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Heterometallic Dinuclear Complexes by Ethene Displacement with Grignard Compounds or Diorganomagnesium Compounds.

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Fig. I . Model of a ( M , ? ) , ?cluster showing
the interplanar spacings d ’ (3.24 b, for Rh/
R u and 3.5 b. f t r Au) and d’ (6.1 1 b. for
KhiRu and, 6.8 A for Au).
place irreversibly between 400 and 500”C, during which
temperature range the superstructures are presumably destroyed. A great disadvantage regarding investigation of
the physical properties of the new metal modifications is
that they are formed in admixture with the normal metal.
Received: June 19, 1986;
supplemented: July 1986 [Z 1824 IE]
German version: Angew. Chem. 98 (1986) 910
[l] G. Schmid, Struct. Bonding (Berlin) 62 (1985) 51.
121 M. N. Vorgaftik, V. P. Zagorodnikov, 1. P. Stolyarow, 1. 1. Moiseev, V. A.
Likholobov, D. 1. Kochubey, A. L. Chuvilin, V. 1. Zaikovsky, K. I. Zamaraev, G. I. Timofeeva, J . Chem. Soc. Chem. Commun. 1985. 937.
[3] M. R. Hoare, P. Pal, J . Cryst. Growth 17 (1972) 77.
[4] M. R. Hoare, P. Pal, Nature 236 (1972) 35.
[S] G. Schmid, R. Pfeil, R. Boese, F. Bandermann, S. Meyer, G. H. M. Calls,
J. W. A. van der Velden, Chem. Ber. 114 (1981) 3634.
161 G . Schmid, U. Giebel, W. Huster, A. Schwenk, Inorg. Chim. Aclu 85
(1984) 97.
[7] G. Schmid, W. Huster, 2. Naturforsch. 8 4 1 (1986) 1028.
[S] Elemental analysis of vacuum-dried precipitates show metal contents of
between 95 and 99%. Preliminary D M C measurements indicate that
traces of methylene chloride, water, or phosphanes are set free upon heating; these are apparently only loosely enclosed in the metal skeleton.
Heterometallic Dinuclear Complexes by Ethene
Displacement with Grignard Compounds or
Diorganomagnesium Compounds**
By Klaus Jonas,* Gerd Koepe, and Carl Kriiger
tig. 2. Left- Model of a
cluster ( n = 13) along a sixfold symmetry
axis: right. motel of a [(M,j),J, cluster ( n = 13), showing the interplanar
spacing d (15.3 A for R h i R u and 16.8 b, for Au).
Figure 3 shows a scanning electron (SEM) photomicrograph of [ ( R u ~ ~ crystallites
) ~ ~ ] ~ and Ru,, the latter of
which appears amorphous. Platelet- and column-shaped
crystallites of hexagonal morphology are indicated by arrows. The formation of hexagonal faces upon coupling of
the (Mi3),3clusters as in Figure 2a is understandable. Crystallites of hexagonal morphology are also detectable by
S E M in the case of gold and rhodium.
Preliminary DMC (differential microcalorimetry) measurernents on [ ( A U ~ ~ show
) , ~ ] that
phase-transitions take
Cyclopentadienylbis(ethene)cobalt 1 ,[‘I a preparatively
useful starting material which is a source of the synthetically versatile CpCo m ~ i e t y , ~reacts
l - ~ ~ with phenyllithium
with liberation of ethene to give the CpCo-complex salt 2
On the other hand, when 1 is treated with allyllithium, it reacts as one would expect of an ethenecobalt(r) halide: the C p ligand is smoothly replaced by an
ally1 group to form the lithium-cobalt compound 3a. This
ethene complex contains two n-ally1 groups coordinated to
cobalt and can be converted into the N.N,N’,N‘-tetramethylethylenediamine (TMEDA) complex 3b [Eq. (b)].1’.5.h1
L C n H c . --C:Ha
[Lj(tmeda)21[C~Co(C2H,)ChH51 (a)
ZLrC,H?. € 1 ~ 0
-LLIcp. -cC2Ha
’ Li[(C,Hs)~Co(C2HdI
We have now found that the partial or complete removal
of the ethene ligands in 1 can also be achieved with diorganomagnesium compounds [Eq. (c) and (d)], and that
even Grignard compounds are reactive enough for this
purpose [Eq. (e) and (f)]. A common feature of reactions
(c)-(9 is that, unlike in reaction (b), the C p group remains
bonded to
Reaction of 1 with Mg(C,H,), in tetra[*] Prof. Dr. K. Jonas, DiplLChem. G. Koepe, Prof. Dr. C. Kriiger [’]
Max-Planck-lnstitut fiir Kohlenforschung
Kaiser-Wilhelm-Platz 1, D-4330 Miilheim a. d. Ruhr (FRG)
big 3 S l M photograph of [(Ku,,),,],, crystallites mixed with Ku,.
rows indicate particularly well formed six-membered ring faces.
Angew. Chem. Inr. Ed. Engl 25 (1986) No. 10
The ar-
Crystal structure analysis.
We thank Priv.-Doz. Dr. R . Benn and Dr. R Mynoll for the NMR spectra.
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hydrofuran (THF) leads to formation of 4 [Eq. (c)], while
reaction of 1 with Mg(C3HS), leads to the ethene-free
MgCo dinuclear complex 5 [(Eq. (d)]. 5 contains two different allyl ligands, one of which is n-coordinated while
the other is o-coordinated to the magnesium and shows
dynamic behavior.['I Attempts to synthesize trinuclear
complexes by coupling two CpCo moieties to Mg(C,H,),
or Mg(C,H& failed: for example, upon reaction of 1 with
Mg(C,Hi), in the molar ratio 2 : I , only one equivalent of
L'lhL~ll<, I\
ation of ether~e['~-that it contains a TMEDA-modified,
complete Grignard compound in the coordination sphere
of a transition metal atom (Fig. I). The central cobalt atom
in 6 b is coordinated in an almost pseudo-tetrahedral fashion: ethene and the C p ring each occupy a coordination
site, while the other two coordination sites are occupied by
magnesium and the carbanionic phenyl group. The phenyl
group is o-bonded to the cobalt atom and its ring plane is
so oriented that, in addition to formation of a Co-Mg
bond (2.565(3) A), an ion pair interaction with tpe magnesium atom is also possible (Mg-C8 2.572(9) A)."'] The
presence of a Co-Mg bond is consistent with the finding
that cobalt-containing 18e half-sandwich complexes such
A S [CpCo(CO),] and [CpCo(PMe& have basic metal centers available and therefore can react with metal halides,
for example HgCI,, ZnCl,, to give 1 : 1 adducts such as
[ C ~ C O ( C O ) ~ H ~ Cand
I , ] [CpCo(PMe3),HgC12] with metalmetal bonds.['*I Thus, 6 b can be regarded as a dinuclear
complex which is formed by coupling of the singly negatively charged 18e anion [Cp(C2H4)(C6H5)CoIewith the
electrophilic (tmeda)BrMg' ion (Lewis acid/Lewis base
adduct with Co+Mg bond).
\IL,ili> Ipht.iiylmagnesiurn bromide do not react
with 1 in diethyl ether at room temperature; only when
T H F is added o r used as solvent are the Grignard compounds reactive enough to displace ethene. After addition
of TMEDA, the ethene-complexes 6 are formed [Eq. (e)].
Reaction of allylmagnesium bromide with 1 in T H F leads
to the ethene-free dinuclear complex 7 [Eq. (01.
6a, R = C H ,
H ~ c ' t M g B r1 l i b
' [CpCo(rl'-C,Hc)MgBr(thf),l
1 he composition of the new CoMg-complexes has been
confirmed by elemental analyses. In addition, like 2, 3b,
and 5, the complexes 6 b and 7 have been investigated by
NMR spectroscopy.[61Characteristic for the complex 6 b is
the pronounced upfield shift of the I3C-NMR signals of
the ethene ligand compared to the ethene signal of 1 .['I In
order to obtain more detailed information about the structure and bonding in these compounds, crystal structure
analyses of 6 b and 7 were carried out.
Fig. 2. Crystal structure of 7 [13, IS].
The distances between the Mg atom and terminal C
atoms of the allyl group (Mg-C6 2.89(2)A, Mg-C8
in 7 (Fig. 2) are both significantly longer than
the Mg-C,,,,,,
distance in 6b. Thus, in 7 there is no longer
any bonding between the Mg atom and the allyl group introduced by the Grignard reagent; the C3H,-group is
merely q3-coordinated to the Co atom. As a result, the distance between the tetracoordinated Mg atom and the Co
atom is shortened (2.480(4) A).
F 9 2
Fig. I . Molecular structure of 6b (8, 151.
A novel feature of the dinuclear complex 6 b is-apart
from its formation upon reaction of a halogen-free transition-metal compound with a Grignard compound via liber-
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+ R-MgX
There is no precedent for the insertion of ligand-transition metal fragments L,M into the Mg-C bond of Grignard compounds [Eq. (g)] leading to stable heterometallic
dinuclear complexes with RM-MgX moieties. The reactions of RMgX with [Cp2MoH,] and with [Cp2WH2]described by Green et aI.(l41lead to cyclic hexanuclear complexes [{Cp,MHMgR(p-Br,)Mg(EtO)),]
(M = Mo, W),
which likewise contain magnesium-transition metal bonds.
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Angew. Chem. In:. Ed. Engl. 25 11986) No. 111
However. in these compounds the residues R are bound to
the magnesium and not, as in 6b and 7,to the transition
Received: May 15, 1986;
supplemented: July 2, 1986 [Z 1777 IE]
German version: Angew. Chem. 98 (1986) 901.
[I] K. Jonas, E. Deffense, D. Habermann, Angew. Chem. 95 (1983) 729; Angew. Chem. In!. Ed. Engl. 22 (1983) 716; Angew. Chem. Suppl. 1983,
[2] K. Jonds, Angew. Chem. 97 (1985) 292; Angew. Chem. Inf. Ed. Engl. 24
(1985) 295.
[3] R. Benn, K. Cihura, P. Hoffmann, K. Jonas, A. Rufinska, Organometal1iC.F 4 ( I 985) 22 1 4.
[4] Recent literature: W. Siebert, Angew. Chem. 97 (1985) 924; Angew
Chem I n t . Ed. Engl. 24 (1985) 943; R. Diercks, K. P. C. Vollhardt, Angew. Chem. 98 (1986) 268: Angew. Chem. I n f . Ed. Engl. 25 (1986) 266; B.
Eaton. J. M. O'Connor, K. P. C. Vollhardt, Organometallics 5 (1986) 394.
S. Gamharotta, S. Stella, C. Floriani, A. Chiesi-Villa, C. Guastini, Angew. Chem. 98 (1986) 283; Angew. Chem. Int. Ed. Engl. 25 (1986) 254.
[5] G . Koepe, Dlplomarbeit. Universitat Freiburg 1980.
[6] NMR data: 2 : "C-NMR (25.2 MHz, [D,]toluene, -3OOC): 6=82.9
(Cp), 25.1 (ethene), 55.7, 44.8 (tmeda I), 58.3, 46.1 (tmeda 2), 141.4,
126.3, 119.6 (phenyl).-3b: 'H-NMR (80 MHz, [D,]THF, C 3 5 " C ) :
6=2.26 (ethene), 3.5 (hr. s, meso-allyl), 1.25 (d, 3J=6.5 Hz; syn-allyl),
-0.45 (d, 'J=9.5 Hz; anf+allyl).-S: 'H-NMR (400 MHz, [D,]THF,
- 115'C): 6=4.47 (s, 5 H , Cp), 4.67 (dd, 'J,,,=4 Hz, 'J,,,,,=7 Hz; 1 H,
meso-allyl), 0.81 (d, syn. 2 H ) ; 6 = -1.27 (d, anti, 2 H ) ; n-ally1 group.
6=0.86 (d, ' J = 9 Hz, 2 H ; Ha-o-allyl), 6.22 (m, '5,,,=10 Hz, 'JXr,<",=16
Hz, I H ; H,!-n-allyl), 3.6, 3.97 (Hy, 2H); dynamic o-ally1 group, equilibration of H, and H, with AG?,,..,=8.2
(25.2 MHz, [D,]THF, +40"C): 6=85.0 (d, Cp), 33.0 (I; ethene), 18.1 (t;
ethene), 58.7 (t; tmeda), 46.5 (4; tmeda), 144.9, 125.9, 121.6 (phenyl).7: 'H-NMR (80 MHz, [Dy]toluene, +40"C): 6=4.74 (s, 5 H ; Cp), 5.39
(m, 1 H , meso-allyl), 1.40 ( 2 H ; syn-allyl), -0.72 (d, ' J = 8 Hz, 2 H ; anfrally)), 3.61, 1.24 (br. s; THF).
[7] Procedure for 4 and 5 : A solution of 1 in T H F was treated at -78°C
with Mg(C,H,), or with Mg(C,H& ( 1 : I ) ; the reaction mixture was
warmed to room temperature and finally recooled. 4 crystallized out at
-3O"C, S at -78°C.-6
and 7 : 1 in T H F was treated with (a) an equimolar amount of RMgX in Et20 ( R = C H 3 , C6HSjo r (h) with C,H5MgBr
in T H F at -78"C, respectively, and the reaction solution warmed to
+20'C. After addition of TMEDA to (a) 6 crystallized out at -30°C.
while on reducing the volume of (h) and addition of E t 2 0 7 crystallized
out at -3O"C.-AII cobalt-magnesium complexes were washed at 0°C
with EtzO and dried under oil-pump vacuum at 0°C.
IS] Crystal structure analysis of 6b: Crystal size: 0.36, 0.36, 0.36 mm; space
group P2,/n. a = 10.022(2), b = 12.142(2), c= \7.562(3)
p= 101.26(1)":
Z = 4 , p(MoK,)=27.368 c m - ' (A=0.71069 A), 5072 reflections measured ( k h , + k , + I ) , 1915 observed ( / > 2 0 ( I ) ) , 225 refined parameters,
R=0.0582, R,=0.0519 ( w = I/02(Fo)),
max. residual electron density
0.48 eA - 3 , empirical absorption correction, may 1.242, min. 0.655; see
also [ 151.
[9] In contrast lo this, the reaction of halogen-containing transition metal
compounds with Grignard reagents is a classical type of reaction in
which the halogen atoms on the transition metal are replaced by organic
groups. Since MgX,-salts are thus formed, these metathetical reactions
lead to magnesium-free organo-transition metal compounds and not to
compounds of type 6, in which an entire Grignard compound is incorporated.
[lo] The Mg-Fe distance in [CpFe(diphos)MgBr(thf),].THF (diphos= 1,2bis(dipheny1phosphino)ethane) is 2.593(7) A: H. Felkin, P. J. Knowles,
B. Meunier, A. Mitschler, L. Ricard, R. Weiss, J . Chem. SOC.Chem.
Commun. 1974. 44.
[ I I ] K. Jonas, C . Kriiger, Angew. Chem. 92 (1980) 513; Angew. Chem. Int. Ed.
Engl. I9 (1980) 520.
[I21 H. Werner, Anqew. Chem. 95 (1983) 932; Angew. Chem. Inf. Ed. Engl. 22
(1983) 927, and references cited therein.
[I31 Crystal structure analysis of 7: crystal size 0.40, 0.11, 0.54 mm; space
group Pi, u=7.552(1), b = 11.003(2), c= 11.805(2)
P=X2.26(1), y=76.46(1)", V=935.18
2 = 2 , p(MoKn)=30.65 c m - '
(1=0.71069 A), 4201 reflections measured ( f h . + k , + I ) , 1919 observed
( / > 2 n ( I ) ) , 190 refined parameters, R=0,0797, R,=0.106 ( w = I /
max. residual electron density 1.15 eA-', analytical absorption
correction, max. 0.775, min. 0.536; see also [IS].
[I41 M. L. H. Green, N:T. Luong-thi, G. A. Maser, J. Packer, F. Pettit, D. M.
Roe, J Chem. SOC.Dalton Trans. 1976, 1988.
[ I S ] Further details of the crystal structure investigations are available on
request from the Fachinformationszentrum Energie, Physik, Mathematik GmhH, D-75 I4 Eggenstein-Leopoldshafen2 (FRG), on quoting
the depository number CSD-51933, the names of the authors, and the
full citation of the journal.
First Dinuclear Complexes with
Fourfold Alkyl-Bridging
By Klaus Jonas,* Wolfgang Russeler, Carl Kriiger. and
Eleonore Raabe
The bridging of metal atoms by alkyl or aryl groups via
multicenter bonds is an important means of stabilizing
electron-deficient organometallic compounds."] Methyllithium, for example, exists as a tetramer in the solid state,[*]
with each of the four methyl groups bound to three lithium
atoms (structure type I). [(CU(CH,S~M~,))~]['~
was the first
example of an organometallic compound in which neighboring metal atoms are present as singly alkyl-bridged centers and in which each organo-ligand is attached to only
two metal atoms (structure type 11). Prototypes of dinuclear compounds with double alkyl-bridging are, in the
case of main-group elements, hexamethyldialuminum, the
structure of which has been investigated by several groups
(structure type IIIa),[4j and in the case of transition metals,
the nickel(r1) complex [ ( ( z - C , H , M ~ ~ ) N ~ C H , (structure
type IIIb).''] We now report on the first dinuclear complexes whose metal atoms are coupled via more than two
alkyl bridges.
For the synthesis of the new divanadium complex 3 we
used the vanadium(1) complex 1, which can be prepared
according to reaction (a) by five-rnembered ring/six-membered ring exchange, and in which the naphthalene is
markedly more loosely bound than the C,H, ligand in the
analogous benzene complex [CpV(C,H,)].[".']
Anyew <%em. Inr. Ed. Engl. 25 (1986) No. 10
We assume that the reaction of 1 with ethene (tetrahydrofuran (THF), 20"C, 15 bar), which leads to the dinuclear complex 3 in ca. 30% yield, proceeds via the metallacycle 2. This coordinatively unsaturated 12e species stabilizes itself by dimerization. The four terminal methylene
carbon atoms thereby take u p bridging positions.
The new divanadium complex 3 not only constitutes the
first dinuclear complex with four pentacoordinated bridging carbon atoms, it also demonstrates that C,H, ligands
created by coupling of ethene molecules can function
[*] Prof. Dr. K. Jonas, DipLChem. W. Russeler, Prof. Dr. C. Kriiger
Dr. E. Raahe ['I
Max-Planck-lnstitut fur Kohlenforschung
Kaiser-Wilhelm-Platz I , D-4330 Miilheim a d. Ruhr (FRG)
['I Crystal structure analyses.
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dinuclear, ethene, heterometallic, compounds, displacement, diorganomagnesium, grignard, complexes
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