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A new approach to group IVBb metallocenes
C25 Journal of Organometallic Chemistry, 291 (1985) C25--C27 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands
Preliminary communication
A NEW APPROACH TO GROUP IVB METALLOCENES
PETER JUTZI and BERND HIELSCHER Fakultgt
fiir Chemie der Universitb? Bielefeld,
Universit&tsstrasse,
D-4800 Bielefeld
1 (F.R.G).
(Received May 16th, 1985)
Summary Reduction of bis(pentamethylcyclopentadieny1) dihalides of the Group IVB elements germanium and tin with alkali metal cyclooctatetraenides or naphthalenides gives the corresponding decamethylmetallocenes.
Up to now syntheses of Group IVB metallocenes have always started with divalent IVB compounds. The usual method involves reaction of the dihalides or dinitrates with alkali metal cyclopentadienides [l-9] ; this can also be performed in two steps [ 9,101. Some derivatives were prepared from the metallocenes themselves by modification [ 11-131 or substitution [ 141 of the cyclopentadienyl ligands. We now report a new approach to Group IVB metallocenes involving reduction of tetravalent halides bearing two pentamethylcyclopentadienyl ligands. Treatment of bis(pentamethylcyclopentadienyl)tin dichloride (1)[41 or bis(pentamethylcyclopentadienyl)tin dibromide (2) [ 41 with dilithium cyclooctatetraenide, LizCsHs, in l/l molar ratio gives decamethylstannocene (3) [ 41 in good yield. Li,CsHB, prepared from lithium and cyclooctatetraene in ether, is added to a solution of 1 or 2 in THF at -80°C. Evaporation of the solvent and extraction of the residue with petroleum ether gives a bright yellow solution, from which the metallocene 3 crystallizes after concentration. Analytical data are given in Table 1. Using lithium naphthalenide LiCOHB as reducing agent, complete conversion of 1 and 2 was confirmed by NMR spectroscopy. However, the separation from naphthalene proved to the difficult, and an analytical pure product was obtained only in low yield (Table 1). (C,Me,),SnX, (1, x = Cl; 2, X = Br) 0022-328X/85/$03.30
Li, CsHs 2 Lit H w (C,Me&Sn 10 8 (3)
o 1985 Elsevier Sequoia S.A.
C27 7
P. Jutzi
8
P. Jutzi,
9
M.J.
and
E. Schliiter,
E. Schliiter.
Heeg,
C. Janiak
and
10
P. Jutzi
11
E.J.
12
A.H.
Cowley,
R.A.
13
A.H.
Cowley,
P. Jut&
14
96 (1984) 603. P. Jutzi, F. Kohl,
Bulten
(1984) 15
and
P. Jutzi
J. Organomet.
M.B.
B. Hampel. and
A.H.
Chem.,
Hursthouse. J.J.
A.M.
Zuckennan,
263 Arif
J. Amer.
313.
R.L.
Short.
Chem.
Sot.,
in preparation. 106
(1984)
4259.
in preparation. Budding,
Kemp
and
F.X.
E. Schlbr,
J. Organomet. C.A.
Kohl,
Stewart, J.G.
M.B.
Lasch.
Hursthouse
Chem..
B. Hielscher,
manuscript
157
J. Amer. N.C. and
393. and
(1983)
and
In preparation.
(1978)
Chem.
Norman N.C.
Sot., and
Walker,
C3. 104
(1982)
E. Schliiter, J. Organomet.
3239. Angew.
Chem.,
Chem..
271
Preliminary communication
A NEW APPROACH TO GROUP IVB METALLOCENES
PETER JUTZI and BERND HIELSCHER Fakultgt
fiir Chemie der Universitb? Bielefeld,
Universit&tsstrasse,
D-4800 Bielefeld
1 (F.R.G).
(Received May 16th, 1985)
Summary Reduction of bis(pentamethylcyclopentadieny1) dihalides of the Group IVB elements germanium and tin with alkali metal cyclooctatetraenides or naphthalenides gives the corresponding decamethylmetallocenes.
Up to now syntheses of Group IVB metallocenes have always started with divalent IVB compounds. The usual method involves reaction of the dihalides or dinitrates with alkali metal cyclopentadienides [l-9] ; this can also be performed in two steps [ 9,101. Some derivatives were prepared from the metallocenes themselves by modification [ 11-131 or substitution [ 141 of the cyclopentadienyl ligands. We now report a new approach to Group IVB metallocenes involving reduction of tetravalent halides bearing two pentamethylcyclopentadienyl ligands. Treatment of bis(pentamethylcyclopentadienyl)tin dichloride (1)[41 or bis(pentamethylcyclopentadienyl)tin dibromide (2) [ 41 with dilithium cyclooctatetraenide, LizCsHs, in l/l molar ratio gives decamethylstannocene (3) [ 41 in good yield. Li,CsHB, prepared from lithium and cyclooctatetraene in ether, is added to a solution of 1 or 2 in THF at -80°C. Evaporation of the solvent and extraction of the residue with petroleum ether gives a bright yellow solution, from which the metallocene 3 crystallizes after concentration. Analytical data are given in Table 1. Using lithium naphthalenide LiCOHB as reducing agent, complete conversion of 1 and 2 was confirmed by NMR spectroscopy. However, the separation from naphthalene proved to the difficult, and an analytical pure product was obtained only in low yield (Table 1). (C,Me,),SnX, (1, x = Cl; 2, X = Br) 0022-328X/85/$03.30
Li, CsHs 2 Lit H w (C,Me&Sn 10 8 (3)
o 1985 Elsevier Sequoia S.A.
C27 7
P. Jutzi
8
P. Jutzi,
9
M.J.
and
E. Schliiter,
E. Schliiter.
Heeg,
C. Janiak
and
10
P. Jutzi
11
E.J.
12
A.H.
Cowley,
R.A.
13
A.H.
Cowley,
P. Jut&
14
96 (1984) 603. P. Jutzi, F. Kohl,
Bulten
(1984) 15
and
P. Jutzi
J. Organomet.
M.B.
B. Hampel. and
A.H.
Chem.,
Hursthouse. J.J.
A.M.
Zuckennan,
263 Arif
J. Amer.
313.
R.L.
Short.
Chem.
Sot.,
in preparation. 106
(1984)
4259.
in preparation. Budding,
Kemp
and
F.X.
E. Schlbr,
J. Organomet. C.A.
Kohl,
Stewart, J.G.
M.B.
Lasch.
Hursthouse
Chem..
B. Hielscher,
manuscript
157
J. Amer. N.C. and
393. and
(1983)
and
In preparation.
(1978)
Chem.
Norman N.C.
Sot., and
Walker,
C3. 104
(1982)
E. Schliiter, J. Organomet.
3239. Angew.
Chem.,
Chem..
271