Abstract: The present paper covers three silabridged hafnocene dichlorides(1, 2 and 3) prepared by sequential reactions of α, ω-dichloropermethyl polysilane with cyclopentadienyl sodium, n-butyl lithium and hafnium tetrachloride. Their structures were characterized by elemental analyses, UV, ¹H(¹³C) NMR and MS. Furthermore the crystal and molecular structures of 1 and 2 were determined by X-ray diffraction method. The crystal of 1 is monoclinic, space group C2/c with a=1. 3401(4), b=0. 9977(3), c=1. 0922(4) nm; β=94. 07(1)° V=3. 6342 nm³, Z=2, D_c= 2.155 g·cm^-3. The final deviation factor R=0. 064. The crystal of 2 is monoclinic, space group P2₁/c with a=0.0847(1), b=1.5181(1), c=2.9824(2) nm; β= 94. 07(1)°, V=3.634 nm³; D_c= l. 805 g·cm^-3. The final deviation factor R=0. 033. The relationship between the silabridged structure and spectral properties is also discussed.

Key words: Silabridged hafnocene dichloride, Synthesis, Molecular structure