Covalent rigid-rod organometallic polymers with alternating transition metal clusters and conjugated spacers in the main chain

The first rigid-rod cluster-containing sigma-alkynyl polymers E-[({Pt-6}-CC-Ar-CC)](x-{Pt6})-E[(3),{Pt-6} = Pt-6(mu-PBut(2))(4)(CO)(4), E = end group; M-n = 22 000-38 000] have been prepared by step-growth polycondensation of {Pt-6} Cl-2 and 1,4-didodecyl-2,5-diethynylbenzene (HCC-Ar-CCH) under Sono-gashira-type conditions. The monodisperse oligomers HCC-Ar-CC-({Pt-6}CC-Ar-CC)(x)-{Pt-6}-CC-Ar-CCH [(4) x = 0; (11) x = 2; (15) x = 4] were also prepared by stepwise procedures, still based on Cu(I)-catalyzed dehydrohalogenation reactions. A red-shift of the UV-vis absorption centered at ca. 470 nm, on increasing chain length, suggests some degree of electron delocalization along the backbone.