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Extreme 13C-NMR Data as Information on Organometal Radicals.

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Table I . Influence of added phosphanes on selectivity in the hydroformylation of I - and 2-pentene with H,/CO (1 : 1) in the presence of the catalysts ( I ) or (2).
No.
Catalyst
la1
Substrate
I
2
3
4
(1)
I-pentene
I-pentene
I-pentene
I-pentene
5
6
7
8
9
10
I1
I2
13
14
15
16
(1)
(1)
(1)
(1)
(1)
i 1)
11)
(1)
(11
(21
(21
(11
(1)
(1)
(1)
I-pentene
I-pentene
I-pentene
1 -pentene
I-pentene
I-pentene
1 -pentene
I-pentene
2-pentene
2-pentene
2-pentene
2-pentene
Phosphane
[a1
T
["CI
None
None
None
None
None
PPh,(2)
PPh2(4)
PPhZfCH2-fLPPh2
PPhlfCH2hPPh2
PPh2fCH2+PPh2
None
PPh,(2)
None
None
None
Ph2PfCH&PPh2
130
130
130
I30
150
150
150
150
150
150
150
150
130
130
150
150
Yield [%] [c]
Aldehydes
Alcohols
P [bl
[bar1
33.8-28.9
47.6-43.4
62.0-55.4
82.6-78.5
41.4
41.4
41.4
41.4
41.4
41.4
41.4
41.4
35.5-29.6
64.8-58.6
77.1-68.2
41.4
65.0
62.5
94.8
49.9
67.1
59.8
48.4
26.2
47 7
46.1
45.9
51.7
87.4
88.7
95.2
44.4
0
0
3.4
0
0
4.1
3.2
0
0
28.4
15
5.4
0
I .o
0
39.5
[hl
Selectivity
[dl
63.5
88.0
23.0
30.0
12.4
30.0
52.0
44.5
45.0
47.0
34.0
72.3
72.0
70.5
22.5
75.0
2.6
2.7
3.9
I .4
2.9
3.6
3.8
2.5
3.8
3.1
38
1.2
1.3
0.6
1.5
I
I .5
[a] Phosphane refers to the phosphane added to the catalyst solution. The number in brackets indicates the number of moles of phosphane per mol of ( I )or (2). All chelating phosphanes PhlP(CH2),PPhl were used in the ratio 1 mol per mol of (1) [i. e. P: ( I )= 2: 11. [b] Pressure range refers to initla1 and final pressures ( ? 5 ' X ) at the reaction
temperature. Those entries with one pressure were done under constant pressure during the entire reaction. [c] Yields are based on pentene consumed. Major products: hexanal (3). 2-methylpentanal (4) and 2-ethylbutanal (5). The amounts of pentane formed were 5 2 % in all cases. [d] Selectivity = ( 3 ) / ( ( 4 )+ (5)).
121 E. L. Mueirerties, Bull. Sac. Chim. Belg. 84, 959 (1975): 85,451 (1975); C. U.
tions conducted with a fourfold excess of PPh,. This behavPitimon, Jr., R. C. Ryan, Chemtech 1978, 170: A. L. Robinson, Science 194,
ior contrasts with that of Coz(CO)8-catalyzedreactions where
I150 (1976): E. L. Muefieriies, ibrd. 196, 839 (1977).
only [ C O ( C O ) ~ P Pcould
~ ~ ] ~be isolated when PPh3 was the
131 E. L. Mueilerlies. T N . Rhodin, E. Band. C. F Bmcker. W. R Preirer. Chem.
added ligand. Thus, cluster (1) could not have fragmented to
Rev. 79. 91 (1979).
HCo(CO), or H C O ( C O ) ~ P during
P ~ ~ the hydroformylation.
[41 a) T. J. Meyer, Prog. Inorg. Chem. 19, 1 (1975); h) M. Orrhin. W. Rupilius,
Catal. Rev. 6, 85 (1972); c) E. Cesaroiii. A. Fusr. R. Ugo. G. M . Zanderighr. J
Thirdly, the selectivity increased from 2.9 to 3.8 and the rate
Mol. Catal. 4, 205 (1978).
decreased (entries 6 and 8, Table 1) when PPh3 was replaced
I51 R. C. Ryon, C. U Pillman, Jr., J. P. OTonnor, J. Am. Chem. SOC.YY, 1986
by Ph,PCH,CH,PPh, as the ligand. This response of selec(1977).
tivity and rate is just the opposite of that observed for
161 R. C. Ryon, L. F. Doh/. 1 Am. Chem. SOC.97. 6904 (1975).
171 R. C. Ryan. J. P. O'Connor. C. U . Pirrman, Jr., unpublished.
C O ~ ( C Owhen
)~
PPh3 was replaced by Ph2PCH2CH2PPh2:
[8l E. R. Tucci, Ind. Eng. Chem. Prod. Res. Develop. 7. 32. 125. 227 (1968); Y,
there was a decrease in selectivity (from 1.9 to 1.3) and an in516 (1970).
crease in ratel']. Taken together, these results show that (1)
[91 L. H. Siaugh, R. D. Mullineaux, J. Organomet. Chem. 13, 469 (1968).
does not fragment to mononuclear species.
Despite the effect of PPh3 on selectivity and rate, when (2)
was used as the catalyst, only (I) could be recovered at the
Extreme I3C-NMR Data as Information on
end of sample reactions. Use of HPLC demonstrated that unOrganometal Radicals[**]
der hydroformylation conditions (145 "C, 68.9 bar) (2) was
rapidly converted into CO~(CO)~(JL~-CO)~(PP~~)(~~-PC~H~)~
By Frank H. Kohler, Karl-Heinz Doll, and Wo@am
and then into (I).
Prossdorf -1
Dedicated to Professor Helmut Behrens on the occasion
of his 65th birthday
Since both (1) and (2) contain two stable PPh bridges, they
cannot easily dissociate to mononuclear species. If such dissociation did occur, it is difficult to imagine how such fragments would be able to reassemble into (I) at 100-150°C
and 30-100 bar CO/H2. Our results do not rule out possible
fragmentation to (6) during the reaction, although the reconversion of (6) to (1) would require loss of two CO ligands.
Received October 8. 1979 [Z 479 IE]
German version: Angew Chem 92,494 (1980)
CAS Registry numbers:
( I ) ,58092-22-1; (2). 73804-98-5: I-Pentene, 109-67-1; 2-Pentene. 109-68-2; PPh3.
603-35-0,
Ph2P(CHl)lPPhl,
1663-45-2;
PhlP(CHL),PPhl,
6737-42-4
PhlP(CHZ),PPhl. 7688-25-7
111 C. U. Pitlmon, Jr., R. C. Ryon. Chemtech IY78, 170 A. L. Robinson, Science
194. 1 150 ( 1976): E. L. Muefleriies. ibid. 196. 839 ( I977
Angew. Chem. Int. Ed Engl 19 (1980) No. 6
The problem of numerous radicals failing to give any ESR
spectra has been resolved step by step in recent years, particularly regarding organometal radicals: at first by paramagnetic 'H- and later by I3C-NMR spectroscopy (cf. earlier
communications in this series). Unfortunately, however, the
applicability of I3C-NMR spectroscopy was hitherto greatly
restricted. Signals broader than ca. 500 Hz are routinely regarded as unobservable; the not very satisfactory results obtained by Kreilick et aI.[']with a spectrometer of special construction confirmed this view.
We have now obtained "C-NMR spectra of the partially
substituted nickelocenes (1)-(7)12], whose individual signals
have halfwidths >5000 Hz (signal groups > 20000 Hz) and
cover a range of > 2200 ppm. A typical example is shown in
Figure 1. Nickelocenes, for which we had predicted very
broad signals[31,are a special test case for the extension to
other types of compounds, since here very narrow and very
['I
Prof. Dr. F. H. Kohler, DlplLChem. K:H. Doll, Dr. W. Prossdorf
Anorganisch-chemisches Institut der Technischen Universitat Miinchen
Lichtenbergstr. 4, D-8046 Garching (Germany)
["I
NMR spectroscopy of paramagnetic complexes. Part 21.--Part 2 0 F H.
Kshler, Z . Naturforsch. B 35, 187 (1980).
0 Verlag Chemre, GmbH. 6940 Wernherm, 1980
0570-0833/80/0606-479
S 02 SO/O
479
151
'w
LI
Table I . 6("C) values [a] of the nickelocenes (1)-(6) at 298 K [b]: syntheses of
( 1 ) and f3)-f6): [Sbl. of 12): [9].
l
Cpd.
Icl
c-1
c-2/5
[dl
C-3/4
Id1
other C
-1356
- 1367
a
a
- 1368
3
(4)
(C5HS)?Ni
(CSDS)?Ni
(MeC5H&Ni
(EtCIH&Ni
- 1536
- 1518
-1446t2
- 1438t2
- 1510
- 1504
(5)
(nBuCSH&Ni
- 1532
- 1509
(1)
(2)
(3)
p
I
C-314 C-215
a
p
y
6
(6)
(tBuCSH4),Ni
- 1547
- 1470
-1332
a
p
I
-1600
-1200
-800
4 0 0 pprn
0
-400
Fig. 1 . "C-NMR spectrum of (nBuC<H&Ni (5) in C,H, at 77°C. A) Overview.
B) C-l to C-5 amplified; L solvent. C,, and C,, expanded.
635.9
600.3;
-506.0
599.3;
-571.5;
- 51.1;
- 18.6
522.8
-487.4
[a] Measured rel. to solvent [(1)-(4): tetrahydrofuran; (5) and (6). benzene]. calculated rel. to analogous ferrocene [6]; accuracy [ppm] (if not otherwise quoted):
C-l to C-5: t 10; other C: + I: downfield shift negative. [b] After recalculation
from the measuring temperatures according to the Curie law. [c] Concentration
[mol-Yo]: (1)= 15.5: (2)= 15.9. (3). 14). (6)= 15-25: (5)=47.4. [d] Proposed
assignment (cf. Text).
one, in substituted nickelocenes the other orbital determines
broad signals occur close to each other at the same time. As
Figures 1B and 1C show, the spectrum of ( ~ B u C ~ H pro~ ) ~ N ~ the transfer of unpaired electrons to the ligand. Hence, the
assignment of C-3/4 and C-2/5 (cf. Table 1) should also be
vides information on C-H coupling[41and the symmetry of
opposite to that in cobaltocenes[xl.
the five-membered ring. The poorly developed shoulder for
We have checked the accuracy with which such I3C-NMR
C-1 is clearly recognizable in the spectrum of (tBuC,H,),Ni
spectra are obtainabte with perdeuterated nickelocene. Table
(6) (Fig. 2). This spectrum also provides the long sought151
1 shows the very small difference of 8 ppm between the signals of (1) and (2), which to our knowledge is, nevertheless,
L
the largest I3C-NMR isotope shift observed so far. This value
falls neatly in line with our findings on other metalloC-314 C-215
cenes"].
Received: November 30. 1979 [Z 480 I€]
German version: Angew. Chem. 92, 487 (1980)
CAS Registry numbers
( I ) , 1271-28-9 (2). 51510-35-1; (3). 1293-95-4; (4). 31886-51-8; (5). 60064-87-1;
(6). 32964-16-2
97%
-1600
-1200
-800
-400
0
4 0 0 pprn
Fig. 2. "C-NMR spectra of(rBuC$H&Ni (6) in C,D, at 35, 77 and 97OC; C-1 to
C-5 amplified; V = impurity.
evidence for strong temperature dependence of the shifts and
halfwidths.
The I3C-NMR data of the nickelocenes investigated are
collected in Table 1.
According to these data the nickelocenes (1)-(6) are radicals, which, with two unpaired electrons, shift in particular
the signals of the five-membered ring C-atoms to an extreme,
characteristic region. The number and position of the signals
afford proof of structure just as easily as in the case of diamagnet; , molecules.
Surprisingly, the C-1 signal in the compounds (RC5H4)2Ni
[(3)-(6)] is shifted further than the rest of the five-membered ring signals. In analogy to c o b a l t ~ c e n e sthe
[ ~ ~opposite
~
was to be expected. It can be concluded, therefore, that the
unpaired electrons in both metallocenes are in e f gorbitals['"I,
but slight perturbation of the degeneration (by substitution
with R) leads to e & and e lg[7b1,each of which give opposite
signal splittings. In substituted cobaltocenes apparently the
480
@ Verlag Chemie, GmbH. tiV40 Weinheim, IY80
111 C. F. Halch. J. W. Neely, R. W. Kreilrck. J. Magn. Res. 16. 408 (1974).
[2] Spectrometer. Bruker CXP 200; typical parameters: frequency 50.3 MHz.
spectral width 125 and 166 kHz. pulse width 8 and 6 p.s, 32 K accumulations,
data collection time 44 min, data points 8 K (after zero point filling).
[3] F. H. Kdhler. Z. Naturforsch. B 29, 708 (1974).
[4] The signals of C,. and C,, are also observable as tripiets after using appropriate filter functions.
[S] a) We could not reproduce the preliminary results quoted in [Sb]: b) F. H.
Kohler. J. Organomet. Chem. 110. 235 (1976).
[6] F H. Kohler. G. Marsubayashi, J. Organomet. Chem. 96. 391 (1975): F. H.
Kohier. Z. Naturforsch. B 31, L151 (1976).
[7] a) M. Nussbaum. J. Voirlunder. Z. Naturforsch. A 20, 1417 (1965). b) Simplified. On going from (C,H,),M to (RC5H4),M with staggered conformation,
D5,, changes to Clh
[S] F. H. Kohler, J Organomet Chem. 160, 299 (1978).
191 F. H. Kohler. W. Prossdorf: J. Am. Chem. Sac. /OO,5970 (1978).
N-Isocyanoirninotriphenylphosphorane:Synthesis,
Coordination Chemistry, and Reactions at the
Metal" 'I
By Bernd Weinberger and Wolf Peter Fehlhammerl'l
Dedicated to Professor Helmut Behrens on the occasion
of his 65th birthday
Isodiazomethane (CNNH2) cannot be obtained as a pure
substance owing to its ready decomposition"'; it can however
[*] Prof. Dr. W. P. Fehlhammer, DipLChem. B. Weinberger
Institut fur Anorganische Chemie der Universitat Erlangen-Niirnberg
Egerlandstrasse 1. D-8520 Erlangen (Germany)
["I
Metal complexes of functional isocyanides. Part 4. This work was supported
by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.-Part 3: 121.
0570-0833/80/0606~4RO $ 02.50/0
Angew. Chem. Inr. Ed. Engl. 19 (1980) No. 6
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