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Dinuclear Nickel Complexes with Bridging Allyl Ligands.

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RR$'Nil-,NiZPRRi
.
.
. .
'.X"
Hydrosilylation of I with diphenylsilane, 2a, furnishes
4a in 80-8SY0 relative yield (total yield 30-40%; Table I ,
entries 1 and 2). Increasing or lowering the reaction temperature reduces the selectivity with respect to 4a in the
same way as addition of BF3.0Et2, which should catalyze
the Beckmann rearrangement (Entries 3-7). 4a is also obtained with dichloromethylsilane, 2b, on homogeneous catalysis with Zeise salt and on heterogeneous catalysis with
PtOz. H 2 0 (Entries 8-10).
Hence, the enantiomerically pure primary amine ( +)-4a
which, hitherto, has only been described in the form of a
4a/4b diastereomeric mixturei8' can be synthesized in one
step by catalytic hydrosilylation of (D)-camphor oxime.
Received: March 29, 1985 (Z I244 IE]
German version: Angew. Chem. 97 (1985) 713
[I] a) H. Brunner, R. Becker, Angew. Chem. 96(1984) 221; Angew. Chem. I n / .
Ed. Engl. 23 (1984) 222; b) H. Brunner, R. Becker, S. Gauder, Organometallies, in press.
(21 Work-up with metbanol/2Ouh aqueous hydrochloric acid, addition of
KOH in excess, extraction with ether, and purification by distillation
(5S0C/O.l torr).
131 A solution of the amine (100 mg) in 2 mL of tetrahydrofuran (THF) was
treated with 0.2 m L of trifluoroacetic anhydride. After 10 min, the mixture was neutralized with 3 mL of a Saturated NaHC03 solution. The amines were extracted with ether (1.5 mL). The ether phase was dried with
Na2C0,. GC: silicon phase Chirasil-L-Val@;glass capillary 25m, 1 10°C;
injector 230°C. Error 1%.
[4] 4a.HCI (enriched by recrystallization from ethyl acetate to 97%): 'HNMR (250 MHz, CDCI,, TMS): S=0.53 (s, 3H), 0.83 (d, 3H), 0.89 ( s ,
3H), 1.09-1.23 (m,2H), 1.47-1.56 (m, 3 H ) , 1.71-1.95 (m. 3H), 2.86-3.09
(m, 2 HI.
[5] 4a .HCI: "C-NMR (22.64 MHz, 20% solution in CDCI,, TMS, broadband decoupled): 6 = 13.7 (q), 14.4 (q), 25.6 (q), 27.8 (t), 28.7 (t), 30.1 (I),
39.7 (t), 42.5 ( s ) , 45.0 (d), 48.0 (d).
161 F. Tiemann, Chem. Ber. 29 (1896) 3006.
[7] H. Frank, G. J . Nicholson, E. Bayer, J . Chromalogr. 146 (1978) 197.
[S] G. Pirisino, F. Sparatore, Farmaco Ed. Sci. 2 7 (1972) 480; Chem. Abstr. 77
(1972) 61 286.
+
In the following communication a simple and versatile
entry to this special class of compounds is described:
Reaction of a 1 : 1 mixture of a triorganophosphane 7 and
a nickel(o)-complex 4 or 5 with an q3-allylnickel halide
complex 2 [Reactions (1) and (2), respectively (Scheme l)]
or of the bis(phosphane)ethylenenickel complex 6 with the
complex 3 [Reaction (3)] leads, via displacement of the
olefin ligands to formation of a crystallizable dinuclear
nickel compound of the type 1 in high yields. The liberated olefin can be removed under vacuum o r by recrystallization. Reaction (1) affords the best yields (ca. 80%)"] (Table 1). With exception of the PMe,-adduct la, these winered, dinuclear complexes 1 are stable under argon at room
temperat~re.'~]
[(113-C3H5)Ni(PRR'2)X]
1
(2)
Product
la
lb
Ib
X
PRRl
€ducts
Br
PMe,
P(W,
P(W3
P(c-C,H,
P(c-C,H, J1
P(c-COHI+
P(rBu)(rPr),
P(rPr),
2a,4,7a
2b,4,7b
2b. 5,7b
2c,4,7c
CI
CI
CI
CI
Br
Br
C,H,
3c, 6c
2d,4,7d
2e, 4,7e
21,4,7f
Reaction
Yield [%I]
82 la1
63
54
80
41 [a]
82
81
84
[a] Determined by NMR spectroscopy.
The great synthetic and catalytic potential of mononuclear q3-allylnickel-X compounds 2 (X = halogen, allyl,
H)['] and the increasing importance of multinuclear transition metal complexes in homogeneous catalysis attracted
interest in multinuclear Ni-complexes with bridging allyl
ligands (type 1). To my knowledge no such complexes
have, as yet, been documented, although unsuccessful attempts at their synthesis have been reported.l2]
['.I
Max-Planck-Institut fur Kohlenforschung
Kaiser-Wilhelm-Platz I, D-4330 Mulheim a. d. Ruhr (FRG)
AG
Postfach 10 1709, D-5600 Wuppertal I (FRG)
I wish to thank Professor G . Wilke for his participation in and support
of this work.
0 VCH VerlagvgerelI.~chaftmbH. 0-6940 Weinheim, 1985
+ 7
Table 1
If
By Rudolf Hanko*
Dedicated to Professor Giinther Wilke on the occasion
of his 60th birthday
704
(1)
Scheme 1. C D T = all-tranf- I,5,Y-cyclododecatriene; COD = cis.cic- 1,s-cyclooctadiene.
le
[**I
1
5
Id
1'1 New address: Bayer
-CDT-
7
4
2 + Nl(cod)z
IC
[*] Dr. R. Hanko
N i ( c d t ) + PRR'z
2
lc
Dinuclear Nickel Complexes with Bridging
Ally1 Ligands**
+
The nuclear resonance spectrai5] are reconcilable with
dinuclear structures. In each case, only one signal is to be
seen in the 3'P-NMR spectrum. In the I3C-NMR spectra".'] the signals of the carbon atoms bound to phosphorus can be interpreted as X-parts of ABX spin systems
(A,B= "P; X = ',C), from which a phosphorus-phosphorus coupling constant of ca. 25 Hz can be calculated for l b
and Id. According to the I3C-and 'H-NMR spectra the allyl groups are symmetrically bound. Particularly striking is
the upfield shift of the signal (6=32-38) of the meso-carbon atom of the halogen-bridged compounds compared to
that of the mononuclear analogues (e.g. 6=31.8 for l e
compared to 6 = 107.2[81for 2e). In the case of the bis(ally1)
compound If, the upfield shifts of the allyl carbon atoms
are less pronounced compared to those of the mononuclear starting complex (6= 87.1 (meso), 27.6 (terminal) for
If compared to 6= 112.2 (meso), 52.6 (terminal) for 2fl9]).
0570-0833/85/0808-0704 $ 02.50/0
Angew. Chem. I n t . Ed. Engl. 24 (1985) No. 8
From the "C-NMR spectrum of If, it follows that the ally1
groups are cis oriented. A structure with more than two
nickel atoms was ruled out in the case of If by spectra simulation.15'
The structure proposed for le on the basis of N M R
spectra was confirmed by an X-ray structure analysis,'lol
according to which the nickel atoms are separated at a distance typical for Ni-Ni bonds and are almost symmetrically bridged by an ally1 group and a halogen atom.
The catalytic properties of the new Ni complex of type 1
are presently being investigated.
Received: March 12, 1985:
revised: May 15, 1985 [ Z 1220 IE]
German version: Angew. Chem. 97 (1985) 707
C A S Regi5try numbers:
la, 97416-01-8: lb, 97416-02-9: Ic, 97416-03-0; ld, 97416-04-1; le, 9741605-2: If, 97416-06-3: Za, 97416-07-4: Zb, 97416-08-5: Zc, 97416-09-6: Zd,
47315-25-3: Ze, 97416-10.9; 2f, 97416-11-0; 3c, 12145-00-5: 4, 37246-55-2:
5, 1295-35-8: 6c, 41685-59-0; 7a, 594-09-2; 7b, 6476-36-4; 7c, 2622-14-2; 7d,
5 1567-05-6.
[ I ] P. W. Jolly, G. Wilke: The Organic Chemistry ofNickel. Academic Press.
New York 1974.
[2] H. Werner, Ado. Organomef. Chem. 19 (1981) 155.
131 Experimental: A solution of Ni(cdt) (362 mg, 1.64 mmol) in tetrahydrofuran (THF) ( I 0 mL) was treated with 240 pL (289 mg, 1.64 mmol) of
tert-hutyldiisopropylphosphane at -78°C under argon. and, after 10
min, further treated with a solution of 2e (599 mg, 1.69 mmol) in T H F
(10 mL). T h e reaction mixture was then stirred for 15 h at -78°C and,
finally for I h at 0°C. All volatile components were removed from the
purpli\h wine-red solution at 0°C by evaporation and the residue was
then dried at 5 x lo-' mbar and 20°C for 24 h. The oily crude product
was recrystallized from n-pentane/perfluorohexane. Yield: 760 mg
(819b). correct elemental analysis. l e : ' H - N M R (400 MHz, [DJbenzene,
27°C. "P-decoupled) 6=2.18 ( m ; 2 H , syn-allyl, 'J(2,3)=3.1,
'J(2,1)=7.8 Hz), 2.12 and 2.08 (each m ; 1 = 7 Hz, 4 H , PCH), 1.38 ( s ) ,
1.15 and 1.10 (each d : J = 7 Hz. 24H. PCHCH,), 1.24(s; IXH, PCCH,),
0.50 (dd: '1(3,2)=3.1, '5(3,1)= 12.3 Hz, 2 H , anti-allyl). The signal for
meso-ally1 is superposed.
[4] The elemental analyses are consistent with the empirical formula.
[S] NMR data collection, Max-Planck-lnstitut fur Kohlenforschung,
Kaiser-Wilhelm-Platz 1, D-4330 Miilheim a. d. Ruhr.
[6] I wish to thank Dr. R . Mynoit and his co-workers for recording and interpreting the "C-NMR spectra, and for valuable help and discussions
in elucidating the structure of I .
171 Typical "C-NMR data: Ib (75 MHz, [D,]toluene, -20°C): 6=34.8 (allyl-CH, J(PC)=5.9 Hz), 24.8 (PCH, 'J(PC)= 15.8, 1(P'C')=2.0 Hz), 21.9
(allyl-CHI. J(PC)+J(P'C)= 10.2 Hz), 20.5 and 20.0 (each CH3),
J(PP)=25.3 Hz, from analysis of the A B X spin system for PCH
(A,B="P), &(P)=51.3.
[8] R. Mynott, R. Hanko, unpublished.
[9] B. Henc. P. W. Jolly, R. Salz, G. Wilke, R. Benn, E. G. Hoffmann, R.
Mynott, G. Schroth, K. Seevogel, J. C. Sekutow$ki, C . Kriiger, J . Organomet. Chem 191 (1980) 425.
110)
Kruger. K. Angermund, R. Hanko, unpublished. Selected distances
[A]: Nil-Ni2 2.471(1), Nil-PI 2.167(2), Nil-CI 1.928(8), N i l L C 2
2.179(8). N i l - B r 2.324(1), Ni2-P2 2.172(2), Ni2-C3 1.926(8), Ni2-C2
2.197(8). Ni2-Br 2.333(1), CI-C2 1.40(1), C2-C3 1.43( I).
S.
Selective 'H, '"C-NOE Difference Spectroscopy
for the Elucidation of Structures
By Peter Bigler* and Matthias Karnber
Development of the modern technique of nuclear resonance spectroscopy has been so rapid in recent years that
the spectroscopist now has a wide 'spectrum' of informative methods at his disposal. We report here on a method
that has proven very useful in the solution of problems regarding structural configurations and conformations. Used
[*I
Dr. P. Bigler. Dr. M. Kamber
lnstitut fur Organische Chemie der Universitat
Freiestrassc 3, CH-3012 Bern (Switzerland)
Angn,.. Chmi. I n / . Ed. Enql. 24 (1Y85J N o . 8
in combination with other NMR methods it enables unequivocal interpretation of the mutual positions of molecular fragments. The nuclear Overhauser enhancement
(NOE) effect"] resorted to in our method has been exploited ever since the advent of "C-NMR spectroscopy. It
is responsible for the enhanced intensity of the I3C-NMR
signals in 'H broad-band decoupling. In the case of quaternary carbon atoms the total observed nuclear Overhauser effect is made u p of the individual contributions of
the protons in the immediate vicinity. The contributions of
the individual protons differs according to their relative
distances from the C-atom under observation. Selective
'H-irradiation, i.e. irradiation with the resonance frequency of these protons, allows these contributions to be
measured and, consequently, also the relationships to be
established that are important for structure elucidation. If
usually well separated ' H - N M R signals have been selected
for the irradiation, which severely limits the scope of the
method, then the technique proposed here[2-41can, similarly to modern homonuclear methods (Fig. I), be used
even when large signal overlapping occurs in the ' H - N M R
spectrum.
1 H J f;l :'2:'3:
\
'H broad-band decoupling
i!,' k
J"
Fig. I . Pulse scheme for the hetero-NOE experiment: During the NOE generation, the selected ' H - N M R frequencies f , to f, are rapidly irradiated one
after the other.
The high selectivity required for this, is achieved
through the selected 'H-NMR signals-more precisely associated I3C satellites-being irradiated one after the other
in rapid succession during the phase of the NOE generation with very small decoupler power. This also guaranties
high efficiency, in that the signals of several protons, e.g.
of a methylene group, with different chemical shifts, can
be concomitantly saturated and the sum of several NOE
contributions detected. The sensitivity of the method can
be further increased by ' H broad-band decoupling during
the detection phase and representation of the effects in the
form of difference spectra.
The NOE method has certain advantages over other
methods which enable the environment of quaternary carbon atoms to be explored, e.g. the recently reported CHshift correlation on the basis of long-range couplings:L51As
a 1 D experiment, the method is favored by a relatively
short measuring time. A knowledge of the coupling constants-in the case of geminal and vicinal C,H-couplings
there are often uncertainties-is not required.
We have used the method for investigating the isomeric
b-keto esters 1 and 2 (Fig. 2), which were formed during
the synthesis of a tetraquinacane derivative."] An NMR
spectroscopic investigation of the main components was
expected to allow differentiation of the two isomers and to
permit elucidation of the stereochemistry in the eightmembered ring (Fig. 3).
On the basis of signals which, due to their chemical shift
and their multiplet structure, must be assigned to the H
atoms on C6 and C8, the strongly overlapping signals of
the other eight-membered ring protons on C5 and C9
could be located by decoupling experiments. In a prelimi-
0 VCH Verlag.~ge.Fel~~chafr
mbH. 0 - 6 9 4 0
Weinheim. 1985
0570-083?i85/0808-0705 !$ 02.50i0
705
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