STRUCTURE OF A SILICON ANALOG OF THE PSYCHOTROPIC-DRUG PERATHIEPIN - 5,5-DIMETHYL-10-(4-METHYLPIPERAZINYL)-10,11-DIHYDRO-5H-DIBENZO[B,F]SILEPIN HYDROFUMARATE

The solid state structure of the hydrofumarate salt of 5,5-dimethyl-10-(4-methylpiperazinyl)-1O,11-dihydro-5H-dibenzo[b,f]silepin (II), a silicon analog of perathiepin (I) in which divalent sulfur is replaced by the (CH3)2Si moiety, has been determined by X-ray diffraction methods. The compound, C25H32N2O4Si, crystallizes in the orthorhombic space group, Pbc21 with a 9.304(2), b 23.010(7), c 11.599(3) Å; the structure was refined by full-matrix least-squares techniques to a conventional R of 0.039 for 1858 counter reflections. The structure consists of a network of hydrogen-bonded hydrofumarate anions and the protonated heterocyclic unit. The tricyclic framework of the cation adopts a folded boat conformation with a dihedral angle between benzo group planes of 151.2°. In contrast to related systems, the piperazinyl substituent which has the expected chair conformation occupies a pseudoaxial site on the ethano bridge. Structural parameters of the tricyclic framework of the title compound and related compounds are compared. © 1979.