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Optically Active Iron Complexes with Tetrahedral Structure.

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Reaction of 2 in excess with 4a-d in the presence of
Br- in Br(CH2)zOH as solvent leads to formation of the
cyclic dioxycarbenes 10a-d in 81Y0[~~,
SOYO,73%, and 81%
yields, respectively. High yields (> 70%) of 10a, lob, and
10d are also obtained when Br(CHZ),0H is used instead of
Br(CHJZ0H.
4 a -d
2
1Oa-d
Unlike 1 and 2, 3 does not react with 4a-d to form the
oxy(thio)carbene. However, it does form the dithiocarbene
13[Io1on reaction with 6 in presence of NaBr.
6
3
ganometallic compounds of elements of the transition series with actual tetrahedral structure are, as yet, unknown.
A plausible strategy for the synthesis of such compounds would be the use of Fe(CO)Z(NO)zas starting material, a member of the pseudo-Ni(CO), series in the sense
of the nitrosyl-shift principle[31. Replacement of a C O
group in Fe(CO)Z(NO)z by another two-electron ligand,
e.g. a phosphane, and of an NO group by another threeelectron ligand, e. g. an aryldiazenyl group, would result in
the Fe atom in the compounds Fe(CO)(NO)(NNR)PR, being a center of chirality. On using a pure phosphane enantiomer, e . g . one of the aminophosphanes (S)PPh,(N(R)CHMePh}151of Scheme 1, each complex is
formed in the form of two diastereomers a and b, which
differ only in the configuration at the Fe atom.
13
All the cyclic carbene compounds have been fully characterized as PF; salts by elemental analysis, and I R and
’H- and I3C-NMR spectral data. The formation of carbene
ligands has been conclusively proven by the I3C-NMR signals of the carbene carbon atoms [(CD,CN), 5a-d:
6=220.24, 228.56, 206.28, 234.20; 10a-d: 6=242.51,
253.43, 227.08, 254.00; 7 : 6=234.36; 13: 6=295.40].
Received: October 4, 1982 [ Z 166 IE]
revised: November 19, 1982
German version: Angew. Chem. 95 (1983) 160
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1983, 184-192
131 W. P. Giering, M. Rosenblum, J. Tancrede, J . Am. Chem. SOC.94 (1972)
7 170.
[4] b) W. Danzer, W. P. Fehlhammer, A. T. Liu, G. Thiel, W. Beck, Chem.
Ber. 115 (1982) 1682, and references cited therein.
171 H. Motschi, R. J. Angelici, Orgnnometnllics I (1982) 343.
[lo] F. B. McCormick, R. J. Angelici, Inorg. Chem. 20 (1980) 1 1 1 1 .
H
la, b
3a,b
2a,b
4a,b
5a. b
7a, b
6a, b
Scheme 1
Optically Active Iron Complexes
with Tetrahedral Structure
By Henri Brunner* and Wolfgang Miehling
Most of the previously documented optically active organometallic compounds of the transition elements have
a n (arene)ML’L2L3-type structure[’]. These complexes are
designated as pseudotetrahedral, because the central metal
is bound to four ligands, and consequently only the isomeric “image” and “mirror image” tetrahedral structures
are possible. The geometry of these compounds is, however, octahedral with the 6 .n-arene ligand, frequently benzene or cyclopentadienyl, occupying three cis-positions of
the octahedron. This is born out, in particular, by the angles between the ligands L’, Lz and L3 to the metal atom,
which are always approximately 9OoLZ1.
Optically active or[*] Prof. Dr. H. Brunner, W. Miehling
(**I
Institut fur Anorganische Chemie der Universitat
Universitatsstrasse 31, D-8400 Regensburg (Germany)
Optically Active Transition Metal Complexes, Part 82. This work was
supported by the Deutsche Forschungsgemeinschaft, the Fonds der
Chemischen Industrie, and BASF AG, Ludwigshafen.-Part 81: I. Bernal, W. H. Ries, H. Brunner, D. K. Rastogi, Inorg. Chem., in press.
164
0 Verlag Chemie GmbH, 6940 Weinheim, 1983
The anion Fe(CO),(NO)- reacts with diazonium ions
arylNN+ in acetone at -78 “C to give the complex
Fe(CO),(NO)(NNaryl), which is unstable at room temperatureL6].However, if one equivalent of aminophosphane is
added at - 78 “C, further exchange of C O takes place with
formation of the complexes 1-7 (Scheme l), which can be
isolated in 40-65% yield after warming to room temperature: 1 and 2 as readily decomposable red oils, 3-7 as
stable reddish-brown powders.
The IR spectra of the complexes 1-7 in pentane solution each show sharp, very intense bands for vco (19751980), vN0 (1730-1735) and vNN(1662-1682 cm-’). The
diastereomers a and b of complexes 3, 4, and 6 d o not
differ in their ’H-NMR spectra. In the case of compounds
3 and 4 substituted in the p-position or without substituents on the diazoaryl moiety this is not surprising, but is,
however, for the complex 6 which has phenyl substituents
o n the o-position. Only the compounds 5 and 7, substituted by methyl in the o-positions, showed different chemical shifts in the o - C H ~signals [6=2.22 (7a) and 2.28 (7b),
C&], the C*CH,, and the NCH3 signals, from which the
diastereomeric ratio a : b can be determined.
None of the diastereomers of complexes 3-7 can be enriched by fractional crystallization. In contrast, the diastereomeric pairs Of 4,
and can be separated by preparative liquid chromatography on Merck-Lobar B-columns.
0570-0833/83/0202-0164 $02.50/0
52
Angew. Chem. Int. Ed. Engl. 22 (1983) No. 2
For this purpose, 200-300 mg of each of the complexes in
petroleum/ether 5 :1 were chromatographed on a two-column systeml5].In all three cases the (+),,,-diastereomer a
was eluted more rapidly then the ( -)436-diastereomer b.
In the case of complex 7 a distinct partition into two
zones is achieved after passage through three columns,
corresponding to a complete separation of 7a and 7b. In
contrast, in the case of complexes 4 and 5 a broad zone is
formed after passage through four columns in which a is
enriched in the fronts and b in the tails. As shown by the
C D spectra, the front and tail fractions can be obtained in
high optical purity by cutting out the central part of the
zone.
Of all the compounds investigated the diastereomers of
7 are the easiest to separate and to detect by 'H-NMR
spectroscopy. Therefore, 7a was chosen for investigation
of the configurational stability at the Fe atom. No epimerization occurs up to 50 "C in C6D6 solution in a sealed 'HNMR tube, with or without addition of free N-benzylaminophosphane (S)-PPh,{N(Bz)CHMePh]; at about 55 "C
the epimerization 7 a e 7 b takes place within a few hours.
However, the fact that the change of configuration at the
Fe atom is accompanied by side reactions e.g. formation
of Fe( NO)2[PPh2(N(Bz)CHMePh]]2prevents kinetic measurements.
For generation of 2, l a was sublimed into an oven,
which was directly attached to a mass spectrometer operating at a low (-9 ev) ionizing voltage[61.At an oven temperature of 500°C the peak characteristic of l a (m/z 59,
C02CH,) was almost entirely replaced by peaks clearly
characterized by dicyanoketene ( m / z 92 and 64, (NC)2C)
and methanol ( m / z 32 and 31)r3b1.
When the products of pyrolysis of l a were codeposited
with argon directly on a CsI window cooled to 12 K, infrared bands appeared assignable to residual l a and methanol. Dicyanoketene appeared at 2251 (w), 2246 (m), 2175
(vs), 1081 (w), and 571 (m) cm-'[61. When the argon was
omitted during the deposition, the thin film (Fig. 2)
showed broader bands for residual l a , methanol ( v = 1130
(w), 1030 (m, broad) cm-') and dicyanoketene (v=2230
(w), 2175 (vs), 1090 (vw) and 580 (w) cm-').
Clearly, dicyanoketene is an extremely reactive intermediate. Upon slowly warming the thin film devoid of argon,
the dicyanoketene absorptions (Fig. 2) started disappearing near 60 K as the methanol absorption also disappeared
(probably by sublimation) and new bands appeared
(v=2295 (s), 2090 (s), 1125 (m) and 745 (w) cm-')191. Dicyanoketene has been reported elsewhere to react below
100 K['I.
Received: October 15, 1982 [Z 176 IE]
German version: Angew. Chem. 95 (1983) 162
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1983, 84-91
[I] H. Brunner, Adu. Organomef. Chem. 18 (1980) 151.
[2] G. M. Reisner, 1. Bernal, H. Brunner, M. Muschiol, Inorg. Chem. 17
(1978) 783.
[3j F. Seel, Z. Anorg. Allg. Chem. 249 (1942) 308.
[Sj H. Brunner, J. Doppelberger, Chem. Ber. 111 (1978) 673.
Lalor, J . Organomef. Chem. 54 (1973) C37; W. E. Car161 W. E. Carrol,
rol, F. A. Deeney,Y. J. Lalor, ibid. 198 (1980) 189.
'2
z
2
Dicyanoketene : Flash Vacuum Thermolysis of
Alkyl Dicyanoacetates**
By James E . Gano*, Roy H . Jacobson, and
Richard H . Wettach
A need to know the spectral data of dicyanoketene"], 2,
prompted a search for a direct and unambiguous synthesis
of this compound[31.Although precedent suggested (a) dehydration of dicyanoacetic acid with phosphorus(v) oxide,
(b) pyrolysis of metal enolates of alkyl dicyanoacetates,
and (c) pyrolysis of alkyl dicyanoacetates would all produce dicyanoketene, ],[ only route (c) proved successful.
Methyl dicyanoacetate la1'], which slowly became yellow upon storage at room temperature, was purified by vacuum sublimation.
la
2
3a
[*] Prof. Dr. J. E. Gano, R. H. Jacobson, Dr. R. H. Wettach
[**I
Department of Chemistry, Bowman-Oddy Laboratories
University of Toledo, Toledo, OH 43606 (USA)
Financial support of this work by the Research Corporation and The
University of Toledo Faculty Research Award and Fellowship program,
and the technical assistance of L. Cooley, J. Werstler, and W. Opdycke
are gratefully acknowledged.
Angew. Chem. Int. Ed. Engl. 22 (1983) No. 2
2300- I 2000
I200
900
600cm-'
I
Fig. 2. IR spectrum (Csl window) of the oven effluent, which contains dicyanoketene 2, on pyrolysis of la. (a) Window temperature 12 K, (b) window
temperature 160 K.
Received: August 26, 1981 [Z 413 IE]
revised: November 24, 1982
German version: Angew. Chem. 95 (1983) IS5
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1983, 193-197
CAS Registry numbers:
Methyl dicyanoacetate, 2040-70-2; dicyanoketene, 4361-47- 1
[2] Dicyanoketene appears to be an intermediate in the low-temperature
photolysis of 1,3-dioxolane-2-methylenedicarbonitrile;J. E. Gono et a[.,
Nouv. J. Chim., in press.
131 During the tenure of this work, an alternate route to dicyanoketene, requiring multiple steps to obtain a rather unstable precursor, was reported:
a) R. Neidlein, E. Bernhard, Angew. Chem. 90 (1978) 395; Angew. Chem.
Inr. Ed. Engl. 17 (1978) 369; b) A. Hotzel, R. Neidlein, R. Schultz, A.
Schweig, ibid. 92 (1980) 751 and 19 (1980) 739; c) W. H. Gilligan, M. J.
Kamlet, Tefrahedron Lett. 1978, 1675.
141 a) D. C. England, C. G. Krespan, J. Am. Chem. SOC.88 (1966) 5582; b) D.
Org. Chem. 42 (1977)
F. Sullivan, R. P. Woodbury, M. W. Rathke, .I.
2038; c) T. J. Jorwski, S . Kwiatowski, Rocz. Chem. 44 (1970) 691.
[5j a) F. Arndt, H. Scholz, E. Frobel, Jusfus Liebigs Ann. Chem. 521 (1935)
95; b) some new spectral data of l a : 'H-NMR (CDCI,): 6=4.72 ( 1 H),
3.99 (3 H); I3C-NMR (CDCI3): 6 = 157.8 (C=O), 107.8 (CN), 55.9 (CH,,
JC.H= 150 Hz), 29.3 (CH, Jc.H= 129 Hz).
[6] The oven was fitted with a quartz tube (I.D. 0.8 cm, length = 15 cm),
which was lightly packed over one third its length with quartz wool. The
0 Verlag Chemie GmbH, 6940 Weinheim. 1983
0S70-0833/83/0202-016S $02.50/0
165
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