An infinite 2D polyrotaxane network in Ag2(bix)3(NO3)2 (bix = 1,4-bis(imidazol-1-ylmethyl)benzene)

Full text of DOI:10.1021/ja9642626

2952
J. Am. Chem. Soc. 1997, 119, 2952-2953
An Infinite 2D Polyrotaxane Network in
Ag (bix) (NO (bix )
,4-Bis(imidazol-1-ylmethyl)benzene)
2
3
3 2
)
1
Bernard F. Hoskins, Richard Robson,* and Damian A. Slizys
School of Chemistry, UniVersity of Melbourne
ParkVille, Victoria 3052, Australia
ReceiVed December 11, 1996
A quarter of a century after the appearance of Schill’s famous
1
book, interest in catenanes, I, and rotaxanes, II, continues
unabated.2 In the true rotaxanes, II, the stops at the ends of
the dumbell-like component condemn the two otherwise free
and independent partners to everlasting intimacy: in the
psuedorotaxanes, III, the stops are lacking.
Figure 1. One of the {Ag (bix) } linear polymeric chains. Larger
circles represent Ag. Smaller circles represent C/N.
2
3 n
It has been pointed out that interpenetrating networks, of
which many new examples have been discovered in recent years,
3
display ordered polycatenane associations on a grand scale.
Polypsuedorotaxanes in which macrocycles such as cyclic
polyethers and cyclodextrins are threaded onto polymer chains
4
of various sorts have been described. Sauvage has recently
reported yet another elegant application of coordination chem-
Figure 2. A 2D polyrotaxane network showing parts of six independent
linear polymeric chains. Larger circles represent Ag.
istry in the generation of polyrotaxane-like thin films on
electrode surfaces.5 A very recent report describes a true
polyrotaxane in which every ring is restricted to a particular
segment of the polymer by two flanking stoppers.6 We report
here a coordination polymer consisting of 1D polymeric chains
of type IV which are knitted together, as in V, to generate a
2
D polyrotaxane sheet.
(
0.78 g, 4.46 mmol) in methanol (50 mL) was heated under
reflux (18 h). Removal of methanol by evaporation gave a
yellow syrup which was dissolved in aqueous K2CO3 (6.13 g,
1
00 mL). This solution, upon standing, yielded crystalline bix
dihydrate which was further recrystallized from water. Yield
of bix dihydrate: 0.65 g (53%). Anal. Calcd for C14H14N4‚
2
2
H2O: C, 61.3; H, 6.6; N, 20.4. Found: C, 61.3; H, 6.5; N,
0.3. The product was further characterized by single-crystal
8
X-ray diffraction. Unsolvated Ag2(bix)3(NO3)2 separated from
reaction mixtures obtained by combining bix dihydrate (411 mg)
in methanol (25 mL) with silver nitrate (170 mg) in aqueous
methanol (3 mL of H2O, 22 mL of CH3OH). Anal. Calcd for
C42H42Ag2N14O6, i.e., Ag2(bix)3(NO3)2: C, 47.9; H, 3.7; Ag,
The ligand affording this polyrotaxane coordination polymer
is 1,4-bis(imidazol-1-yl-methyl)benzene, VI, hereafter bix,
7
which has been previously reported but which can be more
conveniently obtained as follows: a solution containing imi-
dazole (3.16 g, 46.4 mmol) and R,R′-dichloro-p-xylene
2
0.5; N, 18.6. Found: C, 47.8; H, 4.0; Ag, 20.5; N, 18.6.
Crystals obtained directly from the reaction mixture in this way
were suitable for single-crystal X-ray diffraction study.9
(
1) Schill, G. Catenanes, Rotaxanes and Knots; Academic Press: New
The C/N/Ag arrangement within an individual polymer chain
of the basic type represented in IV is shown in Figure 1. The
York, 1971.
(2) Glink, P. T.; Schiavo, C.; Stoddard, J. F.; Williams, D. J. J. Chem
Soc., Chem. Commun. 1996, 1483 and references therein. Vogtle, F.;
Dunnwald, T.; Schmidt, T. Acc. Chem. Res. 1996, 29, 451 and references
therein.
(8) To be published.
(9) Crystal data: Ag2(bix)3(NO3)2, MW ) 1054.62, monoclinic, space
(
3) Hoskins, B. F.; Robson, R. J. Am. Chem. Soc. 1990, 112, 1546.
4) Agam, G.; Graiver, D.; Zilkha, A. J. Am. Chem. Soc. 1976, 98, 5206.
group P21/n (nonstandard setting of no. 14), a ) 13.763(2) Å, b ) 10.580-
-
3
(
(2) Å, c ) 14.812(2) Å, â ) 95.94(1)°, Z ) 2, Fc ) 1.63 cm , Fm )
-
3
-1
Shen, Y. X.; Xie, D.; Gibson, H. W. J. Am. Chem. Soc. 1994, 116, 537.
Harada, A.; Li, J.; Kamachi, K. Nature 1993, 364, 516. Harada, A.; Li, J.;
Kamachi, M. J. Am. Chem. Soc. 1994, 116, 3192. Gibson, H. W.; Bheda,
M. C.; Engen, P. T. Prog. Polym. Sci. 1994, 19, 843.
1.64(1) g cm , µ(Cu KR) ) 78.73 cm , F(000) ) 1068. Intensity data
were measured at 295(1) K with Cu KR radiation (graphite monochromator)
using an Enraf-Nonius CAD-4 MachS diffractometer and employing the
ω/2θ scan method; absorption and extinction corrections were applied. A
2
(
5) Kern, J.-M.; Sauvage, J.-P.; Bidan, G.; Billon, M.; Divisia-Blohorn,
B. AdV. Mater. 1996, 8, 580.
6) Yamaguchi, I.; Osakada, K.; Yamamoto, T. J. Am. Chem. Soc. 1996,
18, 1811.
7) Dahl, P. K.; Arnold, F. H. Macromolecules 1992, 25, 7051.
full-matrix least-squares refinement based on F (SHELXL-93) was then
employed with anisotropic thermal parameters applied to all non-hydrogen
(
atoms. At convergence R1 ) 0.0542 and wR2 ) 0.1444 for the 4144
2
2
1
reflections with I g 2σ(I), where R1 ) ∑|∆F|/∑|Fo| and wR ) [∑[w(Fo
2
2
2 2 0.5
(
- Fc ) ]/∑[w(Fo ) ]] .
S0002-7863(96)04262-X CCC: $14.00 © 1997 American Chemical Society

Communications to the Editor
J. Am. Chem. Soc., Vol. 119, No. 12, 1997 2953
provides both the rodlike segments and two half-loops for
each of the rings of composition Ag2(bix)2. Figure 2 represents
the way the individual chains associate to produce the poly-
rotaxane sheets of type V. The nitrate ions, all of which
are equivalent, are omitted from Figure 2 for the sake of
clarity; they interact very weakly with two neighboring silver
ions through a single one of their oxygen atoms (Ag‚‚‚O )
2
.926(5) and 3.166(6) Å).
All rings are equivalent, as are all rods. Ag‚‚‚Ag distances
are 14.626(2) Å along a rod and 10.503(1) Å across a ring.
Two detailed views of the rod-to-ring rotaxane interaction are
shown in Figure 3 in which no particular association of
component funtional groups is immediately obvious. No face-
to-face aromatic interactions are apparent. There are many
contacts in the range 2.7-3.2 Å of the edge-to-face type recently
1
0
surveyed by Dance et al., the two shortest of which are
highlighted in Figure 3b.
Ag2(bix)3(NO3)2 is unquestionably a polyrotaxane and not a
polycatenane, for no catenane associations are present. A related
polycatenane coordination polymer utilizing a similar 1,4-
1
1
xylene-based ligand was reported recently.
The structure
reported here hints at the likelihood that bix and related ligands
may provide other examples of unusual polyrotaxanes and
polycatenanes. These are possibilities we are presently explor-
ing.
Figure 3. Two detailed views of one rotaxane association. Circles in
order of decreasing radius represent Ag, C/N, and H, respectively. (a,
top) A view almost perpendicular to the ring component. (b, bottom)
A view showing, by broken lines, the two closest hydrogen-to-aromatic
ring atom contacts (two symmetry-related pairs) (distance between the
H of the central phenylene unit and the N indicated, 2.772(5) Å; distance
between imidazole H and the N indicated, 2.684(4) Å).
Acknowledgment. We are very grateful to the Australian Research
Council and the Petroleum Research Fund for support.
Supporting Information Available: Crystal data and data collec-
tion, structure determination and refinement, numbering scheme, and
tables of crystal data, fractional atomic coordinates, isotropic thermal
parameters, and interatomic distances and angles (13 pages). See any
current masthead page for ordering and Internet access instructions.
3
-connecting centers required for the topology shown in IV are
JA9642626
provided by silver, all atoms of which are equivalent. The
metal is located almost exactly within the plane of the N3 donor
set, the angle at silver internal to the ring being 127.3(1)°. Bix
(
10) Dance, I.; Scudder, M. J. Chem. Soc., Chem. Commun. 1995, 1039.
(
11) Goodgame, D. M. L.; Menzer, S.;Smith, A. M.;Williams, D. J.
Angew. Chem., Int. Ed. Engl. 1995, 34, 574.