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Flash Photolysis of Os(CO)5 in Benzene Solution. Detection of Os(CO)4 Benzene by Fast Time-Resolved IR Spectroscopy

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forms monoclinic crystals ( P 2 , / m , a=950.7(7), b=2453.2(9),
1395.1(8)pm,fi=99.12(5)", Y=3212.7.10" pm', Z = 2 ) . An empirical
absorption correction was applied. The structure was solved by heavy
atom methods (R=0.098, R, =(Zw(lFI,I-IF,I)'/ZwIF,112)"2=
0.095 (11
w = o s ' ( F ~ , ) + 0 . 0 0 0 2 Ffor
~ )4802 unique reflections (F,,>3.92u(Fc,)); Syntex P 2 , diffractometer, MonGiradiation, graphite monochromator). Further details of the crystal structure investigation may be obtained from
the Fachinformationszentrum Energie, Physik, Mathematik GmbH, D7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository
number CSD-51954, the names of the authors, and the journal citation
171 The Cu-CI distance in the "more closed" (Cu,ReS3C1] cube (cf. Fig. 1) is
roughly comparable to the larger Cu-CI distance (276.4(4) pm) in
[(CulMoSiCI)(PPh3)S]181 with cubane structure (compare the discussion$ in IS] and A ) .
181 A. Muller. H. Bogge, U. Schimanski, J . Chem. Soc. Chem. Commun.
[6] 1
198(J. 91.
191 By use of a thiomolybdate synthon, it was possible to prepare, "by unit
construction," specific cluster and cage structures: a complete cubane
and cubes with one or two missing corners; the latter structural unit then
represents "half' of another prismatic cage system [lo].
[lo] A. Muller, U. Schimanski, J. Schimanski, Inorg. Chim. Acia 76 (1983)
Flash Photolysis of Os(CO), in Benzene Solution.
Detection of OS(CO)~.
benzene by
Fast Time-Resolved IR Spectroscopy**
By Stephen P. Church, Friedrich- Wilhelm Grevels, *
Gong-Yu Kiel. William A . Kiel, Josef Takats, and
Kurt Schaffner
Although the photochemistry of Fe(CO), has been extensively studied,"' very little has been reported on the related photoreactions of OS(CO),.[~' Conversions to
Os,(CO),,'" and OS(CO),PP~,'~'are known.
However, no mechanistic details have been published to
By means of fast time-resolved IR spectroscopy, we recently observed Fe(CO),- benzene as an intermediate in
the photochemistry of Fe(CO)S in benzene ~ o l u t i o n . We
now wish to report on the first experiments with the analogous osmium compound.
Flash photolysis of an 8 x l o p 4 M solution of Os(CO), in
CO-saturated C6D6["I yielded the transient difference
spectrum shown in Figure 1, which exhibits four positive
(2097, 2010, 1966 (sh), 1948 cm-') and two negative absorptions (2040, 1990 cm-') in the CO stretching vibrational region. The positive bands are different from those
reported for Os(CO), in a methane matrix["] and are assigned to the species Os(Co), .c,D, formed through reaction (1).
+ CO
The characteristic four-band pattern is in accordance
with a C,, structure of the Os(CO),
as has been
proposed for the analogous Fe(CO), .C6D6 complex.[b1The
two negative absorptions, corresponding to photodepleted
[*I Priv.-Doz. Dr. F.-W. Grevels, Dr. S. P. Church, Prof. Dr. K. Schaffner
Max-Planck-Institut fur Strahlenchemie
Stiftstrasse 34-36, D-4330 Miilheim a. d. Ruhr (FRG)
Dr. G.-Y. Kiel, Dr. W. A. Kiel, Prof. Dr. J. Takats
Department of Chemistry, University of Alberta
Edmonton, Alberta T6G 2G2 (Canada)
["I This work was supported by the Alexander von Humboldt Foundation
through a stipend (to S. f. C.). We thank Dr. H. Hermann for his collaboration, Miss K . Fichs for technical assistance, and Johnson Matthey
& Mallory Ltd. for a generous loan of osmium tetroxide.
A n y e w Chem In(. Ed. Engl. 25 (1986) No. I 1
Figure I . IR difference spectrum ca. 5 ps after flash excitation of Os(CO), in
CO-saturated C6D6. Positive bands correspond to O S ( C O ) ~ . C ~ D
bands to photodepleted OS(CO)~.The experimental setup for flash photolysis with fast IR detection has been described elsewhere [S, 91. Instead of the
previously used conventional flash lamps, an excimer laser (Lambda Physik
EMG 200, operating on XeCI, A = 308 nm) was employed as the excitation
source. For further details see text.
OS(CO)~,occur in an intensity ratio of I : 1.4 as found in
the IR spectrum of the pure compound, thus confirming
that the absorptions of Os(CO),. C6D, are not overlapped
by those of the starting material.
The transient Os(CO), .C,D, decays by first-order
kinetics. The rate constant, koh\, for the disappearance of OS(CO),.C,D~ ([Os(CO),I=S x lo-, M ; [CO]=
1.1 x l o p 2MLl3I) is 940 s - l , i.e., two orders of magnitude faster than for Fe(CO),.C,D, under the same conditions.['' Os(CO), is regenerated concurrent with the decay of Os(CO),.C,D, and no other product is observed.['4J
In a similar experiment, but with a CO concentration of
M,'l3l kob, is markedly reduced to 150 s - I . Furthermore, under these conditions the formation of
Os,(CO), [S(C0)=2084 (s), 2042 (vs), 2032-2012 (unresolved), 1772 (m) cm-'],'''] as a permanent product on the
second time-scale, is also evident. Thus, the decay of
os(Co), .C& is CO-concentration dependent and the
formation of Os,(CO), is favored at higher [Os(CO),]/[CO]
ratios. Further, k,,, was shown to be inversely dependent
on the C6D6 concentration in experiments performed in
C6D6/cyclohexane mixtures. These observations are explained most simply in terms of reactions (2)-(4).
+ co
+ OS(CO),
0 VCH Verlagsgesellschafr mbH. 0-6940 Wernheim. 1986
Os(CO), + CeD,
0570-0833/86/1111-0991$ 02.50/0
99 1
For [Co]=
l o - ' M and [Os(CO),]=S x lop4 M, further
depletion of the OS(CO)~band at 1990 c m - ' occurs concurrent with the decay of Os(CO),.C,D,; thus, k,>k,.
However, at [CO]= 1.1 x
and [Os(CO),]=
M, reaction (4) does not compete with reaction
( 3 ) . Thus, a reasonable estimate is k,/k3 S= 2.
Fe(C0)4.benzene reacts with C O two orders of magnitude slower than does OS(CO)4.benzene. This sharply contrasts with the behavior of the pentacarbonylmetal .benzene compounds of the chromium group, where the complex of the heavier metal, W(CO),.benzene, reacts significantly slower than Cr(CO)S.benzene.['"] The opposite behavior of the iron and osmium species might be due to the
triplet nature of Fe(CO)41'h1or to the involvement of other
The Use of (+)-8-Phenylneomenthol in the Synthesis
of Enantiomerically Pure ( - )-Jasmonate Methyl
By Gerhard Quinkert, * Hans-Giinther Schmalz,
Elmar M . Dzierzynski, Gerd Diirner, and Jan W. Bals
Dedicated to Professor Vladimir Prelog on the occasion
of his 80th birthday
(-)-8-Phenylmenthol 1"' has proved to be valuable as a
chiral auxiliary reagenti3' for the synthesis of dimethyl ( R ) ( + )-2-vinyl-l ,I -cyclopropanedicarboxylate 2b,'4' a chiral
building block for the synthesis of enantiomerically pure
( + ) - e ~ t r o n e [or
~ ~ (-)-norgestrel.['] (+)-8-Phenylmenthol
Prof. Dr G. Quinkert, Dr. H -G. Schmalz,
DipLChem. E. M. Dzierzynski, Dr. G. Durner, Dr. J. W. Bats
lnstitut fur Organische Chemie der Universitat
Niederurseler Hang, D-6000 Frankfurt am Main 50 (FRG)
This work was supported by the Deutsche Forschungsgemeinschaft
(project Qu 15-20), by the Bundesrninisterium fur Wirtschaft (project
AIF No. 581 I), by the Fonds der Chemischen Industrie, and by Hoechst
0 VCH Verlagsgerellschafi mbH, 0-6940 Wernheim. 1986
X Z O C % ~R = H
X H - 1; R = CH3
ba: R=H
Received: June 9, 1986 [Z 1807 IE]
German version: Angew. Chem. 98 (1986) 993
[I] a) E. Koerner von Gustorf, F:W. Grevels, Top. Curr. Chem. 13 (1969)
366: b) G. L. Geoffroy, M. S. Wrighton: Organomerallic Phororhemisrr.v,
Academic Press, New York 1979.
121 For the synthesis of OS(CO)~
see [?I.
131 F Calderazzo, F. L'Eplattenier, Inorg. Chem. 6 (1967) 1220: R. Rushman, G. N. van Buuren, M. Shiralian, R. K. Pomeroy, Organomefallics 2
(1983) 693.
[4] J. R. Moss, W. A. G. Graham, J . Chem. SOC.Dalton Trans. 1977, 95.
[ 5 ] F. L'Eplattenier, F. Calderazzo, Inorg. Chem. 7 (1968) 1290.
[6] S. P. Church, F.-W. Grevels, H. Hermann, J. M. Kelly, W. E. Klotzbucher, K. Schaffner, J . Chem. Soc. Chem. Commun. 1985. 594.
171 S. P. Church, F.-W. Grevels, H. Hermann, K. Schaffner, unpublished.
[S] a) H. Hermann, F.-W. Grevels, A. Henne, K. Schaffner, J. Phvs. Chem.
86 (1982) 5151.
191 S. P . Church, F.-W. Grevels, H. Hermann, K. Schaffner, Inorg. Chem. 23
(1984) 3830; 24 (1985) 418.
[lo] C,,D,, is much more transparent than ChH, in the IR spectral region of
[ I I ] M. Poliakoff, J. J. Turner, J . Chem. Sue. Dalion Trans. 1974. 2276.
1121 Cf. the CO bands i n the IR spectra of (q'-01efin)Os(CO)4 complexes; M.
R. Burke, J. Takats, F.-W. Grevels, J. G. A. Reuvers, J. Am Chem. Soc.
105 (1983) 4092.
[I31 CO concentrations are calculated from the CO pressure using literature
data for C,H,: E. Wilhelm, R. Battino, Chem. Reu. 73 (1973) 1.
[I41 At all points of the spectrum shown in Figure I. the same kinetic behavior was observed.
[IS] O S ~ ( C Owas
) ~ previously identified in n-heptane solution as a product of
the photolysis of O S ( C O )[4].
~ Unlike the familiar triply CO-bridged
Fe,(CO),,, which is insoluble, O S ~ ( C Ois) ~singly
bridged and soluble.
[I61 M. Poliakoff, Chem SOC.Rev. 7(1978) 527.
ent-1 would be a welcome chiral auxiliary reagent for the
synthesis of enantiomerically pure ( -)-jasmonate methyl
ester 3''.'' via dimethyl (S)-(-)-2-vinyl- I , I-cyclopropanedicarboxylate ent-2b, but ent-1 is difficult to prepare.lZh'
Thus, u p to now it has only been possible to obtain the
chiral synthetic building block ent-2b via a detour by diastereomerization of 2c to 4a,"-91 which is then converted
into 3.
As suggested by an analysis of the stereoelectronic requirements for cyclopropanation via an ScN.reaction,""'
(+)-8-phenylneomenthol 6 should act similarly to ent-1.
Indeed, reaction of 6 (in the presence of imidazole and
4-(N,N-dimethylamino)pyridinein CH,CI,) with malonyl
dichloride gives the corresponding malonic diester
(m.p.= 132"C, [a]::,= +31.4": >SO% yield), which, by
reaction with (E)-l,4-dichloro-2-butene
(analogously to the
preparation of 2c according to ref. IS]), affords the diastereomers 5 (in 57% yield based on the malonic diester) and
2d in a ratio of 92 :8.11'.121
The sterically congested threemembered ring compound 5 , which can be smoothly separated from 2d, is converted into ent-2b by ester hydrolysis
followed by treatment of the resulting dicarboxylic acid
with diazomethane (analogously to the preparation of 2b
according to ref. [S]). This procedure considerably simplities the synthesis of enantiomerically pure 3."'
The new chiral auxiliary 6 can be conveniently and
more easily prepared than the chiral auxiliary (+)-8-pheby reduction of a mixture of (-)nylisomenthol ll'2u.3h1
8-phenylmenthone 7 and (+)-8-phenylisomenthone 8
with NaBH,, and, therefore, 6 may be prepared from ( R ) (+)-pulegone 9 ; overall yield of 6 : 47%, based on 9
0570-0833/86/1111-0992 $ 02.50/0
Angew Chem. Int. Ed. Engl. 25 (1986) No. I 1
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spectroscopy, resolved, solutions, photolysis, times, detection, flash, fast, benzenes
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