Communications
The Mo and W compounds, however, do show significant
arrangement; we have now isolated and carried out prelimi-
nary structural studies on over 30 different derivatives of this
structural differences from the Sn compound as outlined
below. Whereas all the macrocycles in the Sn compound have
the same absolute configuration, the (fluorene)12 clusters in
the Mo and W compounds contain equal numbers of fluorene
units from macrocycles of opposite hand as shown in Figure 5.
IV
2+
type. The metallic macrocyclic components, [Sn (OH) ] ,
2
VI
2+
VI
2+
[Mo O ] , and [W O ] in the examples described above,
2
2
all of which carry an overall 2 + charge, can be replaced by
II
2+
II
2+
II
2+
[Co (H O) ] , [Zn (H O) ] , and [Cd (H O) ] (and prob-
2
2
2
2
2
2
V
2+
ably by other divalent cations) and also by [Nb (O)(OH)]
cations. The Na components can be replaced by other alkali-
metal cations. Various nitrogenous cations such as NEt Me ,
NMe Et , NEt , the choline cation, protonated dabco
dabco = 1,4-diazabicyclo[2.2.2]octane),
and N-ethyldabco , and also PMe and OS(Me)3 can
replace the NMe4 component. This collection of 30 or so
+
+
3
+
+
3
4
+
(
N-methyldabco ,
+
+
+
4
+
solids all have in common the following features: a) the
presence of tetra-anionic, chiral, 2:2 macrocycles, b) the
presence of a fcc array of (fluorene)12 clusters, c) collections
of counter cations at the tetrahedral sites of the fcc array, and
d) large solvent-filled voids at the octahedral sites. It is
remarkable that the same unusual overall structure is
observed for such a wide range of compositions and, in
particular, for such widely differing metallic components of
the macrocycle. We have no doubt that the range of
combinations of components giving rise to this structure
could be extended beyond the current 30 or so examples. It
does appear that hydrophobic interactions between the
fluorene units favor the formation of clusters of 12 and that
this is a dominant contributor to the preference for the
unusual “Swiss cheese” like structure.
Experimental Section
Figure 5. a) Arrangement of the fluorene units in solvated
Synthesis of ligand LH (I): Concentrated hydrochloric acid (3 mL)
4
(
NMe4)4/3Na8/3[L (MO ) ] (M=Mo or W). Fluorene units frommacro-
2 2 2
was added to a molten mixture of catechol (8.8 g, 0.08 mol),
mercaptobenzoic acid (100 mg, 0.6 mmol), and fluorenone (3.6 g,
cycles of different hand are indicated as dark and pale. b) A space-
filling representation of the (fluorene)12 cluster. The oblate spheroidal
shape of the cluster is apparent.
0.02 mol). The reaction mixture was heated at reflux at 1408C for 8–
9
h, after which time the reaction mixture had solidified to a pale
yellow gum. The solid was redissolved in methanol (20 mL) and then
added to 500 mL of boiling aqueous methanol (30% methanol by
volume). The solid obtained after cooling was recrystallized from
dioxane and dried under vacuum. The purified crystals were isolated
as colorless rod-shaped crystals.
Also, the M (C ) (M = Mo or W) systems are slightly
2
f 2
deformed from planar. Whilst the C centers of the (fluo-
f
Preparation of (NMe4)4/3Na8/3[(Sn(OH) )L ]·14H O : A solution
2
2
2
rene) clusters in the Sn compound are located on the surface
1
2
containing I (50 mg, 0.13 mmol) and a large excess of NMe OH
4
of a sphere, those in the Mo and W compounds are located on
the surface of an oblate spheroid (a sphere that has been
(0.25 mg, 2.7 mmol) in water (3 mL) was added to a solution of
SnCl ·5H O (45.6 mg 0.13 mmol) and NaCl (15.2 mg 0.26 mmol) in
4
2
+
flattened at the poles) as shown in Figure 5. The Na and
water (3 mL). Green crystals began to separate after 24 h. The
crystals were filtered off after 48 h, washed with water, and dried in
air. Yield: 48.1 mg (45%). Elemental analysis (%) calcd: C 40.0, H
+
NMe4 cations and associated solvent molecules in the Mo
and W compounds are located, as in the Sn compound,
generally in the vicinity of the tetrahedral sites of the cubic
close-packed (ccp) array of (fluorene)12 clusters, but the
detailed arrangements of the cations differ significantly.
Whilst the centers of the 12 “face-on” macrocycles surround-
ing the large cavities in the Sn compound are located on the
surface of a sphere, those in the Mo and W compounds have
the shape of a prolate spheroid (one elongated along its polar
axis).
4.6, N 1.1; found: C 40.0, H 4.5, N 1.1.
Preparation of (NMe4)4/3Na8/3[(WO )L ]·10H O : A solution of I
2
2
2
(50 mg, 0.13 mmol) in MeOH (0.25 mL) was added to a solution of
Na WO ·2H O (42.8 mg, 0.13 mmol) and NMe Cl (9.4 mg,
2
4
2
4
0.086 mmol) in water (10 mL). Yellow crystals began to separate
after a few hours. The crystals were filtered off after 48 h, washed with
water, and dried in air. Yield: 40.3 mg (40%). Elemental analysis (%)
calcd: C 43.1, H 4.2, N 1.2; found: C 43.1, H 4.2, N 1.5.
Preparation of (NMe4)4/3Na8/3[(MoO )L ]·12H O : A solution of I
2
2
2
in MeOH(0.25 mL) was added to a solution of Na MoO ·2H O
2
4
2
The above compounds are not isolated “freak” structures,
but rather are part of a very extensive series afforded by the
ligand I, all with essentially the same “Swiss cheese” like
(
(
31.5 mg, 0.13 mmol) and NMe Cl (9.4 mg, 0.086 mmol) in water
5 mL). Red crystals began to separate after a few hours. The crystals
4
were filtered off after 48 h, washed with water, and dried in air. Yield:
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2007, 46, 8640 –8643
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