METAL OLIGO-YNE POLYMERS - ELECTRONIC-STRUCTURES OF [-(L)NMCCRCC-]X POLYMERS

The electronic structures of poly-ynes containing transition metals, -[-(L)(n)MC=CRC=C-]x-(L = e.g. PR3, CO, H; n = 0, 2, 3, 4; M = e.g. Mo, Fe, Rh, Pt, Hg; R = e.g. C = C, p-C6H4) have been studied using the extended Huckel theory. Their optical properties depend on several factors: (i) the size and the nature of the oligo-yne bridging ligand, C = CRC = C, (ii) the coordination of the metal, n, and finally the metal itself. Bonding properties are accounted for by the usual 16 and 18 electron rules. The d8 square-planar configuration (e.g. M = Pt, n = 2) presents a larger conduction bandwidth than the d6 octahedral one (e.g. M = Fe, n = 4), offering a better chance for electrical conduction. The HOCO is delocalized, for both n = 2 and n = 4 coordinations.