close

Вход

Забыли?

вход по аккаунту

?

Fluorine-Bridged Heteroadducts of Organometallic Lanthanoid and Actinoid Complexes.

код для вставкиСкачать
ESR Studies on Vanadyl-Phosphorus Complexes "1
Table 1 . ESR data of the coniplexes investigated
second-order effects). Solvent: toluene.
(corrected for
By Gisela Henrici-OlivP and Salvador Olive'[*]
Vanadyl chloride, which is insoluble in toluene, can be made
t o dissolve in the presence of a n excess of triethylphosphine
(P;V B 4). The solution exhibits the ESR spectrum shown
in Fig. l a . T h e intensity of the signal corresponds t o essentially all the vanadium present in the solution. The signal is
characteristic of the interaction of the unpaired electron of
V(iv) with the j l V nucleus (nuclear spin I = 7/2) and with
two equivalent 3LP nuclei (I = 1/2), the latter interaction
being responsible for the triplet splitting (1 :2 : 1) of the eight
vanadium lines. The ESR data, which are shownIin Tablell,
line 1, are consistent with structure ( I ) or (2).
When the phosphine is replaced by triethyl phosphite,
VOCIz again dissolves but the ESR spectrum of the solution
consists mainly of'the VOClz signal (eight lines showing no
splitting) overlapped by a low-intensity doublet signal (one
phosphorus nucleus, up % 110 MHz). Addition of ethylaluminum dichloride (AI/V > 6), however, immediately
gives a triplet signal (Fig. l b a n d line 2 of Table 1). The
Lewis-acid character of VOC12 is probably too low for a
comparable EDA interaction t o occur with the weaker base
(CZHj0)3P. However, complex formation between VOC12
and the alkylaluminum lowers the electron density o n the
vanadium and thereby permits a n ESR-active interaction
between V and P. A possible formulation which takes account of the equivalence of the two P nuclei is shown in ( 3 ) .
0
N o ESR signal indicative of phosphorus nucleus interactions is obtained o n treatment of vanadyl acetylacetonate
[VO(acac)Z] with phosphine or with phosphite. Instead, the
unchanged eight-line signal of VO(acac)z is observed. On
addition of (CzH5)AIClz, however, triplet spectra appear
almost immediately which are in good experimental agreement with Fig. l a (for ethylphosphine) and l b (for ethyl
phosphite) - see Table I . These complexes are decomposed
1.981 L 0.001
1.980 :0.001
1.981 t- 0.001
1.981 t 0.001
1.968 :! 0.001
1.970 0.001
1.965 :. 0.001
250-i 2
254 _'. 2
250
2
252j: 2
300+ 2
287 i_ 2
300 i- 2
-
by tetrahydrofuran. Thc vanadyl signal then observed is no
longer that of VO(acacf2 but rather resembles that of VOCIz
(line 7 in Table I). We tentatively interpret this observation
in terms of repIacement of the (acac) ligands by C1 ligands
and formation of the abovc-mentioned bridged complex in
order t o reduce the electron density at the vanadium t o the
required value. T h e processes appear to be very rapid.
Comparison of the a p values in Table 1 shows that in the
phosphite complexes the unpaired electron has a higher
probability of being found at the phosphorus nucleus.
Phosphites are better ~i acceptors and poorer G donors than
t h e corresponding phosphines. The electrons that effect x
and G bonding between transition metal and phosphorus
compound are shifted more toward the phosphorus atom
in the phosphite than in the phosphine. The highest occupied molecular orbital of the complex, t h e frontier orbital,
which contains the unpaired electron, seems to reflect the
general donor-acceptor properties of the ligands. Similar
observations have already been made with other complexes 121.
I n all those cases in which alkylaluminum is present in the
reaction solution, a reduction V(IV) + V(III) is observed
which is first order in V(rv). (Magnitudes measured: magnetic susceptibility and intensity of ESR signals.) Reduction
is very slow with the phosphine complex (ti/* z 200 h),
significantly faster with the phosphite complex (& w 50h),
and faster by powers of ten when diethylaluminuin chloride
is used in place of ethylaluminum dichloride (ry2 % 10 min
for the phosphite complex of VO(acac)z). Reduction
presumably proceeds by the same route as that of similar
titanium complexes [31, i.e. via alkylation of the transition
metal and cleavage of the unstable V-C bond, the ratedetermining step probably being that of alkylation. The
higher electron density on vanadium in the phosphine complexes opposes alkylation.
Received: October 5, 1970
[Z 295 IE]
German version: Angew. Cheni. S2, 955 (1970)
...
[ * ] Dr. G . Henrici-OlivC and Dr. S . OlivC
Monsanto Research S.A.
CH-8050 Zurich, Eggbuhlstrasse 36 (Switzerland)
[ l ] ESR Studies o n transition metal complexes, Part 14. Part 13: C . Henrici-OlivQ and S . OlivP, J. organometal. Chem.
23, 155 (1970).
[Z] G . Henrici-Olive and S . OlivP, J. organometal. Chem. 17,
83 (1969).
[3] G . Henrici-Olive and S . OlivP, Angew. Chem. 79, 164
(1967); Angew. Cherr. internat. Edit. 6 , 790 (1967).
100 gauss
Fluorine-Bridged Heteroadducts of Organometallic
Lanthanoid and Actinoid Complexes[**I
By Basil Kanellakopulos, Ernst Dornberger,
Reinhard von Ammon, and Ruiner Dieter Fischer [ * I
Fig. 1 . ESR signals of vanadsl-phosphorus complexes in toluene
= 2 0 ° C , [VOClzl = 7 x 10-3 rnole/liter.
a) [ ( C L H ~ J P=
] 4 x 10-2 rnoleiliter;
b) [ ( C ~ H ~ O ) I P=
] 4 x 10-2 rnole/liter;
I(CzH5)AIC121
7 y 10-2 rnoIe/liter.
T
~~
Angew. Chem. internat. Edit.
/ Vol. 9 (1970) I No.
12
-
[a] Measured i n tetraliydrofu;-.iii f o r compari5on with No. 7.
-
+
+
+
71
1
100
I
71 1 1
101
1
The selfassociation[ll of the complex 121 (CSH~),UF( 1 )
indicates that in monomeric ( I ] neither the central U(rv)
ion nor its F(--I) ligand would be completely coordinately
saturated. I H - N M R studies have shown that ( I ) behaves
957
as a Lewis m i d towards bases such a s pyridine and tetrahydrofuran (THF). We have now been able t o prepare two
novel a n d remarkably stable heteroadducts of the type
markable long-wave shifts compared with the relevant absorption bands of other M . . . F . . . M’ systemsr91,
including ( I ) “1. Although in the case of ( 5 ) , in contrast t o
(3), a molecular structure with a strictly symmetrical
U . . . F . . . U bridge is conceivable, n o support for such
a n assumption comes from the rather numerous absorption
bands between about 100 and 350 cm-1 (range of metal-ring
and have thus obtained independent evidence for the exskeletal vibrations, see Fig. 1). Instead, similarities beceptionally high basicity of the fluorine compound ( I ) .
tween the solid-state electronic spectra of the adducts and
When equimolar solutions of ( I ) and the Lewis acidc31
their components, as well as the results of magnetic suscep( C 5 H 5 ) 3 Y b ( ~(2)
~ ~ )are mixed and stirred at room temperatibility measurements between 4.2 and 300”K, suggest
ture, a fine yellowish green crystalline precipitate is formed
rather the conservation of the original electronic configualmost immediately; after the precipitate has been washed
rations of U(rv), Yb(rir), and U(III) (i.e. 5f2,4f13, and 5f3).
with pentane and dried under high vacuum it is found t o
Unlike polycrystalline ( I ) , compounds ( 3 ) and ( 5 ) give no
have the composition of the 1:1 adduct
evidence for U . . . M spin exchange, even at low temperatures.
Apart from a non-linear fluorine bridge (which could be
stabilized by a C S H ligand
~
with partial bridging characIn a very similar reaction, the THF-ligand of ( C ~ H ~ ) ~ U ( I I I ) . ter “01) the possibility of an unsymmetrical linear
T H F ( 4 ) 141 is substituted by ( I ) to give the bronze-colored
U . . . F . . . M arrangement is also open t o discussion.
complex ( 5 ) , which can be extracted with benzene without
Received: October 6, 1970
[Z 296 IEI
decomposition.
German version: Angew. Chem. 82. 956 (1970)
[*] Dr. B. Kanellakopulos, E. Dornberger, Dr. R. v. Ammon
Surprisingly, no adduct of comparable stability is formed
I ) the reaction of
from ( 1 ) and ( C ~ H ~ ) ~ T ~ (( 6I )I 151;
( C ~ H ~ ) ~ U ( I V )(7)
C I with (2) or ( 3 ) seems t o proceed
beyond the hypothetical Cl-bridged adduct [GI.
Unlike their components, the adducts (3) and ( 5 ) are pyrophoric in air a n d are neither substantially soluble in C6H6
or T H F nor sublimable in high vacuum. Whereas ( I ) , ( 2 ) ,
a n d ( 4 ) give rise t o excellent mass spectra”] below
20O0C[4.81, even the strongest signals of ( 3 ) and (5) are
only detectable above 350 and 400°C, respectively. The
appearance of fragments of composition (C~HS),UMF
( X = 0 t o 6; relative intensities: 0.5 t o 7.0 based o n
I(C5H5UFt) = 100) could indicate a t least some volatility
of the binary heteroadducts ( 3 ) a n d ( 5 ) .
Differences in fragmentation behavior suggest that the
bond strength of the U . . . F . . . M bridge decreases
(1).
along the series ( 5 ) > (3)
The IR spectra of ( 3 ) and (5) are almost identical between
600 and 3000 cm-1 and compatible with the assumption of
centrally coordinated C5H5 ligands. The absorption bands
highly characteristic for the U . . . F . . . M group at 432
( 3 ) and 423 cm-1 (51, respectively, (see Fig. 1 ) show re-
Institut fur Heisse Chemie des Kernforschungszentrums
7 5 Karlsruhe, Postfach (Germany)
Doz. Dr. R. D. Fischer
Anorganisch-Chemisches Laboratorium
der Technischen Universitat
8 Munchen 2, Arcisstrasse 21 (Germany)
(to whom correspondence should be addressed)
[**I This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
[I) R . D . Fischer, R . v. Ammon, and B. Kanellakopulos, J. Organometal. Chem., in press; according to recent studies,
crystalline (CsHS)3Th(Iv)F also exists in an associated form
similar to that of ( I ) .
[2] P. G. Laubereau, Dissertation, Technische Hochschule
Miinchen, 1966.
[3] E. 0.Fischer and H . Fischer, J. Organometal. Chem. 3, 181
(1965).
[41 B. Kanelfakopulos, E . 0. Fischer, E. Dornberger, and F.
Baumgartner, J. Organometal. Chem. 24, 507 (1970).
[5] I n solution, (6) and ( I ) undergo only weak interactions
similar to those between ( I ) and T H F [l].
[6] Results of 1H-NMR studies suggest the equilibrium
(CsH5)3UCI Yb(CsH5)j Z ( C S H S ) ~tU 1 / 2 [(CsH5)2YbC11~.
171 Varian Mat-CH5 with an internal sampling system (70eV).
[8] B. Papadopulos, L . Stieglitz, W . Rotlt, and B. Kanellakopulos, unpublished.
[9] I . R. Beattie, K . M . S. Livingston, G . A . Ozin, and D. J .
Reynolds, J . cbem. SOC.A 1969, 959.
[ l o ] For X-ray studies suggesting formation of C S H ligands
~
with partial bridging character, see C.-H. Wong and J . - Y .
Lee, Acta Crystallogr. B 25, 2580 (1969).
[ l l ] Cf. H. Schnridbaur and H . F. Klein, Angew. Chem. 78, 750
(1966); Angew. Chem. internat. Edit. 5, 726 (1966).
+
Structure of a Tricarbonyl-l-isopropoxycarbonyl1,2-diazepineiron Complex
By Rudolf Allmann [ * J
Substituted 1 H-l,2-diazepines (2) have been prepared
from pyridinium imidates ( I ) by photochemically induced
ring expansion (11.
In order t o gain information about the conformation of the
1,2-diazepine ring and particularly about the existence of
W
700
600
500
LO0
-v
300
250
200
150
icm-’]
mulls;
~
Beckman
Fig. I . FIR spectra of the adducts ( 3 ) and (5). ( N U J O
Model IR 11 instrument).
958
Angew. Chem. internat. Edit.
1 Vol. 9 (1970) / No.
12
Документ
Категория
Без категории
Просмотров
0
Размер файла
232 Кб
Теги
organometallic, bridge, lanthanoids, actinoide, complexes, fluorine, heteroadducts
1/--страниц
Пожаловаться на содержимое документа