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Novel Octahedral Si and Ge Complexes with a Hexadentate Diphenol Ligand.

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references cited therein; c) V. J. Jephcote, A. J. Pratt, E. J. Thomas, J.
Chem. SOC.Chem. Commun. 1984, 800; d) P. Lesimple, J.-M. Beau, P.
Sinay, ihid. 1985. 894.
[21 For example, see: T. Cohen, M.-T. Lin, J. Am. Chem. SOC.106 (1984)
1130; J.-M. Lancelin, L. Morin-Allory, P. Sinay, J. Chem. SOC.Chem.
Commun. 1984. 355.
131 a) Review: D. Hoppe, Angew. Chem. 96 (1984) 930; Angew. Chem. Int.
Ed. EngL 23 (1984) 932; see also b) D. Hoppe, R. Hanko, A. Bronneke,
F. Lichtenberg, E. van Hulsen, Chem. Ber. 118 (1985) 2822.
[41 a) (R)-4 [4bl: Prepared from rue-4 by kinetic resolution of enantiomers
(according to Sharpless [4cl) using (R.R)-diisopropyl tartrate, [a]&s
f7.18 (c= 1.2, CHCI,), 67% ee. Determined for the (S)-I-methoxy-Iphenyl-I-(trifluoromethy1)acetate by "F-NMR spectroscopy [4d].-b)
K . Chan, N. Cohen, J. P. DeNoble, A. C. Specian, Jr., G. Saucy, J. Org.
Chem. 41 (1976) 3497; c) V. S. Martin, S. S. Woodard, T. Katsuki, Y.
Yamada, M. Ikeda, K. B. Sharpless, J. Am. Chem. SOC.103 (1981) 6237;
d) J. A. Dale, D. L. Dull, H. S . Mosher, J. Org. Chem. 34 (1969) 2543.
[SJ 67% ee. [a];' - 11.6 (c= 1.1, CHC13).
[61 8a and 9a were separated by medium pressure chromatography on silica
gel: 8a (9a): RF=0.48 (0.40), ether/petroleum ether (1 : I ) .
[7] Corrected values, based on enantiomerically pure ( - ) - 5 .
[Sl Averaged values from comparison of optical rotations and determination of the enantiomeric ratio using tris[3-heptafluoropropylhydroxymethy1ene)-( +)-camphorato]europium(ti~).Specific optical rotation, extra1.8, (-)-9a: -5.2
polated to 100% ee: (+)-8a: [& 8.0; ( + ) - 8 b :
(c= 1.0-2.0, CH3OH).
[91 R. Hanko, D. Hoppe, Angew. Chem. 94 (1982) 378; Angew. Chem. I n t .
Ed. Engl. 21 (1982) 372.
[lo] Reviews: M. T. Reetz, Top. Curr. Chem. 106 (1982) 1; B. Weidmann, D.
Seebach, Angew. Chem. 95 (1983) 12; Angew. Chem. Int. Ed. Engl. 22
(1983) 31.
11I] Reaction conditions: 1) (+)-8b (30% ee), acetic anhydride, triethylamine, 10 mol-% 4-(dimethylamino)pyndine;2) 03,1.0 equiv. methanesulSonic acid in methanol/dichloromethane,-70 t o - 20°C; dimethyl sulfide; 3) LiAIHJtetrahydrofuran, O'C.-(-)-ll:
[a]? - 1.05 (c=2.4,
ethanol), 17% ee [12].
[I21 C. Najera, M. Yus, D. Seebach, Helu. Chim. Acra 67(1984) 289.
[I31 R. W. Hoffmann, B. Landmann, Angew. Chem. 96 (1984) 427; Angew.
Chem. l n f . Ed. Engl. 23 (1984) 437.
[I41 Swern oxidation of (-)-9a ([a]? -0.92), followed by reduction of the
ketone with NaBH., (isopropanol, 20"C), gave (-)-8a ([a]? - 1.55), 19%
ee (corrected [7] 25% ee), along with (-)-9a (59 :4l). Therefore, (-)-9a
must have at least the same enantiomeric purity.
1151 The asymmetric induction cannot be due to chiral associates (e.g.,
rac-6 .(R)-5 o r rac-lO-(R)-S) since similar results are obtained with
completely deprotonated carbamates (e.g., starting from (R)-5, ethyl instead of isobutyl).
1161 Structure of allyllithium compounds (review): P. von R. Schleyer, Pure
Appl. Chem. 56 (1984) 151; see also: M. Schlosser, M. Stahle, Angew.
Chem. 94 (1982) 142; Angew. Chem. Int. Ed. Engl. 21 (1982) 145; Angew.
Chem. Suppl. 1982, 198, and references cited therein.
[I71 Chiral, phenyl-substituted cyclic a-(aminoalky1)lithium derivatives: a)
D. Seehach, J. Hansen, P. Seiler, I. M. Gromek, J. Organomet. Chem.
285 (1985) I ; b) M. F. Loewe, M. Boes, A. 1. Meyers, Tetrahedron Lett.
26 (1985) 3295, and references cited therein.
[IS] Note the change of C I P priorities.
[I91 I. Fleming, M. Rowley, Tefrahedron Lett. 26 (1985) 3857, and references
cited therein. Theory: E. D. Jemmis, J. Chandrasekhar, P. v. R. Schleyer,
J . Am. Chem. SOC.I01 (1979) 527.
[20] H. Roder, G . Helmchen, E M . Peters, K. Peters, H.-G. von Schnering,
Angew. Chem. 96 (1984) 895; Angew. Chem. Int. Ed. Engl. 23 (1984)
898.
+
plexes in aqueous suspension at pH values between 8 and
The question arises whether further stabilization of
the complex can be achieved by intramolecular bridging of
the catechol ligands. Therefore, we have synthesized the
new hexadentate ligands 2 .
28
1
When tris[3-(2,3-dihydroxyphenoxy)propyl]ammonium
chloride 2b is allowed to react with tetraethoxysilane in
refluxing methanol in the presence of triethylamine, the
colorless salt 3 separates out within a few hours.
[HNEt3][MC2,H28N09] 3, M = S i ; 4, M = G e
The 29Si-NMR spectrum of 3 exhibits a singlet at
6 = - 138.55. This value agrees well with known 29Si-NMR
data for other hexacoordinated complex anions of Si with
c a t e ~ h o l . [The
~ ~ protons of the propanediyl chain give
broad multiplets with unresolved fine structure in the 'HNMR spectrum. The propanediyl chains in the complex
are probably present in a fixed conformation, the protons
of the three methylene groups giving rise to a multiline
ABMNCD spin system.
Fig. 1. Structural model of the complex anions of 3 and 4
Several bands are observed in the IR spectrum of 3 between 600 and 700 cm-' (Fig. 2); these have been assigned
Novel Octahedral Si and Ge Complexes with a
Hexadentate Diphenol Ligand
By Bernard0 Wolff and Armin Weiss*
Catechol forms the very stable complex anions 1 with
silicon1'.2Jin which silicon has sixfold coordination, which
is unusual for an oxygen environment at normal pressure.
The structure of 1 has been elucidated by X-ray structure
analysis.[3JEven quartz can be transformed into such com-
---
800 700 600 500
[*] Prof. Dr. A. Weiss, Dipl.-Chem. B. Wolff
lnstitut fur Anorganische Chemie der Universitat
Meiserstrasse I , D-8000 Munchen 2 (FRG)
162
0 VCH Verlagsgesellschaft mbH. 0-6940 Weinheim. 1986
-
BOO 700 600 500
Fig. 2 Section of the IR speclrd 01 the tree Iigdnd 2b
compounds 3 and 4
0570-0833/86/0202-0162 $ 02.5010
800 700 600 500
v[cm-'I
ds
well as the complex
Angew. Chem. Int. Ed. Engl. 25 (1986) No. 2
to the Si-0 stretching vibrations in the SiO, octahedron.
With ligand 2b, no absorptions are observed in this region
(Fig. 2). A value of v= 692 cm - ' has been reported for the
Si-0 stretching vibration in (NH,)2[Si(o-02C,H,)3].161
When a saturated solution of 3 is evaporated, 3 slowly
crystallizes as small cubes. It is moderately soluble in dimethylsulfoxide (DMSO), sparingly soluble in CH,CN,
and insoluble in water. The striking stability of the complex anion of 3 is demonstrated by two observations. If a
suspension of fine-grained 3 in aqueous 2~ acetic acid is
stirred at room temperature, no major changes are observed in the I R spectrum and in the X-ray powder diagram after 24 h; however, after about 3 weeks, the compound has undergone quantitative decomposition under
these conditions. The simple catechol complexes 1 undergo immediate cleavage to catechol and silicic acid in
dilute acetic acid. On the other hand, a suspension of
finely divided amorphous SiOz ("Aerosil 380") in a refluxing methanolic solution of 2b (ca. 0.04 M) and excess sodium acetate is completely transformed in one week into
the sodium salt analogous to 3. NaF is required as a catalyst in this reaction. The product was characterized by both
spectroscopy and X-ray diffraction.
2b reacts with GeCI4 to form the salt 4, which, like 3, is
moderately soluble in DMSO and sparingly soluble in acetonitrile. Upon slow evaporation of acetonitrile solutions,
4 forms small, birefringent cubes. The IR spectra of 3 and
4 are virtually identical, apart from small shifts of the
bands. Between 600 and 670 cm-', 4 exhibits absorptions
that are assigned to G e - 0 vibrations. They are characteristically shifted to smaller wave numbers compared with the
analogous bands of 3 (Fig. 2).
Weissenberg photographs confirm that the germanium
and silicon compounds are i ~ o t y p i cThe
. ~ ~ lattice
~
constant
of 4 is only 6.0 pm larger ( a = 1841.5(22) pm) than that of
3. This is in accord with the replacement of the Si by the
somewhat larger Ge atom. In addition, the structure of 4
(Fig. 3 ) corresponds to the model of Figure I, as estab-
the central atom when 2a is used in place of 2b as ligand.
Owing to the short bridges, the intramoIecular complex
formation apparently results in unfavorable conformations
and, therefore, ring strains.
Experimental Procedure
Preparation of 3: 2b (2 g, 3.6 mmol), tetraethoxysilane (0.81 mL, 3.6 mmol),
and triethylamine (1.5 mL, 10.9 mmol) were dissolved under nitrogen in
50 mL of refluxing methanol. After the solution had been refluxed for 12 h,
the precipitate was filtered off, washed with methanol, and dried in high vacuum. Yield: 2.17 g (93%) colorless powder. The product was recrystallized by
dissolving it in ca. 200 m L of refluxing acetonitrile (1 h), filtering off the insoluble matter, and allowing the clear solution to evaporate slowly in the air.
Small cubic crystals formed. The undissolved residue may be treated similarly. Correct elemental analysis. The crystals turn dark above ca. 230°C and
decompose at 300°C. IR (KBr): v [cm-'1: 3055 (m-s), 2940 (m), 1592 (vs),
1481 (vs), 1465 (vs), 1272 (vs), 1257 (vs), 1230 ( s ) , 1219 (s), 1060 (vs), 847 (s),
740 ( s ) , 670 (m). 573 (m), 562 (m), 533 (m-s). 'H-NMR ([D,jDMSO): 6 = 1.17
(t. 'J=7.20
Hz, 9 H , NCH2CH3), 1.78 (m, br., unresolved, 6 H ,
OCH2CH2CH2N), 3.08 (q, 'J=7.20 Hz, 6 H , NCH2CH,), 2.97 (m, br., unresolved, covered by the preceding signal, 6H, OCH2CH2CH2N),3.74 (m, br.,
unresolved, 6 H , OCH2CH2CH2N),6.01-6.34 (m, ArylH, 9H), 8.14 (s, br.,
1 H, NH). 8.90 (s, br., 1 H, NH). "C-NMR ([D6]DMSO): fi=8.48
(NCHLH,),
22.53 (NCH2CHZCH*O), 45.76 (NCH,CH,),
49.38
(NCHZCH~CHZO),
70.57 (NCH?CH2CH20), 105.99, 110.24, 115.46, 141.00,
144.82, 152.88 (C,,).
The 29Si-NMR spectrum was recorded in
[D,]DMSO.-Preparation of 4 : Zb (1 g, 1.8 mmol) was dissolved in 25 m L of
anhydrous methanol. A solution containing 0.19 m L (1.6 mmol) of GeCI,
and 3 m L (21.7 mmol) of dry triethylamine in 25 m L of anhydrous methanol
was added to the refluxing solution of 2b under nitrogen. A colorless precipitate forms immediately. The solution was refluxed for ca. 30 min following
the addition and then filtered. The product was washed with warm methanol
and dried in high vacuum. Yield: 0.94 g (94%) colorless powder. Crystals
were obtained as described for 3. Correct elemental analysis. The crystals
slowly turn dark above ca. 230°C and decompose at 325°C. IR (KBr):
v[cm-'I: 3085 (s), 2935 (m), 1583 (s), 1460 (vs), 1272 (vs), 1256 (vs), 1230 ( s ) ,
1218(s), l055(~~),839(s),719(~~),653(m),639(m),606(m),412(m),344(s).
'H-NMR ([DeIDMSO): 6 = 1.14 (t, 'J=7.25 Hz, 9 H, NCH2CH,), 1.79 (m, br.,
unresolved, 6 H , NCH,CH2CH20), 3.08 (q, 'J=7.26 Hz, 6 H , NCHKH,), ca.
3.0 (m, br., unresolved, covered by the preceding signal, 6 H ,
NCH2CH2CH20), 3.72 (t, br., unresolved, 6 H, NCH2CH2CH20), 6.07-6.37
(m. 9 H , ArylH), 7.68 ( s , br., 1 H, NH), 8.86 (s, br., I H, NH). "C-NMR
[DhJDMSO): 6 ~ 8 . 5 8 (NCHzCH,), 22.85 (NCH2CH?CHZO), 45.74
(NCHXH,), 49.61 (NCH~CHZO),70.88 (NCH2CH>CH?O), 107.13, 110.38,
115.16, 142.38, 144.69, 152.33 (Car,,).
Received: May 7, 1985;
revised: November 20, 1985 [Z 1294 IE]
German version: Angew. Chem. 98 (1986) 173
[ I ] A. Rosenheim, 0. Sorge, Ber. Dtsch. Chem. Ges. 53 (1920) 132.
[2] Armin Weiss, G. Reiff, Alarich Weiss, 2. Anorg. Allg. Chem. 311 (1961)
312.
131 J. J. Flynn, F. P. Boer, J . Am. Chem. Sot. 91 (1969) 5756.
141 Armin Weiss, G. Hofmann, G. Reiff, Beitr. Silikose-Forsch.. Sonderband 3
(1960) 21.
(51 J. A. Cella, J. D. Cargioli, E. A. Wiliiams, J. Orgunomet. Chem. 186 (1980)
Fig. 3. ORTEP plot 01 the structure of the anion 0 1 4
lished by a crystal structure analysis.[71The C e - 0 bonl
lengths
in
- are 187.2(6) and 188.0(6) i m . The bond angles
"
the central GeO, octahedron deviate somewhat from the
values for a regular octahedron. The isotypism of the structures of 3 and 4 shows that the anions have the same
structure.181
For larger central atoms (e.g., Sn) the ligand 2b tends to
form amorphous (X-ray diffraction) 'ligorners Or pOIYmers. Such compounds are also formed with Si or Ge as
\
I
>
,
.
Angew. Chem. In!. Ed. Engl. 25 (1986) No. 2
.13.
[61 E. Funck in H. Volkmann (Ed.): Handbuch der Infrarotspektroskopie. Verlag Chemie, Weinheim 1972, p. 240.
[7] 3: f a 3, u = 1835.5(2) pm, 2=8,p,,, = 1.37 g/cm',
1.38 g/cm3.4 : Po 3, a = 1841.5(22) pm, Z = 8 , pcXp=1.44
g/cm', &,t,ccf= 1.46 g/cm3.
Single-crystal diffractometer Nicolet R3M, CuKoradiation, graphite monochromator. I134 reflections with IFI23uIFI from 1245 symmetry-independent reflections. Numerical absorption correction @ = 17.28 cm- ').
R = R , =0.084. We thank Dr. H. Lorter, lnstitut fur Pharmazeutische Biologie der Universitat Munchen, for measurements. Further details of the
crystal structure investigation are available on request from the Fachinformationszentrum Energie, Physik, Mathematik GmbH, D-75 14 Eggenstein-Leopoldshafen 2, by quoting the depository number CSD-5 1641,
the names of the authors, and the journal citation.
[S] This was also confirmed by an X-ray diffraction study of Dr. U. Nagel,
Munchen, whom we warmly thank.
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