TRANSITION METAL COMPLEXES OF CYCLOPENTADIENYLGERMYLENES; THE X-RAY STRUCTURE OF (Me5C5)Ge -> W(CO)5

Article abstract of DOI:10.1016/0022-328X(86)84030-X

Pentacarbonyltungsten, Me5C5(Cl)Ge->W(CO)5 (4), the first germylene complex containing a cyclopentadienyl ligand bound to germanium, has been shown to react with nucleophiles.On treatment with lithium mesitylthiolate or mesitylthiotrimethylsilane displacements of both the chlorine and the cyclopentadienyl ligand occur and selective replacement of the chlorine alone could not be achieved.In contrast, treatment of 4 with lithium bistrimethlsilylamide, bis(trimethylsilyl)methyllithium and methyllithium yields the cyclopentadienyl containing germylene complexes Me5C5(R)Ge->W(CO)5 (5: R = (Me3Si)2N; 6: R = (Me3Si)2CH; 7: R = Me) as extremely air-sensitive orange crystals.An X-ray crystal structural investigation of 6 reveal the same dihapto bonding of the cyclopentadienyl ring as was found for 4, suggesting that the electron deficiency at the Ge-center is mainly satisfied by acceptance of ?-electron density from the cyclopentadienyl system.Crystals of 6 are orthorombic, space group Pnam with a 19.211(5), b 9.782(1), c 14.938(5) Angstroem, Z = 4, and the structure has been refined to R and R_w values of 0.040 and 0.042, respectively, for 2021 observed/2571 measured reflections.The Ge-W bond length is 2.632(4) Angstroem longer than in the analogous chloride, 4.