close

Вход

Забыли?

вход по аккаунту

?

Hofmann- and Lossen-Rearrangements of Metal Carbonyl Complexes.

код для вставкиСкачать
The reaction of AsPh4[Au(N3)4] with cyclohexene in THF,
however, probably leads, by analogy with the reaction of
cyclohexene with N-bromosuccinimide or highly dilute
bromine, not to addition t o the double bond but t o substitution in the allylic position: the mass spectrum of the
reaction solution was shown to contain the molecular ion of
diazidocyclohexene.
Azido Metal Complexes as N, Generators
By Worfsang Beck and Karl SchorppI*J
The deep red solutions of tetraphenylarsonium salts with the
complex anions [Au(N&- and [Pb(N3)612-[ I ] in tetrahydrofuran (THF) or methylene dichloride are rapidly decolorized by the action of diffuse daylight, the central metal
ion being reduced t o form gold(1) and lead(r1) complexes,
respectively, and nitrogen being formed as oxidation product
of the azide ligand:
+3
N3 transfer aIso occurs in the reaction of PtO(PPh3), (n =
3,4) with AsPh4[Au(N&] in THF/benzene. In these reactions
N3 behaves formally as a pseudohalogen in a n oxidative
addition, as in the reactions of halogens 161 or cyanogen 171
with Pt(PPh&. However, the reaction probably follows a
bridge mechanism 181.
+1
[A~(N3)41-
+
fAu(N3)zI- t 3 NZ
I't(PPh3),
The color of these AuIII and PbIV complexes arises from
C T transitions, which can be regarded as electron transfer
from the azide ligand to the metal[ll. Formation of nitrogen
is preceded by the following primary process [ZJ:
hv
-+
[Mz+(N;),](*-z)-
Pt(PPh3)2+ ( n - 2 ) P P h 3
I
\o
[M(Z-l)+(N:) (N:)fl-l](n-z)-
In accordance with this scheme, it was possible to detect a
one-electron reduction proceeding via AuII for tetrachloroaurate(1n) 131.
We attempted to detect the expected species N! by interception with olefins. Thus AsPh4[Au(N&] was dissolved in
acrylonitrile, ethyl acrylate, or acrolein and the course of
reaction followed by I R and N M R spectroscopy. When the
solutions are exposed to daylight, the va,N3 bands of the
complex [Au(N3)4]- become less intense and the characteristic
absorptions of organic azides appear (Table 1).
Received: June 15, 1970
[Z 242 IE]
German version: Angew. Chem. 82, 701 (1970)
[*I Prof. Dr. W. Beck and Dip1.-Chem. K. Schorpp
Institut f u r Anorgdnische Chemie der Universitat
8 Munchen 2, Meiserstrasse 1 (Germany)
[l] W. Beck and W . P. Fehlhammer, Angew. Chem. 79, 146
(1967); Angew. Chem. internat. Edit. 6, 169 (1967); W. Beck,
W. P . Fehlhammer, P. Pollmann, E. Schuierer, and K . Feldl,
Chem. Ber. 100, 2335 (1967).
Table 1. vasN, bands of organic azides formed from azido complexes
and olefins.
I
~
olefin
[2] H. L . Schlufer, 2. physik. Chem. N.F. 11, 65 (1957).
vasN3 (cm-*) [a1
[3] R . L. Rich and H. Taube, J. physic. Chem. 58, 6 (1954).
[4] Independently of us, C. Bartocci and F. Scandola, Chem.
Commun. 1970, 531, have reported o n the photochemical decomposition of [Pt(diene)N~JNO3by U V light; acrylamide
added to the aqueous solution polymerizes. The authors regard
this as proof of the occurrence of N3 radicals.
[ 5 ] H. Schufer, Angew. Chem. 82, 134 (1970); Angew. Chem.
internat. Edit. 9, 158 (1970), has been able to add N3 groups
to olefins by electrolysis of NaN3 in acetic acid; azidoalkanes
were formed.
2112
acrylonitrile
ethyl acrylate
acrolein
cyclohexene
2132,2107
2157, 2110
2141, 21 14
[a] The vasN, bands of the azido complexes
appreciably from those of the organic azides.
(%
2030 cm-1) differ
In the IH-NMR spectrum, the effect of exposure to light is
to reduce the intensity of the olefinic proton signals while
simultaneously giving rise to new aliphatic proton signals.
[ 6 ] R . Ugo, Coordinat. Chem. Rev. 3, 319 (1968).
[7] B. J. Argento, P . Fittun, J . E . McKeon, and E. A . Rick,
Chem. Commun. 1969, 1427.
Reaction of (AsPh& [Pb(N&] with acrylonitrile or acrolein
gives the same products.
[8] H. Tartbe and H. Myers, J. Amer. chem. SOC. 76, 2103
(1954), R . Snellgrove and E . L . King, ibid. 84, 4609 (1962).
On prolonged action of light on solutions of AsPh4[Au(N3)4]
in the olefins mentioned above, the AuIII present is reduced
to the metal; with acrolein in particular a coherent film of
gold appears on the wall of the reaction vessel within a few
hours at room temperature.
Hofmann- and Lossen-Rearrangements of
Metal Carbonyl Complexes
Photochemical reaction of the azido complexes with ethyl
acrylate or acrylonitrile leads to polymerization 141. The
stability of the solutions in the dark and the observation that
polymerization starts at the side of the reaction vessel that
is turned to the light suggest a free-radical chain mechanism
in which N: acts as chain initiator. The following reaction
course is consistent with the experimental data [5J:
By Wolfgang Beck and Boris Lindenberg [*I
Reactions of metal carbonyl complexes in which a nucleophile attacks the positively charged C atom of a CO ligand
include those with alkyl- and aryllithium compounds 111,
hydroxide and alkoxide ions (21, ammonia 131 and amines [41,
hydrazine [51, and the azide ion [61. The latter reactions, i. e.
of N2H4 or N3- with metal hexacarbonyls of chromium,
molybdenum, and tungsten, lead to isocyanato complexes as
stable end products.
R
9
N; +
R
\
\
/
/c=c\
+
(I), R
(2). R
=
=
CHO
CN, COOEt
/
\
N3
/R
;c-c.
N3
\
/
-.cc.-
N3
(1)
I.
R
R
\
I
I I
. , -' cI - c - ( c - c ) n -Ic - c <I
I
I
N3
(2)
Angew. Chem. internat. Edit. J Vol. 9 (1970) I No. 9
We have now found that isocyanatopentacarbonylmetal= Cr, Mo, W) are also formed
under mild conditions in the reaction of M(CO)6 with
hydroxylamine or chloramine, presumably in accordance
with the following reaction mechanism:
/R ates(0) [M(CO)xNCO]- (M
735
6-
a+
(CO)sM-C=O
+ NHZX
+
(C0)5M-C=0
-€I+
t
NH2X
r (CO),M~--,c=Ol\:
N
(I)
-140 "C yields bis(~-allyl)nickel,which, according to the
IH-NMR spectrum[sl, is mainly present as the trans
isomer (2) (94 %).
a [(CO),M-N=C=O]'
d'x
(2)
2
-140%
-
r
X = OH, C1
The intermediates (11, which can be formulated as the
hydroxamic acid R-C(0)-NHOH or N-halogeno acid amide
R-C(0)---NHCl (R = M(C0)5), form stable isocyanato
complexes by loss of H 2 0 or HCl respectively: this corresponds to the rearrangement in the Lossen degradation of
hydroxamic acids and in the Hofmann degradation of
carboxylic amides, in the same way that the reaction of
M(CO)6 with N; [61 corresponds to the Curtius degradation
of carboxylic azides. In contrast to organic isocyanates, which
give primary amines and urethanes respectively o n reaction
with water or alcohol, the isocyanato complexes are stable
toward solvolysis.
In reactions of longer duration both chloramine and hydroxylamine react oxidatively toward hexacarbonyls with
formationof COz andmetaloxides.Furthermore,W(CO)5NH3
was detected as secondary product; in this case ammonia is
present as a result of reduction or disproportionation of
hydroxylamine. Other metal carbonyl compounds, e . g .
Mn(CO)sBr, react with NH2OH to give isocyanato complexes.
+ 2 NaJHB(CH,),]
<Ni-Br'..Nl)
.Bi-'
+
[<Ni-H]
2 NaRr
+
2 B(CH,),
If, however, the 1:l adducts (3) of phosphines and x-allyibromonickel are used as starting material then reaction
with Na[HB(CH&] a t -1 30 OC gives the red-brown
crystalline x-allylhydridonickel compound ( 4 ) , which reacts
with an excess of triphenyl phosphite with transfer of the
hydrogen bound t o nickel to the x-ally1 group and loss of
propene.
<N<PR3
+ Na[HB(CH3)31
-135%
Br
(3)
Experimental procedure:
e<zR3
On uniting a suspension of the hexacarbonylmetal complex in
ethanol with an ethanolic solution of hydroxylamine or
chloramine (molar ratio M(C0)6:NH2X = 1:4) the mixture immediately turns yellow. After a few minutes the
tetraphenylarsonium salt of [2) [61 can be precipitated from
the filtered soIution with [ A s ( C ~ H ~ ) ~ }by
C Iaddition of water.
+ NaBr + B(CH,),
Received: May 25, 1970
[Z 241 IEI
German version: Angew. C h e m . 82, 701 (1970)
I*] Prof. Dr. W. Beck and DipLChem.
B. Lindenberg
Institut fur Anorganische Chemie der Universitat
8 Munchen 2, Meiserstrasse 1 (Germany)
[ l ] E . 0. Fischer and A . Mansbol, Chem. Ber. 100, 2445 (1967).
121 Th. Kruck, M . Hoiper, and M . Noack, Chem. Ber. 97, 1693
(1964); 99, 1153 (1966).
[3] H. Behrens, E. Ruyter, and H. Wakamatsu, Z. anorg. allg.
Chem. 349, 241 (1967); H . Behrens, E . Lindner, and P . Passler,
ibid. 365, 131 (1969).
[4] W . F. Edgelland B. J . Bulkin, J. Amer. chem. SOC.88, 4839
(1966), L. Busetro and R . J . A n g e k i , Inorg. chim. Acta 2, 391
(1968).
[ 5 ] R . J . Angelici and L . Busetto, J. Amer. chem. SOC.91, 3197
(1969).
[6] W. Beck and H . S . Smedal, Angew. Chem. 78, 267 (1966);
Angew. Chem. internat. Edit. 5, 253 (1966); W . Beck, H. Werner, H, S . Smedal, and H. Engelmann, Chem. Ber. 101, 2143
(1968); Inorg. chim. Acta 3, 331 (1969).
The triphenylphosphine addition compound ( 4 a ) is stable
up to-30 "C. I t can be seen from the 1H-NMR spectrum 151
that the syn- and anti protons are not equivalent so far as
pairing is concerned, thus suggesting a tetragonal-planar
arrangement of ligands. The H atom attached to the nickel
does not give a resonance signal in the region up t o T = 15.
H~
H B H ~ H~
H"
TMS
Z-Allylhydridonickel Compounds111
By Helmut Bonnemann [*I
The thermally labile compound x-allylmethylnickeI[21 decomposes a t temperatures above -80 "C with ligand exchange to give predominantly the trans isomer of bis(xallyl)nickel[31.
The corresponding x-allylhydrido complex of nickel, which
is not stabilized by further ligands, undergoes such a disproportionation even a t extremely low temperatures. Thus,
reaction of x-allylbromonickel with Na[HB(CH3)3] [41 at
136
The 1H-NMR spectrum [51 of the trifluorophosphine
adduct ( 4 6 ) is remarkably dependent upon temperature.
At -75°C the characteristic signals of a symmetrically
arranged x-ally1 group appear a t T = 5.30 (meso), 7.27 (sun),
and 8.50 (anti). If the sample is allowed to warm over a few
hours to -40 "C the spectrum shows three further signals
(multiplet, T = 4.15; double doublet, centered at T = 4.85;
doublet a t T = 8.43) in the intensity ratio 1:2: 3, which can
Angew. Chem. internat. Edit.
Vol. 9 (1970)
/ No.
9
Документ
Категория
Без категории
Просмотров
2
Размер файла
213 Кб
Теги
carbonyl, rearrangements, metali, hofmann, losses, complexes
1/--страниц
Пожаловаться на содержимое документа