenyl rings of the
dppp as well as the hydrogen atoms are omitted for clarity. Selected
bond lengths (A): Ag1–N1, 2.479(9); Ag1–N2, 2.478(8); Ag1–Cl1,
2.497(2); Ag1–S1, 2.914(2); Ag1–Pt1, 2.9396(8).
R1 = 0.0361, wR2 = 0.0981 for I 4 2s(I) and R1 = 0.0539, wR2
0.1140 for all data. Crystal data for [(3)AgBr]2(CH2Br2)(H2O), 11:
=
ꢀ
C79H68Ag2Br4N4OP4Pd2S4, M = 2089.67, triclinic, space group P1
metallamacrocycles of the [(L, Ma, Mb, X)]2 type. The systema-
tic study revealed the possibility of combining Pd and Pt d8 and
Cu and Ag d10 cations with two different dithiolate and halide
(Clꢀ, Brꢀ) ligands. We have also demonstrated that the size of
the cyclic structure may be modulated by the length of the
ligand. Finally, the formation of the metallamacrocycles results
from three types of interactions (S–Mb, p–p stacking and
d8–d10). Extension to Au(I) as well as other extended sulfur
based ligands and blocking phosphines is currently under way.
(No. 2), a = 10.2098(3), b = 12.0948(4), c = 17.5469(6) A, a =
101.960(2), b = 95.545(2), g = 104.022(2)1, V = 2031.83(11) A3, T =
173(2) K, Z = 1, Dc = 1.708 g cmꢀ3, m = 3.104 mmꢀ1, 26 156 collected
reflections, 9324 independent (Rint = 0.0467), GooF = 1.073, R1
=
0.0794, wR2 = 0.2239 for I 4 2s(I) and R1 = 0.1168, wR2 = 0.2579
for all data. Crystal data for [(6)AgCl]2(CH2Cl2)2(CH3CN)2, 12:
C88H74Ag2Cl6N6P4Pt2S8, M = 2414.51, monoclinic, space group
P21/c (No. 14), a = 9.8721(2), b = 16.2902(4), c = 27.9170(7) A,
b = 100.0700(10)1, V = 4420.41(18) A3, T = 173(2) K, Z = 2, Dc =
1.814 g cmꢀ3, m = 4.084 mmꢀ1, 34440 collected reflections, 10 142
independent (Rint = 0.0600), GooF = 1.046, R1 = 0.0549, wR2
=
0.1507 for I 4 2s(I) and R1 = 0.0905, wR2 = 0.1798 for all data.
We thank the Universite Louis Pasteur, the Institut Uni-
´
versitaire de France, the Ministry of Education and Research
and CNRS for financial support.
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Notes and references
z Analytical data for 3: dH(300 MHz, CDCl3) 8.78 (2H, dd, J = 1.2 and
8.1 Hz), 8.47 (2H, dd, J = 1.2 and 4.6 Hz), 7.62 (8H, m), 7.42 (12H, m),
7.11 (2H, dd, J = 4.6 and 8.1 Hz), 2.59 (4H, br m), 2.11 ppm (2H,
Fischer, Chem. Commun., 1998, 1625; (b) A. Jouaiti, M. Loı, M. W.
¨
br m); dP(121.5 MHz, CDCl3) 9.22 ppm. ES-MS: 783.05 [3 + Na]+
,
Hosseini and A. De Cian, Chem. Commun., 2000, 2085; (c) C.
Klein, E. Graf, M. W. Hosseini, A. De Cian and N. Kyritsakas-
Gruber, Eur. J. Inorg. Chem., 2003, 1299; (d) P. Grosshans, A.
Jouaiti, V. Bulach, J.-M. Planeix, M. W. Hosseini and N.
Kyritsakas, Eur. J. Inorg. Chem., 2004, 453; (e) E. Deiters, V.
Bulach and M. W. Hosseini, New J. Chem., 2006, 30, 1289.
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5260; (b) S. A. Baudron and M. W. Hosseini, New J. Chem., 2006,
30, 1083; (c) S. A. Baudron, M. W. Hosseini, N. Kyritsakas and M.
Kurmoo, Dalton Trans., 2007, 1129.
761.06 [3 + H]+. lmax(CH2Cl2)/nm 319 (e/dm3 molꢀ1 cmꢀ1, 22400),
370 (25 000, sh), 388 (37 400), 406 (37 300). Analytical data for 4: dH(300
MHz, CDCl3) 8.69 (2H, d, J = 8.4 Hz), 8.46 (2H, d, J = 4.8 Hz), 7.66
(8H, m), 7.42 (12H, m), 7.14 (2H, dd, J = 8.4 and 4.8 Hz), 2.68 (4H,
br m), 2.15 ppm (2H, br m); dP(121.5 MHz, CDCl3) ꢀ2.97 ppm (JPtP
=
2813 Hz). ES-MS: 873.10 [4 + Na]+, 850.11 [4 + H]+. lmax(CH2Cl2)/
nm 319 (e/dm3 molꢀ1 cmꢀ1 9800), 370 (20 000), 394 (32 700),
412 (35 700). Analytical data for 5: dH(300 MHz, CDCl3) 8.53 (2H, dd,
J = 1.3 and 4.8 Hz), 7.97 (2H, dd, J = 1.3 and 8.1 Hz), 7.59 (8H, m),
7.39 (12H, m), 7.24 (2H, dd, J = 4.8 and 8.1Hz), 2.64 (4H, br m),
2.21 ppm (2H, br m); dP(121.5 MHz, CDCl3) 3.99 ppm. ES-MS: 870.98
[5 + Na]+, 848.00 [5 + H]+. lmax(CH2Cl2)/nm 292 (e/dm3 molꢀ1 cmꢀ1
42500), 320 (29 900, sh), 442 (11 800, sh), 492 (26 400). Analytical data
for 6: dH(300 MHz, CDCl3) 8.55 (2H, dd, J = 1.5 and 4.8 Hz), 8.00 (2H,
dd, J = 1.5 and 8.4 Hz), 7.60 (8H, m), 7.39 (12H, m), 7.25 (2H, dd, J =
4.8 and 8.4 Hz), 2.75 (4H, br m), 2.23 ppm (2H, br m); dP(121.5 MHz,
4 P. Kulkarni, S. Padhye, E. Sinn, C. E. Anson and A. K. Powell,
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CDCl3) ꢀ5.29 ppm (JPtP = 2692 Hz). ES-MS: 961.05 [6 + Na]+
,
938.07 [6 + H]+. lmax(CH2Cl2)/nm 307 (e/dm3 molꢀ1 cmꢀ1 23900), 321
(25 900), 334 (20 000, sh), 488 (24 100). Analytical data for 7: ES-MS:
1729.39 [(3)2Cu2Br]+, 1585.44 [(3)2Cu]+. Analytical data for 8: ES-MS:
1904.69 [(5)2Cu2Br]+, 1761.85 [(5)2Cu]+. Analytical data for 9: ES-MS:
2081.94 [(6)2Cu2Br]+, 1939.10 [(6)2Cu]+. Analytical data for 12: ES-
MS: 1883.18 [(6)2Ag]+
.
y Crystal data for [(3)CuBr]2(CH2Cl2)2, 7: C80H68Br2Cl4Cu2N4P4Pd2S4,
M = 1979.00, monoclinic, space group P21/c (No. 14), a = 16.2955(4),
b = 9.4183(2), c = 26.7138(7) A, b = 103.598(2)1, V = 3985.00(17) A3,
T = 173(2) K, Z = 2, Dc = 1.649 g cmꢀ3, m = 2.339 mmꢀ1, 57135
collected reflections, 9202 independent (Rint = 0.0682), GooF = 1.078,
7 (a) D. Coucouvanis, N. C. Baenziger and S. M. Johnson, Inorg.
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and P. G. Jones, Inorg. Chem., 2001, 40, 6193; (d) J. Vicente, P.
R1 = 0.0496, wR2 = 0.1361 for I 4 2s(I) and R1 = 0.0844, wR2
0.1612 for all data. Crystal data for [(5)CuBr]2(CHCl3)6, 8:
=
Gonzalez-Herrero, Y. Garcia-Sanchez, P. J. Jones and D. Bautista,
´ ´
Inorg. Chem., 2007, 46, 4718.
ꢀ
C88H70Br2Cl18Cu2N4P4Pd2S8, M = 2701.64, triclinic, space group P1
8 (a) Q. Y. Zhu, Y. Zhang, J. Dai, G. Q. Bian, D. X. Jia, J. Z. Zhang
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P.-T. Chou, Inorg. Chem., 2004, 43, 4781.
(No. 2), a = 13.5736(5), b = 13.6129(6), c = 14.8510(6) A, a =
69.876(2), b = 87.186(2), g = 82.441(2)1, V = 2554.17(18) A3, T =
173(2) K, Z = 1, Dc= 1.756 g cmꢀ3, m = 2.283 mmꢀ1, 29 900 collected
reflections, 11264 independent (Rint = 0.0593), GooF = 1.130, R1
=
0.0961, wR2 = 0.2409 for I 4 2s(I) and R1 = 0.1289, wR2 = 0.2714 for
ꢁc
This journal is The Royal Society of Chemistry 2008
4560 | Chem. Commun., 2008, 4558–4560