close

Вход

Забыли?

вход по аккаунту

?

Carbanion Complexes of Nickel(0).

код для вставкиСкачать
The 'H-NMR spectrum (60 MHz; rel. C6H6 int.) of (3)
shows only one signal at 1.33ppm (converted to TMS), which
expectedly exhibits no coupling with cadmium ("'Cd, I = 1/2,
rel. abundance 12.86 %; 'I3Cd, I = 112, rel. abundance
12.34%). In contrast the I3C-NMR spectrum (20 MHz; rel.
C6D6 int.) shows two signals at 95.06 and 102.58ppm, both
flanked by coupling satellites [2J("C-"""3Cd)=31
Hz,
3J('3C-11"1'3Cd)=11.4Hz]. N o Si-H stretching vibrations
are observed in the IR spectrum (solution in Nujol, CsI disks).
Experimental:
All operations were carried out under an atmosphere of
dry oxygen-free argon. The starting compounds (1) and (2)
were prepared by known methods[41.( I ) (7.5mmol) and (2)
(3.75 mmol) were transferred to a 25 ml flask furnished with
an argon inlet and a reflux condenser connected to a gas
burette via a bubbler. O n heating to 9 0 T , 156ml gas was
evolved within 24h (IR: C&; ca. 86 %). Unconsumed (1)
could be removed at 60°C/2.5 x 10- mbar. The crude product
was purified by recrystallization from benzene. (3) was
obtained as pale yellow crystals m.p. ca. 140°C (decomp.)
which turned green-black on exposure to air and moisture.
Received: June 8, 1976 [Z 513 IE]
German version: Angew. Chem. 88, 681 (1976)
CAS Registry numbers:
( I ) , 18159-55-2: ( 2 ) , 592-02-9; ( 3 ) , 60349-27-1: " C , 14162-74-4
r
--
~
N. S. Vva-anliii. Organomet. Chem. Rev. A3,323 (1968); N. S . Vvuzankiti,
E. N. Glatlrsher, S . P. Knriiran, G . A . Ra;iiuueu, and E . A . Arkhaiiyel'skayu,
Zh. Obshch. Khim. 38, 1803 (1968); R. A. Jacksoti, Chem. Commun.
1966. 827.
N. S. Vwzafikifi.G. A. RUZWUN,and V T Bln.hknr, Zh. Obshch. Khim.
35, 395 (1965).
M . P. D n d e and C . 71 Wcw, J. Am. Chem. SOC.97. 3777 (1975).
a ) M . Weidetihrirrh and W Peter, Angew. Chem. 87, 670 (1975); Angew.
Chem. Int. Ed. Engl. 14, 642 (1975); b) Houben-Weyl, Methoden der
Orgdnischen Chemie, Vol. I3/2a. Thieme-Verlag, Stuttgart 1973, p. 868.
Carbanion Complexes of Nickel(o)
By Klaus Jonas, Klaus Richard Porschke, Carl Kriiger, and
Yi-Hung ~ s a y [ * ]
Transition-metal(0) compounds in which simple carbanions
such as CH; o r C2H; are coordinated as electron donors
to the metal atom were, to our knowledge, previously
unknown".21. We report here on novel nickel(0) complexes in
which such a o - M o - C bonding is present.
During investigations on alkali metal compounds of nickelI31
we found that reaction of binary Nio-olefin complexes such
as (CDT)Ni or (COD)2Ni[41with organolithium compounds
LiR (Ni/LiR= 1 : 1) and ethylene in the presence of strong
(COD),Ni
+ LiK +
2 CZH,
+
EI2O
2 (CH~)ZN-CH~CH~-N(CH~)~
n-donor ligands such as tetrahydrofuran or N,N,N',N'-tetramethylethylenediamine'leads to complexes in which two ethylene molecules besides a carbanion ligand R- are bonded
to a nickel atom with formation of a R-Nio(C2H4)2 anion.
The complexes (1 ) are characterized by elemental analysis
and 'H-NMR data, as well as by reaction with ethanol or
carbon monoxide. With ethanol two equivalents of diamine
are liberated per equivalent of Li;.the ethyl compound ( I b )
yields the calculated amount of ethylene and ethane, while
the methyl compound ( 1 a ) yields also the calculated amount
of methane together with ethylene and ethane (from ethylene).
O n the other hand, the ethylene moiety in ( I a ) , ( I b ) and
(1 c) can also be displaced quantitatively (as C2H4)by carbon
monoxide.
In the 'H-NMR spectrum of (1) (in [D,]-THF) the signals
of the amine protons are not shifted compared to free amine;
it thus follows that the amine ligands initially coordinated
to the lithium are completely displaced by [D,]-THF. In
all three cases singlets are found for the protons of the ethylene
ligands coordinated to nickel, for (1 a ) at T = 8.26, ( I b ) at
~ = 8 . 4 2and for (I c) at r=8.34. The signals of the phenyl
protons in ( l c ) appear at r=2.4 and 3.4 (intensity ratio
2: 3). The methyl protons in ( 1 a ) are observed as a singlet
at T = 10.58, while the ethyl compound ( I b ) shows a triplet
for the methyl protons at ~ = 8 . 7 6and a quartet for the methylene protons at r=9.42 with J = 7.5 Hz. All 'H-NMR spectra
are essentially temperature-independent in the range - 80°C
to +2O"C. Exchange between complexed and added free ethylene is not observed.
The specific conductivities of complexes ( I ) are 1-2 x
R-' cm-' (0.25 M in T H F at -3O"C), and thus correspond
closely to the value quoted for LiC104 in T H F ; hence the
compounds are obviously largely ionic. Also in agreement
with this is the result of X-ray structure analysis, according
to
which
(la)
is
composed
of
separated
Li[(CH3)2NCH2CH2N(CH3)2]2cations and CH3Ni(C2H4)2
anions in the crystalline state.
Crystal data [ ( l a ) ] [ ' ] : a=10.022(2), b= 16.121(3),
c= 14.501(1)A; p=96.82(1)"; space group P21/n, Z = 4 ; 3395
reflections, 1694 of which are considered unobserved;
R = 0.069.
CT)
c3
- 2 COD
Fig. I . Crystal structure of the carbanion complex ( I a )
COD = 1 , 5 - ~ y ~ l 0 -
(lo),R = CH,
( I b ) , R = CzH,
( 1 ~ )R
. = CsH,
octadiene
-
['I
Dr. K. Jonas, Dr. K. R. Porschke, Dr. C . Kriiger [**I, and Dr. Y.-H.
Tsay [**I
Max-Planck-Institut Fir Kohlenforschung
Kaiser-Wilhelm-Platz 1, D-4330 Miilheim-Ruhr (Germany)
[**I X-ray structure analysis.
In (I a ) the two ethylene molecules together with the methyl
group are oriented exactly trigonal-planar about the nickel
atom (Fig. 1). The Ni-C1 o-bond with a value of 1.91 A
is unusually short16]. The short C=C bond lengths in the
ethylene indicate only weak bonding to the nickel. The two
diamine ligands surround the lithium cation tetrahedrally.
In the solid state the complex is one-dimensionally polymeric;
each lithium cation is situated equidistant between two NiCH3 units (Li-CI* 5.351 and 5.390A; Li-Ni* 5.777 and
5.800 8).
62 1
Experimental:
A mixture of
(COD),NiL4] (6.368, 23.1 mmol) and
N,N,N',N'-tetramethylethylenediamine
(20 ml) in ether (80 ml)
is saturated with ethylene at -20°C. A solution of LiCH3
(24mmol) in ether [from Hg(CH,), and Li in (C,H,),O] is
then added and the mixture stirred and allowed to warm
to room temperature. A clear, yellow solution is obtained.
On re-cooling to -60°C (1 a ) crystallizes out (yield 7.6g,
89 %). (1 a ) and ( I c ) are stable under argon at room temperature.
Received: June 8, 1976 [Z S14a IE]
German version: Angew. Chem. 88, 682 (1976)
CAS Registry numbers:
( l a ) , 60349-34-0; ( l b i , 60384-04-5; i l c ) . 60349-37-3; (COD),Ni, 1295-35-8
__
both complexes the spectra show only a narrow, slightly split
(evidently by 'P-coupling) signal at T = 7.7 for all 16 ethylene
protons, even at -80°C. Unlike ( l a ) , for ( Z b ) exchange
between complexed and added free ethylene is observed.
As displacement experiments have already shown, the bound
ethylene in ( I ) can be readily replaced quantitatively by other
olefins such as butadiene, as well as by carbon monoxide,
with complete retention of the anionic R2PNiz-moiety. Thus,
on reaction with C O the previously unknown carbonyl complexes (2) are formed, which are characterized by elemental
( I ) + 6 CO
-[
THF
- 78 "('
R
.~
[2] R . R. Schrock and G. G. Parrlioll, Chem. Rev. 76, 243 (1976).
[3] K . Joims, Angew. Chem. X8, 51 (1976); 87, 1109 (1975); Angew. Chem.
Int. Ed. Engl. 15, 47 (1976); 14, 752 (1975).
141 €3. BugduiiociC, M . K r i k r . and G . Wilke, Justus Liebigs Ann. Chem.
699, I (1966).
[S] For measuring and calculating techniques, cf. D. .I. B r u u u , C. Kruger,
P. J . Roberts, and E-H. 7 k J , Chem. Ber. 107, 3706 (1974).
[ h ] P. Biiiger. M . J . Doj'lr, C . Kriiger, and E-H. T\u)., Transition Met.
Chem.. in press.
= C,H11, vc0 i n T H F : 2030
(w),
2 0 0 6 ( s ) , 1 9 4 5 cm-' ( b r , v s )
[I] P . J . Duuidsori, M. F . Loppert, and R . Perirs, Chem. Rev. 76, 219 (1976).
(2b). R = C&5, vco i n T H F : 2039 ( s ) ,
2 0 1 9 ( s ) , 1 9 6 0 cm-' ( b r , vs)
analysis and IR spectra. Reaction of (C0D)zNi and LiPR,
in the molar ratio 1 : 1 with ethylene leads to formation of
the lithium phosphide-nickel(o) complex in which the phosphorus atom is bound to only one Nio(CZH4),group.
The Anion PR; as Single Bridge between Two Nickel(o)
Coordination Centers
By Klatis Jonas and Ludwig Schiejersteinp]
The previously known transition-metal complexes with
phosphido bridges contain almost without exception relatively
tightly bound groups such as CO, PR3 or q5-C5H5as further
ligandslll, thus making ligand exchange reactions relatively
difficult. The observation that treatment of organolithium
compounds with ethylene leads to formation of stable carbanion-nickel(0) complexesfz1gave us cause to investigate also
the reactivity of lithium diorganylphosphidestowards nickel(o)olefin complexes. In contrast to the carbanion, the anion
PR; should be able to bind two Ni"-olefin moieties via the
two donor orbitals of the phosphorus to give an ionic multimetal system ( I ) containing two neighboring nickel atoms
and easily displaceable olefin ligands.
R\ /R
/P\
(Olefin),Ni
Ni(O1efin)m
The specific conductivities of the complexes ( I ) and (3)
R - ' cm-' for ( 1 )
( 0 . 2 5 ~in T H F at -30°C) are ca.
and ca.
0-' cm-I for (3) in the series:
As expected the complexes ( I ) prove to be the stronger
electrolytes, since both donor orbitals of the phosphorus interact with Ni0(CzH4), groups and as a consequence there is
hardly any chance for interaction with the lithium cation.
The greater conductivity of ( 3 b ) compared to that of ( 3 a )
can be explained in terms of a higher stabilization of the
anion by the two phenyl groups bound to the phosphorus.
Whether the Li-P bond in (3 a ) can be utilized for introduction of other metal centers is at present under investigation.
Experimental:
We have found that reaction of (COD),NiI4I with LiPRZr3]
(Ni/LiPRz = 2 : 1 ) and ethylene leads to complexes of type
( I ) in high yields.
2 (C0D)ZNi
+ LiPRz +
THF
4 CzH4
- 30°C bis 0°C
( 1 ) + 4 COD
(lo), R = CsHII, n - D o n o r = T H F ,
O l e f i n = C2H4, m = 2
(Jb), R = CsH,, n - D o n o r = T H F ,
O l e f i n = CzH4, m = 2
A mixture of (COD),Ni[41 (2.75g, 10mmol) and
LiP(C6H11)2131
(1.02 g , 5 mmol) in tetrahydrofuran (20 ml) is
stirred at - 3 0 " 4 " C under ethylene until a clear solution is
obtained. After addition of diethyl ether ( I a ) crystallizes at
-8O0C(l6h)[yield3.25g(90%)]. ( I n ) and ( 3 a ) havelimited
stability at room temperature.
Received: June 8, 1976 [Z S14b IE]
German version: Angew. Chem. X X , 681 (1976)
CAS Registry numbers:
60349-40-8; ( 1 b J , 60372-85-2; ( 2 u J , 60349-42-0; 126). 60349-44-2;
COD = 1.5-cyclooctadienr
( 3 u ) , 60385-02-6: ( 3 6 ) . 60349-46-4: (COD),Ni, 1295-35-8: "P,
The novel compounds ( 1 a ) and (I b ) are characterized
by complete elemental analysis and 'H-NMR spectra. For
S . D. Rohiiison, MTP Int. Rev. Sci. Inorg. Chem. Ser. I, Vol. 6, 121
(1 972).
[2] K . Joiias, K . R. Porschke. C . Kvugrr and Y - H . Tsay, Angew. Chem. 88,
682 (1976): Angew. Chem. Int. Ed. Engl. 15, 621 (1976).
131 K . Issfeib and A . Tzschticli, Chem. Ber. 92. I 1 18 (1959).
~-
[*] Dr K Jonas and Dip1 -Chem L Schieferstein
Max-Planck-lnstitut fur Kohlenforschung
Kaiser-Wilhelm-Plat7 I , D-4330 Mulheim-Ruhr (Germany)
622
7723-14-0
[I]
[4] B. Bogrluiiori?, M. Kroner and G. Wilke, Justus Liebigs Ann. Chem.
699, I (1966).
Aiiyeii. Clieiii. I n i . Ell. Em]/.
&I/.
1.5 ( 1 9 7 6 ) N o . 10
Документ
Категория
Без категории
Просмотров
6
Размер файла
235 Кб
Теги
nickell, carbanion, complexes
1/--страниц
Пожаловаться на содержимое документа