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CC-Linkages of Ethene with CO2 on an Iron(0) ComplexЧSynthesis and Crystal Structure Analysis of [(PEt3)2Fe(C2H4)2].

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4): the approximate "formula" for So is therefore:
x S x . yHZS,06.z H,0.-S8, which is very sparingly soluble
in water (solubility of a-S8at 25°C: 5 pg/kg['''), can, e.g.,
be rapidly reactivated[201via reactions such as (e) and, in
this way, can even be transported through membranes.
[ 141 R. Steudel, H.-J. Maude, D. Rosenbauer, H. Mockel, T. Freyholdt, Angew. Chem. 93 (1981) 402; Angew. Chem. Int. Ed. Engl. 20 (1981) 394; R.
Strauss, R. Steudel, Fresenius 2. Anal. Chem.. in press.
[IS] R. E. Davis, J . Am. Chem. Sot. 80 (1958) 3565; R. Steudel, H.-J. Maude,
2. Anorg. Allg. Chem. 457 (1979) 165.
[I61 P. A. Trudinger, Aust. J. Biol. Scr. 17 (1964) 446.
[I71 M. Schmidt, 2. Anorg. Allg. Chem. 289 (1957) 158.
[I81 In the case of those phototrophic and chemolithotrophic sulfur bacteria,
which likewise form "So globules" (some extra., some intracellular),
probably other compounds with polar groups instead of polythionates
can cover the surface of the hydrophobic S8 globule and thus make them
hydrophilic; cf., e.g., the stabilization of sulfur particles in wafer by adsorption of organic carboxylic acids (e.g. polyacrylic acid): A. Asanov,
A. Il'yasov, K. S. Akhmedov, Dokl. Akad. Nauk UzSSR 1985. 35 (Chem.
Abstr. 104 (1986) 136611). and references cited therein.
[I91 J. Boulege, Phosphorus Su[fur 5 (1978) 127.
I201 G. W. Donaldson, F. J. Johnston, J . Phys. Chem. 73 (1969) 2064; R. H.
Dinegar, R. H. Smellie, J. Colloid Sci. 7 (1952) 370.
CC-Linkages of Ethene with CO, on an
Iron(o) Complex-Synthesis and
Crystal Structure Analysis of I(PEt3)2Fe(C2H4)21
By Heinz Hoberg,* Klaus Jenni, Klaus Angermund, and
Carl Kriiger
Fig. 4. Simplified model of a sulfur globule as is formed extracellularly by
7hiobacillusferrooxiduns.It consists mainly of Sti and small amounts of other
compounds (Sh, S,, Sp, and S I 1 ) which impede crystallization, as in globules
of supercooled liquid sulfur. Long-chain polythionate ions are deposited on
the surface and make the globule hydrophilic. Hence it is surrounded by a
hydrate-sheath in which cations are possibly also present. The average density of such a micelle must be significantly smaller than that of liquid sulfur
(1.85 g/cm').
The chromatographic detection of polythionates as described here, which, e.g., requires a concentration of only
5 pg/mL in the case of the tetrathionate, should now be
extended to a systematic search for these compounds in
the culture media of other sulfur bacteria.
Received: October 3, 1986 [Z 1946 IE]
German version: Angew. Chem. 99 (1987) 143
We recently reported the 1/1 CC-linkage of CO, with
1,3-butadiene o n a n iron(0) system."' We have now extended our investigations to reactions of ethene on iron(0)
complexes. CC-linkages between ethene and CO, can be
controlled o n nickel(o) in such a way that, depending o n
the ligand, either propionic acids['] or n-pentenoic acids[31
are formed in the course of acid hydrolysis. On molybdenum(o) or tungsten(0) complexes acrylic acid is formed.141
We have now found that the iron(0) system induces further unexpected CC-coupling steps between CO, and ethene. The n-bonded ethene in the well already known 18ecomplex ethenebis[P,P'-ethylenebis(diphenylphosphane)]iron(o)['] does not react with CO, ( 5 bar, 80°C) to give the
carboxylate. However, we have been able to prepare a
novel ligand-Feo-CzH4 complex o n which the desired
C C couplings are possible for the first time.
In the reduction of FeCl, with Mg*I6l in tetrahydrofuran
(THF) in the presence of ethene and PEt3 the 16e-complex
1 is formed in
72% yield [m.p. 16°C (dec.), paramagnetic, black crystals].[']
[ 11 Gmelin. Handbuch der Anorganischen Chemie. 8rh edition. Schwefel, Teil
B2. Verlag Chemie, Weinheim 1960, p. 969-1046.
121 L. Szekeres, Tulunta 21 (1974) 1; E. Blasius, E. Thiele, Z . A n d Chem.
197 (1984) 347.
[3] a) E. Weitz, K. Spohn, Chem. Ber. 89 (1956) 2322; b) E. Weitz, F. Becker, K. Gieles, ibid. 89 (1956) 2345; c) E. Weitz, F. Becker, K. Gieles, B.
Alt, ibid. 89 (1956) 2353.
141 S. Oden, Nova Acra Regiue SOC.Sci. Upsaliensis Ser. IV 3 (1913) No. 4,
Z. Phys. Chem. 80 (1912) 709.
151 E. Weitz, K. Gieles, J. Singer, B. Alt, Chem. Ber. 89 (1956) 2365.
[6] J. Weiss, M. GobI, Fresenius Z . Anal. Chem. 320 (1985) 439.
[7] R. Steudel, G. Holdt, J . Chromafogr. 361 (1986) 379.
[8] R. Steudel, R. Strauss, D. Jensen, Chem. Zrg. 109 (1985) 349.
191 Varian 5000 chromatograph with microcomputer-controlled gradient adjustment, Rheodyne loop injector (10 pL), Chrompack cartridge glass
column (CT'"SpherC18; I= 10 cm), Varian UVS detector (215 nm),
Hewlett-Packard 3390A integrator, Knauer recorder. For further experimental details see Ref. [7].
1101 See e.g. M. Eccleston, D. P. Kelly, J . Bacteriol. 134 (1978) 718, and references cited therein.
[I I] P. A. Trudinger, Reu. Pure Appl. Chem. 17 (1967) 1.
1121 D. P. Kelly, Philos. Trans. R . SOC.London Ser. 8 2 9 8 (1982) 499; Microbrol. Sn. 2 (1985) 105.
[I31 W. Hazeu, W. Bijleveld, J. T. C . Grotenhuis, E. Kakes, J. G. Kuenen,
Antonie uan Leeuwenhoek 52 (1986) 507; the bacteria were cultivated in
Delft by W.H . and transported by express mail to Berlin for the oxidation and extraction experiments.
Angew. Chem. Int. Ed. Engl. 26 (1987) No. 2
+ Mg* + 2CzH4+ 2PEt3 -:",rC
(PEt3)2Fe(CzH4)2 MgClz
The structure of 1 (Fig. 1) was determined by a crystal
structure analysis. In the crystalline state the complex has
C2 symmetry, with the symmetry axis passing through the
Fe atom and bisecting the PI-Fe-PI* angle. The metal
atom is surrounded pseudotetrahedrally by two ethene
molecules and two triethylphosphane molecules (angle between the plane through the atoms Fe, P1 and P1* and the
plane through the iron atom and the midpoints of the C1C2 and Cl*-C2* bonds: 89.9O); the ethene ligands, however, form a n angle of 35.8" with respect to each other (torsion angle Cl-C2-Cl*-C2*).
[*I Prof. Dr. H. Hoberg, DipLChem. K. Jenni,
Dr. K. Angermund ['I, Prof. Dr. C. Kriiger ['I
Max-Planck-Institut fur Kohlenforschung
Kaiser-Wilhelm-Platz 1, D-4330 Miilheim a. d. Ruhr 1 (FRG)
['I Crystal structure analysis.
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For investigating the behavior of 1 towards CO, the
complex was first dissolved in T H F at -78°C and treated
with a stream of CO, (1 bar). This, however, merely resulted in "reductive disproportionation" to iron carbonate
and carbon monoxide,""I and not in the desired formation
of carboxylate. Apparently, the molar ratio PEt3/Fe of 2 : 1
asserted for 1 is too small for this.
+ cop
Fig. I . Crystal structure of I [XI2 u = 14.572(6)
b=7.314(3) A,
c = 18.487(8) A, 8=98.13(3)", V = 1950.6 A', T = 100 K, /1=0.71069
Z=4,pC.,,,= 1.19 g cm-', ~ ( ~ ~ ) = 9cm-',
. 2 3 empirical absorption correction
(0.911 min., 1.135 max.), 2658 reflections measured ( + h f k + O , 1347 independent reflections, 1271 observed reflections (1>2u(f)), H-atom positions
found but not refined, 87 refined parameters, R =0.028, R, =0.036 (w=
l/u2(Fo)),maximum residual electron density 0.27 e/A'). Selected bond
and angles I"]: Fe-PI 2.267(1), Fe-CI 2.083(2), Fe-C2 2.105(3),
PI-CII 1.854(2), P l - C l 3 1.855(3), PI-C15 1.850(2), CI-C2 1.382(4); Pl-FePI* 106.2(1), PI-Fe-CI 98.0(1), PI-Fe-C2 120.0(1), CI-Fe-C2 38.5(1), CI-FeC1' 100.4(1), CI-Fe-C2* 103.3(1), C2-Fe-C2* 128.9(1) (9).
A CC-linkage between ethene and CO, is achieved on
iron(o) when the reaction is carried out after addition of
further ligands such as, e.g., PMe3, P,P'-ethylenebis(dicyclohexylphosphane) (DCPE), or P,P'-ethylenebis(dimethylphosphane) (DMPE).["I The iron carboxylates formed
thereby could be recognized by the C = O stretching vibration bands at 1580 c m - ' in the IR spectrum. The type of
carboxylate formation that had taken place was determined by acid-hydrolysis of the complex mixture in methanol on the basis of the methyl ester that was formed
(Table 1). Surprisingly, no monocarboxylic acids but exclusively dicarboxylic acids, namely succinic acid 4 and
the isomeric methylmalonic acid 8, are formed.
As can be seen from Table 1 the ligands have a significant influence on the course of the C C coupling reaction.
Whether this is of a steric or electronic nature or due alone
to the chelate-effect of the bidentate phosphanes cannot be
inferred from the present observations. Apparently the
iron carboxylates 3 and 7 derive from a common unstable
intermediate, the oxaferracyclopentanone 2.
Whereas the formation of 4 (insertion of CO, into the
Fe-C a-bond of 2 to give 3, Route A ) is comparable with
the corresponding reaction sequences in the reaction of
1,3-butadiene on nickel(o)"" and iron(0) systems,"] the
reaction course B is postulated for the unexpected formation of 8 : P-H elimination leads to 5 ; renewed hydrometalation affords the methyloxyferracyclobutanone 6,'l3I
from which 7 is formed by CO, insertion. Finally, the diester 8 is liberated from 7 by methanolic HCI.
2 Me
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Table I. Influence of ligands on the yield and molar ratio of the dicarboxylic
acids 4 and 8 in the reactions of 1 with C 0 2 .
[Me2P-CH2-I2 (DMPE)
[(r-C,H,,)2P-CH2-]2 (DCPE)
Molar ratio
L/ 1
3/ 1
2/ 1
Molar ratio
I /7
Received: October 17, 1986;
revised: November 17, 1986 [Z 1954 IE]
German version: Angew. Chem. 99 (1987) 141
[ I ] H. Hoberg, K. Jenni, C. Kruger, E. Rdabe, Angew. Chem. 98 (1986) 819:
Angew. Chem. fnr. Ed. Engl. 25 (1986) 810.
[2] H. Hoberg, D. Schaefer. J . Organomel. Chem. 2 5 / (1983) C51.
[3] H. Hoberg, Y. Peres, A. Milchereit, J Organomel. Chem. 307 (1986)
[4] R. Alvarez, E. Carmona, D. J. Cole-Hamilton, A. Galindo, E. GutierrezPuebla, A. Monge, M. L. Poveda, C. Ruiz, J . Am. Chem. SOC./07(1985)
[ 5 ] G. Hata, H. Kondo, A. Miyake, J . Am. Chem. SOC.90 (1968) 2278.
161 Mg* signifies a suspension of Mg powder, particle size 50 mesh, in T H F
with addition of 0.5 m L of ethyl bromide.
[7] Procedure for 1: A mixture of Mg* (3.20g, 131.69 mmol) in T H F
(20mL) was cooled to -78°C and saturated at this temperature with
ethene. The resulting mixture was then combined with an ethene-saturated suspension of FeC12 (15.83 g, 125 mmol) and PEt3 (36.4mL,
250 mmol) in T H F (240 mL), likewise cooled to -78°C. After 36 hours'
stirring at -40°C the T H F was distilled off at - 15°C
bar), the
residue taken up in I L of cold pentane (-3O"C), filtered, washed several times with cold pentane, and the combined filtrate and washings
cooled to -78°C. The large needles of 1 that subsequently crystallized
out were isolated and dried. Yield 31.45 g (90.36 mmol, 72%): m.p. 16°C
(dec.); IR (KBr, -55°C): G [cm-']=3040, 1194, 1178 (C2HI), 2961,
1458, 1417, 1373, 1039/1028. 763, 724 (PEt,); correct elemental analysis.
[S] The calculations were carried out on VAX-I 1/780, VAX-I 11730, and
MicroVAX-ll computers. In addition to some self-written programs, the
following software was used: TRACER by S. L. Lawton and R. A. Jacobson, SHELX-76 by G. M. Sheldrick, FMLS, a modified version of
the ORFLS by W. R. Busing and H. A. Levy, XANADU by P. Roberts
and G. M. Sheldrick, DAESD by R. E. Davis, and ORTEP by C. Johnson.
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Angew Chem. Inr Ed. Engl 26 (1987) No. 2
191 Further details of the crystal structure investigation are available on request from the Fachinformationszentrum Energie, Physik, Mathematik
GmhH. D-75 14 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD-52 153, the names of the authors, and the journal
[lo] H. H. Karsch, Chem. Ber. 110 (1977) 2213.
[ I I] Typical procedures for 4 and 8 : 1.48 g (4.25 mmol) of 1 and 0.97 g
(1.29 mL, 12.76 mmol) of PMe3 were dissolved in 7 0 m L of THF
(-78°C); the solution was then treated, via a buret, first with 286 m L
(12.76 mmol) of ethene, and then with 286 m L (12.76 mmol) of CO1.
With careful equalization of built-up pressure, the solution was slowly
warmed (6 h) to room temperature, whereupon a dark brown precipitate
separated out. This was filtered off and dried. Yield: 1.12 g; IR (KBr): V
[cm ‘I= 1580 (C=O). The dried solid was treated at -30°C with 4 m L
of 6 N methanolic HCI. After 24 hours’ stirring the solution was neutralized with NaHCO,. The volatile components were distilled off under
vacuum (2 x
bar). According to a G C analysis the distillate contained 0.93 mg ( 6 . 3 6 ~lo-’ mmol, 0.15%) of 4 and 370.84mg
(2 54 mmol, 59.76%) of 8 . The products were identified by comparison
of the M S spectra obtained after combined GC-MS with literature data
and quantitatively determined by calculation from the G C curves taking
into consideration the response factors referred to isopentyl acetate a s
internal standard. The reactions of 1 in the presence of the ligands
DMPE and DCPE in the molecular ratios given in Table 1 were carried
out analogously.
[I21 H. Hoberg, B. Apotecher, J . Organornet. Chem. 270 (1984) CIS.
1131 Ring contractions have also been observed on platinacyclopentane complexes (cf. G. €3. Young, G. M. Whitesides, J . Am. Chem. Soc. 100 (1978)
5808), tantalacyclopentane complexes (cf. S. L. McLain, J. Sancho, R. R.
Schrock, rbid. 101 (1979) 545 I), and oxanickelacyclohexanone complexes (cf. K. Sano, T. Yamamoto, A. Yamamoto, Chem. Lett. 1982.
Isolation and Photoisomerization of
Simply Substituted Nitrile Oxides**
--+ NH
corresponding hydroximic acid halides by HHal-elimination with based3’ has attracted renewed interest in connection with the synthesis of the antitumor reagent acivicin.[’]
Furthermore, molecules such as 2 , 5, 8, and in particular
their photoisomers, could perhaps occur in interstellar
space.[41Both aspects have prompted us to attempt the direct detection of such species.
When the fragments formed in the gas-phase pyrolysis
(600”C, lo-’ torr) of the dihaloformoximes 1 and 4 are
condensed with argon on a cold window ( T = 10 K) the
halonitrile oxides of interest, namely 2 and 5, can be detected as main products o n the basis of their typical IR
bandsl’l (Table 1). Of the five fundamental vibrations to be
expected for a linear atomic arrangement161only two are
intense enough for observation.[’] Besides these, the IR absorptions of the respective hydrogen halides and, to a
[ * ] Prof. Dr. G. Maier, DipLChem. J. H . Teles
lnstitut fur Organische Chemie der Universitat
Heinrich-Buff-Ring 58, D-6300 Giessen (FRG)
[“*I This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
Angew Chem. Int. Ed. Engl.
26 (1987) No. 2
j N- C - C g N
The haloformonitrile oxides 2 and 5 should, according
to Wieland,[’I be formed as intermediates upon reaction of
the mercury salt of fulminic acid (formonitrile oxide) with
chlorine and bromine to give the respective dihalofuroxanes [Eq. (a)]. The in situ generation of 2 and 5 from the
By Giinther Maier* and Joaquim Henrique Teles
lesser extent, those of the corresponding haloisocyanates 3
and 6, respectively, are also observed.
- 2HCl
The structures of 2 and 5 fotlow also from the fact that
these compounds are smoothly converted into the haloisocyanates upon irradiation in the matrix (A = 254 nm,
10 min),’*I as shown by a comparison with the spectra of
authentic samples[’] of 3 and 6. Vacuum pyrolysis of chlorocyanoformoxime 7 at 400°C leads to formation of cyanogen mono-N-oxide 8, which can be isolated as the only
product besides HCI in the argon matrix.‘lo1f n the case of
a linear structure, seven bands should occur in the IR; five
were observed (Table 1). Irradiation in the matrix
(A = 254 nm, t = 20 min) affords cyanogen isocyanate 91”1
and C,O.[’*] Gas-phase pyrolysis of chloroglyoxime 10
analogously afforded the nitrile oxide 11. Its constitution
follows, once again, from the IR spectrum (Table I): irradiation of 11 in the matrix at 10 K affords the isocyanate
12 (IR bands at 3638, 2276, 1646, and 9 7 6 c m - ’ ) within
2 min.
Table 1. IR spectra [Ar matrices, 10 K, V [cm-’1 (relative intensity)] of the
nitrile oxides 2, 5 , 8, and 11.
1326.3 (100)
2261.7 (21) [a]
2281.4 (31)
2643.5 (11)
1305.6 (100)
2252.5 (19) [a]
2271 3 (34)
2602.1 (10)
1445 (25)
2356 (100)
1453 (34)
2301 (100)
[a1 Splitting due to matrix effects. [b] Additional bands: 407 (2). 717 (I), 2192
(9). [c] Additional bands: 423 (30), 425 (63). 914 (28), 940 (21), 989 ( 5 3 , 1241
(I I), 1258 (30), 1346 (9), 3621 (83).
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crystals, linkage, c2h4, structure, ethene, iron, 2fe, complexчsynthesis, pet3, analysis, co2
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