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Crystal and Molecular Structure of Co3(CO)9COH A Possible Intermediate in the Reduction of CO by Molecular Hydrogen.

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(small temperature coefficient, see Table 1) can only be
brought about by a y-loop of the amino acids 5-3, while the
NH proton of Gly3can form a 6-loop to the Leu5-CO or a yloop to the Tyr'-CO (Fig.1). We do not as yet wish to stipulate a particular conformation, though the sizes of the
NH-C,H
coupling constants would appear best explained
in terms of a yy-conformation. The poor solubility of (c2) in
water thwarts a check on the biological activity.
Received: July 21. 1980 (2648 IE]
German version: Angew. Chem. 93, 90 (1981)
CAS Registry number:
, 75975-40-5
view of the already established[21reaction (a) these findings
were believed to represent an unprecedented example of a
cluster-formation assisted four-electron one-step reduction of
CO by molecular hydrogen.
The IR and 'H-NMR spectra (in solution)['"] suggested
the basic structure shown in equation (b) for (1). However, it
was important to verify whether the molecular parameters of
(1) were in agreement with a substantial reduction of the apical CO group. For the X-ray structure analysis solvent-free
(1) was prepared by acidification of L ~ C O ~ ( C O )with
, ~ . [an~~
hydrous HCl in a hydrocarbon solvent at low temperature
(see Procedure).
-
Peptide Conformations. Part 11. This work was supported by the Fonds der
Chemischen Industrie and der Deutschen Forschungsgemeinschaft.-Part
10: P. Kondor. H . Kessler in E. Gross, J. Meienhofer: Peplides. Pierce Chemical Comp., Rockford, Illinois 1979. p. 181.
M. Anleunis, A. K Lala, C. Garbay-Jaureguiberry, B. P. R o p e s . Biochemistry 16, 1462 (1977); C. R. Jones, V. Garsky, W. A . Gibbons, Biochem. Biophys. Res. Commun. 76. 619 (1977). and references cited therein.
J. Koba.vashi, U . Nagai, T. Higashipma. T. Miyazawa, Biochim. Biophys.
Acta 577. 195 (1979).
Y A . Bara, A . Friedrich. H Kessler, M. Molter, Chem. Ber. 111, 1045
(1978)
H. Kessler. P. Kondor. Chem. Ber. 112. 3538 (1979).
cyclo-Met'-enkephalin (c2) could previously not be obtained free of S-oxide
(101.
Y. A . Bara. A. Friedrich, W. Hehlein. H. Kessler, P. Kondor. M. Molter, H. J.
Veilh. Chem. Ber. 111. 1029 (1978).
The amino acids have been numbered in analogy to (clj.
A quantitative evaluation of the effects for the determination of conformation is m progress.
Note added in proof(January 1981): Meanwhile we have been able to prepare (c2) and found the same conformation as in ( c l ) and (3.
FJ
f
Crystal and Molecular Structure of Co,(CO)&OH,
A Possible Intermediate in the Reduction of CO
by Molecular Hydrogen[**]
By Hans-Norbert Adams, Giuseppe Fachinetli, and Joachim
Strahlei''
Co3(C0)&-0H (1) can be obtained in solution by acidification of the [Co,(CO),,]- anion1'"'. (1) has the property of
being quantitatively converted into HCo(CO), and
Co4(CO),, (or CO,(CO)~,depending on the CO partial pressure), thus demonstrating the first conversion of an 0bonded hydrogen to a metal-bonded hydrogen['"]. Moreover,
HCO(CO)~was converted into the trinuclear cluster
Co,(CO),C-OH
( 1 ) on reaction with C O ~ ( C Oin
) ~the presence of NEt,, thus showing for the first time that the previously mentioned hydrogen migration can be revertedfih'.In
1'1
Dr. G. Fachinetti [ ' 1
Istituto di Chimica Generale, Universita di Pisa
Via Risorgimento 35, 1-56 100 Pisa (Italy)
Prof. Dr. J. Strahle. Dr. H.-N. Adams
lnslitut fur Anorganische Chemie der Universitat
Auf der Morgenstelle 18. D-7400 Tiibingen (Germany)
["I
This work was supported by the C.N.R. (Rome) and by the Deutsche Forschungsgemeinschaft.
The Authors wish to thank Prof. F. Calderozzo for
~helpful discussions.
I '1
Author to whom correspondence should be addressed.
Angew. Chem. In!. Ed Engl. 20 (1981) No. I
P
,/
C
Fig. 1. Part of the unit cell of (1). Relevant bond distances (average): Co-Co.
2.47815); Co-C(termina1). 1.81 l(8): C-O(termina1). 1.131(10~Co-C(apica1).
C(456)-0(456),
1.314(10);
1.928(8);
C(123)-0( 123).
1.328(10):
O( 123)-0(456), 2.771 I); O( 123)-O(53)'. 2.94( I ) A. (I) crystallizes monoclinically. space group P2,. a=7.750(3). b=22.96(2). c=8.683(2) A. p = I 1 t.68(3)",
2 = 4 . four circle single crystal diffractometer CAD4F-PDP 11/60 (Ermf-Nanius), Mo-K.. radiation, graphite monochromator. Data collection at - I 10 'C.
1632 independent reflections with 1>3u(1) in the range of 9=3-25". Program
System SDP. The structure model, derived from Patterson methods, was refined
with anisotropic temperature factors for the Co and 0 atoms to a reliability index
R=0.051. A final difference Fourier map did not show any significant electron
density for the H atoms.
In the C O ~ ( C Oclusters
) ~ ~ (Fig. 1) each Co atom is bonded
to three terminal CO groups. The three Co atoms form a regular triangle which is completed to a tetrahedron by an apical CO group. The Co-C and C-0 distances in the terminal CO groups as well as the Co-Co distances are of the
same magnitude as observed in LiCo3(CO),o.iPr20[41.The
position Of the hydrogen atom
not be determined with
certainty. However, the C-0 bond length of the apical CO
group was found to be 1.33(1) A, which clearly indicates that
0 Verlag Chemie. GmbH. 6940 Weinheim, 19x1
0570-0X33/tl1/0101-0125
S OZ.SO/O
125
the H atom is bonded to the oxygen atom of the apical CO
group. In addition, short intermolecular 0-0 distances are
found between the apical 0 atoms of two neighboring clusters as well as between O(123) and O(53)' of a third cluster,
thus supporting the assumption of intermolecular hydrogen
bridges.a
1.33 A is the longest CO distance found for metal-coordinated CO, thus showing a considerable reduction of CO
bond order (the average terminal C-0 distance is 1.15
the C-0 distance in methanol is 1.43 A). For comparison:
in [HFe4(CO)i,]-L51,
which is presented as a modelr6".hJof
CO scission to hydrocarbons, the CO distance is 1.26(3)
We suggest (1) as a model for hydrogenation of CO to methanol in homogeneous phase. We believe that (1) behaves in
solution as a discrete molecule with no important intermolecular contacts, as evidenced by its high solubility in hydrocarbons. On the other hand, the multisite interactions in the solid state, similar to those already foundr41in the lithium derivative L ~ C O , ( C O ) ~ ~ .qualify
~ P ~ ~ O( l j as a possible model
also for the hydrogenation of CO in the heterogeneous
phase.
(1) could possibly be a real intermediate in the homogeneous phase hydrogenation of CO to methanoll'1; high
H2-CO-partial pressures and high temperature are necessary for HCo(CO),-assisted low-nuclearity endothermic('1
cluster formation. The thermaF"] and photochemical['] hydrogenation of Co,(CO),C-R
to hydrocarbons provides
further experimental evidence for this claim.
A;
A.
Procedure
Ether-free
L~CO~(CO)~~
A:
suspension
of
L ~ C O ~ ( C O ) ~ ~(10
.E~
g), O
in diphenyl ether (50 cm') stirred
at 28.5 "C/ca. 5 x lo-* torr for 12 h under argon. The resulting green pyrophoric solid is filtered after addition of toluene
(50 cm3), washed with toluene and dried in uacuo. The yield
is almost quantitative. The IR spectrum of the product
in dibutyl ether is superimposable on that of
L ~ C O ~ ( C O ) , ~ . ~and
P ~L
~ ~OC[ ~
O'~ ( C O
Et20r31
) , ~ ~ in
~ the same
solvent.
Solvent-free (1): A suspension of LiCo3(C0),o (2.8 g) in
toluene (10 cm') and hexane (30 cm') is acidified, under an
Ar atmosphere, at - 80 "C with the stoichiometric amount of
anhydrous HCI; after 5 minutes' stirring at about - 17 "C the
mixture is filtered at this temperature. The solution is cooled
to - 65 "C under a CO atmosphere and allowed to stand
overnight; the crystals which separate are finally filtered off
and dried in UQCUO (25% yield). During all of these operations
the temperature should not exceed - 10 "C. The brick-red
compound (1) is unstable thermally and must be kept under
a CO or an Ar atmosphere at liquid nitrogen temperature.
Received: July 23. 1980 [Z 651 IE]
German version: Angew. Chem. 93, 94 (1981)
11) a ) G. Fachinetti, J. Chem. SOC.Chem. Commun 1979. 397: b) G. Fuchrnerri.
L. Balocchi, E Secco. M Venlurini, Angew. Chem., in press.
(2) W Hieber. H . Srhulten, R. Marrin. Z . Anorg. Allg. Chem. 240, 261 (1938).
13) G. Fachinerri, J. Chem. SOC.Chem. Commun. 1979. 396.
141 H.-N.Adams, G. Fachinelti, J. Strahle. Angew. Chem. 92.41 1 (1980); Angew.
Chem. Lnt. Ed. Engl. 19, 404 (1980).
[5] M. Manassero. M. Sansoni. C Longoni. J. Chem. SOC.Chem. Commun. 1976.
919
161 a) E. L. Muetrerties, T N . Rhodm. E. Band, C. F. Brucker, W. R. Pretzer,
Chem. Rev. 79,91 ( I 979); b) E. L. Muetterries. J. Stein. ibid. 79. 479 ( 1979). c)
R. Bergman, L. S. Stuhl, personal communication to E. L. Muettertres, cited
in (6bl.
[7] J. W. Rathke, H. M. Feder, J . Am. Chem SOC.100. 3623 (1978).
IS] P Chini. B. T Heaton, Top. Curr. Chem 71, 1 (1977): J. A. Connor. ibid. 71.
71 (1977).
[9] G. L. Geoflroy, R. A . Epstein. Inorg. Chem. 16. 2795 (1977)
126
0 Verlag Chemre. GmbH. 6940 Weinherm. 1981
Trimethylsilylmethyl Isothiocyanate,
An Isothiocyanatomethanide Equivalent'"'
By Toshikazu Hirao, Atsushi Yamada, Yoshiki Ohshiro,
and Toshio Agawa'']
Functionalized isothiocyanates""1 are useful reagents for
heterocycle synthesisllbl,particularly when a carbanion center can be generated in the a-position relative to nitrogen.
The metalation of activated isothiocyanate was reported by
Hoppe"', but this method is unsatisfactory in the case of methyl isothiocyanate. The well known fluoride ion-induced liberation of carbanions from silyl compounds131would indicate that trimethylsilylmethyl isothiocyanate (la) is a suitable
precursor for isothiocyanatomethanide (2).
( I ) was prepared by the addition of
to trimethylsilylmethyl isocyanidei5]in 76% yield. It is a stable liquid at
room temperature and can be stored for some time under
S 2180 and 2080 cm - '). Compound (lb) was
nitrogen ( v N C =
prepared analogously (80% yield).
Me,SiCH-NC
k
+
S,
C6H6
_ _ _ f
26 h, S O T
Me,SiCH-NCS
k
(la), R
(Ih), R
=
=
H
SiMe,
The isothiocyanate (la) was allowed to react with carbonyl
compounds in the presence of a catalytic amount of tetra-nbutylammonium fluoride['"I to produce the oxazolidine-2thiones (3j (Table 1). The reaction proceeds smoothly at
R.
F'
Table 1 . Synthesis of oxazolidine-2-thiones (3). Catalyst: n-Bu,NF (0 I equivalent).
~~
w
Icl
[dl
fb)
IC)
ldi
(e)
Ph
Ph
Ph
Et
rPr
Ph
Ph
H
H
H
H
H
Ph
Me
8
2
5
5
10
40
23
130- 131
74
74
65
63
67
25
35
87-89
101-I02
186-188
201-203
~~
[a] Isolated yield. [b] Uncorrected. [c] Catalyst: KF( 1.0)+ TEBACI (0.1 equiv.).
[dl Catalyst: KF( l.O)+ [ 181crown-6 (0.1 equiv.). [el Together with 17% 5-methyl3-(N-methylthiocarbamoyI)-5-phenyloxazolidine-2-thione
as a by product.
room temperature. Potassium fluoride with triethylbenzylammonium chloride (TEBACI) or [18jcrown-6 is also effective as a catalyst (Table I).
When bis(trimethylsily1)methyl isothiocyanate (lb) was
used in the reaction with benzaldehyde under similar conditions, 6-styryl isothiocyanate (7)[61was obtained as a major
product along with 5-phenyl-4-(trimethylsilyl)oxazolidine-2['I Dr. T. Hirao, A. Yamada, Prof. Dr. Ohshiro [ ' ).
Prof. Dr. T Agdwa
Department of Petroleum Chemistry, Faculty of Engineering
Osaka University. Yamadakami, Suita. Osaka 565 (Japan)
[**I This work was supported by a Grant-in-aid for Scientific Research No
475669 from the Ministry of Education and with financial support from
Watanabe Memorial Foundation
I ' 1 Author to whom correspondence should be addressed.
0570-0X33/XI/0101-0126
$ 02 50/0
Angew Chem. In/. Ed Engl 20 (1981) No 1
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hydrogen, crystals, structure, molecular, reduction, intermediate, possible, co3, 9coh
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