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Noncyclic Cryptates.

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[6] B. Zschochr, Staatsexamensarbeit, Bonn 1977.
[7] W Schuh, Staatsexamensarbeit, Bonn 1977.
(81 The measurements were made using a four-circle dilfractometer and
the calculations were carried out using the X-ray program system of
the IBM;370-168 computer at the regional university computer center
at Bonn.
Noncyclic Cryptatedl1
By Fritz Vogtle, Walter M . Miiller, Winfried Wehner, and Egon
Buhleier [*I
Cryptates have been defined as complexes in which a bicyclic
or larger neutral ligand of the crown ether type encloses
a central ion in three dimensions[']. We will now describe
a new type (1 ) of neutral ligand for alkali metal ions which
is not cyclic but still shows cryptand properties as regards
the complete envelopment of the ion as well as the strength
and selectivity of its complexation.
As is shown in Table 1 , readily crystallizing complexes
are formed with alkali, alkaline-earth, and heavy metal ions.
A first index of the cryptand-analogous complexation of
(1) compared with that of the crown ether type dipode ( 5 ) ,
is provided by the clearly stronger phase transfer of solid
K M n 0 4 and (aqueous)Na and K picrates into organic phases;
this phase transfer surpasses that of dibenzo[l8]crown-6. The
participation of the terminal quinolyl groups of ( 1 ) in cation
complexation is supported by the similar 'H-NMR spectra
of all three quinolyl groups in the (I).KSCN complex and
of the OCH3 protons in the (2b).NaSCN complex; further
support comes from the considerably lower phase transfer
capacity of the comparable compound (2a) which has a
phenyl group as donor atom free terminal group.
/Zl
111
A
The topology of open chain cryptands is given by consequent
combination of the polypode"] ("octopus" m ~ l e c u l e ~and
~])
terminal group concepts[4*'1.
f51
f61
Potentiometric data confirm and specify these findings
(Table 2).
Table 1 . Noncyclic cryptands and their cryptates.
(1)
M.p.
["Cl
Complex [a]
with
LSW [c]
M.P. [dl
["C l
liq.
NaSCN
KSCN
RbI
1:1:1
1:l
1:1
126-1 28
184-186
NHSCN
1:1
Ni(C104)2.6H20
HZPtCl6.6H Z O
1:l:l
115--118
(104-1 06)
128-1 30
(118)
H
OCH?
liq.
63
PI
NHCOCH3
NO2
CH3
167
liq.
liq.
liq.
liq.
PI
PI
liq.
[0-2,6-C6H3(OMe)2]
[0-2,6-C6H3Mez]
[O-2-C,H4N]
[S-C(S)-NEtz]
liq.
liq.
liq.
78
NaSCN
1:1:4
234-237
195-200
-
-
1:l
78-80
(72)
-
-
-
-
[bl
Ba12
KSCN
RbI
Balz
_.
-
NaSCN
1:l
1:l
C U ( C I O ~6) ~
H.z O
1:1:1
1:l
1:l
l:l:l
1 7 6 174
166-1 67
177-1 79
213-215
(165-168)
235-236
25k254
-
-
-
-
1:l
1:1
125-1 29
111-1 I4
[a] Correct analyses and/or high resolution mass spectra were obtained for all ligands and their complexes.
[b] No crystalline complexes could be produced from these ligands with the following salts: NaSCN, KSCN, Rbl,
C O ( C I O ~ Ni(C104)2,
)~,
Cn(C104)z.
[c] Stoichiometry-ligand: salt: HzO.
[d] Temperature at the beginning of sintering is given in brackets.
-~
["I
548
Prof. Dr. F. Vogtle, W. M. Miiller, Dip1.-Chem. W. Wehner, Dip].-Chem.
E. Buhleier
Institut fur Organische Chemie und Biochemie der Universitat
Max-Planck-Strasse 1 , D-5300 Bonn (Germany)
Of all the noncyclic ligands examined, ( I ) shows the highest
complexation constants for alkali metal ions (in methanol/
water); attention should be drawn to its preference for Na'
over K + (and Li+) and also to its high selectivity for divalent
Anqew. Chem. Int. Ed. Engl. 16 ( 1 9 7 7 ) No. 8
Table 2. Acidity and complex stability constants (log K ) of selected ligands [potentiometric in methanol/H20 (88 : 12);
.temperature 293 K: ionic strength: tetraethylammonium bromide; 10-fold salt excess of the ion to be measured].
Ligand
pK.
Lit
Na+
K+
Cs +
Mg2+
CaZc
Sr2
(1)
(Za)
7.02
6.01
6.40
5.92
7.09
7.78
<2
<2
<2
<2
<2
2.6
<2
2.2
<2
12
2.06
<2
<2
<2
<2
<2
<2
<2
<2
<2
<2
<2
<2
<2
2.14
<2
<2
2.0
<2
2.3
<2
<2
(2b)
(3)
(4)
(5)
<2
ions, especially Ba2+ and Sr2+.The even higher complexation
constants of the pseudocryptand (3) for these divalent cations
is especially striking; this compound has three terminal tropolone ether groups. In agreement with this, a BaIz complex
of (3) could be isolated but a KSCN complex could not.
In contrast, the complex stabilities for the smaller Lii and
Caz+ ions are clearly lower. We attribute this selectivity,
on the basis of studies with space-filling models, to the fact
that the pseudocavity cannot become sufficiently small to
form a “skin-tight’’ wrapping around the small cations for
steric reasons. Only ( I ) also has a logK value which is greater
than 2 for M g Z f .
In contrast with the favorable complexation by the terminal
8-quinaldyl group in spirally wound, open chain crown
ethersC4], the OCH3 groups of the three-armed compound
(2 b ) seem rather to block the pseudocavity: here the K M n 0 4
transfer and the complex stabilities for all cations are lower.
In agreement with this concept of open chain cryptates, even
lower complex stabilities are found with ( 2 a ) which has terminal phenyl groups.
In the ‘H-NMR spectra of the NaSCN and KSCN complexes of ( 4 ) , the methyl protons are shifted to higher fields
(A6=0.78 and 0.88 respectively in CDC13) than those of the
free ligand; on the basis of studies with models, this can
be accounted for by a propeller-like twisting of the three
quinaldyl groups. This interpretation is corroborated by the
finding that the CH3 shift of the K + complex t o higher fields
is larger than that of the N a + complex (AA6=0.1): in the
first case the CH3 protons appear to lie further in the anisotropic region of the quinaldyl system than in the second; due
to the larger volume of the metal ion.
The description and stereochemical formulation of ( I ) as
an open chain cryptand also appears to be justified by the
comparatively low complex stability of the analogous noncyclic crown ether ( 5 ) which also has terminal quinolyl groups:
although ( 5 ) is capable of forming crystalline complexes (Table
I), its complexation constants are an order of magnitude
smaller than those of (1 ) (Table 2); selectivity towards divalent
ions is not observed.
Open chain cryptands such as (1) (whose topography is
characterized by the tetrahedral arrangement of its four
nitrogen atoms and which resembles that of Lehn’s “soccer
ball” cryptands[6]), ( 2 b ) and ( 4 ) may collectively have the
greatest complexation capacity of all neutral ligands so far
investigated when the simplicity of their synthesis and the
price of the starting materials are taken into account.
Received: May 27, 1977 [Z 753 IE]
German version: Angew. Chem. 89,564 (1977)
CAS Registry numbers:
( I )/NaSCN, 63412-82-8; (I)/KSCN, 63412-84-0: ( I )/RbI, 63448-75-9:
( I )/Ni(C10&, 63412-86-2; ( 1 )iH,PtCI,, 63412-87-3; (2b)INaSCN. 6341289-5; (3)/Ba12. 63412-90-8; (4)/KSCN, 6341 2-92-0; (4)/RbI, 63412-93-1 ;
(4)/Bal2, 63412-94-2; (5)/NaSCN, 63412-96-4; (S)/RbI, 63448-76-0; ( 6 c ) J
Th(N03)4, 63493-46-9; (6d)/Cu(CIO&, 63548-64-1 ; ( 1 ), 63373-69-3; /.?a),
26253-40-7; ( Z h ) , 63373-70-6; ( 3 ) , 63373-71-7; (4). 63373-72-8; ( 5 ) . 6337373-9
Angew. Chem. Int. E d . Engl. 16 (1977) N o . 8
<2
<2
<2
<2
[l]
[2]
131
141
[5]
[6]
+
2.7
2.0
3.3
<2
<2
B&2+
3.2
<2
2.1
3.6
<2
<2
Ligand Structure and Complexation, Part 20. Thls work was supported
by the Fonds der Chemischen 1ndustrie.-Part 19: K . Frensch, F. Viigrle.
Tetrahedron Lett. 1977, 2573.
Review: J : M . Lehn, Struct. Bonding 16, 1 (1973); cf. also J . - M . Lehn,
J.-P. Sauoage, J. Am. Chem. Soc. 97, 6700 (1975).
F. Viigtle, E . Weher, Angew. Chem. 86, 896 (1974); Angew. Chem. Int.
Ed. Engl. 13, 814 (1974).
F . Vugrle, H . Sieger, Angew. Chem. 89, 410 (1977); Angew. Chem. Int.
Ed. Engl. 16, 396 (1977).
W RaPhofer. G . Oepeii, F. Yogtle, Chem. Ber. 1 I 0 ( 1 977), in press.
E . G r u i J . - M . Lrhn, J. Am. Chem. Soc. 97, 5022 (1975); 5. M e r z , J .
M . Rosalky, R . Weiss, J. C. S. Chem. Commun. 1976, 533: in analogy,
( 1 ) also forms a stable crystalline ammonium complex (Table I).
Double Ring-Closure Additions to o-(Methy1eneamino)phenyl Phosphites[’l
By Alfred Schmidpeter, Josef Helmut Weinmaier, and EImar
Glaser [*I
Methyleneaminophosphanes react with electron-deficient
double- and triple-bond systems by [3 +2]-~ycloaddition[~l
in which the induced charges are cancelled out by the formation
of a h5-phosphazene:
In the case of o-(methy1eneamino)phenylphosphites (1) however, the formal insertion of the three-membered o-oxyphenylene chain separates the two reaction centers-h3-phosphorus
and the methylene carbon atom-into 1,B-positions from one
another and makes a 7c bond-mediated compensation of
charges impossible. In spite of this, these compounds again
react with unsaturated systems in fundamentally the same
way i. e. by 1,B-addition to P and C. Here, the charges equal
out via a o bond between P and N. Bicyclic 05-phosphoranes
are the products.
2-(4-Nitrobenzylideneamino)phenyl
dimethyl and -diphenyl
phosphites ( I ) react with tetracyanoethylene (2) at 0°C and
also (amongst other compounds) with 4-nitrobenzylideneacetylacetone ( 4 ) , methyl propiolate (6) or ethyl azodicarboxylate
( 8 ) after heating for several hours in benzene, to yield crystalline 1 : 1-adducts.
The 31P-NMR shifts of ( S ) , ( 5 ) and (7) are found at
6 = -35 to -50 and those of ( 9 ) at 6 = -50 to -65 (to
high field); they confirm the pentacoordination of the phosphorus. The ‘H-NMR spectra verify, on the basis of the diastereotopy of the P-methoxy groups, the addition to the benzylidene
carbon atom of ( I ) ; the values of the 31P-1H-and ‘H-’H
[*] Prof. Dr. A. Schmidpeter. Dip1:Chem.
J. H. Weinmaier. E. Glaser
Institut fur Anorganische Chemie der Universitiit
Meiserstrasse 1, D-8000 Miinchen 2 (Germany)
549
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