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New Routes to Alkylidyne-Bridged Ditungsten Compounds Supported by Alkoxide or Siloxide Ligands by the Activation of Ethylene.

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initio calculation of (H,Si),P, is reflected in the good agreement of the calculated and experimental (substituted system)
distances and angles. For the equilibrium structure (C,,) a
longer P-P distance of 2.360 A was calculated, which is only
0.02 A shorter than the experimental value for 1b."] The
negative results of the ab initio calculations regarding the Si
inversion suggest that this process in l a is only forced to
occur by the presence of bulky substituents. Hence, this is no
characteristic of the folded P,Si, bicycle. The incomparability of the parent compound and the derivative with bulky
substituents is probably also true for diarsadisilabicyclo[l .I .O]butanes. The greater stability of the exo,endo isomer 2a in comparison to 1 a is probably due to unfavorable
As-As interactions in the transition state of the Si inversion.
aromat. H), 6.772 (s, 2H, aromat. H); ,'Si NMR: 6 = 1.62 (s, 1Si), 8.51
(s, l a ) . - MS (EI, 70eV): m/z (%) 558 ( M t 25.3),
,
501 ((M - tBu)+,
32.4). 267 (Mes,SiH+, 20.0), 57 (C,H,+, 100).
Zb: 'H NMR (200 MHz, 298K, C,D6): 6 = 1.215 (s, 18H, tBu), 2.368 ( s ,
6H, p-Me), 2.770 (s, 12H, o-Me), 6.289 (s, 4H, aromat. H); 29SiNMR:
6 = - 25.71 (s). MS (EI, 70 eV): identical with 2.
Crystal structure analysis of Zb: Space group C2/c, a = 19.679(20), b =
11.935(30), c = 12.527(10)A, = 108.51(3)", V = 2790 A3, Z = 4, 1049
observed reflections ( I > 20,, four-circle diffractometer, Mo,, radiation,
w scan). The molecule has a crystallographic twofold axis. The refinement
(As, Si.C anisotropic, methyl and phenyl groups as rigid groups) resulted
in R = 0.071, R, = 0.074.[17]
W. Honle, H.G. von Schnering, Z . Naturforsch. B 1980,35, 789.
[(tBu,C,H,)PAs],: P. Jutzi, U. Meyer, S. Opiela, M. M. Olmstead, P. P.
Power, Organometallics 1990, 9, 1459; [(Ph,P),PdAs],: D. Fenske, H.
Fleischer, C. Persau, Angew. Chem. 1989, lOf, 1740; Angew. Chem. Int. Ed.
Engl. 1989, 28, 1665.
E. J. Porter, G. M. Sheldrick, J: Chem. SOC.Dalton Trans. 1972, 1347.
GAUSSIAN 88: M. J. Frisch, M. Head-Gordon, H. B. Schlegel, K.
Raghavachari, J. S . Binkley, C. Gonzalez, D. J. Defrees, D. J. Fox, R. A.
Whiteside, R. Seeger, C. F. Melius, J. Baker, R. Martin, L. R. Kahn, J. J. P.
Stewart, E. M. Fluder, S. Topiol, J. A. Pople, Gaussian Inc., Pittsburgh,
PA, 1988.
P. von R. Schleyer, A. F. Sax, J. Kalcher, R. Janoschek, Angew. Chem.
1987, 99, 374-377; Angew. Chem. Int. Ed. Engl. 1987,26,364-366.
R. Janoschek, Chem. Unserer Zeit 1991, 25, 59-66.
MOLEKEL: H. J. Werner, W Meyer, J: Chem. Phys. 1981, 74, 5794; H. J.
Werner, E. A. Reinsch, ibid. 1882, 76, 3144.
Further details of the crystal structure investigation may be obtained
from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlich-technische Information mbH, D-W-7514 Eggenstein-Leopoldshafen 2 (FRG) on quoting the depository number CSD-55938, the
names of the authors, and the journal citation.
~
Experimental Procedure
3: To a solution of Mes(tBu)SiCI, (4 g, 14.54 mmol) in THF (30 mL) at - 78 "C,
a solution of [LiAsHz(dme)](5.06 g, 29.08 mmol) in THF (30 mL) was added.
This mixture was warmed to -30°C over a 2 h period, stirred for a further 2h
at this temperature, and then slowly warmed to 28 "C. After 8 h at 28 "C all
volatiles were removed at lo-' Torr. The residue was taken up in benzene
(30 mL) and filtered. Concentration of the pale yellow, clear filtrate to ca. 5 mL
afforded trapezoid-shaped, colorless crystals after 2d at 28 "C. Yield 2.52 g
(4.50 mmol, 62%). Mp =188-190"C.
4: To a solution of 3 (1 g, 1.78 mmol) in THF (20 mL), BuLi (227.8 mg,
in hexane) was added at -78 "C. The initial colorless
3.56 mmol, 2 . 5 solution
~
solution immediately changed to an intense orange-yellow. After 30 min at
-40 "C a solution of tBuHgCl(1.046 g, 3.56 mmol) in THF was added slowly
which resulted in a colorless solution. Following this the solvent was removed,
the residue was taken up in hexane (10 mL), filtered, and crystallized at 78 "C.
Compound 4 was isolated as colorless, light-sensitive crystals. Yield 1.859 g
(1.58mmo1, 89%). Mp =176"C (decomp.).
) exposed
Za: A vigorously stirred benzene solution of 4 (100 mL, 0 . 0 2 5 ~ was
to light (150 Watt light bulb) for 24h. The yellow suspension formed was filtered several times over dry silica gel to remove Hg. Any remaining Hg was later
removed under vacuum
Torr). Concentration of the intense yellow solution afforded spectroscopically ('H and z9Si)pure 2. Yield 1.353 g (2.42 mmol,
97%).
Z b: A hexane solution of Za (60 mL, 0.017 M) was irradiated analogously to that
for the preparation of 2 a for 1 week at 25 "C. The solution was concentrated to
ca. 1 mL, and within 2 weeks 2 b crystallized out completely ('H NMR control,
45.6 mg, 8%).
~
Received: October 25, 1991 [24988IE]
German version: Angew. Chem. 1992, 104, 449
CAS Registry numbers:
Za, 139136-93-1;Zb, 139238-72-5;3, 139130-91-9;4, 139130-92-0;MeS(tBu)SiCI,, 89486-31-7; [LiAsH,(dme)], 138435-85-5; rBuHgC1, 38442-51-2.
M. Driess, Angew. Chem. 1991,103,979-981; Angew. Chem. I n t . Ed. Engl.
1991, 31, 1022-1024; M. Driess, H. Pritzkow, M. Reisgys, Chem. Eer.
1991, 124, 1923.
Tetraphosphabicyclo[l.l.O]butane:E. Niecke, R. Riiger, B. Krebs, Angew.
Chem. 1982,94,553; Angew. Chem. Int. Ed. Engl. 1982,21,544; R. Riedel,
H.-D. Hansen, E. Fluck, ibid. 1985,97,1050 bzw. 1985,24,1056; Diphosphadisilahicyclo[l.l.O]butane: M. Driess, A. D. Fanta, D. Powell, R.
West, ibid. 1989, f01,1087, 1989, 29, 1038 respectively: see also [l].
T. Dabisch, W. W. Schoeller, J. Chem. SOC.Chem. Commun. 1986, 896;
W. W. Schoeller, C. Lerch, Inorg. Chem. 1983, 22, 2992.
3: 'H NMR (200 MHz, 340 K, C6D6): 6 = 1.069 (s, 18H, tBu), 2.074 (s,
6 H , p-Me), 2.708 (br., 14H. o-Me and ASH), 6.725 (s, 4H, aromat. H);
"Si NMR (298K, INEPT): 6 = - 14.09(s); MS(EI,70 eV): m/z (%) 560
( M ' , 73.4), 501 ( ( M - ~ Bu-~ H)' , 5.9), 267 (MeszSiHt, 74.1), 163 (100).
Crystal structure analysis of 3 : Space group P i , a = 8.739(4), b
=14.280(7), c =15.336(8) A,C( =109.79(3), B =106.17(3), y =103.07(3)",
V =1617 A3, Z = 2,4327 observed reflections ( I > 2a,, four-circle diffractometer, Mo,, radiation, w scan). The refinement (As, Si, C anisotropic,
methyl groups as rigid groups) resulted in R = 0.049, R, = 0.055. 3 crystallized with benzene.[l7]
4: 'H NMR (200 MHz, 298K, C,D,): 6 = 1.191 (s, 18H, tBuSi), 1.327 (s,
18H, fBuHg, 3J('H, 199Hg)= 166 Hz), 2.107 (s, 6H, p-Me), 2.729 (s,
12H. o-Me), 6.756 (s, 4H, aromat. H); 29SiNMR: 6 = - 2.56(s); correct
C,H analysis.
2 8 : 'H NMR spectra temperature dependent as a result of the hindered
rotation of the Mes groups; 'H NMR (200 MHz, 298K, C,D,): 6 = 0.801
(s, 9 H , fBu), 1.20 (s, 9H, tBu), 1.331 (s, 3H, o-Me), 1.572 (s, 3H, o-Me),
2.078-2.114 (m, 6H,p-Me), 2.757-2.767 (br., 6H, o-Me), 6.745 (s, ZH,
462
0 VCH
Verlagsgesellschaji mbH, W-6940 Weinheim. 1992
New Routes to Alkylidyne-Bridged Ditungsten
Compounds Supported by Alkoxide or Siloxide
Ligands by the Activation of Ethylene**
By Stephanie T Chacon, Malcolm H . Chisholm,*
Cindy M . Cook, Mark J. Hampden-Smith,
and William E. Streib
Dedicated to Professor E. 0. Fischer
Following Fischer's"] discovery of the carbyne ligand
(now more commonly called alkylidyne) numerous other examples emerged with rich and interesting reactivity. The
most common synthetic routes to carbyne complexes involve
reactions of carbonyl ligands, a-hydrogen atom transfer
from alkyl and/or alkylidene ligands, and C-C scission of
coordinated alkynes.C2]We describe here two new reactions
leading to carbyne-bridged ditungsten compounds, together
with the results of labeling studies that reveal potential insight into the reaction pathways involved in these remarkably facile reactions.
The ethyne adduct [W2(p-C,H,){OSi(tBu)Me2}6(py)]~31
and ethylene ( 2 1 equiv) react in hexane at - 20 "C to give
the blue crystalline compound 1.
[W,(H)(p-CCH=CHCH,>(OSi(tBu)Me,),l1
Compound 1 is also formed if the reaction is carried out at
room temperature; however, a competitive reaction leading
[*] Prof. M. H. Chisholm, S. T. Chacon, C. M. Cook,
[**I
Prof. M. J. Hampden-Smith, Dr. W. E. Streib
Department of Chemistry and Molecular Structure Center
Indiana University, Bloomington, IN 47405 (USA)
This work was supported by the Department of Energy, Office of Basic
Sciences, Chemistry Division, and the National Science Foundation.
S. T. C . thanks the American Association of University Women Educational Foundation for an American Dissertation Year Fellowship.
0570-0833/92/0404-0462$3.50+ .25/0
Angew. Chem. Int. Ed. Engl. 31 (1992) No. 4
to the previously characterized compound pNz(pCCH){OS~(~BU)M~,},][~~
is observed. The latter compound
does not react with ethylene to give 1 as determined from a
separate experiment. The structure of 1 has been determined
from an X-ray crystallographic study and is shown in Figure
The NMR data obtained for 1 in [D,]toluene at
provides a synthesis of 2 in ca. 50% isolated yields starting
from [W,(OCH,~BU),(C,H,),].~~~
The structure of the p-ethylidyne complex 2[41is shown in
Figure 2 and the NMR data are consistent with the solidstate structure.
Insight into the reaction pathways leading to the facile
formation of compounds 1 and 2 may be gleaned from the
following observations involving the use of labeled C, compounds: 1) The reaction between [W,(,U-'~C,H,)(OS~(~B~)Me,},(py)] and C,H4 in hexane at -20 "C yields the isotopomer of 1 IW,(H)(p-'3C13CH=CHCH3)(0Si(tB~)Me~}6]
while the reaction between [W,(p-C,D,){OSi(tBu)Me,},(py)]
and C,H, gives [W,(D)(~-CCD=CHCH,){OS~(~BU)M~~)~]
2) The reaction between [W,(OCH,tBu),(C,D,),]
and
tBuOH in hexane yields [Wz(p-CCD3)(OCH,rBu),(OtBu)J
and C,D,H as deduced from NMR studies.
Fig. 1. Top: ORTEP drawing of [W,(H)(~-CCH=CHCH,){OS~(~BU)M~~}~]
(1). Hydrogen atoms have been omitted for clarity. Pertinent distances [A] are
W(l)-W(2) 2.658(1), W(1)-0(7) 2.10(1), W(1)-0(15) I.X9(1), W(1)-O(23)
I.X6(1), W(1)-O(31) 1.94(1), W(l)-C(3) 1.9X(I), W(2)-C(3) 1.92(1), W(2)-0(7)
2.05(1), W(2)-O(39) 1.87(1), W(2)-O(47) 1.92(1). Bottom: The proposed position of the hydride ligand IS indicated in the stick drawing.
ieU
- 70 "C are consistent with the structure found in the solid
state (i.e., all siloxy ligands are chemically inequivalent) and,
in particular, confirm the presence of the hydride and bridging 2-butenylidyne ligands. At - 70 "C the hydride signal
shows a coupling to 183W ( I = 112, 14.5% natural abundance) of 145 Hz, while at 22°C the magnitude of this coupling is only 83 Hz. The relative satellite intensity due to
coupling to le3W is notably larger in the room temperature
spectrum. This, together with the low-temperature NMR
behavior of the OSi(tBu)Me, signals, leads us to believe that
in the structure of 1, the hydride ligand occupies a terminal
position on W2, which is otherwise only four coordinate. It
is evident, however, that a fluxional process involving terminal-bridge interchange of both siloxide and hydride ligands
is rapid on the NMR time scale at room temperature.
The compound [W,(p-CMe)(OCH,tBu),(OtBu)] (2), was
first discovered as a minor product in the reaction between
[W,(OCH,tBu),] and ethylene (2 equiv).l5]The origin of the
OtBu ligand can reliably be traced to the presence of adventitious tBuOH that was present in the solution as a residual
impurity from the preparation of [W,(OCH,tBu),] by alcoholysis of [W,(OtBu),]. The reaction shown in Equation (a)
[W,(OCH,tBu),(C,H,),]
+
rBuOH ----t
[W2(p-CMe)(OCH,tBu),(OrBu)]
2
Angew. Chem. Int. Ed. Engl. 31 (1992) No. 4
0 VCH
+ C,H,
(4
Fig. 2. Top: ORTEP drawing of [W,(p-CMe)(OCH,tBu),(OtBu)]
(2). Hydrogen atoms have been omitted for clarity. Pertinent distances are W(l)-W(2)
2.644(1), W(1)-O(5) 2.05(1), W(1)-O(28) 1.90(1), W(1)-O(34) 1.94(1), W(1)O(40) 1.91(1), W(l)-C(3) 1.94(1), W(2)-0(5) 2.03(1), W(2)-O(10) 1.90(1), W(2)O(16) 1.94(1), W(2)-O(22) 1.90(1), W(2)-C(3) 1.94(1). Bottom: Stick drawing of
2.
The stereospecific transfer of H/D atoms and the stereochemistry about the C-C double bond in 1 lead us to suggest
that the alkylidyne ligand is formed by initial C-C bond
formation to generate a metallacyclopentenyl moietyf71followed by jl-H elimination and reinsertion to generate an
alkenyl ligand. By subsequent a-CH activation the hydride
and alkenylidyne ligands are formed (see Scheme 1).
The formation of the isotopomer of 2 containing the
[W,(p-CCD,)] moiety indicates that the ethylidyne H/D
atoms arise exclusively from those on ethylene and as such
parallels the reaction of ethylene on a Pt"' surface that generates the p,-ethylidyne ligand.[']
In conclusion, we have discovered two facile reactions
leading to alkylidyne-bridged ditungsten compounds supported by alkoxide or siloxide ligands from ethylene. It seems
quite plausible that these are merely the first examples in the
reactions of ditungsten alkoxides/siloxides and alkenes.
Verlaggesellschafr mbH, W-6940 Weinheim, 1992
0570-0833/92J0404-0463$3.50+.25/0
463
H
[W,(OCH,IB~),(O~B~)(~~-'~C'~CH,)]:
'H NMR (360 MHz, 22 "C, C,D,):
S=4.47(dd,3H, 'JH,,-130Hz, 'JH,,=7Hz, 13C13CH3).
13C{'H} NMR (75 MHz, 2 2 T , C,D,): 6 = 34.4 (d, 'J,,,, = 30 Hz,
13C13CH3);297.3 (d, 'JC,,= 30Hz, 'JC,,=160Hz, I = 26%. 13C13CH3).
\
Received: October 28, 1991 [Z 4993 IE]
German version: Angew. Chem. 1992, 104,467
CAS Registry numbers:
1, 139524-19-9; 2, 139563-95-4; [W,@-C,H,){OSi(tBu)Me,),(py)],
13438451-3; [W,(OCH,tBu),(C,H,),], 128659-38-1; [W,(p-13C,H,){OSi(tBu)Me,}6(py)],
134384-63-7; [W2@-C,D,){OSi(tBu)Me2},(py)],134384-37-5;
[W,(OCH,tBu),(C,D,),],
139524-20-2; [W,H@-'3C'3CH=CHCH,){OSi(iBu)Me,),], 139524-21-3;[W,D(p-CCD=CKCH,){OSi(tBu)Me,},],
1395243 39524-23-5.
22-4; [W2(p-CCD3)(OCHz~B~)6(0tB~)],
H
R'OQ
H
H
I
H3C C
I
H3C-C0
C-H
%-"
1
Scheme 1. A possible reaction pathway leading to the formation of 1 from
[W,(p-C,H,){OSi(tBu)Me,},(py)]and ethylene. R = Si(iBu)Me,. a) C-C coupling, b) p-H elimination, c) insertion, d) cc-H elimination.
Experimental Procedure
[l] E. 0. Fischer, G. Kreissl, C. G. Kreiter, J. Miiller, G. Huttner, H. Lorenz,
Angew. Chem. 1973,85, 618; Angew. Chem. Int. Ed. Engl. 1973, 12, 564.
[2] J. P. Collman, L. S. Hegedus, J. R. Norton, R. G. Finke, Principles and
Applications of Organolransition Metal Chemistry, University Science
Books, Mill Valley, CA, 1987, pp. 137-146, and references cited therein.
[3] M. H. Chisholm, C. M. Cook, J. C. Huffman, W. E. Streib, J. Chem. Sac.
Dalton Trans. 1991, 929.
[4] Crystal data for 1 at -172°C: a = 14.037(2), 6 = 18.453(2), c =
11.681(2)A, z = 91.20(1), B =106.63(1), y =100.35(1)", 2 = 2, esalCd
=
1.41 g ~ m and
- ~ space group PT. Of the 8821 reflections collected (Mo,,,
6" < 2 0 < 45") 7482 were unique and the 6625 having F,, > 3a(F) were used
in the least-squares refinement. In the final cycles of refinement, the non-H
atoms were varied with anisotropic thermal parameters. The final residuals
are R ( F ) = 0.0535 and R,(F) = 0.0527. Crystal data for 2 at - 147°C:
a =12.619(4), h =18.459(5), c =10.316(2)A, c( = 91.42(1), p=102.35(1)",
y =70.74(1)", Z = 2, ecs,cd
=1.49 g ~ m and
- ~space group PI. Of the 7489
reflections collected (Mo,,, 6" < 2 0 < 45") 5810 were unique and the 4999
having F > 3a(F) were used in the least squares refinement. The final residuals are R ( F J = 0.0473 and R,(F) = 0.0466. All non-H atoms were refined
anisotropically. Further details of the crystal structure investigations may
he obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur
wissenschaftlich-technischeInformation mbH, D-W-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD-56004, the
names of the authors, and the journal citation.
[5] M. H. Chisholm, J. C. Huffman, M. J. Hampden-Smith, J. Am. Chem. Soc.
1989, f If, 5284.
[6] R. H. Cayton, S. T. Chacon, M. H. Chisholm, J. C. Huffman, Angew.
Chem. 1990, 102, 1056; Angew. Chem. Int. Ed. Engl. 1990, 29, 1026.
[7] The coupling of two alkyne ligands to give a PN,(p-C,RJ] center is well
documented in the chemistry of [W,(OR),] compounds. See M. H.
Chisholm, D. M. Hoffman, J. C. Huffman, J. Am. Chem. SOC.1984, 106,
6806.
[S] L. L. Kesmodel, L. H. Dubois, G. A. Somorjai, J. Chem. Ph-vs. 1979, 70,
2180.
[W,(H,)(C.C,H,=C,H,C,H,,)(OSi(tBu)Me2},]
(1): A 50 mL Kontes flask
crystalline solid (330 mg,
charged with black [W,(p-C,H,){OSi(tBu)Mez}6(py)]
0.26 mmol) and a stir bar was placed in a CO,(s)/ethanol cold bath at - 72 "C.
Toluene (10 mL) was then added. The heterogeneous mixture was immediately
frozen at -196"C, evacuated, and C,H, (1.31 mmol) introduced through a
calibrated vacuum manifold. The flask was immediately placed in a cold bath
at -72 "C for 30 min, during which time the mixture became homogeneous,
and the brown solution gained a blue tint. The solution was placed at -20 "C
for 12 h. Reduction of the volume to ca. 5 mL, and crystallization at - 20 "C led
to the isolation of deep blue-black crystals of 1 . Combined crystallizations gave
1 in 45% isolated yield.
'H NMR (300 MHz, 22 "C, C,D,): 6 = 15.76 (s, JW,H
= 83 Hz, I = 32%. HJ;
= 1 Hz, Hb); 5.64 (dq, 3JHc,Hb
=11 Hz,
8.22 (dq, 3JHb,Hc=11Hz, 4JHb,Hd
3JHd,Hr=6H~,4JHd,Hb=1H~,Hd);1.10(~.br.
3 J H , , H d = 6 H ~ , H1.88(dd,
J;
OSi(tBu)Me,); 0.34 (s, br, OSi(tBu)Me,).
'H NMR (300 MHz, -70"C, C,D,): S =15.56 (s, JW,H
=145 Hz, I = 22%,
((Ph,PAu),Mn(CO),]+, a Cluster with
HJ; 8.22 (dq, HJ; 5.64(dq, He); 1.88 (dd, HJ; (OSi(rBu)Me,): 1.35,1.24, 1.14,
Pentagonal-Bipy ramidal Structure
1.12, 1.06, 1.02 (swithintensityratio 1 : l : l : l : l : l ) ; (OSi(rBu)Me,):0.70,0.66,
0.48, 0.47, 0.32, 0.30, 0.29, 0.26, 0.21, 0.17, 0.16 (s with intensity ratio
By Jorg Mielcke, and Joachim Strahle*
1 : 1: 1:1:1 :1:2: 1 : 1: 1. The signal of intensity 2 is apparently due to accidental
degeneracy).
Dedicated to Professor Ernst Bayer on the occasion
13C{'H} NMR (75 MHz, 22 " C , C,D,): 13C,"CbHb='3C,H,'3C,H,, ligand
ofhis 65th birthday
= 45 Hz, 'J,,., =142 Hz, I = 22%, CJ; 152.0 (dd,
only; S = 313.8 (d, lJCn,Cb
'Jcb,c,
=70 Hz, 'Jcb,,. = 45 Hz, CJ; 127.1 (dd, 'Jc,,cb
=70 Hz, lJCc.Cd
=
The cluster cations [(Ph,PAu),M(CO),]+ are obtained
43 Hz, CJ; 16.7 (d, lJCd.Cs
= 43 Hz, Cd). Chemical shifts and coupling confrom
the photolysis of [Ph,PAuN,] in the presence of metal
stants are invariant at low temperatures (-70°C).
carbonyls.['
The composition of the cations is determined
"C NMR (gated decoupled) (75 MHz, 22"C, C,D,): S = 313.8 (dd. 'Jc,,cb=
by the electronic requirement of the transition metal M,
45 Hz, zJc8,Hb
= I 0 Hz, CJ; 152.0 (dddd, lJCb,Hb
=154 Hz, 'JCb,Co
=70 Hz,
which tries to achieve a stable noble-gas electron configura'Jo.c. = 45 Hz, 2JCb,Hc = 4 Hz, C,,); 127.1 (dddq, 'Jc,,Hc
=157 Hz, lJC.,Ch
=
70 Hz, lJCc.cd
= 43 Hz, 'Jc,,Hd
=7 Hz, CJ; 16.7 (dq of virtual triplets,
tion (for a qualitative explanation of the bonding see 1'1). In
'J,,,,=126Hz,
'Jc,,,,=43Hz, z J C d , H b ~ 4 J C d.,,=IlHz,C,givingrise
.Ha
the
series of cluster cations which we have so far structurally
to second-order fine coupling which appears as virtual triplets).
characterized with the metal center Au,M (x = 4-7), we
[61 (389 mg,
[w,(~-CMe)(oCH,tBu).(O~Bu)I (2): [W,(OCH,tBu),(C,H,),l
0.41 1 mmol) was placed in a 30 mL Schlenk flask equipped with a Teflon-coated stir bar and 10 mL of hexane was added at 0 " C . 100 pL of a 4.4 M rBuOH
[*] Prof. Dr. J. Strahle, Dip1.-Chem. J. Mielcke
solution in toluene was added by syringe. The solution was allowed to stir for
Institut fur Anorganische Chemie der Universitat
four days and then cooled to -20°C. Three hatches of 30,48, and 148 mg of
Auf der Morgenstelle 18, D-W-7400 Tiibingen (FRG)
crystals were isolated for a total yield of 55% (226 mg, 0.228 mmol).
[**I Cluster synthesis by the photolysis of [R,PAuN,J, Part 7. This work was
'H NMR (300 MHz, -40 "C, C,D,): 6 = 4.54 (s, 3 H, CCH,), OCH,C(CH,),:
supported by the Deutsche Forschungsgemeinschaft and the Fonds der
4.67 (S, 4H), 3.60 (d, 4H, Z J H , a= 10 Hz), 3.34 (d, 4H, 'J,,,, =10 Hz); 1.97 (s,
Chemischen Industrie. We thank Degussa AG for tetrachloroauric acid.9H, OC(CH,),; OCH,C(CH,),: 1.35 (s, 18H), 0.86 (s, 36H).
Part 6:[6].
**
464
8 VCH
Verlagsgesellschafi mbH, W-6940 Weinheim, 1992
0570-08331'92/0404-0464$3.50+.25/0
Angew. Chem. Inr. Ed. Engl. 31 (1992) No. 4
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compounds, bridge, ethylene, activation, alkoxide, supported, ditungsten, siloxids, alkylidyne, new, ligand, route
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