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Electron-ElectronSpin-Spin Long-Range Interaction as Studied in the Diradical Dication [Di{bis(dimethylphosphino-6-benzene)chromium(I)}-nickel(0)].

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[I] E. Vogel, W. Haas, B. Knipp, J. Lex, H. Schmickler, Angew. Chem. 100
(1988) 445; Angew. Chem. Int Ed. Engl. 27 (1988) 406.
[21 F. Sondheimer, Pure Appl. Chem. 7 (1963) 363; H . Baumann, J. F. M.
0 t h . Helu. Chim. Acta 65 (1982) 1885: J . Bregman, F. L. Hirshfeld, D.
Rabinovich, G. M. J. Schmidt, Acta Crystallogr. 19 (1965) 227; F. L.
Hirshfeld, D. Rabinovich, rhid. 19 (1965) 235.
131 a) E. Vogel, M. Kocher, H. Schmickler, J. Lex, Angew. Chem. 98 (1986)
262. Angew. Chem lnt. Ed. Engl. 25 (1986) 257; b) E. Vogel, M. Balci,
K. Pramod, P. Koch, J. Lex, 0. Ermer, rbid. 99 (1987) 909 and 26 (1987)
928; c) E. Vogel, M. Kocher, M. Balci, I. Teichler, J. Lex, H. Schmickler,
0. Ermer, rhid. 99 (1987) 912 and 26 (1987) 931; d) B. Wehrle, H.-H.
Limbach, M. Kocher, 0. Ermer, E. Vogel, ibid. 99 (1987) 914 and 26
(1987) 934: e) P. F. Aramendia, R. W. Redmond, S. Nonell, W. Schuster,
S . E. Braslavsky, K. Schaffner, E. Vogel, Phorochem. Photobiol. 44 (1986)
5 5 5 ; f , H. Ofir, A. Regev, H. Levanon, E. Vogel, M. Kocher, M. Balci, J .
Phjs. Chem. 91 (1987) 2686.
141 Compare the loss of peripheral cyclic delocalization on going from
1,4:7,10: 13,16-trioxido[l8]annuleneto the corresponding trithia compound: G. M. Badger, J. A. Elix, G. E. Lewis, Aust. J. Chem. 18 (1965)
70; rbid. 19 (1966) 1221.
Electron-Electron/Spin-Spin Long-Range
Interaction as Studied in the Diradical Dication
[Di(bis(dimethyiphosphin~-~~-benzene)chromium(r)}nickel(o)]++**
By Christoph Elschenbroich, * Gottfried Heikenfeld,
Martin Wiinsch, Werner Massa, and Gerhard Baum
Facile change in the oxidation state and favorable ESR
properties make the (~f'-arene)~M(d~)'~]
unit a suitable
probe for the study of mixed valence and intermediate valence states as well as of electron-electronlspin-spin interaction. After considering the cases of rigid parallel orientation (e.g., l l']) and conformationally flexible orientation
(e.g., ZI4l), we focused our attention on oligonuclear sandwich compounds with orthogonally arranged moieties. A
tetrahedrally coordinated Ni atom lends itself well as a
spacer for the two orthogonal halves of the molecule.
-
[51 I n addition to tetraoxido[20]annulene 8 , small amounts of higher macrocyclic products can be isolated, but only hexaoxido[30]annulene has
been identified so far.
161 R. Grigg, J. A. Knight, M. V. Sargent, J . Chem. Soc. C 1966. 976.
[7] T. Mukaiyama, T. Sato, J. Hanna, Chem. Leu. 1973. 1041; J . E . McMurry, M. P. Fleming, J . Am. Chem Soc. 96 (1974) 4708; J . E. McMurry,
Acc. Chem. Res. 16 (1983) 405; D. Lenoir, Synthesis 1977, 553.
[8] G. Schroder, J. F. M. Oth, Tetrahedron Lett. 1966, 4083: B. W. Metcalf,
F. Sondheimer, J. Am. Chem. Soc 93 (1971) 6675; 1. C. Calder, F. Sondheimer, Chem. Commun. 1966,904.
[9] a) H. Ogawa, M. Kubo, 1. Tabushi, Tetrahedron Letr. 1973, 361; b) J . A.
Elix, Aust. J . Chem. 22 (1969) 1951: c j D. Tanner, 0. Wennerstrom, E.
Vogel, Tetrahedron Lett. 23 (1982) 1221; d) E. Vogel, U. Kiirschner, H.
Schmickler, J. Lex, 0. Wennerstrom, D. Tanner, U. Norinder, C. Kruger, ibid. 26 (1985) 3087; e) see also E. Vogel, 8 . Neumann, W. Klug, H.
Schmickler, J. Lex, Angew. Chem. 97(1985) 1044; Angew. Chem. Int. Ed.
Engl. 24 (1985) 1046.
[ 101 C z a H , 2 0 4 ,m.p. = 270-27 I "C, crystals from ether/hexane; monoclinic,
space group P2,/c, Z = 2 ; a=9.926(2), b=4.855(1), c = 15.507(3)
I = 106.17(2)"; pcdlcd=
1.464 g cm313;intensities measured on a four-
A,
circle diffractometer [room temperature, &, = 0.71069 A, B,,,(max) =
27'1; refinement (C, 0 anisotropic, H isotropic) using 1369 reflections
with Fo>4n(F,,);R=0.045, R,, =0.048 1171.
[ I I] W. von E. Doering, L. H. Knox, J. Am. Chem. So;. 76 (1954) 3203.
[I21 5 is unstable in nonacidic aqueous medium, since, as oxonium ion, it is
subject to rapid nucleophilic attack by the solvent. The possibility of
making 5 resistant to water by the introduction of alkyl substituents is
being investigated. Cf. the stabilization of the pyrylium ion by 2,4,6trialkyl substitution: G. P. Ellis in A. R. Katritzky, C. W. Rees (Eds.):
Comprehensive Heterocyclic Chemistry, Vol. 3, Pergamon Press, Oxford
1984, p. 652.
[13] M. J. Broadhurst, R. Grigg, A. W. Johnson, J . Chem. Soc. C 1971, 3681:
A. W. Johnson in K. M. Smith (Ed.): Porphyrins and Metalloporphyrins.
Elsevier, Amsterdam 1975, p. 729. We will describe elsewhere dioxaporphycenes (as salts), which are obtainable from the corresponding
bridged [2O]annulenes by two-electron oxidation.
[I41 H.-0. Kalinowski, S . Berger, S. Braun: "C-NMR-Spektroskopie, Thieme,
Stuttgart 1984, p. 88; see also B. Eliasson, U. Edlund, K. Miillen, J .
Chem Soc. Perkin Trans. 2 1986, 937.
1151 The hydrogen dinitrate ion takes on two distinctly different configura-
tions in the crystal. The configuration observed for 5b, containing coplanar nitrate groups linked by a short hydrogen bond, has precedence
in the structure of tetraphenylarsonium hydrogen dinitrate (B. D. Faithful, s. C. Wallwork, Chem. Commun 1967, 121 I), but this appears to be
an exception. In most cases, a configuration is present in which four
oxygen atoms of two nitrate groups form a distorted tetrahedron around
the bridging hydrogen atom: J. Roziere, M.-T. Roziere-Bories, J . M. Williams, Inorg. Chem I S (1976) 2490, and other examples listed there.
1161 CZ,H,,N,O,,, dec. above 270"C, crystals from 6 5 % HNO,; triclinic,
space group P i , Z = I : a=8.097(2), b=8.707(2), c=9.365(2)A,
1.638 g
conditions
0=73.18(2),P=89.81(2), y=66.32(2)"; pLIllCil=
of measurement as for 8. refinement ( C , N, 0 anisotropic, H isotropic)
using 1889 reflections with F,!>4u(FCJ; R=0.032, R.,=0.044 [17].
[I71 Further details of the crystal structure investigations may be obtained
from the Fachinformationszentrum Energie, Physik, Mathematik
GmbH, D-75 14 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD-52871, the names of the authors, and the journal
citation.
4 14
0 VCH Verlagsgesellschaji mhH.
0-6940 Weinheim. 1988
I
I
Cr
Cr
1
-PPh,
w
I
3
-
I
V
2
I
I
Cr
P P
I
V
Cr
h
2
4
In continuation of earlier work (3ls1),
we have now synthesized the "organometallic diphos ligand" bis(dimethy1phosphino-$-benzene)chromiurn 6 and allowed it to react
with bis( 1,5-cyclooctadiene)nickel to obtain the title compound 7 (Scheme 1).
The air-sensitive dimethylphosphino derivatives 5 and 6
are also labile towards hydrolysis; they are rapidly dephosphinylated in THF/S% H 2 0 , especially at the complex cation stage. The C-P bond in the bis(che1ate) complex 7 as well as in the Ni(CO)* adduct 8, synthesized for
comparison, is more inert. Figure 1 shows the molecular
structure of 7.") Physical data are collected in Table 1.
The structural features of both the NIL, and (tf-arene)$3 units are largely retained upon formation of 7.
The methyl groups of the PMe2 bridges assume axial and
equatorial positions with respect to the plane of the arene;
overall, the "ligands" 6 coordinate to Ni to produce the
meso form. The axes of the two sandwich moieties lie mutually perpendjcular and the distance between their central
atoms is 8.49 A. The eclipsed arrangement of the benzene
rings and the C-P-Ni bond angle, however, result in the
three central atoms Cr, Ni, and Cr being non-colinear. In
solution, 7 is conformationally flexible; only one 'H['I Prof. Dr. C. Elschenbroich, Dr. G. Heikenfeld,
DiplLChem. M. Wiinsch, Priv.-Doz. Dr. W. Massa, G. Baum
Fachbereich Chemie der Universitat
Hans-Meerwein-Strasse, D-3550 Marburg (FRG)
[**I Metal TZ Complexes of Benzene Derivatives, Part 31. This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen 1ndustrie.- Part 30: 111.
0570-0833/88/n303-0414 $ 02.50/0
Angew. Chem. I n t . Ed. Engl. 27 (1988) No. 3
Table I . Physical data for the new compounds 5-8. 'H-NMR, 400 MHz;
"C-NMR, 100.6 MHz: MS (electron-impact ionization), 70 eV; ESR, X
band.
5 : m.p.=69-7l0C: MS: m / z 268 (23.9, S"), 190 (79.7, LCrO), 175 (7.2.
HKPC6H5Cra), 138 (20.5, Le), 123 (18.6, CbH5PCHY),78 (25.6, CaHf), 77
(9.1. C , H % 52 (100, "CrO), L=C6H5P(CH&; 'H-NMR (C,D,): 6= 1.06 (d,
H M ~'J(H,
.
P)=3.6 Hz), 4.12 (m, H,,), 4.16 (m, H,,,. H118,j. 4.42 (m, H,,); "CNMR (C,D,): 6 s 18.3 (CM~,
'J(C, P)= 14.4 Hz, 'J(C, H)= 128 Hz), 74.3 (C,,,
J(C, P)<Z Hz, ' J ( C ,H)= 162 Hzj, 75.3 (C,,,, J(C, P ) = 4 Hz, ' J ( C , H)= 167
Hz), 77.1 (C,,, J ( C , P j = 19.1 Hz, 'J(C, H)= 166 Hz), 86.2 (C ,,,,,,, J(C. P)= 13.4
Hz), 75.9 (C,,.,,,, 'J(C, H ) = 167 Hz); "PI'HJ-NMR (C,D,): 6- -42.2; ESR
(5",THF,
+ 2 5 a n d -14OoC):(g)=1.9863,a(ll ' H ) = 3 . 2 9 G , a ( " P ) ~ 0 . 5 5
G, a("Cr)= 17.8 G, g. = 1.9764, gll=2.0087, A,,('H)=3.75 G, A,('H)=2.96
G, AL(5'Cr)=24.6 G ; cyclic voltammetry (DME, TBAP 0.1 M, 20°C versus
SCE): E,,l(5/500)= - 0 6 2 V, reversible.
7
Scheme 1. a) nBuLi, TMEDA, cyclohexane, S O T , I h; b) MelPPMe2 in cyclohexane, 0 ° C 1 h, then 20°C. 24 h ; chromatography o n silylated silica: 5
golden yellow flakes (38%), 6 brown needles (40%) from petroleum ether; c)
( 1,5-cyclooctadiene)zNi,toluene, 2 0 ° C 2d: 7 brown crystals (13%) from toluene/petroleum ether; d) two-phase system toluene, KPFJH20 (OZ-free),
and 4-pyridinecarbaldehyde 161, O T , 10 min, precipitation: 7(PF& brown
powder (quantitative); e) Ni(CO),, toluene, 20% 3d; chromatography on
AI20, (active, neutral): 8 brownish yellow needles (42%) from toluene/petroleum ether.
6: m.p.=65-67'C, MS: m/z 328 (32.0, 6'), 190 (100, 6--L), 175 (7.1.
H,CPC6HSCra), 138 (24.2, La), 123 (16.0, C,HSPCH?), 78 (19.6, C6Hf), 52
(96.0, "Cr'),
L=CbHrP(CH3)?: 'H-NMR (C,D,). 6= 1 13 (d, H,,,
J ( H , P)=3.5 Hz), 4.30 (m, H,,,,,,), 4.51 (m,H,,); "C-NMR (C,D6): 6= 15.3
( C M ~J, ( C , P)= 14.1 Hz, ' J ( C , H)= 127.8 Hz), 75.7 (C,,, J ( C , P ) < 2 Hz,
' J ( C , H)= 168.8 Hz), 76.6 (C,,,, J(C, P)=6.4 Hz, ' J ( C , H)= 166.5 Hz), 78.1
(C,,, J ( C , P)= 19.3 Hz, 'J(C, H)=169.4 Hz), 87.7 (C,,,,,, J ( C , P)= 17.7 Hz);
"PI'HI-NMR
(C6D,).
6=-42.6;
ESR (60°, THF, 25 and
- 140"C):(g)= 1.9865, a(10 'H)=3.23 G, a ( 2 3'P)50.55 G, a ( Y r ) = 17.7 G,
g L = 1.9780, g11=2.0027, A,(lH)=3.35 G, Al,('H)=3.00 C; cyclic voltammetry: E , , ? ( 6 / 6 Q ) = -0.57 V, reversible at 20°C.
7 : m.p.= 140°C ( d e c ) ; MS: m / z 714 (16.5, 7'). 386 (2.6, (6)Nia), 328 (27.3,
6'), 190 (63.9, 6-Lo), 138 (100.0, Lo), 123 (91.4, C,HsPCH$), 121 (69.7,
C7HhPa), 91 (44.5, C,H?), 58 (2.1, "Nil), 52 (62.3, 52Cr0),L=CaH,P(CH,)Z;
'H-NMR ([Dx]toluene:6= 1.48 [ s . HMJ, 4.17 (t, H,,, J(H,,, H,,,)=5.1 Hz), 4.22
(t. H,,,, J ( H ,,,, H,,)=J(H ,,,, H,,)=S.I Hz), 4.80 (m, H,,); "C-NMR ([Dxltoluene):6=23.9 (C,,, 'J(C, H ) = I27 Hr, "Ci'HJ: "quint," line separation 8 Hz
[131), 74.8 (C,,, 'J(C, H)= 166 Hz), 75.4 (C,,,, ' J ( C , H ) = 169 Hz), 78.7 (C,,,
'J(C, H ) = 164 Hz, "C{'H): "quint," line separation 3.8 Hz (13]), 98.9 (C,,,,,,
'3CI'HI: "quint," line separation 10 Hz 1131); "PI'HI-NMR (C,D,):
6 = - 11.1; ESR and cyclic voltammetry, see text.
8 : m.p.= 140OC (dec.). FDMS: m / z 442 (M=443.02): 'H-NMR (ChDh):
b'= 1.32 (d, HMc.J(H, P)=4.4 Hz), 4.14 (m, H,,,. p ) , 4.29 (m, H<)); "C-NMR
(C,D,): 6= 19.7 (C,,, ' J ( C , H)= 130 Hz): " C ( ' H ) - N M R : m, 6 lines, overall
width 42 Hr), 74.7 (C,,, 'J(C, H)==169 Hz; "CI'HJ-NMR: s), 77.2 (C,>$,
'J(C, H ) = 168 Hz; "CI'HI-NMR: "t," line separation 3 Hz), 79.7 (C,,,
' J ( C , H)= 165 Hz: "CI'HJ-NMR: m, 5 lines, overall width 40 Hz), 8 5 9
',C{'H)-NMR: m, 6 lines, overall width 47 Hz), 202 (CO, 'J(P, C ) = 5
Hz); "P{'H)-NMR (C,D,): 6= -3.9: ESR (8".
CH,OH, +25"C):
(g)= 1.9872, a(10 'H)=3.25 C, a("Cr)= 18.2 G, 8'" (CHIOH, - 140°C).
g11=2.0019,g L = 19794; cyclic voltammetry: E , 4 8 / 8 ' @ ) = -0.84 V, reversible, (20°C. DME, TBAP, 0.1 M, versus SCE).
Fig. I . Molecular structure of 7 (ORTEP). The thermal ellipsoids are drawn
at the 30% probability level. Atoms that are symmetrically equivalent with
respect to the C, axis are indicated by primes. Important interatomic distances [A] and angles ["I: Ni-P 2.146(1), Ni-P,, 2.151(1), P.Cmelhyl(mean)
1.839, P-CI 1.845(5), P,-CI, 1.844(4), Cr-C (mean) 2.144, Cr-ring center (2)
(mean) 1.617, C r ~ N 4.319;
i
Cr-Cr' 8.490; Cr-Ni-Cr' 150.4, P-Ni-P,, \03.0(1),
P - N i - P l16.9(1), P,-Ni-P: 107.5(1), P'c-Ni-P' Il3.2(1), Ni-P-Cl l18.9(2)
Ni-P,,-CI,, I19.2(2), 2-Cr-Z,, 177.6(4), angle between the sandwich axes 84.5.
7=[(6)?Ni]
+20"C:
-25°C:
- 2CC'
I
Angew. Chem- Inr. Ed. Engl. 27 (1988) No. 3
mvs-'):
' [(6"o)2Ni]'0
' [(6°0)2Ni]2e
E ; n = -0.70V
E1/2= -0.73 V
NMR signal is observed for the methyl groups in the range
- 80°C < T < + 40°C.
The redox behavior of 7 was investigated by cyclic
volt-ammetry (Fig. 2c). It is characterized by three
electron-transfer steps, the first and second of which
( E iI2 = - 0.70 V, E = - 0.52 V) are reversible in dimethoxyethane (DME) at room temperature. The third step
(E:,,= -0.16 V) becomes reversible only at T < -25°C
:/,
and v > 100 mVs-'. Comparison of the peak currents for
samples of known concentration of 7 using 6 as standard
indicates that E ;, is associated with the transfer of two
electrons. Thus, the following assignment accrues (in
DME, (nBu),NCIO, (TBAP), at a glassy carbon electrode
versus the saturated calomel electrode (SCE), u= 100
E?/z= -0.52 V
Ef,q = - 0.55 V
-e"
>
[(6°0)2Ni]40
E;,= -0.12 V(irrev.)
E:,,= -0.16 V(rev.)
The potentials
and E:/2 are similar to those of the
mononuclear complex bis(dipheny1phosphinoethane)nickE ; , , is shifted cathodically in comparison to the
value observed for the free ligand 6 ( E , / 2 =-0.57 V, reversible at 25°C). The shape of the signal and the peak current of the first wave indicate that no electrochemically
measurable interaction exists between the two redox centers of the sandwich moieties; that is, electron transfer at
0 VCH VerIagsgeselischaft mbH. 0-6940 Weinheim, 1988
0570-0833/88/0303-04Is $ 02.50/0
4 15
I
' I
'
I
168 7
,"T
!
I /
3343 I
mT
I
Fig. 2. a) ESR spectrum (2nd derivative) of 7(PF,)* in dimethylformamide
(I)MF)/chloroform (I:I),T=25"C. b) ESR spectrum of 7(PF& in glassy
solution, DMF/CHCII ( I : I), 7'= - 160°C; * not identified. c) Cyclic voltammogram of 7 in DME/TBAP (0.1 M), 20°C, at the glassy carbon electrode
versus SCE, r=50 m V s - ' .
the two centers occurs independently and in a purely statistical fashion.['l
The first redox step 7 - t 7 2 0 can also be realized on a
preparative scale if the dication, once formed, is precipitated from solution as the hexafluorophosphate, thus preventing further attack by the oxidizing agent (see Scheme
1); O2 or-preferentially-4-pyridinecarbaldehyde
are
suitable as oxidants.l6I From the ESR spectra of 7(PF& in
fluid solution, hyperfine coupling constants a( 10 'Ha,,,,)
and a ( ] "Cr) can be derived. The multiplicity and the
magnitude of these hyperfine splittings, which largely correspond to those of the monoradical cation 8'@, indicate
that, for the diradical dication 7" the exchange interaction J is much smaller than the hyperfine interactions
a ( ' H ) and u ( ~ ~ CThus,
~ ) . in fluid solution, the ESR line
width for 7 + is only slightly increased compared with
8'". This behavior is in accord with the presence of two
singly occupied, ophogonal, Cr(3dZz)orbitals centered at a
distance of 8.49 A. A sensitive means of detecting longrange electron-electron/spin-spin interaction is provided
by the classical dipole-dipole coupling, which is manifested most clearly in the appearance of a "half-field sig(Fig. 2b). In accordance
nal" (AM, = 2) in glassy solutionsfio1
with the large separation of the two unpaired electrons
in 7 f?, the intensity of the half-field signal is only ca.
that of the main-field signal.["' From the latter may be
derived-and confirmed by spectral simulation"21- the
zero-field splitting parameters D = 2.7 x
cm- I,
E=0.67 x lo-' c m - ', which, according to the equation
r=(0.650 g 2 / 0 ) " 3 [A],"Obl in turn, give an average interspin
distance r and thus a Cr. . .Cr distance of 9.91 A. In order
to account for the only moderate agreement of this value
with the results of the X-ray structure analysis, we are attempting to replace Ni in 7 by other bridging metal
atoms.
Received: August 25, 1987;
revised: November 11, 1987 [Z 2414 IE]
German version: Angew. Chem. 100 (1988) 397
CAS Registry numbers:
4, 1271-54-1; 5, 113008-25-6; 6, 113008-26-7; 7, 112988-51-9; 7 . ( P F &
113034-67-6: 8, 112988-52-0; Ni(CO),, 13463-39-3; Ni (cod)*. 1295-35-8.
4 16
0 C'CH Verlagsyerell~chaflm b H . 0-6940 Weinherm, 1988
C. Elschenbroich, J. Schneider, M. Wbnsch, J . ~ L .Pierre, P. Hare!, P.
Chautemps, Chem. Ber. 121 (1988) 177.
C. Elschenbroich, R. Mockel, U Zenneck, D. W. Clack, Brr. Bunsenge.s.
Phys. Chem. 83 (1979) 1008.
C. Elschenbroich, J Heck, J Am. Chem. Soc. 1 0 1 (1979) 6773.
C . Elschenbroich, J. Heck, Angew. Chem. 93 (1981) 278; Angen. Chum.
Inr. Ed. Engl. 20 (198 I ) 267.
C. Elschenbroich, F. Stohler, Anqew. Chem. 8 7 (1975) 198: Angew.
Chem. Int. Ed. Engl. 14 (1975) 174.
4-Pyridinecarbaldehyde has proved to be a mild, homogeneous oneelectron oxidant for the generation of organometallic radical cations
which contributes no signal of its own to the ESR spectrum.
CJ2H44P4CrZNir
space group P 2 , 2 , 2 , , 2 = 2 , a = 15.185(6). h=9.562(5),
c = I1.260(7) A; 2765 unique reflections with F , , > 3 a : four-circle diffractometer (CAD4, Enraf-Nonius), MoKo radiation, 295 K ; no absorption
correction @ = 13.6 cm-'), H atoms refined with istropic temperature
factors. 265 parameters, R,. =0.036 (weighting i v = I/a '(fi,)).Further details of the crystal structure investigation may be obtained from the
Fachinformationszentrum Energie, Physik, Mathernatik GmbH, D-75 14
Eggenstein-Leopoldshafen2 (FRG). on quoting the depository number
CSD-52822, the names of the authors, and the journal citation.
a) M. Martelli, G. Pilloni, G. Zotti, S. Daolio, Inorg. Chim. Acra I 1
(1974) 155; b) G. Gontempelli, F. Magno,G. Schiavon, B. Corain, Inorg.
Chem. 20 (1981) 2579.
a) F. Ammar, J. M. Saveant, J . Electroanal. Chem. 47 (1973) 2 15; h) J. B.
Flanagan, S. Margel, A. J. Bard, F. C. Anson, J. Am. Chem. Soc. 100
(1978) 4248; c) A. J. Bard, 1.Faulkner: Electrochemical Methods, Wiley
New York 1980, p. 232.
a) S . P. McGlynn, T. Azumi, M. Kinoshita: Molecular Specrroscopi o/ the
Triplet State. Prentice Hall, Englewood Cliffs 1969: b) N. D. Chasteen.
R. L. Belford, Inorg. Chem. 9 (1970) 169.
S. S. Eaton, G. R. Eaton, J. Am. Chem. Soc. 104 (1982) 5002; S. S. Eaton.
K. M. More, 8. M. Sawant, G. R. Eaton, ibrd. 105 (1983) 650.
Simulation program POWDER, C. Daul, B. Mohos, c' W. SchlZpfer,
Universitat Fribourg, Switzerland.
C atoms bonded to P in metal complexes containing cis phosphane ligands can give rise to five-line multiplets in the "C-NMR spectrum if
'J(P, P ) is small. (I). A. Redfield, L. W. Cary, J. H Nelson. Inorg
Chem. 14 (1975) 50).
The First Diphosphaallyl System Coordinated to
Two Metal Centers**
By RolfAppel.* Winfried Schuhn, and Martin Nieyer
The complexation of transition-metal complex fragments to compounds in which phosphorus is involved in
multiple bonding has been intensively investigated in recent years. Both terminal (q') coordination, as found for
phosphanes, and side-on (q') coordination, as found for
alkenes and alkynes, have been observed. Combination of
both types of bonding has also been described."' The two
modes of coordination of phosphaallyl compounds (q3
and q') have so far only been realized with the I-phosphaallyl system.['!
We have now obtained the first diphosphaallyl complex
in which, in addition to the q3 coordination of the tricarbonyliron fragment via the lone pairs of the two phosphorus
atoms, a further metal atom is bonded. Reaction of the sodium [(diphosphaallyl)ferrate] l l3] with nickelocene 2 in
T H F at room temperature results in cleavage of cyclopentadienylsodium and formation of a black-brown solution
of 3. Chromatographic workup of this solution afforded
black crystals of 3.
Elemental analysis, IR and NMR spectroscopic data
(Table I), and the mass spectrum are in agreement with the
structure given. Particularly characteristic is the singlet for
the two phosphorus atoms in the 3iP-NMR spectrum at
high field.
[*] Prof. Dr. R. Appel, W. Schuhn, M. Nieger
Anorganisch-chemisches lnstitut der Universitdt
Gerhard-Domagk-Strasse I. D-5300 Bonn I (FRG)
[**I Low-Coordinate Phosphorus Compounds, Part 63.-Part 62: R. Appel,
J. Kochta, V. Winkhaus, Chem. Ber., in press.
0570-0833/88/0303-0416 $ #2.50/0
Angew. Chem. lnr. Ed. Engl 27 (1988) N o . 3
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nickell, spina, long, ranger, electro, dication, chromium, diradical, dimethylphosphino, interactiv, electronspin, bis, studies, benzenes
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