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Na14K6Tl18M (M = Mg Zn Cd Hg) and Na13.5Sm0

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formation of 1 from Me,SbSbMe, and Me,SbBr. In the gas
phase the components are separated. Mass spectra contain the
characteristic signals of Me,SbSbMe, and Me,SbBr."] The
chemical behavior justifies the description of 1 as an adduct with
dative bonds." 61 The observed equivalence of the dimethylantimony groups is attributed to the inability to distinguish between
dative and covalent Sb-Sb bonds in 1. In addition to the reversible dissociation into the starting materials there are irreversible decomposition processes of 1 leading to the formation
of Me,SbBr,, Me,Sb. and (MeSb),. Even the formation of
these products can be rationalized by consideration of the results of the structural analysis, since both the reversible and the
irreversible decomposition processes may be described as reductive elimination reactions." '1
Na,,K6Tl1,M (M = Mg, Zn, Cd, Hg) and
Na, 3.5Sm0.5K6Tll,Na: Novel Octahedral and
Centered Icosahedral Cluster Phases Related to
the Mg,Znl l-Type Structure **
Zhen-Chao Dong and John D. Corbett"
Alkali-metal-thallium systems are extremely rich in phases
containing thallium cluster anions," -'I perhaps because of both
the approximate 1 : 1 ratio between number of atoms and cluster
charge in the polyanions and the strong relativistic effect for the
element TI.['] The use of more than one type of cation has
proven to be a powerful means for tuning structural stability
because of the increased flexibility for packing the cations and
polyanions efficiently, thereby affording effective routes to new
E2xperirnmtal Procedure
clusters not known in the simpler binary systems. Examples are
All operations were carried out in an argon atmosphere. Dimethylantimony hroTI:- (approximately D3,,) and TI:- (C,,, defect icosahedron)
mide (0.21 g. 0.91 mmol) was added slowly to tetramethyldistibane (0.50 p.
in Na,K,,T1,,[41 and T l ~ : - / T l ~ ~(centered
icosahedra) in
1.65 mmol) [18] through a syringe After the addition. a small amount ofhlack solid
Na,A,TI,, (A = K , Rb. Cs) and Na3K,Tlt,.~61Subsequently.
material precipitated together with yellow crystalsof 1 (yield 0 18 g. 51 4 % ) Compound 1 was stable for several days at room temperature when stored under teNa,,K,TI,,H, a phase structurally related to Na,A,TI,,, has
tramethyldistibane.
been synthesized and shown to contain both T1,H7- and
Received: November 9. 1995
TI,,Na'
3 - p o l y a n i o n ~ .Wade's
~ ~ ~ rules (and extended Hiickel
Revised version: February 9. 1996 [ZX53X IE]
calculations) predict 14 skeletal electrons for the closed-shell
German version: Atigeii Chcrn 1996. f 0 K . 1081~-1082
octahedral TI:- and 26 for either the icosahedral TI;:- or the
Keywords: antimony compounds . structure elucidation
centered TI,,(Na)13-. The composition Na,,K,Tl,, found by
X-ray crystallography indicated a one-electron deficiency for
[I] H. J. Breunig. K . H. Ehert. S. Gulec. M. Drdger. D. B. Sowerhy. M. J. Begley.
the thallium clusters, similar to that for TI::- .I6, 71 However, the
U. Behrens, J Orgutiotner. Chem 1992. 427. 39-48.
I21 H J. Breunig. M. Denker. K . H. Ebert. .
I
Chmn. So(. C h n i C ~ ~ r i i t n ~1994,
n.
compound's contradictory Pauli-paramagnetic and ESR-silent
875-876.
properties, as well as the absence of cluster distortions, gave us
131 Crystal dimensions 0.7 x 0.2 x 0.15 mm. crystal system monoclinic. space
the first hint that hydrogen was present, which was then verified
group i'2,11n, cell dimensions u = 851.30(10) pm. h =1096.60(10)pm.
by the results of subsequent syntheses and and comparisons
('=1137.6(2)pm. ~ = l l 0 . 5 1 0 ( 1 0 ). V=0.9947(2)nrn3. Z = 2 . pLdlL,,=
2 561 M g m - ? 2OmaX= 55 ,Siemens P4 four-circlediffractometer. Mo,, radiawith the structures of related phases. The amazing stabilization
tion , 2 =71.073 pm. scan mode ~ 0 ~ 2 8T ,= 173(2) K. 3198 measured reflecafforded by this small amount of hydrogen (about 0.02 wt %)
tions, 2394 independent reflections. absorption coefficient 9.367 mm- I .
further
suggested a strong electronic drive for closed-shell anion
seiniempirical absorption correction from Jt scans. method of structure soluconfigurations, and therefore opened prospects of further election: direct methods. program used for gtructure solution. SHELXS-X6.
method ofrefinement: full matrix least squares refinement at F2. program uscd
tronic tuning.
for refinement: SHELXL-93, number of free parameters: 76. hydrogen atoms
The most straightforward modification is the substitution of
geometrically positioned and refined with a riding model. final R ( / > 2 u / ) .
the centered Na atom within each TI,, icosahedron by a diposRI = 0.0297, 1rR2 = 0.0682 Further details of the crystal structure investigaitive cation, or partial replacement of exopolyhedral alkalition may he obtained from the Fdchinformationszentrum Karlsruhe. D-76344
Eggenstein-Leopoldshafen (Germany). on quoting the dcpository number
metal cations by higher vaient ions. Ofcourse, the final products
CSD-404399.
are determined not only by electronic and size factors, but also
141 S Samaan in Mutliou'm &lcr Otgurii.sr.h~wC/rcwiic,,H i i i d w - W d . M c ~ r t i h r g u i r i by
generally complex matters of phase stability. We report here
schr Verhinrlrm:$eti A,\ Sh Bi(Ed.: H. Kropf), Thieme. Stuttgart. 1978. p. 479.
the successful tuning of the Na,,K,Tl,,H phase with retention
[5] K . Issleih. H. Hamann. Z. Anor:$. A/!?. Clioii. 1965. 33Y. 289-297.
[6] A. J. Ashe 111. E. G. Ludwig. Jr.. J. Olksyszyn. I. C. Huffinan. Or:$~rnon?~,rolli~\ of the cubic Pn7J symmetry and the formation of novel (H-free)
1984. 3. 337.
TI: - (0,)and M-centered icosahedral TI, ,M1 - ( Th)clusters.
171 0.
Mundt. H. Riffel. Ci. Becker. A . Simon. Z.Nutrufolcr.sch. B 1984, 3Y. 317
These compounds turn out to be related to the long-known
322.
, [91 structure and further demonstrate what kind of
[8] M. Ates. H. J. Breunig. K . Ehert. S. Giilec. R. Kaller. M. Driiger. O r p ~ ~ ) n ~ ~ ~ r r Mg,Zn,
i//its 1992, il. 145-150.
chemical tuning can be performed to produce new duster spe[9] H. J. Breunig, M. Denker, K. H Ebert, J. Or:$unomc,r.Clierii. 1994. 471). 87-92.
cies. Effects of different electron counts on the structures, as well
[I01 R . A. Bartlctt. H. V. Rasika Dias. H Hope. B. D. Murray. M. M. Olinstead,
as correlations with properties, are also briefly discussed.
P. P. Power. J A m . Clioii. So<. 1985. 108. 6921 6926.
Of the substitutions attempted with Zn. Cd, Hg, Mg, Ca, Sm,
[ I l l N C. Norman. Phosphoriu, Sdfirr, Silicon. Relut €/mi.
1994. 87. 167- 176.
[I21 M. Hall. D. €3. Sowerhy. J Organotnrr. C'herii 1988. 347. 59- 70
Eu, Yb, Ni, Pd, and Pt, only those with Zn, Cd, Hg, Mg, and Sm
[13] W. S. Sheldrick. C. Martin, Z. N~i/tir-/ot-.sc/i.
B 1991. 46. 639-646.
were successful. according to both X-ray diffraction data (with
(141 M. Hall. M. Nunii. M . J. Begley, D B. Sowerhy. J Cliiwi. Soc. D d / ( i n 7i.iim
small lattice shrinkages, Table I ) and energy dispersive analysis
1986. 1231 1238.
by X-ray (EDAX) on several single crystals of each product.
[ I 51 L. P;iuling. T/ir /Vuriire o/ tlir Cl~~~rnicul
Butid. 3rd ed.. Cornell University Press.
Ithdc21. I960
Cuinier powder patterns for the rest showed no line shifts with
~
[I61 A. Haaland, Atigrw. Chen?.1989, I O I . 1017- 1032: A t i p i i . Chcwi.I n / . Ed. €ng/.
1989. 28. 992-1007.
[I71 Compound 1 can be described as a stibonium ion of the type [R:RLSb]X.
Reductiveelimination of R'X gives R'RISb. When R'X is eliminated RiR'Sh
is formed. With R' = MezSh. R' = Me and X = Br (coordinated at Me'ShBr)
the elimination of R ' X describes the reversible decomposition to MeZShBrand
Me,Sb2 The irreversible decomposition of 1 with formation ofMc,SbBr2 and
MeSh(ShMe& corresponds to the elimination of R'X. The neutral tristibane
gives (Mesh), and Me,Sh2 on further decompositioii.
[IX] H. J. Breunig. V. Breunig-Lyriti. T. P. Knohloch, Cho?i.-%r,q. 1977. 101. 399400.
[*] Prof. J. D. Corhett. Dr. Z.-C. Dong
Ames Laboratory and Department of Chemistry
Iowa State University
Anies. I A 5001 I (USA)
Fax. Int. code +(515)294-5738
[**I This research was supported by the Office of the Basic Energy Sciences. Materials Sciences Division. U.S. Department of Energy (DOE). Ames Laboratory
is operated lor DOE by Iowa State University under Contract N o D-7405Eng-82.
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[A]
dress how delicately different electron counts can affect both the cluster dimensions and the solvation by
cations
around them. First. the TI-TI distance in the
Ya,,K,Tl,,Ka(H) [a] Na,,K,TI,,Mg Na,,K,TI,,Zn N a , , ,Sm,, ,K,TI,,Na
Empircal
octahedron apparently increases slightly (by
formula
0.008(2) A), from TI,H7- to TI:-. although the cells
11.6194(7)
11 6245(4)
11.5914(6)
l1.6405(4)
0 SJI
contract (by about 0.05 for Mg and 0.02 8, for Zn
3.28912)
3.2113(2)
3.284 ( 2 )
TI1 -TI1
XJ
1.276(1)
and Sm), evidently because (polar) covalent bonding
3.1434(8)
3.1420(8)
3.159817)
M TI7
xi?
31569(5)
from interstitials like hydride usually increases the
3.3105(9)
3.3285(8)
3 312019)
TI2 '1.12
x 4
3.3244(6)
x 1
3.271112)
3.277(2)
3.298(2)
3.299(1)
stabilities of clusters and decreases bond distances
3 345 (9)
3.364 (9)
3.361 ( S )
3.375(6)
a(T11 N;i) x 6
when no matrix effects are involved. While cation in4.449 (6)
4.455(6)
4 473 (6)
TI1 K
x1
4.493(4)
teractions with icosahedral clusters in these com3.258(9)
3.257(8)
3 258(6)
3.25419)
a(T12 Ni l) x z
pounds remain basically the same, solvation of TI:3.687(4)
3.703(4)
3.694(4)
TI?-K
x3
3.700(3)
appears slightly stronger than that for T16H7- as
[a] Ref: [XI. [h] Guinicr data. i = 1.540 562 A, T = 23 C. The cell dimensions for Na,,K,TI,,Cd
judged from the approximately 0.02 A shorter
.ind Na,,K,,Tl,,tlg ;ire 10 62613) A and 10.630816) A. respectively.
(Na,K)-TI distances about the former, consistent
with the cluster's higher formal charge. Second, Mgor Zn-centered icosahedra present shorter center-surface and
respect to the lines for Na,,K,TI,,H (<0.005 A, about 6 o),
surface-surface distances with respect to the Na-centered clusand none of the targeted substitution metals was observed in the
ter (by about 0.02 A), presumably from both the stronger couEDAX data. Single-crystal studiesr1'] were carried out for
lombic and covalent interactions and from the smaller sizes of
Na,,K,(TI,,M) (M = Mg, Zn) and Na,, ,Sm, ,K,(TI,,Na).
M g and Zn. The T1-Mg distance of 3.143(1) 8, compares very
The M elements in the former replace the centering Na to give
well with that of 3.14 A reported in MgTl (CsCI type),1131but
icosahedral TI,,ML2- (and regular octahedral TI:-) while the
the TI-Zn distance (3.142(1) A) is considerably longer than the
Sm atoms in the latter partially substitute [8.3(8)%] on the
2.928 ( 1 ) 8, found in the Zn-centered bicapped square antiprisexopolyhedral Na3 positions leaving the parent T l I 2 N a l 3 - but
matic T1,,Zns- ion in KsTl,oZn.['41The presence of an under;I regular and closed-shell TI:- (Fig. 1). The ascribed closedsized Zn atom within the icosahedron is indicated by its relatively large Be, value (4.88 A')>, and this conclusion is supported by
an anomalously large, spherical residual shell (4.3 e k 3
against
a background near 1.6 e A3) found just 0.02 8, away from the
central Zn site in the difference Fourier map. This is consistent
with the occurrence of the same Na,,K,TI,,M phase for the
somewhat larger Cd and Hg.["] A 3.14 8, center-surface distance appears to be about the lower limit for a thallium icosahedron.
Also noteworthy is the close structural correspondence of
Na,K6TIl3 (bcc, Ims)[61with the present Na,,K,TI,,M ( P d ) ,
namely, [(Na:+) (Ki:+)] [(Tli:-) (TI:!-)] vs. [(Na:+)(Na:+)(K,6+)][(T112M12-)(T1~-)].
The most substantial differences are
the replacement of half the icosahedral units related by I-centering with smaller octahedra, and half of the K + about the latter
by Na', and the change from a TI atom at the center of the
icosahedron to M = Mg, Zn, Cd, or Hg. Otherwise, the cation
dispositions in the two phases show only slight coordinate shifts
that give greater cation-anion interactions with TI:-. A notaFig. I . Atimgerneiit of the discrete Mg-centered icosahedral TI,,Mg"- (T,) and
ble contraction of the icosahedra is also observed, the centeroctahedral TIE- (0,)anions in the unit cell of Na,,K,TI,,Mg (90% thermal ellipsurface distance decreasing from 3.22 8, in TI;:- to 3.14 in
soids).
TI 2 ~ 1 -2.
Of particular interest is the close relationship of the
shell bonding with M is consistent with the weakly Pauli-paraNa,,K,(TI,,M)
structure to the isotypic Mg2Zn,
(and
magnetic property
Na,Cd, ,[I6]), which can also be structurally formulated as
(xM = 8.5(2) x
emu mol-')
for
Na,,K,(Tl,,M), where M = Mg. Zn. A Curie-Weiss-type
Zn,,Mg,(Zn,,Zn,) with Zn in the center of the icosahedron.
Figure 2 shows the alkali-metal cation distributions around the
paramagnetism for Na,,,Sm, ,K,(TI,,Na) (perf= 0.43 (3) pB)
"naked" TI:- (left) and T I l 2 M l 2 - (right) clusters, while Figis consistent with a trivalent Sm state (electron configuration
4f5) and the refined composition (the calculated magnetic moure 3 demonstrates how these units are connected into a threement pe,(for the latter is exactly 0.43 p8), because the S m 2 +(4fb)
dimensional structure, here as well as for Mg2Zn , (see below).
would make no contribution to the magnetic moment, because
The linked network shown about the polyhedra in "salt-like"
alkali-metal-thallium compounds (Fig. 3) does not imply
J = 0. In parallel with their weak Pauli paramagnetism, these
compounds are expected to be poor metals in spite of their
bonding interactions among the cations, but it does highlight a
different zinc substructure in the parent Mg2Zn, The larger
closed-shell configurations, as exemplified by the hydride phase
icosahedral units are held within a cage defined by six zigzag
( ? p / p ? T = 0.34(1)O/0
=100pRcm).Theycantherefore be classified as Zintl phases that are incidentally metaleight-membered rings, while the smaller octahedron is surlic 16. 1 1. 121
rounded by twelve five-membered rings. The accompanying
It is interesting to notice the small but appreciable dimensionshrinkage around the octahedron to preserve suitable bonding
interactions results in six extra contacts between pairs of atoms
al variations between the above phases and Na,,K6TIl,H. Lattice constants and important interatomic distances (Table 1) ad(Na or Zn, represented as gray spheres) that make the former
Table 1 Lnttice constants and important distances
(M = Mg. Zn) and Na,, ,Sm,, ,K,TI,,Na.
in Na,,K,TI,,H.
Nal,K,TIi,M
~~
A
A
,
,.
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Fig. 2. Environments around the octahedral (left) and icosahedral (right) thallium
clusters with the Na sites interconnected to emphasize the relationship to Mg,Zn,,
The doso-deltahedra (large circles, and small shaded circles) represent either TI
clusters. K, atid the two types of Na atonis in Na,,K,TI,,M. o r Zn cluster fragments, Mg, and Zn atoms in Mg,Zn,, , respectively.
atoms (in the place of Na) connect Cu or Au octahedra and
icosahedra. The nature of the interactions between the linked
network and polyhedra undoubtedly undergoes dramatic
changes from Mg,Znt through Mg,AI,Cu, to Na,,K,Tl,,M
as the bonding character changes from homonuclear covalent
through heteronuclear covalent to predominantly ionic. The last
is mechanically the weakest in this series and extremely brittle,
but i t still has a metallic luster.
The title compounds are examples in which electronic tuning
among closed-shell structures is successfully realized. More
chemical tuning about this structure type and new octahedral
and icosahedral clusters can be expected through appropriate
combinations of elements from Groups 1 and 2 and Groups
11-13. In other words: dissection of a structure followed by
manipulation of the numbers and types of atoms in a cluster
compound may produce new cluster materials with novel properties.
E.uperimenta1 Procedures
Fig 3. View ofthe Na,,K,TI,,M and Mg,Zn,, structures onto [OOl] showing three
different substructures and the interconnections among the cations between clusters. Symbols for the atoms are the same as in Fig. 2.
eight-membered ring bicyclic. Inclusion of isolated cations (represented as open circles for K or Mg) leaves all of the T1 or Zn
polyhedra sheathed by 32 atoms functioning in two ways: every
triangular face in both polyhedra is capped whereas each vertex
is exo-bonded to one atom for the icosahedron but to two Na
(or Zn) and two more distant K (Mg) for the octahedron. The
eight atoms face-capping the octahedron (black circles) need
special attention. These positions, always fully occupied by a
single Na or Zn type, are located along the body diagonals in
distorted octahedral holes defined by the neighboring polyhedral units, and so demonstrate that the octahedron and icosahedron are the only two interchangeable cluster units with suitable
cubic symmetry and comparable environments.
Three different substructures are evident in Mg,Zn, : the
same zinc polyhedra (octahedral Zn, and Zn-centered icosahedral Zn,,), in the holes a zinc spacer substructure (linked Zn,,,
like Na), and solvatingcations (Mg", K'). It is these different
structural functions that afford broad chemical variability
through changes in the atom types in the polyhedra, spacers, or
cations. While the parent Mg,Zn,, probably represents the
highest condensation limit, because the two zinc substructures
strongly interact with each other through homonuclear bonding, the present Na,,K,TI, 8M phase represents the opposite
extreme with isolated polyhedral thallium clusters, well-separated by the solvating alkali-metal cations. Some intermediate degrees of condensation {or bonding polarity) must be also possible and are indeed observed in the isomorphous Mg,AI,Cu,
(that is, [(A1,,)(Mg,)][(Cu,,Al)(Cu,)])"71and Na,In,AU,
(that is, [(Ini,)(Na,)J[(Au,,In)(Au,)])['81in which A1 or In
Pure phases of the title compounds were obtained through reactions of stoichiometric amounts oftheconstituent elements i n welded Ta tubing by using the techniques
described previously[4]. The surfaces of the Na chunks (99.9%. Alpha) and TI
metal bar (99.998%. Johnson-Matthey) wereclraned with a scalpel in the glovebox
before use. whereas the K (99.9%. Baker. sealed under Ar). Mg turnings (99.9%.
Aldrich), Zn fillings (99.9%. Fisher), and Sm granules (99.9%. Aines Lab) were
used as received. I n order to establish that hydrogen interstitials were not involved 181, parallel reactions were run both under vacuum (equilibration at 800 C
for 5 h followed by slo\c cooling to room temperature) or jacketed by fused silica
tubing (equilibration at 500 C for three days followed by annealing a t 250 C for
one week) and with different heating profiles. EDAX studies were carried out on a
JEOL X40A SEM with a REBEX DELTA detector with several single crystals of
each phase. The single-crystal X-ray diffraction data were collected on a CAD4
diffractoineter (Mo,,) at room temperature for a n angle of 2 0 up to 55'. Empirical
absorption corrections included $-scans and DIFABS 1191. Magnetic susceptibility
nieasureinents were made at '1 field of 3 T over the range of 6-300 K with
u Quantum Design MPMS SQUID magnetometer on powdered samples of
Na,SK,,TI,,H (52 ing). Na,,K,Tl,,blg (47 mg). Na,,K,TI,,Zn (43 ing). and
N a , , ,Sin,, ,K,TI,,Na (50 ing) iii the container type described elsewhere [16]. The
raw data were corrected foi- the susceptibilities of the container and the diamagnetism of the cores [lo]as well as for the Larmor precession contributions of the
deiocalized valence electrons in the clusters. as before 16. 21). Results arc shown in
the supplementary inateriai
Received: November 21. 1995 [Z 8568 IE]
German version: Ai?goii. Cliiw 1996. 108, 1073- 1076
Keywords: clusters . intermetallic compounds . thallium compounds
[ l ] D. A. Hansen. J. F. Smith. A < . I ~Cj:i.srtr//ogr.
I
1967, 22, 836.
[1]G. Cordicr. V Muller. Z KrurtrNogr. 1992. 198. 281.
[3] 2.-C. Dong. J. D.Corbett. J. A m . Cliwi. Sot. 1993, I l j . 11299.
[4] 2.-C. Dong. 1. D. Corbett. J A m Choir. Soc. 1994. 116. 3429.
[5] 2.-C. Dong. J D. Corbett. J Cflrstrr 5ci. 1995. 6, 187.
[6] Z -C. Dong, J. D. Corbett. J A m . Clwm. Soc. 1995, 117. 6447
[7] G Cordier. V. Muller, Z. Nnrirr/or.sd. 1994, 4 9 B . 935
[8] Z.-C. Dong. J D. Corbett. Iiiorg. Clirnr. 1995, 34. 5709.
[9] S Samson. AI.I[I Chrm Scum/ 1949. 3. 835.
[lo] Crystal data forNa,,K,(TI,,Mg). Na,.K,(TI,,Zn), and N a , , 50,s,Sm,s,,s,K,(TI,,Na) ( i f the data differ. the values are separated by commas): cubic Pm3.
Z = l . u = I l 5914(6). 11.619417). 11.6245(4).k. p = 7 5 3 , 621. 621 cm-',
R, = 0 04. 0.029. 0.03.Typical coordinates (listed for the Mg-phase are: TI1
(6/1).0.2808(1), 11. 1.2:T12(11j3:0.0.15475(8),025325(7);M g ( l r t ) : 0 . 0 ,
0: K (6//.0.1876(8),0, 1 2; N a 2 ( 8 i ) - 0 2812(6), x. x: Na3 ( h g ) :0.330(1). 1 2,
0 The occupancy of Sm (mixed with Na.7. gray circles) in Na,, ,Sm, sK,(TI,,Na) relined within 2 (r of the listed value and was so fixed. in agreement
with a closed-shell bonding model. All other positions were found fully occupied by a single atoin type Further details ofthe crystal structure investigations
may he obtained from J. D.C. or from the Fachinforinationszentrum Karls(Germany) on quoting the depositoruhe. D-76344 Eg~~nstein-Leopoldshafeil
ry number CSD-404694 (Na,,K,TI,,H), 404695 (Na,,K,TI,,Mg). 404696
(Na,,K,,TI,,Zn). 404697 (Na,, Jm, 5K,TI,,Na)
[l 11 R Nesper. Afi,Ceii,. Clirfii 1991. 103. 806: A j r K e i i . Cliem. Ini. €I/. E!ig/. 1991.30.
189.
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[ l ? ] J. I). C'orhett i i i C'heiiiisiri, Stritciuic uiid Boiiiirri~iJfZirirl P1irt.sr.s u i i d f o r i \ (Ed.'
S. Kaurlarich). VCH. Chapter 4. in press.
[I31 E. Zintl. Ci Brauer. Z. P/ij..5.C/i(wi. 1933. .?//?(IB. 245.
[14] ;I) S c' Sc!ov. J. D. Corbett. frio,:$ Chiwi. 1993, 32. 1059, b) Z:C. Dong and
_I D. c'orbett. unpublished.
(151 A Cd-centcred TI icosahedron has also been found in a derivative of the
Na,K,,Tl,, structure [6]- M. M . Tillard-Charbonnel. C. H. E. Belin. A. P
Manteglictti. I) M . Flot. private communication.
1161 c' - H . Wong. ('. Chich. T.-YLee. Ar.tu Crj sfdlugr. 1965. I Y . 849.
[17] S Sainwn. . A 1 Iu C/iwii. Scoriil. 1949. 3. 809.
11x1 U.Z;tchuiej,i. Z. Krrrrillogr. 1995. Sitppl. Issur No. Y. 25.
[lY] K , Walker. 1) Stuart. A r . r r r Ci.r.s/u//op. 1986. A3Y. 158.
[XI] P W Selv.ood. . l . l r i , ~ ~ i c t o c h ~ i i i i . \ 2nd
~ r i , ed.. Interscience, New York, 1956.
p 70.
[?I] N W. Ashcroft. D N. Mermin. Sirlid Srrir~P/i~~.stc.s:
HolL Rinehart and Win\tan. Pluladclphio. PA. 1976. p. 649.
R3
R3
A Double Calixl4larene in a 1,3-altevnate
Conformation**
Jose-Antonio Perez-Adelmar, Herve Abraham,
Concha Srinchez, Kari Rissanen, Pilar Prados,* and
Javier de Mendoza*
Calixarenes offer attractive possibilities as molecular frameworks for the preparation of highly preorganized, rigid molecular
Double calixarenes, in which the lower rims are
linked by suitable spacers (head-to-head), were recently described.[" Some tail-to-tail (rings linked through the upper rims
or ptrro position^),'^] and head-to-tailr4]arrangements have also
been reported. These structures have received increased attention because they display well preorganized molecular structures, most often in cone conformation. However, only a few
examples of double calix[4]arenes in I ,3-ulternn/e conformation
(whose cylindrical shape features a molecular channel) are
known. and they all belong to the head-to-head"] or to the
tail-to-tail['] series. We report herein the synthesis of a 1,3-distal
bridged double calix[4]arene in 1,3-u/ternate conformation, the
first X-ray crystal structure of such a dimer, and a preliminary
N M R study o f its complexation with silver(1) ions.
The 1.3-distal 0-alkylated derivative 2 was obtained from the
parent p-H-calix[4]arene I (2.2 equiv potassium carbonate.
2.2 equiv 2-ethoxyethyl tosylate, acetonitrile, 2 atm, 130 T.
74% yield). Reaction of 2 with N-bromosuccinimide in 2-butanone gave the dibromo compound 3 as the major component
( 7 6 % yield after chromatography) and small amounts of the
monobromo derivative 4 ( I -4% yield). The
and 13C
N M R spectra'" of these compounds indicate that they are in
c m c conformations.
~
Dibromo compound 3 was then fully 0-alkylated under Reinhoudt's conditions (15 equiv cesium carbonate, 12 equiv 2ethoxyethyl tosylate, DMF, 80 'C)[9Jto give 5 as a 9 2 : s mixture
of 1.3-crltcriicitc~ and purtiul-cone conformers from which the
major 1 . 3 - t r / t c w m t c conformer was isolated in 829'0 yield.
[*] Prof 111- P P ~ i d o s .Prof. Dr. J de Mendoza. JLA Perez-Adelmar.
Dr H.Abraham. Dr. C . Sincher
Departamento de Quiinica Orginica
Univei-sidad Aulirnoina de Madrid
C'antohlanco. E-18049 Madrid (Spain)
Fa\ I t i t code +(1)3Y7-3966
Prof DI- K. Ri\h,inen
Dep;irtmeiit 01 Chemistry. University of Jyviiskylii. Jyviiskylh (Finland)
[**I This mork w:i\ supported by Direction General de Investigacion Cientifica y
Tecnica ( I X I C ' Y T PB93 0283) and by the Finnish Academy(project no. 8588)
4 R' = H , R 2 = CH2CH20CH2CH3, R3 = Bf
7 R' = R2 = CH2CH20CH2CH3 , R3 = N3
'1
\
I
8
Bromine/lithium exchange (2.2 equiv ferr-butyllithium, THF,
-78 "C) followed by addition of tosyl azide and heating to
reflux gave diazide 6 ( 5 6 % yield) and small amounts of
monoazide 7 (4% yield). Finally, aza-Wittig condensation of
diazide 6 with terephthaldialdehyde afforded double calix(4larene 8 in 30% yield.
In ' H N M R spectra of compounds 5 and 8 isochronous
signals at 6 = 3.6 were observed for the methylene bridge protons, even though AB systems, like those in the spectra of cornpounds 6 and 7, were expected based on the substitution pattern
of the aromatic rings. In the 13CN M R spectra the signals of the
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