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Molecular Siloxane Complexes of Rare Earth MetalsЧModel Systems for Silicate-Supported Catalysts.

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COMMUNICATIONS
1977. YY. 1064- 1073; C. A. Stein, N. A. Lewis, G. Seitz. ihid. 1982, 104,
2596- 3 9 9 : D.E.Richardson. H. Taube, rhid. 1983, 105. 40-51: M.A.S.
Aquino. F. L Lee. E.J. Gabe. C. Bensimon. J. E. Greedan. R. J. Crutchley. ibrd.
1992. lf4.5130--5140; D. E. Richardson. H . Taube, Coord. Chmi. Res. 1984,
60. I07 t29; S. Woitellier. J. P. Launay, C. W. Spangler. fnovg. Chem. 1989, 28.
75X-762. Y. Kim. C. M. Lieber; hid. 1989.28,3990-3992: J. R. Reimers. N. S.
Hush. ihid. 1990. 2Y, 3686-3697: .I.P. Collin, P. Laine, J. P. Launay, J. P.
Sauv'ige. A. Sour. J1 C h m . Soc. Chrin. Cornnirrn. 1993, 434-435.
141 2-4C~C.l~was crystallized without chromatographic purification, (see Experimental Procedure). Crystals suitable for the X-ray structure analysis were obtained from MeOH;CH,CI, layered with Et,O. Crystal data for 2-4CuC1,
2 Et,O. M , = 867.65. dark crystal (0.20 x 0.20 x 0.25 mm). monoclinic, space
group P2, ( with u =12.1907(19). h =18.115(3), c =18.9597(17) A. [j =
125.01(1). I . = 3429.3(10)A3, Z = 2 , p,,,,,=1.680gcm-',
F(000)=1752,
p(Mokx)= 20.1 cin-'. 17010 reflections measured. 7817 independent (1.7 < 0
< 17 5 , l ' J 2 ? f l scan. At9 = (1.28 0.35tan fl ), T = 150 K, Mo,, radiation,
graphite inonochromator. i. = 0.71073 A) on an Enraf-Nonius CAD4T rotating
anode diffractonieter. Data were corrected for Lorentz and polarization effects
and for a linear decay of 3 % . An empirical absorption correction was applied
(DIFABS. coi-rection range0.819-1 277). The structure wassolved byautomated Patterson methods and subsequent difference Fourier techniques (DIRDIF9 2 ) . Rciinement o n F was carried out by full-matrix least squares techniques
(SHELX76). final R value 0.0588. irR = 0.0559. =l:[sz(k') + 0.000114F'J.
S = 1 S37 Ibr 399 parameters and 4379 reflections with I > 2.5a(Z). Hydrogen
atom\ mcrc included in the refinement on calculated positions ( C - H = 0.98 A)
riding on their carrier atoms. All non-hydrogen atoms were refined with anisotropic therinal parameters: the hydrogen atoms were refined with two common isotropic thermal parameters. Weights were introduced in the final refinement cycles. A final difference Fourier showed no residual density outside
-0.X3 .ind 0.85 e k ' (near Ru). Further details of the structure determination.
including atomic coordinates, bond lengths and angles, thermal parameters. and
ii thermal motion ellipsoid plot are available on request from the Director of the
Cambridge Ci-ystallographic Data centre, 12 Union Road. Cambridge CB2 1EZ
( U K ) on quoting the fnll journal citation.
[5] Br2 w i i \ g r d u a l l ) added to the solution while monitoring the NIR band. Its
maximum intensity was reached a t a Br, to Ru, ratio of 1 :2 and it had disappeared complctrly at a 1 : I stoichioinetry.
[6] M. Bcle). J. P. Collin, R. Louis. B. Metz, J. P. Sauvage. .I h i . Cbmi. Soc. 1991,
/ / 3 , 8521 - 8 2 2 . M. Beley. J. P. Collin. J. P. Sauvage, Inorg. C/iem. 1993. 71.
4539 4543.
So(
+
We chose yttrium and neodymium as representatives of the
lanthanoids. The metal complexes 3a, b were obtained in quantitative yields according to the silylamide route given in
Scheme 1 . The course of the reaction was monitored by the
fb
r
TTHF~
+ [ L ~ ( N ( S I M ~ ~2,) THF
~)~]
~
25 " C , - 3 HN(SiMe&
n
1
3a. Ln = Nd
3b, Ln = Y
n = 1,2
Scheme 1. Each corner of the formula representation corresponds to a cyclopentylsilicon group; oxygen atoms are found midway between the connected corners.
liberation of the silylamine (GC/MS analysis). 3a, b are readily
soluble in all organic solvents, even n-pentane, and were characterized by elemental analysis and I R spectroscopy (no v(Si0-H)
bands at ca. 3230 cm-' typical of the starting material). Investigations by mass spectrometry (no signals < 300 'C) suggest
dimeric structures in the solid state (n = 2) as found in the Al"'
and Ti"' complexes.[2a.b1Whilst the 'H, I3C, and 2ySi N M R
spectra could not be conclusively interpreted, the "Y N M R
spectrum contains a single signal which indicates the presence of
a well-defined compound and only one chemical environment of
the Y atom. The shift of 6 = 196.9 is typical of lanthanoid siloxides (cf. [Y(OSiMe,tBu),(THF),], 6 = 266.6[51).Attempts at
recrystallization from common solvents such as THF, hexane,
and benzene produced crystals that were amorphous by X-ray
crystallography. However, with triphenylphosphane oxide as an
auxiliary ligand. 3 b reacted to give the adduct 4 as single crystals.[61Figure 1 shows the structure of the binuclear complex 4.
Molecular Siloxane Complexes of Rare Earth
Metals-Model Systems for Silicate-Supported
Catalysts?**
Wolfgang A. Herrmann,* Reiner Anwander, Veronique
Dufaud, and Wolfgang Scherer
The preparation of realistic models of heterogeneous, Si0,supported transition metal catalysts eluded chemists for many
years."] However, partially condensed oligosesquisiloxanes have
lately proved to be reasonable
,OH
model systems.[*] Since lanthanoid-doped zeolite catalysts
are of considerable technical imp o r t a n ~ e , [ we
~ I have introduced
oligosesquisiloxanes such as [(c1 as molecu~ s ' ~ 0 4 s 'C,H,)Si],O,(OH),
~
lar models in the chemistry of the
1
rare earth
C'I
[*I
[**I
Prof Dr. W. A. Herrmann. Dr. R. Anwander, Dr. V. DuPaud, W. Scherer
Anorganisch-cheinisches Inatitut der Technischen Universitlt Munchen
Lichtenbergstrassc 4, D-85747 Garching (FRG)
Tclefax: I n t . code + (8Y)3209-3473
Lanthanoid Complexes. Part 7. This work was supported by Osram GmbH
and the Alexander-von-Humboldt-Stiftung. We thank Dipl.-Chem. F.-R.
Klingan fw recording the NMR spectra. Part 6: W. A. Herrmann. R. Anwander. W. Schcrcr. F. C. Munck. J. Olgonomer. Cbewr. 1993. 462, 163.
Fig. 1. Model of the molecular structure of 4 in the solid state (SHAKAL representation). To simplify the drawing, the cyclopentyl groups and the four Folvent molecules are not completely represented. Selected bond lengths [A] and angles [ ]:
Y1-01 2.239(9). Y1-02 2.119(7). Y1-03 2.123(9), Y1-013 2 422(7). YI-015
2.391(8), YI-021 2.509(9), Y2-01 2.384(7), Y2-013 2.25(1). Y2-014 2.1 17(X).
Y2-015 2.255(8). Y2-025 2.296(8), Y2-026 2.26(1): Y1-01-Y2 91.3(3): Y1-013Y2 90.0(4). Y1-015-Y2 90.7(3). Y1-021-Six 92.9(4). Y1-021-Si14 115.4(4). Si1402I-Si8 141.1(5). Y2-026-P1 157.0(6). Y2-025-P2 153.3(6).
Both yttrium atoms have six-fold coordination. In contrast, the
addition of the same phosphane oxide auxiliary ligand to the
corresponding aluminum complex causes a cleuvuggr of the
dimer originally
COMMUNlCATlONS
Furthermore, because of the considerable increase in the radius of the metal ion, as well as the increased oxophilicity of the
metal compared to all other metal complexes containing this
type of ligand, three bridging SiO units link the two metal centers (unsymmetrically). One of the yttrium atoms (Yl) achieves
coordinative saturation by coordination to an oxygen atom in
the ligand framework (021 ; Fig. 2). This type of framework
Fig. 2. Simplified representation of the coordination spheres of the yttrium atoms
to emphasize the structural features of 4. The framrivork oxygen atom 0 2 1 acts as
a donor atom and completes the coordination sphere of Y I .
coordination is unknown for any of the known metal complexes
of sesquisiloxanes, not even for any of the other lanthanoid
siloxane cornplexe~.~'~
The distances from the yttrium center to
the terminal [2.117(8)-2.123(9)
and bridging oxygen atoms
[2.239(9)-2.422(7) A] lie within the expected range.17c1The Y
(021) distance of 2.509(9) corresponds to a typical donor
bond (cf. 2.374(20)-2.462(21) A in [Y(OSiR,),(THF),] .
(THF), R = C,H,17C1).
The Si-0-Si bridging oxygen atoms can act as Lewis bases in
zeolite systems as well.[*] The binuclear complex units 4 are
loosely packed in the solid state. Four crystallographically independent solvent molecules (toluene) are located in the resulting
channels. The size of these solvent channels leads to a considerable disorder of the toluene molecules and explains the facile
diffusion of the solvent out of the crystals even at low temperatures.
Organometallic compounds react preferentially with partially
dehydroxylated silica surfaces, that is with [Si(OH),] centers as
opposed to [SiOSi] sites, towards which they usually behave
indifferently.14d1The yttrium complex 4 shows, for the first time,
the coordination of [SiOSi] sites to an extremely oxophilic, electropositive metal center. This may permit interesting analogies
with the structural chemistry of metal-doped zeolites. For example, in investigations of Ga-exchanged zeolites by I R spectroscopy altered lattice vibrations are observed.[3'. 91 which
should correspond to a change in the catalytic properties. Furthermore, the attachment of neutral silicones of low molecular
weight such as (RSiO,,,), (R = iPr. tBu)"'] onto coordinatively
unsaturated organolanthanoid compounds indicates the possibility of supporting a catalyst following the example in
Scheme 1.
A]
-
A
Experimental Procedure
In a glovehox (M. B. BrdUn) amides 2 and an equimolar quantity of 1 were weighed
into a 100-mL round-bottomed flask. Roughly 40 mL of T H F was added by condensation under high vacuum. The mixture was stirred for 1 h at 0 "C then allowed
to warm to 25 C. In the reaction of the yttrium amide a clear solution was obtained
immediately, in the reaction of the neodymium amide only after 30 h. After ca. 40 h
the solvent and the liberated amine were removed under vacuum ( I mbar). The
colorless or light blue residue was dried for 3 h under vacuum ( l o - ' mhar). The
residues are very soluble in n-pentane. Quantiative yields. 3a: Starting from 0.58 g
(0.92 mrnoi) 2a, 0.81 g (0.93 mmol) 1; light blue crystals; correct C,H.Si analysis
(for two THF/Nd: no N): IR: i'[cm-l] =1246 m. 1109 vs, 1088 (sh) vs. 1049 (sh)
s. 998 s. 929 m. 875 w. 846 w, 525 m. 514 m. 3b: Starting from 0.59g (1.04 mmol)
1286
:c) VCH Verlugsp~~.s.sellsc~~ufi
n?hH.D-69451 W~~mheitn.
1994
2b. 0.90 g (1.03mmol) 1; colorless crystals; m.p. 235 'C; correct C.H.N.Si analysis
(fortwoTHF/Y:noN);IR:i'[cm-']
=1244m. 1111 vs. 1 0 8 7 ~ s1051
.
(sh)s. 1009
m. 954 m. 926 m. 914 m. 886 m, 841 (sh) wp, 773 w. 519 m. 506 m. 483 m, 466 w.
C,,I H ) NMR (400 MHr. C,D,. 25 C). d
13
N M R (400 MHz, C,D,, 25 'C): 6
25 .C): 6 = 196.9.
(400 MHz. C,D,.
=
-
=
22.2-30.2 (complex pattern):
65.64. -64.61,
-62.74;
'9s~
"Y N M R
Received: November 25, 1993
Revised version: February 5 , 1994 [Z 6512 lE]
German version: Anpeu. C'/irtn. 1994. l06. 1338
[ I ] F. T. Edelmann. Angmr. Ctwii. 1992, f04.600: .4ng?w. C/im.nl.h t . €d €q/.
1992, 32, 586.
[2] a) F. J. Feher. T. A. Budzichowski. K. J. Weller, J Ant. C ' / i m / . So(. 1989. 111,
7288; h) F. J. Feher. S. L. Gonzales. J. M. Ziller. Inorg. Chenr. 1988, 27, 3440:
c) F. J. Feher. J. F. Walrer. i h d 1990. 29, 1604: d) T. A. Budzichowski. S. T.
Chacon. M. H. Chisholm. F. J. Feher, W. Streib. J. Am. Clieni. So(. 1991. f 13.
689; e) F. J. Feher, T. A. Budzichowski, J. W. Ziller. biorg. C'heni. 1992, 31.
5100; f ) G. Calzaferri. Nuchr. Clwm. 7i.r.h. Luh. 1992. 40. 1106.
[3] a) M. Brurzone in Firnrluinentul and Teho/ogicul Aspects of Orgnrio-/-E/rr?irnr
Chrniritr! (Eds.: T. J. Marks. I. L Fragali). Reidel. Dordrecht, 1985; h) W,
Holderich, M. Hesse. F. Niiumann. Angew. Chein. 1988. /IN). 232; Angol
Chem. h i t . 6 1 . En,?/. 1988.27. 226: c) S. L. Suih. Cheni. Re),.1993. Y3, 803: d) T.
Baba. R. Koide. Y. Ono. J. Clion. Soc. C/ieni. Cnnimuif. 1991. 691.
[4] Synthesis of oligosesquisiloxanes: a) J. F. Brown. Jr., L. H. Vogt. J r . . J. A ~ I .
Chrni. So<. 1965, 87, 4313: b) F J. Feher. T. A. Budzichowski. R. L. Blanski.
K. J. Weller. J. W. Ziller. O , g r r n n ~ i / ~ ~ t n
1991,
/ / ~ ~10,
s 2526; c) F. J. fisher. D A .
Newman, J. F. Walzer. J. An?. Ch~vn.Soc. 1989. If 1, 1741 : d) T. W. Hambley.
T. Maschmeyer. A. F Masters. Appl. Orgunonxv Clwn. 1992. 6. 253:
e ) G . K. 1. Magomedov, E. A. Chernyshev. L. V. Morozova, A. S. Frenkel.
B. V. Molchanov. S Y. Kochev, S A. Sigachev. A I. Shrodov. E. V. Bulycheva.
Mrlu1loor.g. Khiiii. 1992. 3, 151 ; Orpurlonlet. C h i ? . L,SSR fEngl!.sh [runs.,
1992. 3. XI
(51 P. S. Coan. L. G. Hubert-Pfalzgrat K. G. Caulton. h r g . Cliem. 1992, 31.
1262
161 Growth, selection. and mounting of the crystals was curried out in a glove box
with an integrated polarization microscope and capillary sealing apparatus. 4
crystallized from toluene at -35'C in the triclinic space group Pf with
( I =1647.4(9). h = 2064.2(9), c = 2300.4(38) pm. a = 83.35(4). /r =71.83(4).
7 = 89.50(3)'. T = - 80 f 3 C . 2 = 2. V=7379 x 106 pm3,p = I 2 8 9 gcm-'.
F(000) = 3008. Mo,, radiation. Enraf-Nonius CAD4 diffractometer. w-scans.
max. 50s. lO634measured reflections ( 2 - iH < 30'). /1(-15:15). k ( 0 ' 2 0 ) .
I( - 21 2 1 ) . 8625 independant reflections of which 6156 with I > 3.0 ~ ( 1Mere
)
used for refinement; correction of intensity (30% decomposition). no correction for absorption (11 = 9.9 c m - ' ) . R = Cl'Fol lFLll);~lFol
= 0.079:
R, = [Xir(lFu] l ~ l ) ' ~ ~ ~ r l F
=o
0.085.
~ 2 ]residual
' ~ z electron driisity +0.80:
-0.98 e, A?. Further details of the crystal structure investigation may he
obtained from the Fachinformationszentrum Karlsruhe, D-76344 EggensteinLeopoldshafen ( F R G ) , on quoting the depository nuinher CSD-58155.
[7] a) P. S. Gradeff, K. Yunlu. A. Gleizes. J. Galy. Polvherlron 1989. 8. 1001;
b) W. J. Evans. T. A. tilibarri. J. W. Ziller. Orgunofwrullrt~~1991. (0, 134;
c) M. J. McCeary, P. S. Coan. K. Folting, W. E. Streib. K. G. Caulton. Inorg.
Clicin. 1991. 30, 1723.
[XI F. Liebau, Srrrrrfirml Chewnsfry of Siliu/fe.\, Springer, Berlin. 1985
[Y] D. H. Dompas, W. J. Mortier. 0. C. H. Kenter. M. J. G. Janssen. J. P. Verduijn.
J. Cotal. 19Y1, f29. 19.
[lo] a) E. Wiberg. W. Simmler. Z. Anorg. Allg. C h m . 1955,283. 330: b) R. Gewald,
U. Scheim. K. Ruhlinann. H. Goesman. D. Fenske. J Orgunofner.C/i<w.1993.
450. 73.
-
-
Olympiadane**
David B. Amabilino, Peter R. Ashton,
Anatoli S. Reder, Neil Spencer, and J. Fraser Stoddart*
The appearance. toward the end of last year. of a remarkable
paper in a special issue of the New Journal nf'Chemistry, edited by
Sauvage, has drawn attention to the fact that, as long ago as 1960,
[*] Prof. J. F. Stoddart. Dr. D. €3. Amahilino, P. R. Ashton, Dr. A. S. Reder.
Dr. N. Spencer
School of Chemistry, University of Birmingham
Edgbaston. GB-Birmingham B15 2TT (UK)
Telefax: lnt. code + (21)414-3531
[*'IThis work was supported in the tiK by the Science and Engineering Research
Council.
0570-0X33!94;f212-1286 d 10.00+ .25i0
Angms. Chen,.
In[. Ed. Engl. 1994, 33. N o . 12
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