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An Example of the Equilibrium Ethylenehydridometal Ethylmetal Complex.

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CAS Registry numbers:
( I ). 59206-89-2. ( 2 ) , 69277-73-2; ( 3 ) , 69277-75-4; ( 4 ) , 69277-76-5; (S),
69277-78-7: ( h i . 69277.80-1; (7), 69277-82-3; (a), 21021-41-0; ( 9 1 ,
69277.X1-5. ~ltetli~ll1rimeth!Isilvllaininc.996-50-9: 2-nminohen7othia7ole,
1 ? O- ‘ ) ~ -\ 2 . . ~ - J i i i i c ~ l i ~ l h c n ~ ~ perchlorate.
~~l~i~~~~
706-67-2:
~ l i u m I,2-dtmethylquinolliiiuni perchlorate, 20729-X6-6
DonoriAcceptor Substituted Aromatic Systems, Part 5. This work was
supported by the Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie. - - Part 4: R . Gompper, K . Schiinafinger, Chem.
Ber., in press.
a ) R . Brrsiow, 3. M . Hoffian, J. Am. Chem. Soc. 9 4 , 2110 (1972); b)
F . P. Lossing, J . C . Traeqer, ibid. 97, 1579 (1975).
B M . Adger, C . W Rers, R . C . Szorr, J . Chem. SOC. Perkin Trans.
1 lY75. 45.
G . Seyhold, L‘. Jersak, R. Gompper, Angew. Chem. 85, 918 (1973); Angew.
Chem. Int. Ed. Engl. 12, 847 (1973).
H . - U . Wagner, private communication.
K . H Biichrl, H . Erdmann, Chem. Ber. 109, I625 (1976).
B r . Pat. 704595 (1954). Bayer AG; Chem. Abstr. 4 9 , 7001d (1955); H .
I’ollmurin, F . Baumann, B. Bienert, US-Pat. 2701 252 (1955), Bayer AG;
Chem. Ahstr. 4Y, P10374b (19.55).
An Example of the Equilibrium
E thy lrnetat Cornplex I
Ethy lenehydridome ta I
+
By Helmut Wrrrier and Ruiner Feserl’l
It is generally assumed that both the insertion of CzH4
in a M-H bond as well as the reverse of this reaction proceed
oia an intermediate of the type ( 1 ).
Very few examples of stable isolable ethylenehydridometal
complexes have previously been reported in the literature’’?
After having prepared C5H5Rh(PMe3), (2)l3] we have now
also synthesized its monocarbonyl- ( 3 ) and ethylene-derivative ( 4 ) and investigated their behavior as Lewis bases.
[(CzH4)(PMe3)RhCI]2+ 2TICsHs
+
+ 2C5H5Rh(C~H4)PMe3ZTICI
(4)
While (2) even reacts with NH4PF6 to give the complex
[C5H5RhH(PMe3)2]PF6, the stronger acid HBF4 (in propionic anhydride) is necessary for the protonation of (3)
and ( 4 ) ; this is one case where the influence of the ligandPMe, is a much better donor than C O or C2H4-on the
basicity of the metal atom is more marked.
(3). ( 4 )
+ HBF4 + [C5H5RhH(L)PMe3]BF4
(5), L=CO
(6), L = C Z H ~
The products ( 5 ) and (6) form light-brown, extremely airsensitive crystals which are readily soluble in polar organic
solvents such as e. y. CH3NO2.
As shown by the ‘H-NMR spectrum (cf. Table 1 ) ( 5 ) also
exists in solution as the carbonylhydrido complex ; evidence
for insertion of the CO ligand in the Rh-H bond is not
observed. I n contrast. however. the temperature-dependence
of the spectrum of (6) indicates, in this case, that an equilibrium is set up between ethylenehydrido- (a) and ethyl complex
(b),where the free coordination site in the latter could possibly
be occupied by a solvent molecule.
[C5H5RhH(C2H4)PMe3]’ $ [C5H5Rh(C2H5)PMeA]’
(a)
(bi
In CD,NO,-solutions of (6) at room temperature only the
signals of the C5H5-and PMe3-protons are sharp, while those
of the hydridic H atom (6 z - 10.5) and of the C2H4-protons
( 6 ~ 3 . 3 )appear as broad humps. At +lO”C the signal at
6 ~ 3 . 3splits into two less broader signals, which on further
cooling to -20°C give two multiplets at 6=3.0 and 3.52. As
expected, at -20°C a doublet of doublets (Table 1) I S
observed for the RhH signal. The signals of the C5HS- and
PMe3-protons remain unchanged on lowering the temperature141.
Table I . ‘ H - N M R data for 1 3 ) - (11 1 (6 values, TMS int.; J in Hz; solvent for neutral complex: CbHh,for ionic compounds: C D 3 N 0 2 )
Complex
C~HS
PMe3
5.29 d x d
JRhH=0.7. JpH=0.4
5.18 “t”
JK~H
J p=
~=0.7
5.97 d x d
JK~
=H
I .O, JPH
= 0.4
5.88dxd
J R h H = 1 .O, J p H = 0.4
5.70 m.
1.15dxd
J ~ h ~ = 1 . J4 .p ~ = l 0
0.85 d x d
J n h H = 1 .O, JPH
=9
1.90 d x d
JK~
= 1.2,
H JPH
= 12.3
1.63 d x d
J R I , I I0.= J~p ~ = 1 1 . 8
5.70 d x d
J K h H = I .0, E
JW = 0.6
4.88 d x d
JR~
=H
1.4. J p H = 0.4
4.90 d x d
JR~
=H
1.4, J p H = 0.4
4.92 d x d
JK~
=H
I .5, J p H = 0.6
1.67dxd
J K h H = l . O . JpH=10.8
1.60 d x d
J R , , , ~= 0.9, J p H = 10.9
1.15 d x d
J R , ~ H=0.9, J p H = 10.8
1.15 d x d
J K h H =0.8. J p H = 10.8
1.22dxd
J ~ h ~ = 0 . J8P ,H = 10.5
L [a1
Rh-R
1.48 “t” br
2.78 “d” br
3.33 br (see text)
2.23 m
[CH(CH,$),]
1.35 “d x d” [Cl{(C‘H $ 1 ~[b]
1
1.32 “d x d ” [ C H ( C H , ) , ]
3.47 m
i
- 10.7 “1”
JR~H=JPH=~I
- 1 0 . 5 d x d [-2O”C]
J R h H = 18, J p H = 2
X
-12.8 d x d x d
J R h l l = I X , JpH=25: 72
CCI
1.62 “1“ [d]
1.62 “1” [d]
1 59 “t” [d]
[a] L=C,H, for ( 4 ) , ( 6 ) and ( N ) , L = P ( I - C , H , ) ~for ( 7 ) ; [b] because of the chirality center at rhodium the methyl groups of P(i-C3H713 are diastereotropic;
[c] signal for the ethyl group bound to the rhodium is partly covered by the PMe3 signal and is thus not clearly locatable; [d] only the triplet-like A3-part of
the A,B2 spectrum is given; the signal for the methylene protons disappear because of numerous couplings in the base line noise.
[“I
Prof Dr. H. Werner, Dipl.-Chem. R. Feser
Institut fur Anorganische Chemie der Universitat
Am Hubland, D-8700 Wiirzhurg (Germany)
4 1 1 q ~ i tCheni.
.
lnr. E d Enql 1 X ( 1 97Y j N o . 2
0 Verluy Chemie, GmbH, 0-6940 Weinheim, I Y 7 Y
The existence of the equilibrium ( a ) e ( b ) is confirmed by
deuteration experiments. On addition of D 2 0 (excess) to the
CD3N02solution of ( 6 ) at -20°C the previously observed
157
057U-O833:7Y ,0202-0157 $ Ul.00/0
'H-NMR signals for the RhH and CzH4 protons disappear.
If the solution of (6) in D 2 0 is treated with KOH and
the resulting product extracted with benzene, the 'H-NMR
spectrum of the benzene extract is identical-except for the
signals for complex-bound ethylene-with that of ( 4 ) . The
mass spectrum of the product remaining after removal of
solvent shows the line of highest intensity in the range
mle=270-280 at m/e=276, which corresponds to an ion
of composition C5HSRh(C2D,)PMe; ; the occurrence of weak
lines at m/e=277 to 281 indicate that reaction of D,O with
(6) can lead to deuteration not only of the ethylene but
also, at least partially, to deuteration of the cyclopentadienyl
ligand (the relatively low intensity of the C5H5-signal in the
'H-NMR spectrum supports this assumption; cf. also Is]).
The equilibrium between ethylenehydrido- and ethylcomplex is also reflected in the reactivity of (6): the ethylene
of the complex can be replaced by CO or by P(i-Pr)3. Reaction
with C2H4 leads to formation of ( 8 ) , from which (6) can
be regenerated, both in the solid state as well as in solution
with elimination of C2H4; the formation of (8) could be
formulated as involving an addition of ethylene to the free
coordination site of the cation [C5H5Rh(C2H5)PMe3]+.
Analogously as with ethylene, (6) also reacts with NaCl,
NaBr or NaI to give neutral complexes ( 9 ) - ( l l ) , which
have been characterized by elemental analysis, 'H-NMR data
and mass spectra. In the reaction of (6) with NaF (in water
or nitromethane) a deprotonation of the ethylenehydridometal cation takes place and ( 4 ) is obtained.
Stepwise Addition of a Lewis Acid and a Lewis Base
to a Metal-Metal Bond'']
By Helmut Werner and Werner Hofmann[*]
C5H5C~(PMe3)2
( 1 ) reacts with methyl iodide and ethyl
iodide to give ionic compounds of the type (2)['"], and, surprisingly with isopropyl bromide and tert-butyl bromide to give
compounds of type (3)['hl.
(2), R
( 3 ) , R'
= M e , Et
If it is correct that steric factors are responsible for the
different reaction course, it could be possible for a complex
CSHSCoL2-or even CSH5Co(PMe3)L+ontaining a ligand
L which is smaller than PMe3 to react with iPrBr or tBuBr
to give a cation with a stable Co-R' bond. We therefore
attempted the preparation of C5H5Co(PMe2H)2 and/or
C5H5Co(PMe3)(PMezH).
The bis(phosphite) complexes C5H5Co[P(OR)3]2(R= Me,
are accessible from cobaltocene.
Et, Ph)l3"]as well as (1
Dimethylphosphane also reacts cleanly with C O ( C ~ H giving
~)~,
quantitatively the binuclear complex ( 4 ) ; the half-sandwich
complex CSHSCo(PMe2H),expected as intermediate has so
far not been detected.
Me'
(6)
+ NaX + [C5H5Rh(CzH5)(PMe3)X]+ NaBF4
+ NaF
--t
'Me
141
( S j , X=CI
(lo), X=Br
( l l ) ,X=I
(6 j
= i P r , tBu
C5H5Rh(C2H4)PMe3+ H F + NaBF4
(4I
To our knowledge these findings provide the first evidence
that an ethylenehydridometal complex can exist in equilibrium
with an ethylmetal complex under normal conditions in solution. This finding is of general importance for an understanding of the insertion of olefins in M-H bonds.
The bis(pdipheny1phosphido) complex analogous to I 4 I
is accessible by reaction of C ~ H ~ C O ( C with
O ) ~ P2PhI'41.
Attempts to prepare ( 4 ) in this way have proved unsuccessful;
reaction of C s H s C ~ ( C O )with
2 P,Me4 afforded the p-diphosphane complex CSH5(CO)Co(PMe,PMe2)Co(CO)C5H5~41.
Our attempts to synthesize C5H5Co(PMe3)(PMe,H)
also led to ( 4 ) . Its formation from ( 5 ) is noteworthy
insofar as the (Co-Mn)-binuclear complex always reacts with
other Lewis bases L (PPh3,P(OMe)3,P(OPh)3,alkenes, alkynes
etc.) to give C5H5Co(PMe3)Land MeC5H4Mn(CO)3[51.
Received: November 29, 1978 [ Z 143a IE]
German version: Angew. Chem. 91, 171 (1979)
CAS Registry numbers:
(TBA),[Re,CI,], 14023-10-0: (TBA),[Re,Br,],
678 15-33-2
[I]
121
[3]
[4]
[S]
158
14049-60-6; (TBA),[ReZI,],
Basic Metals, Part 15. This work was supported by the Deutsche For-'
schungsgemeinschaft, the Fonds der Chemischen Industrie, and by donations of chemicals from Bayer AG, Leverkusen, and DegusSd, Hanau.
We thank B. Klrnyerr for experimental assistance.-Part 14: K . DcI.,
H . Werner, J . Organomet. Chem., in press.
F. N . Tehhe, G. W Purshall, J. Am. Chem. Soc. 93, 3793 (1971), A .
J . Deeming, B. F . G. Johnson, J . Lewis, J . Chem. Soc. Dalton Trans.
1973, 1848; F. W S . Bmnfield, M . L. H . Green, ibid. 1974, 1324.
H. Werner, R. Feser, W Buchner, Chem. Ber., in press.
On warming to + 60°C the shape of the two broad signals at 6 z - 10.5
and 3.3 remains almost the same. Owing to the large difference in
the chemical shift the coalescence point I S probably first reached at
much higher temperatures.
B. F . G. Johnson, J . Lewir. D. J. Yurroii-, J Chem. Soc. Dalton Trans.
1972. 2084.
[*I Prof. Dr. H. Werner, Dipl.-Chem. W. Hofmann
Institut fur Anorganische Chemie der Universitat
Am Hubland, D-8700 Wurzburg (Germany)
Aiiqeiv.
0 Veerlug Ckemie, GmbH. 0-6940 Weinheim, 1979
Chem.
Iiit.
Ed.
€ii<q/.
1,Y 11979) No. 2
0570-0833/79 0202-0158 S 01 .00/0
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complex, example, ethylenehydridometal, ethylmetal, equilibrium
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