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Macrobicyclic Polyethers as V-Shaped Hosts for cis-Diammine-Transition Metal Complexes.

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thane; it crystallizes in yellow-orange rhombs from diethyl
ether/dichloromethane (1 : 1).
The spectroscopic data of 2 and 3 are listed in Table 1;
Figure 1 shows the structure of the cation 3 (without coordinated dichloromethane).
Table I. Spectroscopic data of 2 (top) and 3 (bottom).
IR (v(CO), pentane): 1886 (m),1878 (m)c m - ' 14, 51
'H-NMR ([Dolacetone, rel. CD3COCD2H): 6=7.43-7.72 (ISH, m ; PPh3),
6.19, 3.87 (each 1 H, sept; NCH(CH&, E / Z isomerism), 4.79 (2H, q ;
OCHzCHs), 1.21-1.64 (15H, m; OCH2CH3, NCH(CH3)2, E / Z isomerism)
"C-NMR (CD2CI2, -2O"C, rel. CD2C12): 6=241.37 (C(carbene),
'J(CP)= 14.64 Hz), 217.49 (C(CO), 'J(CP)=29.30 Hz), 138.39, 135.47, 133.52,
132.87, 129.79, 128.49, 127.84 (C(PPh,), 71.80 (OCH2CH3), 57.18, 50.03
(NCH(CH&, E / Z isomerism), 21.93, 19.65 (NCH(CH,)2, E / Z isomerism),
15.27 (OCHzCH3)
"P-NMR ([Dolacetone, rel. H,PO,). 6=85.8
MS (El source): m / z 559 ( M " ) , 531 (M"-CO), 475 (Ma-3CO)
IR (v(CO), CH2CI2):2081 (vs), 2031 (s), 2009 (vs) cm-' [4]
"C-NMR (CD2C12, -2O"C, rel. CD2Cl2): 6=264.65 (CIO, 2J(CP)=43.95
Hz), 203.78 C1,2,3, 2J(CP)=24.41 Hz), 133.14, 132.49, 132.16, 129.56, 128.74
(CI l,21,3l), 22.14, 21.16 (C41,42,51,52, conformational isomerism). Signals
of C4,5 presumably under the solvent signal
"P-NMR (CD2C12, rel. H,PO,): 6=57.3
MS (FD source): m/z 514 (M"-BClJ
Experimental:
All operations were carried out under N 2 with anhydrous, oxygen-free solvents. 2 : A solution of 1 (8 g, 24.6 mmol) [2] in n-hexane (500 mL) was
treated with 5.15 g (19.6 mmol) triphenylphosphane and the mixture heated
under reflux for 5 h. On completion of reaction, 2 precipitated. The solvent
was removed in a vacuum and the residue chromatographed on silica gel.
After separation from unreacted carbene complex with pentane, 2 could be
eluted with CH2C12.After removal of solvent, 2 was recrystallized from pentane/CH2C12; yield 8.11 g (59%), yellow crystals, m.p. IIO--115"C (decamp.).-3: A solution of 2 (4.88 g, 8.7 mmol) in CH2C12 (100 mL) was
treated at - 100°C with 2 mL (23.0 mmol) BC13. The originally dark green
solution was then allowed to warm within 3 h to -25"C, evaporated to 30
mL, and subsequently treated with precooled dietbyl ether. 3 precipitated as
yellow flocs. Analytically pure 3 was obtained as yellow-orange rhombs by
repeated recrystallization from Et2O/('H2Cl2( I : I ) ; yield 1.63 g (28%), m.p.
110-1 18°C (decomp.).
Received: June 12, 1984;
revised: August 3, 1984 [ Z 876 IE]
German version: Angew. Chem. 96 (1984) 814
CAS Registry numbers:
1, 91071-01-1; 2, 92315-10-1; 3.CH2CI2, 92315-13-4; 3, 92315-12-3; Fe,
7439-89-6; carbon, 7440-44-0
[l] E. 0. Fischer, U. Schubert, J . Orgunomet. Chem. I00 (1975) 59.
121 E. 0. Fischer, J. Schneider, K. Ackermann, Z . Nuturforsch. B 3 9 (1984)
468.
[3] a) M. Nitay, W. Priester, M. Rosenblum, J . Am. Chem. SOF.100 (1978)
3620; b) S. J. LaCroce, K. P. Menard, A. R. Cutler, J . Organornet. Chem.
190 (1980) C79; c) J. J. Bonnet, R. Mathieu, R. Poilblanc, J. A. Ibers, J.
Am. Chem. SOC.101 (1979) 7487.
14) F. A. Cotton, R. V. Parish, J. Ckern. Soc. JY60, 1440.
[5] D. J. Darensbourg, M. Y. Darenshourg, Inorg. Chem. 9 (1970) 1691.
[6] 2: a = 1312.0(2), b=1799.7(3), c = 1468.3(3) pm, 8==92.98(3)",
V=3462.3x lo6 pni'. P2,/n, Z = 4 , Q ~ . , , ~1.44
=
g/cm3, T = -40°C, 4187
structural factors ( F t 3 u ( F ) , 2 " 5 2 8 5 4 8 " ) , MoKn(L=71.069 pm, graphite monochromator), R ,=0.063, R2=0.072 (Syntex/XTL); BCLQ and
CH2C12 disordered. Further details of the crystal structure investigation
are available on request from the ~achinformationszentrumEnergie Physik Mathematik, D-7514 Eggenstein-Leopoldshafen2, on quoting the depository number CSD 50961, the names of the authors, and the journal
citation.
[7] H. Fischer, A. Motsch, U. Schuhert, D. Neugebauer, Angew. Chem. 93
(1981) 483; Angew. Chem. lnr. Ed. Engl. 20 (1981) 463.
Macrobicyclic Polyethers as
V-Shaped Hosts for
cis-Diammine-Transition Metal Complexes**
By David R . Alston, Alexandra M. Z . Slawin,
Fig. I . Structure of the cation of 3 in the crystal (coordinated dichloromethane omitted) with important bond lengths [pm] and one angle ["I.
The X-ray structure analysist6]shows that the iron in 3 is
coordinated in a distorted trigonal-bipyramid with the triphenylphosphane ligand and one carbonyl ligand in the
apical positions. That is, the carbyne ligand is not in the
trans-position to the triphenylphosphane group. The ironcarbyne carbon bond length (173.4(6) pm) is the shortest
iron-carbon bond length so far observed, and is 28 pm
shorter than the comparable iron-carbene carbon bond
The carbyne group is inclined towards the
length in lCZ1.
phosphane ligand, while the equatorial carbonyl groups
are inclined away from it. The Fe-P bond length is
226.4(2) pm (for comparison, in carbynechromium complexes Cr-P 246.4 pmC7'); the Fe-C (carbonyl) bond
length in the case of the axial CO groups (180.6(6) pm) is
shorter than in the case of the equatorial groups (Fe-Cl
182.6(6), Fe-C3 181.916) pm).
Angew. Chem. Int. Ed. Engl. 23 (1984) No. I0
J . Fraser Stoddart*, and Dauid J. Williams
In the supramolecular structures of the 1 :1 adducts
formed"] between dibenzo-crown ethers of the general
type DB3nCn (n = 8- 10) and diammine-transition metal
complexes such as [pt(bi~y)(NH~)~][PF~]],
(bipy = 2,2'-bipyridyl} and [RhL(NH,),][PF,] (L = 1,5-cyclooctadiene
(cod) or norbornadiene (nbd)), X-ray analyses have shown
that, without exception, the two NH3 ligands straddle one
of the polyether chains. This arrangement fails to make
full use of the H bonding potential of these ligands. We
have, therefore, designed host molecules (1) incorporating
a third polyether chain between the two benzene rings. This
constitutional modification produces two 20- or 23-membered
~~
[*] Dr. J. F. Stoddart, D. R. Alston
Department of Chemistry, The University
Sheffield S3 7HF (UK)
Dr. D. J. Williams, A. M. Z. Slawin
Chemical Crystallography Laboratory
Department of Chemistry, Imperial College
London SW7 2AY (UK)
I**] The work was supported by the Johnson Matthey Research Centre and
the Science and Engineering Research Council in the United Kingdom.
0 Verlag Chemie GmbH. 0-6940 Weinheim, 1984
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crown ether rings oriented side-by-side in an appropriate
manner to facilitate H bonding with both of the NH3 ligands.
,d,
,;r".ge>
go% o3
$
wR
w
R
I
2,R=H
3, K = Br
a , X = 0; b, X = OCH,CH,O; c, X = 0-0-C,H,O;
d , X = OCMe,CMe,O
HostsIZ1 l a - Id which fulfill this constitutional criterion, have been synthesized from 2,6-dirnethylphen01[~~.
'HNMR Chemical shift data reveal (Table 1) l a - l d form
Table I . Selected 'H-NMR data [a] for the 1 : I adducts of
[Rh(cod)(NH,),][PF,] and l a - Id in CD2C12 (6 values, TMS as int. standard).
Resonance
NH, [bl
(cod)-He [b]
18C6
2'39
2.39
(cod)-H" I['
(cod)-Hn [b]
4.07
p-Aryl-H [c]
-
m-Aryl-H [c]
-
la
lb
lc
Id
2.00
(-0.39)
2.00
(-0.39)
1.59
(-0.26)
3.54
(-0.53)
7.18
(+0.17)
7.39)
(f0.14)
2.22
(-0.17)
1.32
(-1.07)
1.13
(-0.72)
3.60
(-0.47)
7.27
(+0.27)
7.50
(+0.25)
2.22
(-0.17)
1.52
(-0.87)
1.27
(-0.58)
- [d]
-[dl
7.20
(+0.15)
7.51
(+0.23)
2.20
(-0.19)
1.48
(-0.91)
1.24
(-0.61)
- [d]
-[d]
7.28
(f0.26)
7.50
(+0.22)
escence temperatures of the AB systems for the same
probe protons in l a (AvAB=85 Hz, JAB=9.8 Hz,
TC=-48"C) and l b (AvA,=IOO Hz, J A B = 9 Hz,
T,= 12°C) are much higher, corresponding to k,= 196 s-'
(AG2 = 10.7 kcal mol-I) and to k,=228 s - ' (AG2 = 13.6
kcal mol -'), respectively. The AAG: values of ca. 2.9 and
3.2 kcal mol - I for l a and 1b, respectively, in the presence
and absence of [ R ~ ( C O ~ ) ( N H , ) ~ ] [ Pindicate
F ~ ] , that these
hosts form 1 : 1 adducts of comparable stabilities. This suggests that the macroring and phenolic oxygen atoms in the
host are major sources of binding in these adducts, i.e. the
constitution of the middle portion of the central polyether
chain is relatively unimportant in this respect. This view is
supported by (i) chemical shift data (Table 1) obtained on
adduct formation by the more conformationally rigidL4]
hosts l c and Id -the shifts compare favorably with those
observed for l a and l b - and (ii) X-ray analyses[s1 of the
adducts with l b and l c (Fig. 1 and 2, resp.), which confirm the elegant structural suitability of these large bicyclic
systems with 24-membered macrorings for optimum H
bonding with cis-NH3 ligands. Moreover, there is an obvious redundancy in the middle two oxygen atoms of the
central polyether chains in both hosts. With one exception,
namely N 1 . . . 0 4 0 in the lc-adduct (where N . . . O is
3.43 A), the distances of the nitrogen atoms to the middle
two oxygen atoms are all greater than 3.6 A. The polyether
components of the macrorings in the two hosts adopt very
similar conformations (i.e. a a g - a ag+a a ) from C I to C9
and from C15 to C23, ensuring the encirclement of both
cis-NH, ligands in the guest (cf. Fig. I and 2). Although alternating gauche helicities (i.e. ag-a ag+u ag-a from C30
to C39) also characterize the C-C bonds in the central
polyether chain of the lb-adduct, the enforced syn-rela-
[a] The spectra were recorded at room temperature on a 220-MHz spectrometer (Perkin Elmer R34). [b] The values in brackets indicate the extent to
which signals of the guest protons (H'= equatorial methylene proton;
H"=axial methylene proton; H"=olefinic proton) are shifted relative to the
corresponding signals in [Rh(cod)(NH,),. 18C6][PF61.[cl The values in brackets indicate the extent t o which the signals of the bridging aromatic ring protons are shifted relative to the corresponding signals in the free hosts. [d] Signal obscured by signals for OCH2 protons.
stable 1 : 1 adducts with [R~(CO~)(NH,)~][PF,]
in CD,Cl,
solutions. Upfield shifts of the guest protons are accompanied by downfield shifts for the protons in the bridging
aromatic rings of the hosts. Both l a and l b are conformationally mobile[41on the 'H-NMR time scale at room temperature as a result of rapid passage of the central polyether chain (seven atoms in l a and ten atoms in l b )
through the middle of the (24-membered) macroring. This
inversion process can be slowed down, as evidenced by the
AB system (AvAB = 127 Hz, JAB= 10 Hz) observed14]for the
benzylic-methylene protons in l b below the coalescence
temperature (Tc= - 50°C) and the line broadening observedc4]for the same protons in l a below -85°C (T,=ca.
- l 0 5 T ) . The rate constant (k,) of 287 s-' obtainedf4]at
the coalescence temperatures afforded AG: values of ca.
7.8 and 10.4 kcal mol-' for l a and l b , respectively. In the
presence of 1 mol equiv of [Rh(cod)(NH&.][PFS], the coal:
822
0 Verlug Chemie GmbH, D-6940 Weinheim. 1984
Fig. 1. Structure of [Rh(cod)(NH,)?. Ib][PF6][CH2Cl2]in the crystal. Crystal
data: monoclinic, a = 17.406(2), b = 14.768(2), c = 19.407(2) /J'= 102.82(1)",
V=4865 A', space group, P2,/c, Z=4,pc=1.42 g cm-', pCu-K,=49 cm-',
4123 independent reflections with [lF,,l> 30(lFnI), OC50"], R=0.063,
R,=0.069. Torsional angles ["I associated with the polyether chains are
shown beside the relevant bonds. Bmh NH, ligands have rwo distinct orientations.- Distances for N1 to 016, 019, 022, and 039: 3.19, 3.05, 3.17, and
3.04 A, respectively. Those for N2 Lo 02, 0 5 , 08, and 0 3 0 : 3.17, 3.07, 3.20,
and 3.01 A, respectively. Atoms NI and N2 are inserted 0.56 and 0.53
respectively, below the mean plane of the six peripheral oxygen atoms. Cleft
angle between the mean planes of the aromatic rings is 63". Separations between these mean planes and the nearest cod hydrogen a t o p s : [C10/
14. . . He(47)] 3.20, [C24/28. . .H,(43)] 2.98 A.
0570-0833/84/1010-0822 $ 02.50/0
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A,
Angew. Chem. I n l .
Ed. Engl. 23 (1984) No. 10
With its V-shaped conformation, free l b has structural
characteristics similar to those of bound l b . However, it is
noticeable that four of the oxygen atoms (08, 016, 019,
and 030) are no longer directed into the cavity and instead
five methylene groups (on C7, C17, C18, C31, and C32) are
oriented inwards. Although these particular conformational changes reflect the inability of l b to sustain an organized cavity in the absence of a guest, the host and its
analogues ( l a , l c , Id) clearly offer a much improved molecular receptor design for transition metal cis-diammines
over the simpler DB3nCn ethers"].
Received: June 18, 1984 [Z 887 IE]
German version: Angew. Chem. 96 (1984) 804
Fig. 2. Structure of [Rh(cod)(NH3)2.Ic][PF6][CH2C12]in the crystal. Crystal
a=89.02(2),
data: triclinic a = 12.984(2), b= 13.674(4), c = 13.973(2)
8=84.13(1), y=86.05(2)", V=2462A, space group P i , Z = 2 , p,=1.47 g
crn-I, 4400 independent reflections with [IFnl>3U(IFnl), 8350"], R=0.042,
R,=0.046. Torsional angles ["I associated with the polyether chains are
shown beside the relevant bonds. One NH3 ligaud has two distinct orientations.- Distances for N I to 016, 019, 022, and 0 4 3 : 3.26, 3.04, 3.05, and
3.00 A, respectively. Those for N2 t o 0 2 , 0 5 , 0 8 , and 0 3 0 : 3.13, 3.08,>.12,
and 3.07 A, respectively. Atoms N1 and N2 are inserted 0.62 and 0.63 A, respectively, below the mean plane of the six peripheral oxygen atoms. Cleft
angle between the mean planes of the aromatic rings is 68". Separation between these planes and the nearest cod hydrogen atoms: [C10/14.. .H"(50)]
3.13; [C24/28. . . Hr(46)] 3.24.
A,
tionship of the catechol oxygen atoms, 0 3 3 and 040, in the
lc-adduct is accommodated by a substantial distortion of
the C31-C32-033-C34
torsional angle.
The X-ray structure analysis[51of free l b (Fig. 3) reveals
the extent to which the polyether chains have to reorganize
themselves conformationally in order to bind the guest.
[l] H. M. Colquhoun, J. F . Stoddart, 0. J. Williams, J. B. Wolstenholme, R.
Zarzycki, Angew. Chem. 93 (1981) 1093; Angew. Chem. Int. Ed. Engl. 20
(1981) 1051; H. M. Colquhoun, S. M. Doughty, J. M. Maud, J. F. Stoddart, D. J. Williams, J. B. Wolstenholme, Israel J. Chem., in press; H. M.
Colquhoun, S. M. Doughty, J . F. Stoddart, D. J . Williams, Angew. Chem.
96 (1984) 232; Angew. Chem. Int. Ed. Engl. 23 (1984) 235.
[2] Since the first report (F. Vogtle, E. Weber, Angew. Chem. 86 (1974) 126;
Angew. Chem. Int. Ed. Engl. 13 (1974) 149) of the use of 2-substituted1,3-xylylene units in macrocyclic hosts, they have found wide application: see, for example, M. Newcomh, S . S. Moore, D. J. Cram, J. A m .
Chem. Soc. 99 (1977) 6405; M. van der Leij, H. J. Oosternik, R. H. Hall,
D. N. Reinhoudt, Tetrahedron 37 (1981) 3661; M. A. McKervey, T.
O'Connor, J . Chem. Soc. Chem. Commun. 1982, 6 5 5 .
[3] A strategy similar to that adopted (W. D. Curtis, J. F. Stoddart, G. H.
Jones, J. Chem. SOC.Perkin Trans. I 1977, 785) in the preparation of
I ,6,13,18,25,30-hexaoxa[6.6.6](
I ,3,5)cyclophane from phloroglucinol was
employed. Experimental: Reactions (NaH, THF) of 2,6-dimethylphenol
with the bistosylates (J. Dale, P. 0. Kristiansen, Acta Chem. Scand. 26
(1972) 1471) of diethylene and triethylene glycols, and with the bistosylates (L. C . Hodgkinson, I. 0. Sutherland, J . Chem. Soc. Perkin Trans. 1
1979, 1908 and N. Ando, S. Ohi, Y. Yamamoto, J. Oda, Y. Inouye, Bull.
Inst. Chem. Res., Kyoto Uniu. 58 (1980) 293, respectively) of the his-2-hydroxyethyl ethers derived from cdtechol and pinacol, afforded the acyclic
polyethers Za (88%, m.p. 28-30"C). 2b (67"4 m.p. 37-39"C), Zc (IS%,
m.p. 102- I03OC), and 2d (68%, m.p. 77-77.5"C), respectively. Photochemical bromination (NBS, CCI4) of Za - 2d gave the corresponding tetrabromides 3a (10%, m.p. 125--126"C), 3b (28%, m.p. 116-117"C), 3c
(27%, m.p. 12 I - 123 "C),and 3d (9%, m.p. I 16- I17 "C). Reactions (NaH,
THF, high dil.) of 3a-3d with dicthylene glycol in the molar ratio 1 : 2
afforded, l a [27%, oil, 'H-NMR (CD,CI,): S=3.55-3.73 (16HX, m),
3.88 (4HY,t), 4.16 (4H', t), 4.52 (8H", s), 7.01 (2H". t), 7.25 ( 4 H n , t)l: l b
[21%, m.p. 113--115"C, single crystals suitable for X-ray (cf. Fig. 3 ) from
EtOAc-light petroleum, 'H-NMR (CD2Cl2): 6=3.56 (16Hx, bs), 3.77
(4 H, S, OCH~CHZO),
3.91 (4 HY,t), 4.04 (4 H', t), 4.52 (8 Hh,s), 7.00 (2 Hp, t),
7.25 (4H"', d)]; l c [31"/0, m.p. 122 -124"C, 'H-NMR (CD,CI,): 6=3.55
(16H", bs), 4.25 and 4.85 (8Hb, A13 system), 4.25-4.42 ( 4 H Y + 4 H T .m).
6.99-7.16 (2H"+C6H4, m), 7.28 (4H"', d)]; Id [45%, m.p. 123--124"C,
'H-NMR (CDZCI~):S=1.30 (12H, S, CHI), 3.58 (16H", bs), 3.96
(4HY+4H", s), 4.24 and 4.80 (8 Hh, AB system), 7.02 (2Hp, t), 7.28 ( 4 H ,
d). The crystalline l b - and Ic-adducts, m.p. 155-157"C and 136139"C, respectively, were obtained by layering E t 2 0 on top of CH2C12solutions (1 :1 stoichiometries). All new compounds and crystalline adducts
gave satisfactory elemental analyses and spectroscopic data.
[4] The benzylic methylene protons H" of the hosts l a and l b appear as singlets in CD2Clz at room temperature, whereas those of the hosts l c and
Id gave AB systems. In both cases, the AB systems showed no signs of
coalescence to singlets when CI2C=CCI2 solutions of l c and Id were
heated u p to 120°C. Values fork, were calculated using the approximation
+
k,=
~ [ ( V A - VR)*
+ 6J$.,]"2/(2) '"*.
For l a , where AvAHand JAHwere not accessible in CD2CI2, these parameters and hence k, were assumed to be similar to those obtained for Ib. In
fact the AG$ value quoted for l a remains almost unchanged over a 25
Hz uncertainty range in A v A B .
[5] Data were measured on a Nicolet R3m diffractometer using the o-scan
routine with graphite-monochromated CuKaradiation. The data for the
two adducts were corrected for absorption. The structures of these adducts were solved by the heavy atom method and that of the free crown
l b by direct methods. All three structures were refined anisotropically.
Further details of the crystal structure investigations can be obtained
from the Director of the Cambridge Crystallographic Data Centre, University Chemical Laboratory, Lensfield Road, Cambridge CB2 IEW. Any
request should be accompanied by the full literature citation for this communication.
*
Fig. 3. Space-filling representation of the structure of l b with the oxygen
atoms numbered. Crystal data: orthorhombic, a = 12.997(3), b = 14.139(2),
c = 16.072(2)
V=2953 A3, space group P2,2,2,, Z = 4 , p,=1.27 g cm-',
2068 independent reflections with [lFnl> 30(iFnl), 8 5 58"1, R = 0.046,
R,=0.049. Cleft angle between the mean pkanes of the aromatic rings is
76".
A,
Angew. Chem. Int. Ed. Engl. 23 (1984) No. 10
0 Verlag Chemie GmbH, 0-6940 Weinheim, 1984
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