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Bis-Dinitrogen and Diethylene Complexes of Molybdenum (0).

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This manuscript is
to be cited as
Dieses Manuskript ist
zu zitieren als
Angew. Chem. Suppl.
7982,1116-1120
Angew. Chem. Suppl.
7982,1116-1120
0 Vwlag Chemie GmbH. D-6840 Weinheim. 1982
0721~4227/82/0606~1116SM.50/0
Bis-Dinitrogen and Diethylene Complexes of Molybdenum(O)**
By Ernest0 Carmona', Jose M. Marin, Manuel L. Poveda,
Jerry L. Atwmd, Robin D. Rogers, and Geoffrey Wilkinson
Although a large number of dinitrogen complexes/1' 2/
of Group VI metals containing tertiary phosphane ligands
have been isolated, for monodentate trialkyl phosphanes,
apparently only cis-(~r(~~)~(PMe,),~/'/ is known. The
Prof. Dr. E. Carmona, Dr. J. M. Marin, Dr. M. L. Poveda
Department0 de Quimica Inorginica
Facultad de Quimica, Universidad de Sevilla
Setilla (Spain)
Prof. Dr. J. L. Atwood, R. D. Rogers
Department of Chemistry, University of Alabama
University, Alabama 3 5 4 8 6 (USA)
Figure 1. Molecular structure with the atoms represented
by their 50% probability ellipsoids for thermal motim
other important lengths and angles include: Mo-C(l) =
2.276(6) R, Mo-C(2) = 2.269(6) R, Mo-C(3) = 2.265(7) R,
MO-C(4) = 2.271(6) R, P(l)-MO-P(2) = 90.97(7)',
P(l)-Mo-P(4) = 90.47(7)',
P(l)-Mo-P(3) = 164.43(6)",
P(2)-Mo-P(3) = 91.73(7)", P(Z)-MO-P(4) = 164.31(7)",
P(3)-Mo-P(4) = 91.06(7)".
Prof. Dr: G . Wilkinson
Department of Chemistry, Imperial College
London SW7 ZAY (England)
**
This work was supported by the U. S. National science
Foundation (J. L. A . ) and the Spanish Ministerio de
Educaci6n y ciencia (J. M. M. and M. 1. P.).
- 1118
- 1116 -
complex [Moc13(PMe3)31
'4',
when treated with dispersed
sodium and H e 3 in tetrahydrofurane (TIP), gives G[t40(N2)2(PMe3)41 &, in yields better than 60%. Using
sodium amalgam, the corresponding trans isomer is formed,
also in good yields. The cis complex has two strong bands
in the IR spectrum (Nujol) at 2010 and 1950 cm-',
while
the trans absorbs at 1930 cm-' with a very weak band at
2 0 0 0 2 .
me H
' pw( spectra of the complexes ( c ~ at
H ~
35'C)
show, respectively, two multiplets at 4 = 1.4 and
1.2, (18 H: 18 H, cia) and a rather broad singlet at 6 =
1.5 (9).
The & isomer is much less stable thermally
than the trans and is more reactive, e.g., towards oxygen
and water.
Interaction of 1 in petroleum with C2H4 (ambient temperature and pressure) gives =-lMo(C
H ) (PMe3)41
2 4 2
as amber, very air sensitive crystals. m e 1~ NMR, spec= 1.4) and PMe3 (% = 1.0 s).
trum has bands due to C2H4
The crystal structure of this compound has been determined./5/
The ORTEP perspective (Figure 1) shows that the molecule is essentially octahedral with the ethylene molecules
staggered with respect to one another and eclipsing the
=-P-Mo-P
This conformational preference
has been predicted from quantitative calculations./8-10/
The four phosphorus atoms lie almost in the same plane and
are on the average 2.492(8) 2 from no. Both ethylene molecules are symetrically bound to the ~d atom, the mean
distance for the C=C bonds being 1.40(1) 2 (0.06 2 longer
than in free ethylene).
In hydrocarbon solutions there appears to be the
equilibrium
2
(a
I M O ( C ~ H ~ ) ~ ( P M+~ ~N2
) ~ I fMO(N2)(C2H4)2(PMe3)31 + FMe3
-3
- 1117 -
-
according to mlecular weight measurements under He and N2
and IR and PMR spectra. Prolonged interaction with N2
followed by reduction in volume in vacuum leads to a bright
yellow crystalline solid which redissolves on admission of
N2. The sequence is reversible and we suggest is due to
[MO(N2)(C2H4) (PMe3)3 1
-N2
t
(M02(!J-N2) (C2H4) (PMe3)61
942
That the dinitrogen in 3 is weakly bound is also indicated by the high value/"/
of vN2 at 2070 cm-' and its
facile displacement by CO to give colourless crystalline
3 1 . This compound was identified by
[Mo(CO)(C2H4)2(PMeJ)
analytical and spectral data. An X-ray structure determination showed =-(C2H4)
groups./12/
EXPERIMENTAL
Trans- and cis-[Mo(N2)2(PMe3)41 were respectively
prepared by sodium amalgam and dispersed sodium reductions
in tetrahydrofurane,under dinitrogen and in the presence
of trimethylphosphane. l%e cis isomer gives yellow crystals from petroleum ether while the
gives orange
crystals from diethyl ether at -20-C.
Synthesis of 2:
- Ethylene was bubbled for six hours
at r c a m temperature and pressure through a solution of 1
(0.91 g, 2 mol) in petroleum ether ( 5 0 ml). The solvent
was removed in vacuo and the residue extracted with 25-30
ml of petroleum ether. Centrifugation, concentration and
cooling at -30°C for twelve hours afforded crystals of
2.
Yield, 0 . 5 6 g (60%).
synthesis of 2: 0.92 g ( 2 nunol) of zwere dissolved
in 30 ml of petrolGum ether under N2. The nitrogen atmosphere was then replaced by CO at -2OOC and the solution
stirred for 20 seconds. Removal of part of the solvent in
vacuo and then cooling the solution at -3OOC for four
hours afforded colourless crystals of 2.
-
-
1119
-
REFERENCES
/1/ J. Chatt, J. R . Dilworth and R . L. Richards,
Rev., 7811978) 589.
- _
/2/
T.
A.
entstanden s o bla6rote Losungen Yon 2a bzw. Zb, allerdings
E.
George and R. A . Kovar, Inorg. Chem., 2011981)
285.
/3/
konnte nur Z b p r b p a r a t i v - g a s c h r o r n a t o g r a p h i s c h bis auf 95%
Reinheit angereichert werden (Tabelle .)l
2a zersetzte
sich beim Isolierungsversuch sehr rasch und auch 2 b ist
H. H. Karsch An ew Chem.
Int. Ed. E n q i . , m 6 :
89(1977) 57; Angew. Chem.
-
/4/ J. L. Atwood, W. E. Hunter, E. Carmona-Guzman and
G. Wilkinson,
Q980). 467.
/5/
2 forms monoclinic crystals, space group P21/n, a =
70.16513). b = 13.683(3), c = 37.139(5) 2, 8=98.84(3P,
U = 2355.5 R3, D, = 1.29 (I cm- , z = 4 . and
lMoKal =
8.1 cm-1. 2715 :ndepende&
observed reflections with
I
3o(I) were collected using graphite crystal monochromated radiation 120 2 5O0) on an Enraf-lonius
CAD-4 diffractometer. The structure was solved by
Patterson and Fourier techniques. Full-matrix leastsquares refinement led to a final R value of 0.043.
J. W. Byrne, H. H. Blaser and J. A . Osborn,..J
Chem. SOC., z(1975) 3871.
/7/
J. W. Byrne, J. R. M. Kress, J. A. Osborn, L. Ricard
/8/
/9/
(1977)
Bachmann, J. Dernuynck and A. Veillard, J. Am. Chem.
x ( 1 9 7 8 ) 2366.
T. A. Albriqht, R. Hoffmann, J. C. Thibeault and D. L.
Thorn, 3. Am. Chem. SOC., g ( 1 9 7 9 ) 3801.
Burdett and T. A. Albright, Inorq. Chem.,
(1979) 2112.
/lo/
J. K.
/11/
G. U . Kubas, J. &em.
/12/
J. L. Atwood,
18
SOC. Chem. Commun., 11980) 61.
R. D. Rogers.
published results.
E.
2
Tabelle 1. Trialkylsilyl(trifluormethy1)diazene 2 aus
R2
R3
Lasungsm.
Ausb. Xmax(cmax)
[%][a]
=.,
C.
i i
Lithiumsilylamiden 1 und Trifluornitrosomethan bei -8OoC.
R1
/6/
and R. E. Weiss, J. Chem. SOC. Chem. Comun.,
662.
1
Carmona-Guzman, un-
Received October 1 2 , 1981 /Z 116 S /
a)
Me
Me
SiMe3
Et20; Bu20
-
b)
Me
t-Bu
H
Et2O
6
c)
Et
Et
H
Et2O
-
d)
Ph
Me
H
Et20
e)
Me
Ph
SiMe2Ph
EtaO
f)
Ph
Ph
H
Et2O
H
Eta0
h)
Me
CH(SiMe3)2[b]
H
THFlb]
i)
Me
C(SiMeg)3
H
Et2O
g)
t-Bu t-Bu
11
520 ( 6 )
548 ( 2 4 )
33
504 (15)
[a] Caschromatographisch isolierte Ausbeute in %.
[bl Ausgehend von 11 trat in THF Abspaltung einer (SiMe3)Gruppe ein.
- 1120
- 1122 -
-
extrem hydrolyseempfindlich: Spuren von Luftfeuchtigkeit
This manuscript is
to be cited as
Angew. Chem. Suppl.
7982,1121-1127
Dieses Manuskriptist
zu zitieren als
Angew. Chem. Suppl.
7982,1121-1127
initiieren die autokatalysierte Zersetzung zu Disiloranen
bzw. Silanolen, Trialkylsilylfluoriden und anderen Trialkylsilylderivaten. Auch die ethyl- und phenylsubstituierten
Verbindungen 2c
0 Verlag Cheme GmbH,0-6940Weinhelm. 1982
0721 4227'82/L%O&t121
SO2 5010
-
2I lieBen sich mangels hydrolytischer
undloder thermischer Bestlndigkeit nur in L8sung erzeugen
-
und mit Hilfe der OCIMS-Kombination nachneisen.
I r i a l k y l s i l y l ( t r i f l u o r m e t h y 1 ~ d i a.. ~ e nals
e
ma6 e -,
schneidertm B e a g e n r i e m zmr nmcleophilcnn I r i f l u o r metbylieruly
*
**
Nit ausreichend volumindsen Gruppen am Silicium wie in 2g
und 211 sind derartige Diazene jedoch v6llig bestlndig. Das
Von Uwe Hartkopf und Armin de Meijere
Tri-e-butylsilylderivat 2s ist ein violetter Feststoff
*
(Fp = 37
-
380C), das himbeerrote kristalline Dimethyl-
[tris( trimethylsily1)methyl lsilylderivat 2i[31 (Fp P 200'C
Neue Methoden zur Einfiihrung von Trifluormethylgruppen in
(Zers.))
organische HolekUle sind nach wie vor gesucht"].
kann an der Luft auf=200°C erhitzt werden (Ta-
Die nubelle 1).
Demnach konnen
2s
und Zi, deren Konstitution
cleophile Ubertragung des Trifluormethylcarbanions war bis
durch 'H-, 13C- und 29Si-NMR eindeutig belegt wird ( T a vor kurzem unbekannt[21. Wir konzipierten deshalb die neubelle 2), auch zur Untersuchung der Bindungseigenschaften
artigen Trialkylsilyl(trifluormethy1)diazene 2, die wegen
dieser neuen Substanzklasse dienen.
der ausgezeichneten Elektrophilie heteroatomgebundener
Trialkylsilylgruppen zur Erzeugung von CF3QAnionen unter
Die beobachtete Hydrolyseempfindlichkeit der anderen Verbindungen 2 uurde als Hinueis darauf gewertet, da0 sie im
extrem milden Bedingungen geeignet erschienen.
erwarteten Sinne unter Freisetzung von Trifluormethylanionen
Far die Reaktion mit Trifluornitrosomethan (CF3NO), mit dem
fragmentieren konnen. Tatsbchlich gelang es bei geeigneter
primlre Alkylamine in Trifluormethylazoverbindungen iiberArbeitsweise, 2a bereits bei -1OOOC zu erzeugen, seine
fUhrt werden"],
erwiesen sich Trialkylsilylamine als zu
Fragment,ierung in situ einzuleiten und die entstehenden
wenig nucleophil. Die Lithiumsilylamide 1 reagieren jedoch
CF3-Anionen mit Carbonylverbindungen abzufangen. Dazu
glatt mit CF3N0. Aus Lithiumbis(trimethylsi1yl)amid
Lithium-w-butyldimethylsilylamid
la und
lb in Diethylether
- 1121 -
-
1123 -
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