SYNTHESIS AND CHARACTERIZATION OF NOVEL OCTAHEDRAL [FeH(DPPE)2(NCR)][PF6] COMPOUNDS

Abstract

Organometallic compounds have been extensively studied in search of new materials with enhanced NLO properties due to their large hyperpolarizabilities, fast response times and architectural flexibility. Organometallic molecules with a highly polarisable π-conjugated backbone with an electron-donor (D) and an -acceptor (A) groups attached to opposite ends can a large second-order nonlinear susceptibility [1]. In the search of new systems, we synthesised iron(II) octahedral complexes with the general formula [FeX(biphosphine)2(NCR)](PF6) (X=Cl, I or H; bisphosphine=DMPE, DPPE, dppen, odppb; NCR=mono- or dinitrobenzonitriles) with interesting results towards NLO properties [2,3]. In this communication, we report the synthesis and characterization of a series of [FeH(DPPE)2(NCR)](PF6) derivatives. The acceptor capacity of the nitrile chromophore was changed due to the position (ortho and para) of the nitro group and with the change in length of the conjugated backbone. The results were analysed to evaluate the electronic richness of the metal centre and the influence of the structural changes of the coordinated nitrile, which may give some contribution to understand the relationships between structure and NLO responses.