Synthesis and optical properties for crystals of a novel organic semiconductor [ Ni(Cl)<Subscript> 2</Subscript>{(Ph<Subscript> 2</Subscript>P)<Subscript> 2</Subscript>CHC(R<Subscript> 1</Subscript>R<Subscript> 2</Subscript>)NHNH<Subscript> 2</Subscript>}]

In this investigation, the synthesis process of the apyrazole derivative for diphenylphosphino-methane hydrazine complexes [ Ni(Cl)<Subscript>2</Subscript>{(Ph<Subscript>2</Subscript>P)<Subscript>2</ Subscript>CHC(R<Subscript>1</Subscript>R<Subscript>2</Subscript>)NHNH<Subs cript>2</Subscript>}] was reported, and the obtained crystals were analyzed by X-ray diffraction. As a result of the growth process, a set of complexes were formed. The structures of these complexes are discussed on the basis of Elemental analysis (EA), IR, <Superscript>1</Superscript>H-NMR, <Superscript>31</Superscript>P-NMR spectroscopic data and FAB mass spectra. The compound under investigation shows typical semiconductor behavior as a result of delocalization of the π-electrons in the structure. The reflectance and transmittance spectra for the crystals were measured and analyzed in the incident photon energy range 1.29 to 3.93 eV and in the temperature range 77 to 300 K. The optical study revealed that the optical transition is direct allowed. Below the absorption edge, the refractive index as a function of wavelength was determined in the low energy region of the used incident photon energy range. From the refractive index-wavelength variations, the oscillator and dispersion energies of the refractive index for the obtained crystals were determined. The static refractive index and static dielectric constant were evaluated. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006