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The First Diphosphaallyl System Coordinated to Two Metal Centers.

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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.(PF&,
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
CAS Registry numbers:
1, 112987-72-1; 2 , 1271-28-9; 3, 112987.80-1
R
/
P
3
Table I . Selected NMR and IR spectroscopic data for 3
"P-NMR (32.2 MHz, H3P04 ext., C,D,): 6 = - 125.8 ( s )
'H-NMR (90 MHz, TMS int., ChD6):6= 1.20 (s, 18 H ; 2 x p-tBu), 1.55 (s,
18 H: 2 x (J-IBu). 1.95 ( s , 18 H ; 2 x o-fBu), 5.05 ( s , 5 H ; CsHs), 6.22 (5, I H ;
CH). 7.31 (s, Z H ; 3/5-H), 7.34 ( s , 2 H ; 3/5-H)
"CI'HI-NMR (50.288 Mhz, CDzCI?): 6=30.66 (s, p-CCH,), 33.59 (5,
o-CCHI), 34.89 (s, o-CCH,), 34.43 (s, p-CCH,), 39.81 (s, o-CCH,), 40.39 (s,
(J-CCH~),63 27 (t. J(CP)= 12.8 Hz; CH), 91.45 ( s ; Cp), 122.97 (s, C 3 / 5 ) ,
123.32 (t. C3/5), 125.38 (br. s, CI), 150.66 ( s , C4), 154.87 (s, C2/6), 159.07
(t. C2/6), 195.0 (br., CO)
IR (KBr). i;(CO)= 1930, 1945, 2010 c m - '
According to an X-ray structure determination (Fig. l),I4]
the C ' atoms of the aryl moieties and the PCHP framework form a plane, which is typical for phosphaallyl systems.['] The q 3 coordination to the iron atom is confirmed
by the short distance to the allyl C atom (202.5 pm). The
lengths of the coordinative bonds to the nickel atom
(220 pm) correspond to those in other (phosphane)nickel
compIexesf6]
b
b
t i g I Stereoprojection of the molecular structure of 3 : 0 be, 8 N I , 8 P.
Important distances [pm] and angles I"]
(standard deviations in parentheses):
Fe-P 231.0(2)/230.7(2), Fe-C(allyl) 202.5(7), P-C(ally1) 176.0(7)/176.8(7),
Ni-P 219.4(2)/220.1(?); PCP 9l.l(3), PFeP 66.l(l), PNiP 69.9(1); dihedral
angle PCP/PNiP 35.1.
[ I ] a) 0. J. Scherer, Angew. Chem. 97 (1985) 905: Angew. Chem. I n t . Ed.
Engl. 24 (1985) 924; b) S. Holand, C. Charner, F. Mathey, J. Fischer, A.
Mitschler, J. Am. Chem. SOC.106 (1984) 826; c) R. Appel, C , Casser, F.
Knoch, J. Organomer. Chem. 253 (1985) 213; d) N. Hoa Tran Huy, J.
Fischer, F. Mathey, J. Am. Chem. Soc. 109 (1987) 3475.
121 a) F. Mercier, J. Fischer, F. Mathey, Angew. Chem. 98 (1986) 347; Angew
Chem. Int. Ed. Engl. 25 (1986) 357; b) J. F. Nixon, Xth Int. Conf: Phosphorus Chem. (Bonn, 1986), lecture 8-48.
[3] R. Appel, W. Schuhn, J. Organornet. Chem. 325 (1987) 179.
[4] 3 : black crystals from toluene, crystal dimensions 0. 15 x 0.2 x 0.4 mm'.
Monoclinic, space group
P2,/n,
a = 949.9(5), b = 2650.8(23),
c = 1816.1(9) pm, 8=90.68(4)", V=4.573 nm', 2 = 4 , P ' . , , ~ ~ =1.2Og cm-':
p =0.83 m m - ' (Mo,,):
6631 measured, 5957 unique reflections
(28,,,=45"), 3710 reflections with IF1>4o(F) used in the structure solution (direct methods) and refinement (469 parameters), non-hydrogen
atoms anisotropic, H atoms (localized by difference electron density determination) refined with a riding model (allyl H atom freely refined,
=0.055, w - ' = ~ * ( F ) + 0 . 0 0 O 2 F 2 ) .Further details of the
R=0.063 (K,
crystal structure investigation are available on request from the Fachinformationszentrum Energie, Physik, Mathematik GmbH. D-75 14 Eggenstein-Leopoldshafen 2 (FRG), by quoting the depository number CSD52777, the names of the authors, and the journal citation.
[ 5 ] a) R. Appel, W. Schuhn, F. Knoch, Angew. Chem. 57 (1985) 421; Angew.
Chem. Inr. Ed. Engl. 24 (1985) 420; b) cf. 121: c) R Appel, W. Schuhn, F.
Knoch, J . Organornet. Chem. 319 (1987) 345.
[6] P. W. Jolly, G. Wilke: The Organic C h e m i . ~ oJNicke1.
y
Vol. 1. Academic
Press, New York 1974.
Weak Intramolecular Bonding Relationships:
The Conformation-Determining
Attractive Interaction between Gold(]) Centers**
By Hubert Schmidbaur, * Wilhelm GraA and
Gerhard Miiller
Structural analyses['. 21 and spectroscopic studies". 41 on
mono- and polynuclear gold( I) compounds have provided
a wealth of indirect evidence of a n attractive interaction
between the d lo-configurated gold atoms. This weak bonding relationship occurs perpendicular to the principle axis
of the linearly two coordinated structural moieties and
leads either to catenated or layered aggregation of the molecules via A u . . .Au contacts, some less than 3.0 A in
length, or to the intramolecular pairing of the gold atoms
with similar equilibrium distances. The 5d lo-Sd'" interaction concerned stems from a mixing of the 6s' states,"]
whose energy gap is reduced by relativistic effects.". In
the case of the neighboring element mercury these effects
are already less pronounced, so the phenomenon rarely occurs.1'1
We have searched for convincing evidence for these interactions and for a possibility of measuring their strengths
quantitatively. From the numerous structural data available['] there emerged astonishingly many striking indications of such interactions,['] yet proof thereof is so far still
lacking, even after specially planned tests.""' A new series
of experiments have now furnished the positive results reported here.
Experimental Procedure
A solution of 2 (0.40 g, 2.1 mmol) in T H F (50 mL) was added to a solution of
1 (1.46 g, 2 mmol) in T H F ( S O mL) at room temperature over 15 min. The
reaction mixture was allowed to stir for 6 h, then concentrated under vacuum
and extracted with 150 mL of pentane. After separation of the precipitate,
the filtrate was purified by column chromatography on AllOi (activity I, neutral, eluent toluene). Recrystallization from toluene/pentane (1 : 1) afforded
1.24g (75%) of 3: m.p.=232 "C.
Received: October 13, 1987 [Z 2473 IE]
German version: Angew Chem. 100 (1988) 437
Angev.. Chem
Int.
Ed Engl. 27 11988) No. 3
['I
Prof. Dr. H. Schmidbaur, DipLChem. W. Graf, Dr. G. Miiller ['I
Anorganisch-chemisches Institut der Technischen Universitat Miinchen
Lichtenbergstrasse 4, D-8046 Garching (FRG)
[ '1 X-ray structure analysis.
[**I
This work was supported by the Deutsche Forschungsgemeinschaft
(Leibniz program), by the Fonds der Chemischen Industrie, and by
Hoechst AG and Degussa AG. We thank Prof. Dr. F. E. Wagner. Physik-Department der Technischen Universitat Munchen, for the '"AuMossbauer spectrum, and Herr J . Riede for supplying the crystallographic data sets.
0 VCH VerlagsgeseIlschaJ? mbH. 0-6940 Weinherm. 1988
0570-0833/88/0303-0417 $ 02.50/0
4 17
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